The Early History of Giant Cockroaches: Gyroblattids and Necymylacrids (Blattodea) of the Late Carboniferous

Abstract

Large-winged blattoids of the Middle to Late Pennsylvanian reveal a striking appearance, diversification, and decline in the fossil record. Among them, the families Necymylacridae Durden, 1969, and Gyroblattidae Durden, 1969, as well as the mylacrid genus Opsiomylacris exhibit, the largest pre-Cenozoic blattoids with forewing lengths up to 7.5 cm. As finds from coal-bearing sedimentary basins in Europe, North Africa, and North America indicate, these giant insects started to spread around the Bashkirian–Moscovian transition and experienced a diversification in late Moscovian and Kasimovian times, until they disappeared in the middle Gzhelian. Whereas necymylacrids are only patchily reported and still lack distributional patterns, we disclose the occurrence and particular habitat preference of gyroblattids. Although appearing first in some vast North American basins, they became successively widespread only in small-sized basins of the European Variscan interior. Frequently found associated with enigmatic gymnosperms, they may have lived in well-drained hinterland areas from where they immigrated into the ever-wet basin centers only with increasing seasonality. Gyroblattids apparently followed meso- to xerophilous plants and likely colonized spaces offering a broader spectrum of edaphic conditions that resulted from the closeness of erosional and depositional areas. The presented analysis and revision of all gyroblattids aim to facilitate future more realistic biodiversity estimations based on fossil taxa.

1. Introduction

Although blattoid insects (stem-Dictyoptera) are evolutionarily much older, they appeared in the fossil record first in the Early Pennsylvanian (middle Bashkirian, Westphalian A; Figure 1). As their paleogeographic distribution at that time indicates, they were already widespread in the whole Euramerican biotic province. Somewhat later, in the late Bashkirian/early Moscovian, they were known in Cathaysia as well [1,2,3]. The initially somewhat monotonous blattoid fauna consists mainly of archimylacrids and mylacrids with forewing lengths of two to three centimeters in the mean [4,5]. However, towards the end of the Moscovian (end of the Westphalian) and especially during the Kasimovian (early Stephanian), a rapid diversification is recognizable [6,7,8]. Mean forewing lengths were about two to three centimeters in the dominating family Phyloblattidae, the family Poroblattinidae Handlirsch, 1906a [9] exhibits even small-sized blattoids with forewing lengths below one centimeter [10,11]. In the middle Gzhelian (late Stephanian), the first blattoid families disappeared from the fossil record, as proven by the present contribution. Subsequent diversification occurred toward the end of the Permian and chiefly in the early Mesozoic [12,13,14,15]. However, forewing sizes remained generally small. Only during the first diversification in the late Moscovian and Kasimovian, suddenly unusually large blattoids appeared with surprisingly great forewings lengths. This concerns the species of the Necymylacridae genus Necymylacris and the Gyroblattidae genus Progonoblattina with forewing lengths up to 7 cm and one species of the mylacrid genus Opsiomylacris with forewing lengths up to 7.5 cm. After a decline in diversity and wing sizes in the late early Permian (Cisuralian) and middle Permian (Guadalupian), relatively large wings of up to six centimeters in length appear again in the late Permian (Lopingian). Similar large post-Paleozoic forewings are only known from the Cretaceous of Mongolia, showing about five centimeters of forewing length [16] (Figure 4), and the modern Megaloblatta having wingspans up to 20 cm and corresponding forewing lengths of nearly 9 cm [17]. We focus on one of these large-winged genera, the Progonoblattina, previously considered as belonging to Archoblattinidae Schneider, 1983a [5], but now regarded as a member of the family Gyroblattidae Durden, 1969 [18]. Based on new finds and the revision of type specimens from the late 19th and early 20th centuries, some of the latter are figured for the first time as photographs and associated drawings. Members of Gyroblattidae show an exciting paleogeographic distribution, particularly concerning the smaller European intramontane basins (Figure 2), which are often associated with mesophytic to xerophytic floral elements of the hinterland. In a detailed analysis, we try to fathom the habitats of these gigantic blattoids of the Paleozoic, as far as historical data on their sites allows. We contribute an additional small tessera to the overall picture designed by Rasnitsyn and Quicke in the “History of Insects” [19]. The revision may improve the reliability of any biodiversity estimation based on the number of fossil genera and species, which is much lower, as shown in several databases.

2. Material and Methods

Photographs were taken with a Canon EOS 500D camera equipped with macro lenses Canon EF-S 2.6–60 mm and Canon MP-E 65 mm, and a KEYENCE VHX-5000 digital microscope. Additionally, crucial type specimens of several species were examined based on photographs supplied by various museums (see below). The pictures show specimens in their natural position; nevertheless, the drawings are presented as left forewings (mirrored if they are right forewings) to facilitate better comparison. The drawings were prepared using photographs with different illumination settings, either dry or wetted with ethanol.

The West European regional stages used herein rely on the re-definition [20] with minor modifications around the Carboniferous/Permian boundary [21], as well as based on [8] (Figure 1). However, instead of formalized stage names that are not all validated until now, we seize the traditional Heerlen subdivisions of Westphalian A to D and Stephanian A to C because many insect finds described in the older literature are designated using these traditional subdivisions; see [8] for discussion. The Cantabrian substage of Wagner [22] is not applied here but is considered the regionally defined basal part of the traditional Stephanian A. For North American regional stages, we refer to the scheme of Heckel [23] with modifications [24]. For correlations of both the European and North American scales with the SGCS, we follow [8,25].

2.1. Repositories and Institutional Abbreviations

The specimens studied here are housed at the Paleontological Collection of the Technical University Bergakademie Freiberg, Germany, abbreviated as FG, and at the Museum für Naturkunde Chemnitz, abbreviated as MfNC, followed by the sample number. Further discussed specimens are stored at the Musée Cantonal de Géologie, Lausanne, Switzerland, abbreviated as MGL; the Albert Ludwig University of Freiburg, Institute of Geosciences, Germany, abbreviated as ALUF; the Smithsonian Institution, National Museum of Natural History, Washington, DC, USA, abbreviated as USNM; the Peabody Museum of Natural History, Yale University, New Haven, CT, USA, abbreviated as YPM; the Museum of Comparative Zoology, Harvard University, Cambridge, MA, USA, abbreviated as MCZ; the Muséum National d’Histoire Naturelle de Paris, France, abbreviated as MNHN; the Muséum d’Histoire Naturelle de Nîmes, France, abbreviated as MHNN; the Muséum d’Histoire Naturelle de Grenoble, France, abbreviated as MHNGr; the Chouaïb Doukkali University El Jadida, Morocco, abbreviated as CDUE; McGill University, Redpath Museum, Quebec, Canada, abbreviated as RMQ; the Museum van het Geologisch Bureau voor het Nederlandse Mijngebied te Heerlen, abbreviated as MGBNH; Martin Luther University Halle-Wittenberg, geoscientific collection, Germany, abbreviated as MH; Charles University Prague, Institute of Geology and Paleontology, abbreviated as KUP; and the University of Kansas, Biodiversity Institute, Division of Invertebrate Paleontology, abbreviated as KUMIP.

2.2. Abbreviations

SGCS—Standard Global Chronostratigraphic Scale (the “marine” timescale). The taxon’s lowest occurrence (LO) and highest occurrence (HO) in a stratigraphic section are used as biostratigraphic datums. The first appearance datum (FAD) and the last appearance datum (LAD) mark biochronological events, i.e., the evolutionary origination and extinction, respectively, of a taxon in an anagenetic lineage. The LO and the FAD of a taxon may coincide in places, though given the problems of the incomplete fossil record and sampling in nonmarine deposits, this will rarely be the case.

3. Systematic Paleontology

The wing venation nomenclature follows the serial insect wing venation pattern paradigm [26]. Wing venation abbreviations relevant for this contribution are as follows (Figure 3): C = costa; Sc = subcosta; R = radius; RA = radius anterior; RP = radius posterior; M = media; MA = media anterior; MP = media posterior; CuA = cubitus anterior; CuP = cubitus posterior. The nomenclature of the anal field veins generally follows [5,7]: AnA = analis anterior; AnP = analis posterior; AnP1 = first posterior anal vein; and so on. For the cross-venation, the following descriptive terms are applied (see also further descriptions and figures in the text): striate = rectangular arranged straight to slightly curved veinlets between the prominent veins; anastomosing-striate = rectangular set straight and erratically joined veinlets; reticulate = a meshwork of regular polygonal veinlets; irregular reticulate = a meshwork of irregular polygonal veinlets. The description distinguishes between vein forking (symmetrical, Y-form) and vein branching (asymmetrical). Despite that, the resulting veins are called branches or twigs in both cases. “Proximal” or “basal” is related to the wing base, and “distal” or “apical” to the wing apex. Because of compaction, the natural relief of the wings is often not preserved. Therefore, a difference between the left and right wings is not made in most cases.

Class Insecta Linnaeus, 1758 [27]. Superorder Dictyoptera Latreille, 1829 [28]. Order Blattodea Brunner von Wattenwyll, 1882 [29].

Family Gyroblattidae Durden, 1969 [18]

Synonymy

1969 Phoberoblattidae—Durden, p. 1171 [18], syn. nov.

1983a Archoblattinidae—Schneider, p. 118–119 [5], syn. nov.

Type genus. Gyroblatta Handlirsch 1906a, p. 726 [9]. Here considered as a new junior synonym of Progonoblattina Scudder 1879, 118–119 [30].

Included genera. Only Progonoblattina Scudder, 1879 [30].

Emended Diagnosis. Oval to reniform forewings of more than four centimeters in length; anterior border more curved than the posterior border. Subcostal field is strip-like, distally tapering; about 60% to 75% of the forewing length. Sc pectinate, branches are mainly simple to multiple forked, from base to apex increasingly inclined; ending at the anterior wing margin. R is very close to the wing base subdivided into RA and RP, both with mainly multiple forked branches; the number of RA branches is a little less than those of RP. R branches terminate at the anterior wing margin, down to just above the wing tip. M is divided in MA and MP close to the wing base just behind the RA/RP division; MA and MP branches arose by multiple forking; number of MA branches mostly smaller than that of MP; M branches covering an area extending from just above the wing tip to the transition from the wing tip into the posterior wing margin. Cu divided at or shortly distally of the wing base into CuA and CuP. CuA is strong to slightly sigmoidal; most twigs arose by multiple forking from CuA stem and each other; the first one or two only emerged by branching. CuP is curved. Distinct AnA; may be forked in the Westphalian and early Stephanian and mostly unbranched in the later Stephanian. The area between CuP and AnA in the Westphalian and early Stephanian is basally extended. Cross-venation dominating striate in Westphalian specimens and striate to irregularly striate and irregularly polygonal in Stephanian forms.

Discussion. The new family Archoblattinidae Schneider, 1983a was based on the incorrect assumption that Handlirsch [4] was the author of Progonoblattina instead of Scudder [30]. Additionally, for the venation pattern of the forewings, the drawing of Archoblattina beecheri Sellards, 1903 in [31] (text-Figures 30–32) used by Schneider [5] as the type for his new family shows the structure of the M and CuA in mostly stippled lines. As recognizable on the now available high-resolution photographs made with different illuminations of the type specimen YPM IP 008,412 at the Peabody Museum, the crucial structure of the CuA is invisible because of overlapping forewings and partially inadequate preservation of wing venation (Figure 4). Even though the genus definition still seems possible with restrictions, the species determination is impossible because discriminating features of the CuA are lacking. As a result, Archoblattina beecheri is regarded here as nomen dubium and consequently, the family Gyroblattidae Durden, 1969 with the type genus Gyroblatta Handlirsch, 1906a is chosen to replace Archoblattinidae Schneider, 1983a. Gyroblatta clarkii (Scudder, 1893) with a well-preserved holotype (Figure 6) is the type species of this genus, which, however, is synonymized here with Progonoblattina Scudder, 1879 [30].

Among contemporaneous blattoids, the gyroblattids differ clearly from archimylacrids by their sigmoidal CuA and the long and distally tapering subcostal field. An additional distinction is the general venation pattern characterized by branches originating mainly by multiple forking (see above). The venation pattern of gyroblattids resembles that of necymylacrids. Recently, the difference between Archoblattina, here considered as a new junior synonym of Progonoblattina, and Necymylacris were discussed [32] (p. 264–265), with some modifications made here: Progonoblattina is very similar in size and venation pattern to Necymylacris, the single genus of the family Necymylacridae Durden, 1969. Both genera differ mainly in the form of the CuA, which runs inclined and straight against the transition of the wing tip into the posterior wing border in Necymylacris (Figure 3) [5] (pl. 2, Figure 2), [32] (Figure 7A–C), but is sigmoidally bent in Progonoblattina (see for Archoblattina [5] (pl. 2, Figure 6). Additionally, the first proximal, mainly more than four twigs at the CuA, arise by branching from the CuA in Necymylacris, whereas in Progonoblattina all other twigs arise by multiple forking latest after one or two proximal branches (comp. Figures 3 and 5–7). From the Moscovian into the Kasimovian and Westphalian into the Stephanian, respectively, the bending of CuA decreased in Progonoblattina, but the venation pattern of the CuA with common furcation persisted. The CuP runs straight against the posterior wing border in Necymylacris, whereas it is evenly bent in Progonoblattina. The wings of both genera are relatively rare in the fossil record.

The presence of an ovipositor in gyroblattids is not reported so far. However, sexual dimorphism is indicated by the wing shape with slender wings in the ovipositor-bearing females, as proven for all Late Paleozoic blattoid families except Archimylacridae and Gyroblattidae, for which finds of females with preserved ovipositor are missing so far [7,32,33].

Occurrence. Pennsylvanian, Moscovian to middle Gzhelian, Westphalian B to Stephanian B/C of Europe, North America and North Africa, i.e., Euramerica.

Genus Progonoblattina Scudder, 1879 [30].

Synonymy.

1879 Progonoblattina—Scudder, 118–119 [30].

1903a Megablattina—Sellards, p. 312 [34], preoccupied.

1903b Archoblattina—Sellards, p. 488 (replacing Megablattina Sellards, 1903a) [35], syn. nov.

1906a Gyroblatta—Handlirsch, p. 726 [9], syn. nov.

1906a Dysmenes—Handlirsch, p. 727 [9], syn. nov.

1906a Phoberoblatta—Handlirsch, p. 728 [9], syn. nov.

1906b Sterzelia—Handlirsch, p. 197 [4], syn. nov.

1950 Bertrandiblatta—Laurentiaux, 71 [36], syn. nov.

1950 Cebenniblatta—Laurentiaux, 72 [36], syn. nov.

1950 Platyblattina—Laurentiaux, 73 [36], syn. nov.

1950 Livetiblatta—Laurentiaux, 74–75 [36], syn. nov.

1963 Guichenbachia—Guthörl, 249 [37], syn. nov.

Type species. Progonoblattina helvetica (Heer, 1864) [38], in [[30], p. 119, pl. 3, Figure 10], here Figure 5A,B; Lower quarry of Erbignon, Wallis, Switzerland, Zone Houillère, Stephanian B; MGL.2551.

Diagnosis. As for the family.

Discussion. The features used so far by many authors for the definition of genera are, in the best case, suited for the characterization of species only, as shown for other Late Paleozoic blattoid families, e.g., for Poroblattinidae [10]; for Spiloblattinidae [39,40]; for Phyloblattidae [7]; for Necymylacridae [32].

The relatively high number of wings demonstrates the high intraspecific variability of forewings in this genus from nearly one stratigraphic level (Table 1) reported in [36] as different genera and species. All these taxa are regarded as belonging to one genus, i.e., Progonoblattina, and one species only, i.e., P. helvetica (Heer, 1864) [38]. An identical high individual and intraspecific variability in the venation pattern has been demonstrated several times for phyloblattids [7,41,42]. In the present case, the left and right forewings are not attached except the indistinctly preserved forewings of Archoblattina beecheri Sellards, 1904 [31] (Figures 30–32), regarded here as an indeterminable species (nomen dubium) of Progonoblattina (Figure 4). Therefore, individual variability estimation seems intricate. Consequently, the intraspecific variation of the wing-venation pattern can only be assessed from gyroblattid wings, described and figured in [36]. As a result, only two species can be discriminated against and characterized by differences in the wing-venation pattern. Indeed, from the oldest to youngest gyroblattids, changes in cross-venation can be recognized. These changes may potentially discriminate species in more detail than proposed here. However, the shift in venation pattern is confluent, as discussed below, and, unfortunately, the preservation of the cross-venation pattern depends much more on taphonomic circumstances and synsedimentary to post-sedimentary deformations, as the main veins exhibit.

Occurrence. As for the family.

Figure 5. (A,B)—Progonoblattina helvetica (Heer, 1864): type specimen of Blatta helvetica Heer, 1864, type species of Progonoblattina Scudder, 1879; Lower quarry of Erbignon; MGL.2551; reconstructed length 37 mm; scale bar 5 mm; photo: MGL.

Figure 5. (A,B)—Progonoblattina helvetica (Heer, 1864): type specimen of Blatta helvetica Heer, 1864, type species of Progonoblattina Scudder, 1879; Lower quarry of Erbignon; MGL.2551; reconstructed length 37 mm; scale bar 5 mm; photo: MGL.

Progonoblattina clarkii (Scudder, 1893) [43], comb. nov.

Figure 6A,B; Table 1

Synonymy.

1893 Etoblattina clarkii—Scudder, pp. 14–15, pl. 2 Figure j [43].

1893 Etoblattina illustris—Scudder, pp. 12–13, pl. 2, Figure I [43], syn. nov.

1893 Gerablattina scapularis—Scudder, p. 19, pl. 2, Figure 1 [43], syn. nov.

1906a Gyroblatta clarkii (Scudder)—Handlirsch 1906a, p. 727 [9].

1906a ? Gyroblatta scapularis (Scudder)—Handlirsch 1906a, p. 727 [9], syn. nov.

1906a Dysmenes illustris—Handlirsch, p. 727 [9], syn. nov.

1906a Phoberoblatta grandis—Handlirsch, p. 728, Figure 48 [9], syn. nov.

1950 Cebenniblatta marcellini—Laurentiaux, p. 72, pl. 2, Figure 2a,b [36], syn. nov.

Figure 6. (A,B)—Progonoblattina clarkii (Scudder, 1893): type specimen of Etoblattina clarkii Scudder, 1893; Pawtucket; MCZ ENT PALE-8614; reconstructed length 45 mm; scale bar 5 mm; photo: MCZ.

Figure 6. (A,B)—Progonoblattina clarkii (Scudder, 1893): type specimen of Etoblattina clarkii Scudder, 1893; Pawtucket; MCZ ENT PALE-8614; reconstructed length 45 mm; scale bar 5 mm; photo: MCZ.

Table 1. Overview of the discussed taxa with their occurrences. Abbreviations: WB, WC, WD—Westphalian B, C, D etc.; StA, StB, StC—Stephanian A, B, C etc.; Fm.—Formation.

Specimen	Locality and Lithostratigraphy	Chronostratigraphy
Progonoblattina clarkii
‘Etoblattina’ clarkii Scudder, 1893	Pawtucket, Rhode Island, Narragansett Basin, USA; lower Rhode Island Fm.	WC to ?WD, early (to ?late) Moscovian
‘Etoblattina illustris’ Scudder, 1893	Pawtucket, Rhode Island, Narragansett Basin, USA; lower Rhode Island Fm.	WC to ?WD, early (to ?late) Moscovian
‘Gerablattina scapularis’ Scudder, 1893	Pawtucket, Rhode Island, Narragansett Basin, USA; lower Rhode Island Fm.	WC to ?WD, early (to ?late) Moscovian
‘Phoberoblatta grandis’ Handlirsch, 1906a	Fishing Creek Gap, Sharp Mountain, Pennsylvania, Appalachian Basin, USA; Pottsville Fm., Sharp Mountain Mb.	WD, late Moscovian
‘Cebenniblatta marcellini’ Laurentiaux, 1950	Molières-sur-Cèze, Gard Basin, France	WD, late Moscovian
Progonoblattina helvetica
‘Blatta’ helvetica Heer, 1864	Lower quarry of Erbignon, Valais, Salvan-Dorenaz Basin, Switzerland; Zone Houillère	StB, Kasimovian
‘Necymylacris boulei’ Agnus, 1903	Commentry, Commentry Basin, France; Grande Couche	StB/C, Gzhelian
‘Etoblattina steinmannii’ Sterzel, 1904	Hinterohlsbach near Oppenau, Oppenau Basin, Germany; Oppenau Fm.	StA/B, Kasimovian
‘Etoblattina fontanensis’ Meunier, 1906	Fontanes, Gard Basin, France; 4th coal seam	StA, Kasimovian
‘Progonoblattina heeri’ Handlirsch, 1906b	Lower quarry of Erbignon, Valais, Salvan-Dorénaz Basin, Switzerland; Zone Houillère	StB, Kasimovian
‘Necymylacris sp.’ Meunier, 1921	Commentry, Commentry Basin, France; Grande Couche	StB/C, Gzhelian
‘Bertrandiblatta inexpectata’ Laurentiaux, 1950	Malpertus pass, Pontil road, Gard Basin, France; Le Pin coal seam	StA, Kasimovian
‘Platyblattina maxima’ Laurentiaux, 1950	Fontanes, Gard Basin, France; 4th coal seam	StA, Kasimovian
‘Platyblattina cf. maxima’ Laurentiaux, 1950	La Grand’Combe, Gard Basin, France; Le Pin coal seam	StA, Kasimovian
‘Platyblattina ampla’ Laurentiaux, 1950	Fontanes, Gard Basin, France; 4th coal seam	StA, Kasimovian
‘Livetiblatta incerta’ Laurentiaux, 1950	La Grand’Combe, Gard Basin, France; Le Pin coal seam	StA, Kasimovian
‘Hispanoblatta cantabrica’ sp. nov. Laurentiaux, 1958, nomen nudum	San Felices de Castilleria, Central Asturian Coalfield, Province Palencia, Spain; San Felices de Castilleria coal seam	StA, Kasimovian
‘Sterzelia lamurensis’ Haudour et al., 1960	La Mure (Isère) Basin, French Alps; “groupe des Trois-Bancs, Cinquième pendage, niveau 12”	early Stephanian, Kasimovian
‘aff. Necymylacris’ (Eumorphoblatta) boulei Haudour et al., 1960	La Mure (Isère) Basin, French Alps; “groupe des Trois-Bancs, Cinquième pendage, niveau 12”	early Stephanian, Kasimovian
‘Guichenbachia gigantea’ Guthörl, 1963	Coal mine Guichenbach near Heusweiler-Saar, Saar-Nahe Basin, Germany; roof of seam Wahlschied, Dilsburg Fm., Ottweiler Subgroup	StA, Kasimovian
‘Dysmenes idoneus’ Laurentiaux, 1966	Saint-Jaques, well B, Bosmoreau-les-Mines Basin (Creuse), France; level “chez Lamé”	early Stephanian, Kasimovian
‘Anthracoblattina meganalis’ Brauckmann and Hahn, 1983	Brandeck-Lindle, NE of Hinterohlsbach near Oppenau, Oppenau Basin, Germany; Oppenau Fm.	StA/B, Kasimovian
‘Necymylacris sp.’ Schneider et al., 2005	Left bank of the Zwickauer Mulde river at Cainsdorf Bridge, Zwickau, Zwickau Subbasin, central Germany; roof of Tiefes Planitzer coal seam, Zwickau Fm.	WD, late Moscovian
‘Anthracoblattina ensifera-gigantea group’, specimen CDUE TaI-13d-25, Belahmira et al., 2019	Tanamert village at Qued Issene Canyon, locality Tanamert I (TAI), Western High Atlas Mountains, Souss Basin, Ida Ou Ziki Subbasin, Morocco; Oued Issene Fm.	StA/B, Kasimovian
Progonoblattina sp. indet. (nomina dubia)
‘Mylacris packardi’ Scudder, 1893	Bristol, Rhode Island, Narragansett Basin, USA; Rhode Island Fm.	WC to WD, early to late Moscovian
‘Archoblattina beecheri’ (Sellards, 1903)	Mazon Creek, Illinois, Illinois Basin, USA; Francis Creek shale, Desmoinesian	WD, late Moscovian

Table 1. Overview of the discussed taxa with their occurrences. Abbreviations: WB, WC, WD—Westphalian B, C, D etc.; StA, StB, StC—Stephanian A, B, C etc.; Fm.—Formation.

Specimen	Locality and Lithostratigraphy	Chronostratigraphy
Progonoblattina clarkii
‘Etoblattina’ clarkii Scudder, 1893	Pawtucket, Rhode Island, Narragansett Basin, USA; lower Rhode Island Fm.	WC to ?WD, early (to ?late) Moscovian
‘Etoblattina illustris’ Scudder, 1893	Pawtucket, Rhode Island, Narragansett Basin, USA; lower Rhode Island Fm.	WC to ?WD, early (to ?late) Moscovian
‘Gerablattina scapularis’ Scudder, 1893	Pawtucket, Rhode Island, Narragansett Basin, USA; lower Rhode Island Fm.	WC to ?WD, early (to ?late) Moscovian
‘Phoberoblatta grandis’ Handlirsch, 1906a	Fishing Creek Gap, Sharp Mountain, Pennsylvania, Appalachian Basin, USA; Pottsville Fm., Sharp Mountain Mb.	WD, late Moscovian
‘Cebenniblatta marcellini’ Laurentiaux, 1950	Molières-sur-Cèze, Gard Basin, France	WD, late Moscovian
Progonoblattina helvetica
‘Blatta’ helvetica Heer, 1864	Lower quarry of Erbignon, Valais, Salvan-Dorenaz Basin, Switzerland; Zone Houillère	StB, Kasimovian
‘Necymylacris boulei’ Agnus, 1903	Commentry, Commentry Basin, France; Grande Couche	StB/C, Gzhelian
‘Etoblattina steinmannii’ Sterzel, 1904	Hinterohlsbach near Oppenau, Oppenau Basin, Germany; Oppenau Fm.	StA/B, Kasimovian
‘Etoblattina fontanensis’ Meunier, 1906	Fontanes, Gard Basin, France; 4th coal seam	StA, Kasimovian
‘Progonoblattina heeri’ Handlirsch, 1906b	Lower quarry of Erbignon, Valais, Salvan-Dorénaz Basin, Switzerland; Zone Houillère	StB, Kasimovian
‘Necymylacris sp.’ Meunier, 1921	Commentry, Commentry Basin, France; Grande Couche	StB/C, Gzhelian
‘Bertrandiblatta inexpectata’ Laurentiaux, 1950	Malpertus pass, Pontil road, Gard Basin, France; Le Pin coal seam	StA, Kasimovian
‘Platyblattina maxima’ Laurentiaux, 1950	Fontanes, Gard Basin, France; 4th coal seam	StA, Kasimovian
‘Platyblattina cf. maxima’ Laurentiaux, 1950	La Grand’Combe, Gard Basin, France; Le Pin coal seam	StA, Kasimovian
‘Platyblattina ampla’ Laurentiaux, 1950	Fontanes, Gard Basin, France; 4th coal seam	StA, Kasimovian
‘Livetiblatta incerta’ Laurentiaux, 1950	La Grand’Combe, Gard Basin, France; Le Pin coal seam	StA, Kasimovian
‘Hispanoblatta cantabrica’ sp. nov. Laurentiaux, 1958, nomen nudum	San Felices de Castilleria, Central Asturian Coalfield, Province Palencia, Spain; San Felices de Castilleria coal seam	StA, Kasimovian
‘Sterzelia lamurensis’ Haudour et al., 1960	La Mure (Isère) Basin, French Alps; “groupe des Trois-Bancs, Cinquième pendage, niveau 12”	early Stephanian, Kasimovian
‘aff. Necymylacris’ (Eumorphoblatta) boulei Haudour et al., 1960	La Mure (Isère) Basin, French Alps; “groupe des Trois-Bancs, Cinquième pendage, niveau 12”	early Stephanian, Kasimovian
‘Guichenbachia gigantea’ Guthörl, 1963	Coal mine Guichenbach near Heusweiler-Saar, Saar-Nahe Basin, Germany; roof of seam Wahlschied, Dilsburg Fm., Ottweiler Subgroup	StA, Kasimovian
‘Dysmenes idoneus’ Laurentiaux, 1966	Saint-Jaques, well B, Bosmoreau-les-Mines Basin (Creuse), France; level “chez Lamé”	early Stephanian, Kasimovian
‘Anthracoblattina meganalis’ Brauckmann and Hahn, 1983	Brandeck-Lindle, NE of Hinterohlsbach near Oppenau, Oppenau Basin, Germany; Oppenau Fm.	StA/B, Kasimovian
‘Necymylacris sp.’ Schneider et al., 2005	Left bank of the Zwickauer Mulde river at Cainsdorf Bridge, Zwickau, Zwickau Subbasin, central Germany; roof of Tiefes Planitzer coal seam, Zwickau Fm.	WD, late Moscovian
‘Anthracoblattina ensifera-gigantea group’, specimen CDUE TaI-13d-25, Belahmira et al., 2019	Tanamert village at Qued Issene Canyon, locality Tanamert I (TAI), Western High Atlas Mountains, Souss Basin, Ida Ou Ziki Subbasin, Morocco; Oued Issene Fm.	StA/B, Kasimovian
Progonoblattina sp. indet. (nomina dubia)
‘Mylacris packardi’ Scudder, 1893	Bristol, Rhode Island, Narragansett Basin, USA; Rhode Island Fm.	WC to WD, early to late Moscovian
‘Archoblattina beecheri’ (Sellards, 1903)	Mazon Creek, Illinois, Illinois Basin, USA; Francis Creek shale, Desmoinesian	WD, late Moscovian

Comments: Mylacris packardi Scudder, 1893, [43] (pp. 11–12, pl. 1, Figure e,g) is the basal fragment of a large forewing that is not of mylacrid affinity. It belongs to Progonoblattina but remains undeterminable at the species level and thus is a nomen dubium. The type specimen of Etoblattina illustris Scudder, 1893 is described in [43], two pages before Etoblattina clarkii Scudder, 1893 (see above). Regrettably, E. illustris is an incomplete forewing lacking the basal and apical parts (Figure 7A,B). Additionally, the Sc shows an abnormality because of amalgamation with the first branch of R. All these characteristics may render it unsuitable for selecting a species-type specimen. Therefore, we choose the much better preserved forewing of E. clarkii as the type specimen. In the following, we provide an appropriate description. Sellards 1903a, [34] (p. 312, pl. 8) erected Megablattina beecheri but realized later that the genus name was preoccupied and renamed it in Sellards 1903b, [35] (p. 488) as Archoblattina beecheri (Sellards, 1903). In 1904 Sellards, pp. 218–221, Figures 30–32 [31] provided a new description and new figures for this species; however, it is not preserved well enough for comparison with other Progonoblattina species; hence it is here regarded as a nomen dubium.

Type specimen. Etoblattina clarkii Scudder, 1893, [43] (pp. 14–15, pl. 2 Figure j). After [43], “Lower (?) Productive Coalmeasures at Pawtucket, Rhode Island”; Westphalian C to D, Desmoinesian, Moscovian, after [44] and Dodge, C.H. (personal comm. 2021); MCZ ENT PALE-8614.

Diagnosis. As for the family with the following specifics: forewing length 40–70 mm; the number of branches ending at the forewing border, without the number of An, is about 45. M and CuA strongly sigmoidal; distinct, mostly forked AnA; area between CuP and AnA basally extended; dimorphism well expressed by stout and mostly shorter, as well as slender and commonly longer, forewings.

Description of the type specimen: Almost complete left reniform forewing of 43 × 19 mm preserved size, reconstructed size is 45 × 19 mm. The anterior border is stronger curved than the posterior border. Subcostal field strip-like, distally tapering; 75% of the forewing length. Sc pectinate, six partially forked twigs arose by branching; eight further twigs originated by multiple forking. All twigs from the base to the apex are increasingly inclined. R is somewhat distant from the wing base subdivided into RA and RP, both with several times forked branches; three RA and three RP branches. R branches terminate at the anterior wing margin above the wing tip. M is strongly sigmoidal and divided in MA and MP close to the wing base; MA and MP branches arose by multiple forking; four MA and five MP branches covering an area extending from short above the wing tip to the transition from the wing tip into the posterior wing margin. Cu is divided at the wing base into CuA and CuP. CuA is strongly sigmoidal; the basally first two twigs arose by branching from CuA and were once forked; further six twigs appeared by multiple forking. CuP curved. The area between CuP and AnA is basally extended. Veins are poorly preserved. The number of branches ending at the wing border, without An number, is approximately 40 to 50. Cross-venation as far as preserved striate with apically increasing distance of the veinlets.

Discussion. Although the individual variation is unknown, the here synonymized species (each represented by one forewing only) show a wide variation of the typical venation ground plans. Accordingly, two alternative hypotheses are possible: (1) each of these single wings so far described as separate species represent a separate species, (2) all these single wings have to be unified into one species. Hypothesis (1) is paleobiologically unlikely. Hypothesis (2) is well supported by the case study of Phyloblatta gaudryi (Agnus, 1903b) [45], as shown in [5,42]. P. gaudryi is known from 58 isolated forewings and three forewing pairs used to describe 55(!) species of 12 different genera [4,46,47]. Based on wing venation analysis of modern Periplaneta species [48,49], Schneider [41] synonymized all these “species” with only one, P. gaudryi. Belahmira et al. [7] provided a similar example for other phyloblattid species based on comparatively high forewing numbers regarded as one species.

Figure 7. (A,B)—Progonoblattina clarkii (Scudder, 1893): type specimen of ‘Etoblattina illustris’ Scudder, 1893; (A,B)—part and counterpart, photo: USNM; (C)—combined drawing; Pawtucket; USNM PAL 38,074 01 and 02; reconstructed length 55 mm; scale bar 5 mm.

Figure 7. (A,B)—Progonoblattina clarkii (Scudder, 1893): type specimen of ‘Etoblattina illustris’ Scudder, 1893; (A,B)—part and counterpart, photo: USNM; (C)—combined drawing; Pawtucket; USNM PAL 38,074 01 and 02; reconstructed length 55 mm; scale bar 5 mm.

P. clarkii differs from P. helvetica, described in the following, in the number of branches ending at the wing border, up to 45 in P. clarkii and higher than 50 in P. helvetica, and the bending of the CuA. Middle to late Westphalian forms, as, e.g., the type specimens of the species ‘E. illustris’ and ‘G. scapularis’, synonymized here with P. clarkii, show strongly sigmoidal M and CuA. The late Westphalian ‘P. grandis’, which matches with P. clarkii in the number of branches ending at the wing border (about 49 without An veins), show a nearly straight and inclined CuA that is more typical for P. helvetica. Obviously, there is no clear cut between P. clarkii and P. helvetica; potential causes are discussed below.

Among the unified forms, ‘Phoberoblatta grandis’ (Figure 8) and ‘Cebenniblatta marcellin’ (Figure 9A,B) represent the slender forewing morphotype of the ovipositor-bearing females among Late Paleozoic blattoids. P. clarkii and ‘Etoblattina illustris’ exhibit the stout morphotype of male forewings.

Occurrence. Pennsylvanian, Moscovian, Westphalian B to D, Europe and North America.

Figure 8. (A–C)—Progonoblattina clarkii (Scudder, 1893): type specimen of ‘Phoberoblatta grandis’ Handlirsch, 1906a; Fishing Creek Gap; USNM PAL38756, (A,B)—part and counterpart; length 50 mm; scale bar 5 mm.

Figure 8. (A–C)—Progonoblattina clarkii (Scudder, 1893): type specimen of ‘Phoberoblatta grandis’ Handlirsch, 1906a; Fishing Creek Gap; USNM PAL38756, (A,B)—part and counterpart; length 50 mm; scale bar 5 mm.

Figure 9. (A,B)—Progonoblattina clarkii (Scudder, 1893): type specimen of ‘Cebeniblatta marcellini’ Laurentiaux, 1950; Molières-sur-Cèze; MHNN; reconstructed length 71 mm; scale bar 5 mm; photo: from Laurentiaux, 1950.

Figure 9. (A,B)—Progonoblattina clarkii (Scudder, 1893): type specimen of ‘Cebeniblatta marcellini’ Laurentiaux, 1950; Molières-sur-Cèze; MHNN; reconstructed length 71 mm; scale bar 5 mm; photo: from Laurentiaux, 1950.

Progonoblattina helvetica (Heer, 1864) [38].

Figure 5A,B; Table 1

Synonymy.

1864 Blatta helvetica—Heer, p. 287, Figure 1 [38].

1879 Progonoblattina helvetica (Heer)—Scudder, p. 119–120, pl. 3, Figure 10 [30].

1903a Necymylacris boulei—Agnus, p. 273 [50], syn. nov.

1904 Etoblattina steinmannii—Sterzel, pp. 71–72, pl. 1, Figure 2 [51], syn. nov.

1906 Etoblattina fontanensis—Meunier, pp. 82–85, 1 fig [52], syn. nov.

1906b Eumorphoblatta boulei (Agnus)—Handlirsch, p. 196 [4], syn. nov.

1906b Sterzelia steinmanni (Sterzel)—Handlirsch, p. 197, pl. 20, Figure 12 [4], syn. nov.

1906b Progonoblattina helvetica (Heer)—Handlirsch, p. 229, pl. 24, Figure 5 [4].

? 1906b Progonoblattina heeri—Handlirsch, p. 230, pl. 24, Figure 6; ? hindwing fragment [4], syn. nov.

1908 ? Phyloblatta fontanensis (Meunier)—Handlirsch, p. 1349, Figure 3 [4], syn. nov.

1921 Necymylacris boulei Agnus—Meunier, pp. 87–89, text-Figure 32, pl. 11, Figure 8 [46], syn. nov.

1921 Necymylacris sp.—Meunier, p. 163, text-Figure 141, pl. 20, Figure 6 [46], syn. nov.

1937 Archimylacridae inc. sed. maxima—Handlirsch, p. 79 (=N. sp. Meunier, 1921) [47], syn. nov.

1950 Phyloblatta fontanensis (Meunier)—Laurentiaux, pp. 70–71, pl. 2, Figure 1a,b [36], syn. nov.

1950 Bertrandiblatta inexpectata—Laurentiaux, p. 71, pl. 2, Figure 3a,b [36], syn. nov.

1950 Platyblattina maxima—Laurentiaux, p. 73, pl. 3, Figure 1a,b [36], syn. nov.

1950 Platyblattina cf. maxima—Laurentiaux, p. 74, pl. 3, Figure 2 [36], syn. nov.

1950 Platyblattina ampla—Laurentiaux, p. 74, pl. 3, Figure 3a,b [36], syn. nov.

1950 Livetiblatta incerta—Laurentiaux, pp. 74–75, pl. 4, Figure 1a,b [36], syn. nov.

1960 Sterzelia lamurensis—Haudour et al., pp. 137–140, Figures 2 and 3 [53], syn. nov.

1960 aff. Necymylacris (Eumorphoblatta) boulei (Agnus)—Haudour et al., p. 141, Figure 4 [53], syn. nov.

1963 Guichenbachia gigantea—Guthörl, p. 249, Figure 2 [37], syn. nov.

1966 Dysmenes idoneus—Laurentiaux, pp. 189–191, Figure 1 and Figure 2 [54], syn. nov.

? 1983 Anthracoblattina meganalis—Brauckmann and Hahn, pp. 70–72, Figure 1a,b [55], syn. nov.

1983b Archoblattina boulei (Agnus)—Schneider, p. 88, pl. 4, Figure 10, pl. 6, Figure 3 [41], syn. nov.

2005 Necymylacris sp.—Schneider et al., p. 452, pl. 9, Figure 4 [56], syn. nov.

pp. 2019 Anthracoblattina ensifera-gigantea group—Belahmira et al., p. 959; Figures 13.5 and 13.6 [7], syn. nov.

Type specimen. Blatta helvetica Heer, 1864 [38]; Lower quarry of Erbignon, Valais, Salvan-Dorénaz Basin, Switzerland; Zone Houillère, Stephanian B; MGL.2551.

Diagnosis. As for the family with the following specifics: forewing length 5–7 cm; number of branches ending at the forewing border, without the number of An veins, higher than 50, causing a much tighter venation of the whole wing; space between AnA and CuP small but distinct; area of anastomosing to (irregularly) reticulate cross venation extending to about the middle of the forewings, the apical part showing increasingly wider spaced cross-veins, as typical for the family and the genus; dimorphism well expressed by stout, mostly shorter and slender, mostly longer forewings.

Comments. The type specimens of Progonoblattina helvetica and ‘E. steinmannii’ have not been published, neither as photographs nor as exact drawings. Accordingly, we provide photographs, drawings, and a detailed re-description of both species.

Description of the P. helvetica type specimen, MGL.2551 (Figure 5A,B; Table 1):

Almost complete but somewhat deformed left forewing with 35 × 17 mm preserved size; reconstructed size is 37 × 17 mm. Subcostal field strip-like, distally tapering; 71% of the forewing length. Sc pectinate, minimally, the last four twigs originate by multiple forking; all twigs from the base to the apex are increasingly inclined. R is subdivided into RA and RP; RA one time forked, and RP multiple forked into seven branches. R branches terminate at the anterior wing margin above the wing tip. M is weakly sigmoidal to nearly straight and divided by forking into MA and MP somewhat distant from the wing base; three MA and four MP branches cover an area extending from the wing tip to the transition from the wing tip into the posterior wing margin. Cu is divided at the wing base into CuA and CuP. CuA is slightly sigmoidal to nearly straight. CuP is curved. The anal field is somewhat pushed taphonomically over the wing base. The veins are poorly preserved. The number of branches ending at the wing border, without the number of An, is more than 50. Cross-venation as far as preserved striate in the apical part of the wing.

Description of ‘E. steinmannii’ type specimen, ALUF 792-14 (Figure 10A,B; Table 1):

Almost complete but somewhat deformed right forewing of 43 × 20 mm preserved size; reconstructed size is 52 × 20 mm. The subcostal field is strip-like, distally tapering; 67% of the forewing length. Sc pectinate, all twigs from the base to the apex are increasingly inclined and mainly forked; the last four twigs originate by multiple forking. R is close to the wing base subdivided into RA and RP; both multiple-forked. R branches terminate at the anterior wing margin above the wing tip. M is nearly straight, divided by forking in MA and MP; indistinct MA with only two twigs, MP with ten twigs; M twigs covering an area extending from the wing tip to the transition into the posterior wing margin. Cu is divided at the wing base into CuA and CuP. CuA is slightly sigmoidal to nearly straight; the first two twigs arose by branching; all other twigs arose by forking. CuP is curved. The anal field is missing. The number of branches ending at the wing border, without the number of An, is 58 as far as preserved but would be higher than 60 at the complete wing. The cross-venation is anastomosing-striate in the proximal part of the wing and striate in the apical part.

Figure 10. (A–C)—Progonoblattina helvetica (Heer, 1864): type specimen of ‘Etoblattina steinmannii’ Sterzel, 1904; Hinterohlsbach near Oppenau; ALUF 792-14; reconstructed length 52 mm; A—illumination perpendicular and B—parallel to the long wing axis; scale bars 5 mm; photo: ALUF.

Figure 10. (A–C)—Progonoblattina helvetica (Heer, 1864): type specimen of ‘Etoblattina steinmannii’ Sterzel, 1904; Hinterohlsbach near Oppenau; ALUF 792-14; reconstructed length 52 mm; A—illumination perpendicular and B—parallel to the long wing axis; scale bars 5 mm; photo: ALUF.

Description of specimen ‘Necymylacris sp.’ Schneider et al. 2005, MfNC F15186 from Zwickau (Figure 11A–D; Table 1):

The counterpart of a whole right, reniform forewing of 51 × 21.5 mm size. The anterior border is more curved than the posterior border. The subcostal field is strip-like, distally tapering; 73% of the forewing length. Sc pectinate, eight mainly forked twigs arose by branching, and six other twigs originated by multiple forking. All twigs from the base to the apex are increasingly inclined. R is close to the wing base subdivided into RA and RP, with several times forked branches; four RA and seven RP branches. R branches terminate at the anterior wing margin down to slightly above the wing tip. M is divided into MA and MP shortly behind the RA/RP division; MA and MP branches arose by multiple forking; five MA and eight MP branches cover an area extending from short above the wing tip to the transition from the wing tip into the posterior wing margin. Cu is divided at the wing base into CuA and CuP. CuA after the basal flexure is slightly sigmoidal to nearly straight and inclined; the basally first three twigs arose by branching from CuA and are once to several times forked; further eight twigs appeared by multiple forking. CuP is curved. AnA is distinct but simple. The area between CuP and AnA is basally extended. The number of branches ending at the wing border, without the number of An, is 61. The cross-venation anastomosing-striate in the basal part of the wing with a fluent transition into striate and increasing space between the veinlets of the cross-venation towards the wing tip (Figure 11C,D).

Figure 11. (A,B)—Progonoblattina helvetica (Heer, 1864): specimen ‘Necymylacris sp.’, Schneider et al., (2005); Cainsdorf near Zwickau; MfNC F15186; length 51 mm; (C)—detail of the cross venation at R; (D)—detail of the cross venation close to the wing tip at M; scale bars 5 mm.

Figure 11. (A,B)—Progonoblattina helvetica (Heer, 1864): specimen ‘Necymylacris sp.’, Schneider et al., (2005); Cainsdorf near Zwickau; MfNC F15186; length 51 mm; (C)—detail of the cross venation at R; (D)—detail of the cross venation close to the wing tip at M; scale bars 5 mm.

Reinterpretation of specimen ‘Anthracoblattina ensifera-gigantea-group’ Belahmira et al. 2019, CDUE TaI-13d-25 (Figure 12A–E; Table 1):

Preserved are the apical two-thirds of a right forewing, preserved size 38 × 19 mm, reconstructed size 57 × 19 mm. The specimen was erroneously described in [7] as belonging to the Anthracoblattina ensifera-gigantea group. The reinvestigation showed a distally tapered subcostal field and, towards the wing tip, a relatively wide-spaced striate cross venation, which is different from Anthracoblattina. Both features could be observed in Necymylacris and Progonoblattina, but the multiple furcations of the CuA twigs correspond much more to Progonoblattina. This makes this specimen the second youngest representative (Stephanian A/B) of this genus behind ‘Necymylacris boulei’ (Stephanian B/C; Table 1). Unfortunately, the cross-venation is not preserved in the latter specimen. Therefore, the excellently preserved cross-venation of CDUE TaI-13d-25 (Figure 12C,D) delivers the last information on the development of cross-venation patterns before the disappearance of the genus. Concerning the reconstructed wing size, an anastomosing cross-venation is recognizable with transitions into irregularly reticulate in the middle of the second third and towards the last third of the wing, the transition via anastomosing into increasingly wider spaced striate cross-veins.

Figure 12. (A–E) Progonoblattina helvetica (Heer, 1864): (A,B)—specimen ‘Anthracoblattina ensifera-gigantea-group’, Belahmira et al., (2019); Tanamert; CDUE TaI-13d-25; preserved size 38 × 19 mm; (C)—the same, reconstructed length 60 mm; (D)—cross-venation in the areas of Sc and R; (E)—cross-venation in the areas of R and M near wing tip; scale bars 5 mm; photo: L. Puschmann, drawing: A. Belahmira.

Figure 12. (A–E) Progonoblattina helvetica (Heer, 1864): (A,B)—specimen ‘Anthracoblattina ensifera-gigantea-group’, Belahmira et al., (2019); Tanamert; CDUE TaI-13d-25; preserved size 38 × 19 mm; (C)—the same, reconstructed length 60 mm; (D)—cross-venation in the areas of Sc and R; (E)—cross-venation in the areas of R and M near wing tip; scale bars 5 mm; photo: L. Puschmann, drawing: A. Belahmira.

Discussion. Due to the partially incomplete preservation of P. helvetica, the type specimen of ‘E. steinmanni’, regarded as conspecific with the first, may serve as a reference, especially for the venation of the Sc. P. helvetica differs from P. clarkii mainly by the higher number of branches, the nearly straight CuA running inclined against the wing border and the somewhat reduced space between AnA and CuP in the youngest representatives, such as ‘Necymylacris boulei’ Agnus, 1903a [50] (Figure 13A,B). The basally anastomosing-striate venation seems to extend increasingly further distally. This is the case, especially in the stratigraphically youngest representatives of P. helvetica, such as the Stephanian A/B ‘Etoblattina steinmannii’ Sterzel, 1904 [51], here Figure 10A,B, and with some further modifications in the specimen CDUE TAI-13d-25, Figure 12A,B,D,E, from the Stephanian A/B of Morocco (see above). As the shifts in the main venation pattern, the differences in the cross-venation seem to be caused by fluent anagenetic changes. Additionally, taphonomic processes often blur primary structures, such as compaction and later tectonic deformations. Therefore, using cross-venation as a discriminating feature seems inappropriate for reliable delimitation between Progonoblattina species. Generally, the boundaries between the species are fluent because of assumed anagenesis, as visible in P. helvetica from the Stephanian A, which has still a slightly sigmoidal CuA.

The above-mentioned well-expressed dimorphism in the forewing geometry of P. helvetica is demonstrated by stout, mostly shorter wings of assumed males, as, e.g., in the type specimen of ‘Dysmenes idoneus’ Laurentiaux, 1966 [54] (Figure 14A,B) and MfNC F15186 from Zwickau (Figure 11A,B), as well as by slender, mostly longer forewings of assumed females, as, e.g., in the type specimen of ‘Necymyalcris boulei’ Agnus, 1903a [50] (Figure 13A,B) and specimen CDUE TaI-13d-25 (Figure 12A–C).

Occurrence. Pennsylvanian, late Moscovian to middle Gzhelian, late Westphalian D to Stephanian B/C of Europe and North Africa.

Figure 14. (A,B)—Progonoblattina helvetica (Heer, 1864): type specimen of ‘Dysmenes idoneus’ Laurentiaux, 1966; Saint Jaques; reconstructed length 56 mm; scale bar 5 mm; photo: from Laurentiaux (1966).

Figure 14. (A,B)—Progonoblattina helvetica (Heer, 1864): type specimen of ‘Dysmenes idoneus’ Laurentiaux, 1966; Saint Jaques; reconstructed length 56 mm; scale bar 5 mm; photo: from Laurentiaux (1966).

4. Implications on Stratigraphy, Paleobiogeography and Paleoecology

4.1. Stratigraphy

Gyroblattids appeared first with P. clarkii in the Sharp Mountain Member of the Pottsville Formation of the Appalachian Basin, USA, in the Atokan (earliest Moscovian) (Table 1). The Sharp Mountain Member in eastern Pennsylvania is lithostratigraphically correlated with the Kanawha Formation in West Virginia, USA [44] (p. A23, Figure 10). The latter formation is radioisotopically constrained to 314.6 ± 0.9 Ma based on a ²⁰⁶Pb/²³⁸U age [57]. This age is close to the upper boundary of the Westphalian B (Duckmantian), i.e., close to the Bashkirian–Moscovian boundary, as several high-precision U-Pb constraints indicate [20,21,58,59] and corresponds biostratigraphically to the Archimylacris johnsoni Zone of [8]. This zone species is also known from the Sharp Mountain Member and the Kanawha Formation. Consequently, a late Westphalian B is adopted here as the so-far-known LO of P. clarkii and the family Gyroblattidae in general. The HO of P. clarkii is below the Le Pin seam in the Gard Basin, SE Massif Central, France [36]. Based on the macroflora, the lower Le Pin seam level is proven to be Westphalian D (Asturian, late Moscovian), possibly transitional to Stephanian A (pers. communication J. Galtier, 2021). The LO of P. helvetica is marked by specimen MfNC F15186 in the (late) Westphalian D of the Zwickau Subbasin (Table 1). The HO of both P. helvetica and the family Gyroblattidae is indicated by the specimen described by Agnus as ‘Necymylacris boulei’ [50], here illustrated as Figure 11 and a further specimen described in [46] (text-Figure 141) as ‘Necymylacris sp.’ from the Grande Couche, Commentry Basin, France, in the Stephanian B/C (early to middle Gzhelian), corresponding to the early part of the Syscioblatta dohrni–Sysciophlebia euglyptica Assemblage Zone [8]. Although the Wettin blattoid entomofauna of the Wettin Subformation, Stephanian C (late Gzhelian), of the Saale Basin, central Germany (Figure 1 and Figure 2), is proven to be diverse and also rich in individual specimens, no gyroblattids are known so far, as for younger entomofaunas, too [5,11,60]. Nevertheless, a sampling bias seems not very likely to be responsible for the disappearance of these conspicuous, large-winged blattoids. Hence, the HO appears to be close to the actual extinction of Gyroblattidae.

4.2. Paleobiogeography and Paleoecology

Gyroblattids appeared with P. clarkii in the fossil record, first in the late Westphalian B (late Atokan; Table 1) of the non-marine, i.e., limnic Appalachian Basin in North America. Gyroblattids seem to be common at Pawtucket, Westphalian C to D, in the limnic Narragansett Basin of Rhode Island, USA, extending into the Westphalian D (Desmoinesian) marine-paralic Francis Creek shale of Mazon Creek in the Illinois Basin, USA (Table 1) [61,62]. In European basins, P. clarkii appeared first in the Westphalian D of the limnic Gard Basin of France (Table 1) [36]. The likely successor species, P. helvetica, nearly contemporaneously appeared in the late Westphalian D of the limnic Zwickau Subbasin of central Germany and somewhat later in the Stephanian A of the Gard Basin, France. Laurentiaux [63] (pl. 40, Figure 3; unpublished) figured a forewing as ‘Hispanoblatta cantabrica’ sp. nov. (nomen nudum) from San Felices de Castilleria coal seams, Stephanian A, of the Central Asturian Coalfield in Spain (Figure 15). The latter specimen is regarded as P. helvetica and extends the species’ paleogeographic range in Europe to the Iberian Peninsula. Surprisingly, gyroblattids are not represented in the blattoid-rich Westphalian entomofaunas of the paralic basins of the Variscan foredeep in Europe [32,63,64,65,66]. However, gyroblattids are known from the early to middle Stephanian in several limnic basins in Europe and North Africa (Table 1). In contrast, gyroblattids apparently disappeared in North America after the Desmoinesian (Westphalian). This is reliably proven by their absence in the well-sampled Stephanian entomofaunas as those from, e.g., the Lawrence Shale of the marine-paralic Midcontinent Basin of Kansas, USA [67], and the nearshore coastal ponds recorded in the Carboniferous/Permian transitional entomofauna of Carrizo Arroyo in the marine-paralic Lucero Basin of New Mexico, USA [11,68].

In contrast to the vast North American cratonic basins, gyroblattids occurred in most European sites in small intramontane basins. However, both regions and the Moroccan Souss Basin are associated with remarkable floral assemblages, as demonstrated in the following part, based on several adequately studied basins. Both facies architectures and floral assemblages could help at least partially understand the paleoecology of these large-winged insects.

Zwickau Subbasin of the Zwickau-Oelsnitz Basin, central Germany

The basin belongs to the Late Pennsylvanian (late Moscovian) Variscan post-orogenic intramontane basins of the Saxo-Thuringian Zone (Figure 2B, No. 21). It was interconnected via several other (sub)basins to the Central and Western Bohemian Basins of the Variscan Internides of the Moldanubian Complex in the south [69,70] and the Variscan foredeep in the north [71]. Its present preserved size is 25 × 7 km; the original size was at most twice as large, as can be concluded from facies patterns [72]. A synsedimentary active swell subdivides this basin into the subbasins of Zwickau and Lugau-Oelsnitz [56] (Figure 1). The Zwickau Formation represents the late Carboniferous basin fill with a preserved thickness of about 420 m [56]. Pennsylvanian sedimentation started locally on a paleorelief with autochthonous weathering debris above Variscan anchimetamorphic and altered basalts. During the basin development, two larger fans grew from the southeast and north, respectively, into the basin. Coal-forming swamps are linked mainly to the front and flanks of these fans [56,72]. Eleven workable seams are known. One of the essential coals was the Rußkohlen seam, traceable across the entire Zwickau Subbasin with a maximum thickness of 10 m that resulted from the amalgamation of three smaller seams. The great content of fusinite in the Rußkohlen seam, up to 45% [73], points to extended wildfires that apparently affected surrounding hillsides and even depositional areas. As a result, repeated destruction and resettlement dynamics may have favored a higher percentage of plants belonging to new evolutionary lines, such as Dicranophyllum. The latter genus is strikingly enriched at that stratigraphic level (Figure 16).

A rich macroflora from the Zwickau and Lugau-Oelsnitz subbasins have been sampled for almost three centuries [74,75,76,77,78]. The stratigraphic benefit of macrofloral remains in correlating coal seams and their associated sedimentary strata has been demonstrated here since the early 19th century [79,80,81,82]. The diverse floral assemblages of the Zwickau Formation comprise well-preserved, low-carbonized, typical Westphalian D forms and several “Stephanian” precursors. This remarkable characteristic applies to different facies throughout the coal-bearing and, therefore, intensively mined strata complex. The oldest occurrence of the coniferophyte Dicranophyllum gallicum is Zwickau, where this species was frequently recognized [83,84,85]. In this regard, the striking leaf variability seems noteworthy. Leaves of up to 15 cm in length and 1–3 mm in width are common in Zwickau-Cainsdorf [85] but probably lie beyond the D. gallicum species range [83]. However, Wagner [86] characterized Dicranophyllum glabrum as an unusual element of even Langsettian floras in Atlantic Canada. In Saxony, Dicranophyllum is also reported together with Omphalophloios and Lesleya from the putative late Westphalian Teplice Rhyolite near Altenberg, Erzgebirge Mts., eastern Germany [87,88]. Sporadically, Dicranophyllum appeared in Westphalian and Stephanian floras as a likely extrabasinal element, and also in other regions, such as the marine-paralic Kinney embayment of the Orogrande basin in New Mexico, USA [89]; several basins in the range of the Massif Central, France [90,91,92]; basins of the French and Swiss Alps and the Souss Basin of Morocco [6,93]. Of course, the ‘Stephanian character’ of the Zwickau macroflora cannot be reliably substantiated by enigmatic elements. However, several widely-distributed hygrophilous plants are among this macroflora, such as the medullosan seed ferns Praecallipteridium subdavreuxi, Odontopteris alpina, and the herbaceous sphenophyte Sphenophyllum angustifolium [78,94,95]. All these forms typically occurred in the grey facies that was gradually repressed in their distribution among Late Paleozoic depositional systems. Moreover, many tree-fern foliations were identified, such as Pecopteris lamuriana, P. densifolia, P. arborescens, P. unita, and P. hemitelioides. Pecopteris bredovii, as reported in [78], has its maximum distribution within Stephanian strata but even reaches into the early Permian [96]. It seems similar to the callistophytalean Dicksoniites plukenetii, which is also proven in the Zwickau Formation [75]. In addition to Praecallipteridium subdavreuxi, a stratigraphically relevant pteridosperm underlining the “Stephanian” aspect is Odontopteris reichiana, recently treated under O. brardii [97] that frequently occurred in the western European Stephanian [98]. We are inclined to ascribe the co-occurrence of Stephanian and Westphalian elements as caused by the small dimensions of the Zwickau and Lugau-Oelsnitz subbasins surrounded by extrabasinal areas or hinterland prone to erosion [99]. However, we assume the possibility of a much more internally structured intramontanous basin [100]. As such, the varying substrate could have favored vegetation types that thrived under confined-space different hydrological and edaphic conditions ranging from peat mires and clastic-substrate wetlands to slightly elevated ones occasionally-dry areas adjacent to the coal swamps. Compared to the large Westphalian parts of the Saar-Lorraine and Bohemian basins, depocenters of the Zwickau and Lugau-Oelsnitz subbasins were at least five kilometers away from the basin margins. The most extensive peat formation took place in front of depositional fans. Dryer areas on the fans and in their source areas and well-drained sand sheets and bars along fluvial channels and distributaries would have provided habitats well suited also for mesophilous elements but were situated close to the increasingly patchy swamp areas. A similar situation is mirrored in the insect fauna, which consists nearly exclusively of mylacrids typical of coal-seam roof shales [101,102]. The here-described Progonoblattina may come from the dryer habitats at the basin border as the mesophilous floral elements too.

Figure 16. Plant remains from the Zwickau Basin, central Germany: Dicranophyllum sp. showing bifurcating, lineal, relatively narrow long leaves attached to axes with spirally arranged leaf-cushions; (A)—Zwickau-Cainsdorf, MfNC F14318; (B)—Oelsnitz, MfNC F14317; scale bars: 5 mm.

Figure 16. Plant remains from the Zwickau Basin, central Germany: Dicranophyllum sp. showing bifurcating, lineal, relatively narrow long leaves attached to axes with spirally arranged leaf-cushions; (A)—Zwickau-Cainsdorf, MfNC F14318; (B)—Oelsnitz, MfNC F14317; scale bars: 5 mm.

Gard Basin (Cévennes), France

This small, fault-bounded basin lies in southeast Massif Central (Figure 2B, No. 36). The Carboniferous sequence formed upon a metamorphic basement made of mica schist and consists of multi-story coal levels, with the most extensive being La Grand’Combe, exhibiting 1600 m of continuous deposits. Throughout the basin, the coal-bearing depositional system was affected by horizontal compression that resulted in high-amplitude folding and intense faulting associated with numerous vertical displacements, which mostly happened before marine Triassic sedimentation. As a result, the strata targeted by coal mining for more than one century are only exposed in restricted parts, morphologically characterized by steep mountain slopes and modern-river valley cuts. Tectonic movements highly complicated the investigation and identification of stratigraphic levels. However, macrofloral assemblages successfully resolved this challenge since the classical work of Grand’Eury [91]. To the east, the coal basin dips shallowly under Triassic limestones.

Insect remains are common and derived from the Rochebelle area, consisting of 15 coal seams, 1.5 to 6 m in thickness [36]. The most famous insect site is the fourth seam, belonging to the uppermost Fontanes Formation with a significant portion of fine-grained white sandstones. Because it is situated in the lower to middle strata of the basin and correlated with the Bessèges level, the stratigraphy seems best determined by the occurrence of Crenulopteris lamuriana, Pseudomariopteris cordato-ovata, Dicksoniites plukenetii, Linopteris neuropteroides, Odontopteris reichiana, Scolecopteris arborescens, and Dicranophyllum gallicum [91]. Due to the first species, the late Kasimovian (Stephanian A) is most likely in this lower part of the sedimentary column. In contrast, younger forms, such as Odontopteris subcrenulata, Scolecopteris arborescens/cyathea, Walchia piniformis, and Sphenophyllum oblongifolium, characterize the La Grand’Combe system. The youngest sediments of the Gard Basin are found in the Champclauson strata and are distinguished by Scolecopteris hemitelioides, Odontopteris brardii, Taeniopteris jejunata, many cordaitaleans, and Sphenophyllum oblongifolium. Consequently, they point to a late Stephanian B age, compared with the base of the middle strata complex in St. Étienne [91,98].

Enigmatic gymnosperms have been known from here since Grand’Eury [91], who mentioned serval species of Dicranophyllum; the most common is D. gallicum, but also unusual small lineal leaves bifurcating up to three times [91] (pl. VI, Figures 12 and 13). Additionally, Taeniopteris jejunata, walchian conifers, and Samaropsis winged reproductive organs were reported from lacustrine fish-bearing beds. Finally, a cordaitalean leaf from the La Grand’Combe system should be mentioned because its striking frass galleries are likely attributed to specialized insects [91] (pl. XXII, Figure 7).

La Mure Basin, French Alps

The La Mure basin (Figure 2B, No. 29) belongs to a chain of the latest Westphalian to early Stephanian basins west and southwest of the Belledonne Massif, one of the external crystalline basement complexes of the French Alps [103,104,105,106]. Belonging to the Variscan Internides, the Belledonne Massif forms the southeast branch of the Variscan chain [107]. Two phases of Late Pennsylvanian extensional processes were responsible for the basin formation in southwest Belledonne and comprised a first, Westphalian to middle Stephanian phase, followed by a second, late Stephanian phase [106,108]. As a result, relatively small, elongated, and narrow fault-bounded coal basins formed. The largest among them is the La Mure Basin, exhibiting a preserved strata thickness of 800 m. Sedimentation likely started in the latest Westphalian D to earliest Stephanian A (Cantabrian), indicated by the pteridosperm Neuropteris ovata [109], on the Variscan basement made of metamorphites and granites. Sandstones and siltstones followed coarse conglomerates at the base with a few dm-thick coal seams of the 80-m-thick La Faurie Formation [104]. The next sedimentary cycle, the approximately 700 m ‘Assise Productive’, started with a basal conglomerate and provided several high-rank anthracite-coal seams in a mean thickness of 2 m (max. 12 m—the Grande Couche). The moderately folded stratigraphic sequence was intensively mined between 1806 and 1997.

The gyroblattids were found close to the base of the productive series, approximately 200 m above the base of the Stephanian. Below a roof with Anthraconaia, the 2-m-thick Trois-Bancs seam is divided by a shale interbed—the insect-containing deposit [53]. The macroflora with the zone species Crenulopteris lamuriana represents a typical early Stephanian assemblage. However, Rastel et al. [109] reported new finds from the northern part of the La Mure basin, Vaulnaveys-le-Bas site. Among them, the gymnospermous taxa Taeniopteris jejunata, Dicranophyllum gallicum, and different Lesleya species are the most prominent ones and indicate the local input of hinterland elements (Figure 17).

Salvan-Dorénaz Basin, western Alps, Switzerland/France

This basin (Figure 2B, No. 28) is situated in the western Alps and belongs to Carboniferous basins located in the internal Variscan domain and originated on the so-called external crystalline massifs of the Swiss and French Alps [110]. However, its sedimentary strata are partly preserved, folded, and low-grade metamorphized. These changes are due to partial erosion before marine sediments were deposited on the top during the Triassic and the later Alpine deformation phases [111]. The basin formed within the Aiguilles-Rouges and Arpille massifs as an asymmetric NE–SW-striking fault-bounded graben, showing its maximum thickness of 1.7 km along the NW border of the elongated trough at 25 km preserved length [111]. The sedimentation started with 350 m thick deposits of wet alluvial braided fans overlying the Variscan metamorphic basement made of granitoids and accompanied by mylonite zones. The basin fill consists of a basal volcanic unit and several siliciclastic units comprising pyroclastic beds, but synsedimentary tectonics affected depositional processes [111,112,113]. The lower-strata age is constrained as late Westphalian based on macrofloral remains [114] and radioisotopic U/Pb zircon data of 308 ± 3 Ma gained from basal dacitic flows [115]. However, the upper strata yielded strikingly younger macrofloral assemblages and radioisotopic U/Pb zircon data of 295 ± 3 Ma based on a tuff layer inside the epiclastic units [113]. The younger flora consists of Sphenophyllum oblongifolium and Sphenophyllum thonii var. minor, the latter also recognized in the Carboniferous–Permian transition of the Oppenau basin, Black Forest, SW Germany [116,117]. Several species, such as Neuropteris ovata, Linopteris neuropteroides, Dicksoniites plukenetii, calamitaleans, and a suite of pecopterids, persisted throughout the sedimentation and underlined the high accommodation rate under locally humid conditions. Otherwise, well-developed pedogenic calcretes indicate increased seasonality on a vertically structured habitat-diverse floodplain [113]. Several macrofloral index species point to a strikingly younger, most likely Stephanian B age, at least for the strata from the lithologic unit II [113] onwards. Among them are Crenulopteris lamuriana, Neurodontopteris auriculata, Neurocallipteris neuropteroides, Callipteridium pteridium, Alethopteris zeilleri, Alethopteris bohemica, and Odontopteris brardii [20,114]. Taeniopteris multinervia and Taeniopteris cf. jejunata may represent an upcoming line of gymnospermous elements, also recorded from the other basins under consideration but offering only minor age constraints. Jongmans [114] emphasized the small floral differences between single collecting sites.

Concerning paleoecology, the Salvan-Dorénaz Basin seems comparable to the Gard Basin and accommodates the type locality of P. helvetica. The insect finds derived from the Zone Houillère [4] may be represented by the coal-containing lithologic units I and II according to [113]: facies associations IC, “micaceous and massive mudstone with abundant plant remains”, and IIA (facies C with “rhythmically interbedded, finely laminated, black mudstones”) are excellent host-rock candidates for animal and plant fossils. Unit II consists mainly of channel sandstones and interbedded fine-grained overbank sediments containing plant fragments and in situ rooting structures. Facies’ architectures and lithology indicate deposition by anastomosed river systems on a fast-aggrading floodplain [113]. Shallow lacustrine areas and restricted peat swamps may have been responsible for appropriate taphonomic conditions preserving organic remains. Otherwise, laterally persisting calcrete horizons within the floodplain deposits indicate the stratigraphic position of Unit II among the younger, likely Stephanian B part of the Carboniferous sequence.

Oppenau Basin, Black Forest, SW Germany

Several small intramontane basins can be traced only by their erosional remnants in the present-day Black Forest (Figure 2B, No. 26). Formed during the Late Pennsylvanian mostly, the sediments overlie deeply eroded, high-grade metamorphites allocated to the Moldanubian-Saxothuringian zones. One of these small basins we will focus on is the Oppenau Basin, a narrow accumulation area of the late Carboniferous bounded by SW–NE striking shear zones and situated at the southern margin of the north Black Forest granite region [117]. The basin fill consists of tens to almost one hundred meters of conglomerates, arkoses, and mudstones with intercalated, only dm-thick coal seams. As usual, the stratigraphy of the Oppenau Basin is traditionally based on macrofloral assemblages provided from different-age fine clastics [116,118,119]. As a result, Sterzel emphasized the notable differences between the lower and upper parts of the Oppenau Formation [116]. He placed the lower part, Hinterohlsbach strata, to the Stephanian, and the upper part, Lierbach, Hauskopf and Holzplatz sites, were assigned to the ‘lower Rotliegend’ [116]. In this context, it seems noteworthy that Renault confirmed the prevailing floral resemblance compared with the ‘Grande Couche’ of Commentry [92].

Palynological investigations undertaken by Hartkopf-Fröder [120], based on dump material collected near Hinterohlsbach, provided arguments to correlate the lower Oppenau Formation, Hinterohlsbach strata with miospore zones OT and ST, according to Clayton et al. [121], whereupon miospore zone ST is more likely due to the common occurrence of Spinosporites. The host rock of the insect fossils, the Hinterohlsbach strata, would therefore point to a Stephanian A/B age. The only insect remains from the Oppenau Basin are two Progonoblattina forewings (Table 1). In contrast, the upper part of the Oppenau Formation, Lierbach Valley north of Oppenau, provided a palynomorph association comparable to the miospore zone NBM, according to [121], with numerous Potonieisporites grains [120]. Nevertheless, the samples from the Weiach Formation, correlated with the Oppenau Formation [119], provided evidence of several miospore zones, including the Vittatina costabilis Zone [122] and even the likely transition to the Disaccites striatiti Zone proven from the Wintersingen well [122]. Well-preserved, sizeable cycadophyte fronds of Pterophyllum blechnoides underline the younger aspect of the upper Oppenau Formation (Figure 18). Particularly, the common occurrence of P. blechnoides as a lowland species in coal-forming fine clastics highlights previously found fragmented P. blechnoides records [118,119,123], reported from the upper Hohengeroldseck Formation, Stephanian B. Enigmatic gymnospermous species such as P. blechnoides and Dicranophyllum fragments without distinct species identification [116] may indicate the early distribution of precocious hinterland elements, as proposed in [99]. Usually hygrophilous to mesophilous macrofloral taxa, such as Callipteridium gigas, Neurocallipteris neuropteroides, and even conifer remains are added to the stratigraphically relevant taxa [116,119]. Finally, the nearly cosmopolitan herbaceous sphenophyte Sphenophyllum thonii may justify at least the latest Stephanian C age of the upper part of the Oppenau Formation.

Souss Basin, Morocco

This sub- to perimontaneous basin is situated at the southern flank of the Mauretanides as part of the Variscan orogen (Figure 2A, No. 8). Sedimentation starts on low-grade metamorphized folded and faulted early Paleozoic rocks (middle Cambrian to Ordovician, in places Devonian) with up to 600-m-thick coarse conglomerates followed by up to 1200-m-thick series of mainly fine- to medium-grained sandstones with intercalated up to meter-thick dirty coal seams and decimeter- up to several meter-thick lacustrine black shales. The last series is called the El Menizla Formation in the Ida Ou Zal Subbasin and the Qued Issene Formation in the Ida Ou Ziki Subbasin. Both subbasins are tectonically subdivided during the latest Carboniferous or Permian and represent erosional remnants of the Permian and younger erosion of a previously uniform large basin. During the deposition of the Oued Issene Formation, the environment of the basin was considered as an extended sand-dominated low-gradient alluvial braid plain with different sedimentary and biotic environments from swamps and mires to shallow and deep lakes within a fluvial-dominated landscape [7,124,125].

The age of this formation is determined by spiloblattinid insect zones as early to middle Stephanian [6,7,41]. Progonoblattina co-occurred there with the large-winged Anthracoblattina and is associated with macrofloral elements, indicating a mixture of Stephanian/early Permian ecological aspects. Broutin et al. characterized the macroflora of the Souss Basin based on both older records [126,127,128] and new finds as a typical Stephanian ecotype. The two uppermost plant-bearing beds in the Ida Ou Ziki Subbasin, the “formation gréso-silteuse” [93] (Figure 2B) (=Oued Issene Formation) and the overlaying 80-m-thick “formation conglomératique” [93] (Figure 2C) (=Tirkou Formation) provided macrofloral taxa, such as Sphenophyllum oblongifolium, Scolecopteris pseudobucklandii (formerly confused with Alethopteris subelegans, compare [129]), Odontopteris cf. subcrenulata, cf. Taeniopteris gr. jejunata, Neuropteris cordata, Neurocallipteris neuropteroides, Poacordaites, Walchia piniformis, Otovicia hypnoides, some Culmitzschia species, and Sphenobaiera sp. (Figure 19). Whereas most taxa are mainly consistent with a Stephanian stratigraphic position, based on the early occurrence of Sphenobaiera sp. and the conifer diversity, Broutin et al. argued for an early Permian (early Autunian) age for the uppermost strata [93]. However, the uppermost plant bed in the “formation gréso-silteuse” corresponds to the insect locality Ta 1 in [6,41] and to the Tanamert CDUE 82-TaI locality in [7] (Figure 3 and 6). Based on spiloblattinid biostratigraphy, a Stephanian A/B age is indicated for this level [41,130], corresponding to late Kasimovian to early Gzhelian [25] (Figure 1). The entomofauna of the Tanamert CDUE 82-TaI locality consists mainly of Phyloblatta, several spiloblattinids, Anthracoblattina and Opsiomylacris, rarely Poroblattina, Compsoblatta, and the Progonoblattina fragment introduced here. From the same locality and beds, Stephanian macrofloral elements originate, but the dominating forms are walchian conifers, common Dicranophyllum cf. hallei leaf fragments, and rarely Autunia cf. conferta [6]. As a result, the joint occurrence of typical Stephanian wetland floral elements and so-called “early Permian” elements exhibiting mesophilous to xerophilous characters should be interpreted with caution [131,132]. During the last years, the mixture of Stephanian-type and Permian-type elements, such as the callipterids Autunia cf. conferta and Dichophyllum moorei, the ginkgophyte Sphenobaiera, the conifers Otovicia hypnoides, Ernestiodendron filiciforme, Dicranophyllum, and diverse cordaitaleans are known for the whole early to middle Stephanian Oued Issene Formation [133]. This floral composition is most likely caused by edaphic disparities in the alluvial braid plain, which provided closely spaced habitats for basinal and extra-basinal/hinterland elements.

Commentry Basin, Massif Central, France

The youngest occurrence of gyroblattids is recorded from the Grande Couche, Commentry, France, at the same level from which the world famous Commentry entomofauna originated (Figure 2B, No. 30). It is a typical small intramontane basin of the Variscan Internides [134], situated close to the northern border of the Massif Central [135] (Figure 18.1). The preserved basin size of 9 km × 3 km seems to reflect its primary dimension based on the facies-pattern distribution [136,137]. The basin development started on the deeply eroded orogenic core complex consisting of granites, granulites, and metamorphic schists. The more than 800-m-thick sedimentary column contains clastics, associated coal seams and bituminous shales. The Commentry strata are correlated with Stephanian B/C based on insect biostratigraphy [8]. The Commentry insect fauna, mainly known for its large-winged meganeurids, originated from the up to 12-m-thick Grande Couche coal seam. The dazzling array of more than 1500 insect specimens has been sampled during open-cast mining between the last decades of the 19th and the first decades of the 20th century [138]. About 1200 insect fossils are blattoids [139]. As a result, the Commentry entomofauna is the world’s richest one in the Late Pennsylvanian (Gzhelian), based on both number and diversity. However, detailed information about the insect sites within the Grande Couche seam is rare. Nevertheless, Bolton provided some general information that can be interpreted as reflecting lacustrine highstands [139]: “The shales in which the insect remains occur, lie upon the coal seams, and are generally micaceous near the base of the Coal Measures, whilst higher in the series they become more clayey, and at times bituminous. All the insects occur in a fine-grained laminated micaceous sandstone, having well-defined bedding planes, but the condition of entombment and preservation varies considerably”. In the context of the depositional conditions of the Grande Couche coal seam, the insects may originate from the plant-rich fine-grained interlayers of the coals or their roof shales. Stevenson described the about 30-cm-thick interbed “Banc de Roseaux” between the coal “Banc inferieur” and the coal “Banc intermédiaire” of the Grande Couche seam as “A more or less sandy, light-coloured to drab shale, highly variable in thickness and containing large numbers of plant impressions, beautifully preserved” [137]. The Commentry coals mainly resulted from the deposition in cordaitalean swamps, but the macroflora of the interbeds and roof shales consisted of not only Stephanian-type hygrophilous elements but also several gymnospermous hinterland forms, such as Taeniopteris, Lesleya, Pterophyllum, and Dicranophyllum [131,136], paralleling the conditions discovered in the other basins mentioned above.

The Commentry blattoid entomofauna differs from typical, nearly contemporaneous roof shales in larger basins, such as the perimontane Saale Basin in central Germany. The Wettin entomofauna in the Stephanian C of the Saale Basin was exemplified in [140] and compared to Commentry in [41]. For example, the large-winged (3.9 cm) Phyloblatta gaudryi is the most common blattoid at Commentry but is represented at Wettin by only two specimens. The next abundant at Commentry is the large-winged (5 cm) Anthracoblattina, known by two specimens only at Wettin [140]. The xeromorphic Opsiomylacris, common in the Souss Basin of Morocco [7] and not rare at Commentry, is lacking in the Wettin entomofauna. In contrast, the large-winged meganeurids of Commentry (60 cm to 70 cm wingspan) [138,141] are proven in the Wettin entomofauna, with one single find exhibiting a wing length of 20 cm. Since these are recorded in fluvial deposits, the taphonomic background likely represents the hinterlands of the Wettin swamps [142].

The specifics of the Commentry biota probably resulted from its location in the Variscan Internides, complemented by the small basin configuration surrounded by mountains of 1000 m estimated elevation [137]. As based on [136,137], the depositional environment of the Grande Couche can be understood as swamps that may have formed along the northern border of the E–W extending basin in areas of limited clastic sedimentation, distally to alluvial fans and laterally to river deltas. Two rivers entered the basin through deeply incised valleys having steep flanks, from the North (Les Bourrus) and the East (Columbier) [137] (p. 186–187, Figure 3). Fluvial coarse clastics, 2–3-m-thick (e.g., Banc des Chavais), interrupted peat accumulation at certain places. Laterally to the east and west, the Grande Couche thins out immersed in sandstones; it passes into carbonaceous-shale layers to the south. Consequently, the Commentry Basin also provides an example of the close neighborhood between erosional and depositional areas and at least recorded a mixture of par-autochthonous swamp biotas with allochthonous elements from the hinterlands. The Commentry insect taphonomy resembles that of the Missourian (Stephanian A, Kasimovian) of the Kinney Brick Quarry, USA [32]: A relatively high number of articulated insects indicate that they were wind-driven on the water-body surface inside the peat-accumulating area and on the pond-surfaces that originated due to peat compaction at the end of Grande Couche formation. Isolated Progonoblattina wings are most probably washed in by the rivers feeding the basin.

5. Discussion

Implications on the Large-Winged Late Paleozoic Blattoids

Five genera of large-winged blattoid insects are known in the Late Paleozoic: Progonoblattina, Necymylacris, Anthracoblattina, Opsiomylacris, and Aissoblatta (Figure 20A,C,E,F). Gyroblattids have forewing lengths with means of 5 to 6 cm (Figure 20A) and occur, as shown above in Table 1, from the Westphalian B (Bashkirian/Moscovian) to the Stephanian B/C (middle Gzhelian) in Euramerica, from North America via North Africa to Europe. The members of the family Necymylacridae have forewing lengths of up to 7 cm (Figure 20C) [32]. They occur from the Westphalian B (Moscovian) to the Stephanian B/C (middle Gzhelian) sporadically in several North American and European basins [32]. Species of the genus Anthracoblattina, family Phyloblattidae, have forewing lengths of up to 5 cm (Figure 20E) [5,7] and appear in the fossil record latest in the early Stephanian (early Kasimovian). They co-occur with Poroblattinidae, the so far known smallest blattoids, with an almost 1 cm forewing length (Figure 20B). Mylacridae could achieve forewing lengths of up to 7.5 cm (Figure 20F), as demonstrated by some punctual finds of an undescribed Opsiomylacris species from the Late Pennsylvanian (Virgilian) Hamilton Quarry of Kansas [143] and the late Carboniferous/early Permian Khenifra Basin of Morocco. Generally, Opsiomylacris species of the Kasimovian to Kungurian have wing lengths of 3 to 4 cm [144]. Dwarfed xeromorphic mylacrids, such as Moravamylacris, have forewing lengths of up to 2 cm (Figure 20D) and appear associated with xerophilous plants in the early Permian Sakmarian to Artinskian of Europe [144]. A similar reduction in size is recognized for some Phyloblatta species. Late Pennsylvanian Kasimovian to the earliest Permian Asselian members of this genus, e.g., Phyloblatta occidentalis (Figure 20H), have forewing lengths of 2 to 3.5 cm [7]. They display a fluent reduction in size, down to almost 1 cm in the Sakmarian to Kungurian (Figure 20I), obviously linked to the increasing aridization in Euramerica, as indicated by their occurrence in progressively dryer environments [145,146].

As far as known, these large-winged blattoids seem to have some particular habitat preferences. Gyroblattids first appeared in the larger North American basins, such as the Narragansett, Illinois, and Appalachian basins (Table 1; Figure 2A). In Europe, their occurrence is almost exclusively limited to fault-bounded, graben-like basins of the Inner Variscides (Figure 2B). In these small basins, the erosional areas of the hinterland are directly adjacent to swamps and lakes as main accumulation areas. Short transport distances are crucial for preserving and fossilizing plants and insects from the hinterland or uplands, respectively, in these intramontane basins. Gyroblattid wings typically co-occur with macrofossils of meso- to xerophilous habitat preferences, such as Dicranophyllum, Lesleya, Taeniopteris, and Pterophyllum, locally with Autunia, other putative peltasperms, often with abundant walchian conifers, and typical Stephanian wetland macroflora.

Necymylacrids are only patchily reported and concern single finds from various Euramerican basins. As a consequence, recognizable distributional patterns have been lacking until now [32]. However, an unusually large number of Necymylacris specimens was described in [68], from the Late Pennsylvanian of Kansas. Among a collection of 289 fossil insects from the Lawrence Shale or Formation, respectively, early Virgilian, earliest Gzhelian, 212 out of them are blattoids. Necymylacris scudderi (Sellards, 1908b) [67] is represented by 16 forewings (length of approximately 5 to 6 cm) and 7 hindwings. Associated with the insects, at localities in the area of the Havercampf Farm near Lawrence, Sellards reported a typical wetland flora [147]. Bashforth et al. discussed the exciting mixture of typical wetland elements with abundant taeniopterids, rare conifers, and one callipterid [148] already described in [149,150] from the Lawrence Shale of the Baldwin and Garnett localities. The deposition of the Lawrence Shale in the vast Western Interior Basin on the low-gradient continental platform in present-day central USA [148] precludes derivation of this mixed xeromorphic-mesomorphic flora and associated well-preserved necymylacrid insects from “uplands” fringing this basin. A more plausible explanation is that a drought-tolerant biome dispersed into the basinal lowlands during the drier phases of 10⁵ year-scale oscillatory climate fluctuations when it co-existed with pockets of remaining wetland elements as habitat heterogeneity increased [148].

Anthracoblattina occurs from the Late Pennsylvanian Westphalian–Stephanian transition to the early Cisuralian (Sakmarian–Artinskian), with single finds in all of the European and North American insect sites, from the Gondwanan Parana Basin of South America and with relatives (Kunguroblattina) in the Kashmir region of India [41,151]. However, the genus has seemingly particular habitat preferences (Figure 21) [5,7,151]. In the insect associations of thickly vegetated mires, e.g., the Wettin roof-shale insect sites, Anthracoblattina is rare [5]. By contrast, lake deposits such as Commentry, France [42], Sperbersbach, central Germany, and marine lagoonal sediments like those of the Parana Basin can be rich in Anthracoblattina [42,151]. Further occurrences are known from the coastal pond deposits of the mixed marine-continental Bursum Formation of Carrizo Arroyo, New Mexico [11,68] and the brackish-marine prodelta/bayfill succession of the Kinney Brick Quarry, New Mexico [32,152]. In the Kinney Brick Quarry Lagerstätte, Anthracoblattina is a member of the conifer-dominated hinterland of this marine embayment [32,89,153]. Likewise, the Anthracoblattina-bearing plant fragment and bivalve-rich lacustrine littoral sediments of the CDUE 82-TaI site of the Souss Basin [7] support the assumption that sparsely vegetated shores of lakes and seas were the preferred habitats of this genus. Recently, re-described finds of several Eneriblatta Teixeira, 1941 [154], which are nothing but tectonically deformed representatives of Anthracoblattina, occurred together with a Lesleya-Taeniopteris-Dicranophyllum hinterland flora in the Stephanian Douro Basin, Portugal [155,156] and may underline our paleoecological conclusion.

The sudden appearance of these large-winged blattoids might be caused by the decreasing differences between basinal wetlands and better-drained hinterlands by increasing climate seasonality since the latest Westphalian. These effects may have generated temporally and locally drier habitats even within basinal lowlands [146,157,158,159,160,161,162,163]. This first appearance of gyroblattids and necymylacrids corresponds well with significant vegetational changes during the Desmoinesian-Missourian transitional period (Westphalian-Stephanian = approximately Moscovian-Kasimovian transition) [158]. Climatic warming and drying began in the early Middle Pennsylvanian and had the first culmination near the Desmoinesian–Missourian (Westphalian–Stephanian) boundary [157]. As a result, biomes experienced directed change and migration. During this time, plants and associated animals started to occupy dryland areas in the hinterland of the small European intramontane basins, close to the wetter depocenters. In the much more vast North American basins, organisms repeatedly dispersed into basinal lowlands stimulated by suitable local climatic and edaphic conditions [148]. A much more diverse partitioning of potential habitats is indicated and may have resulted in a simultaneous patchy distribution of biotopes that exhibited either wetland or dryland characteristics.

Figure 21. Preferred habitats of the most common blattoid and meganeurid insects during the Late Pennsylvanian. The insect localities of this time frame (see Figure 1) are situated in the basinal gray facies of the Euramerican biotic province. Localities in the surrounding wet red bed facies are virtually unknown so far due to sampling bias.

Figure 21. Preferred habitats of the most common blattoid and meganeurid insects during the Late Pennsylvanian. The insect localities of this time frame (see Figure 1) are situated in the basinal gray facies of the Euramerican biotic province. Localities in the surrounding wet red bed facies are virtually unknown so far due to sampling bias.

The disappearance of the large-winged gyroblattids and necymylacrids before the end of the Stephanian is, at present, hard to explain because the mesophilous and xerophilous floras, with which they are seemingly associated, just started to flourish and became more common during the increasing dryer cycles during the early Permian [146,164,165,166,167]. Anthracoblattinids were the last large-winged blattoid insects in the Paleozoic of Euramerica. The stratigraphic highest occurrence of Anthracoblattina is the Obora locality in the Boskovice Graben, Czech Republic, late early Cisuralian [5,168] (Figure 1). There, the relatively large-winged Anthracoblattina co-occurs with the Phyloblatta species by having an almost 10 mm forewing length (Figure 20I) [145]. The somewhat younger entomofauna of the Lodève dry playa red beds display similar, very small phyloblattids of 9 mm forewing length [169] (Figure 26c). The level of the Obora pond and Bačov lake deposits corresponds with the level of the last perennial lakes in Europe at almost 290 Ma, i.e., the wet phase E of [146] (Figure 15a,b). After the wet phase E, perennial rivers and lakes disappeared entirely during the next dry phase in Euramerica. Starting from there, dry evaporitic red beds, increasingly poor in plant and insect remains, dominated the remaining Permian deposits up to the late Permian Wuchiapingian, when the marine Zechstein transgression flooded vast parts of Europe [169] (Figure 30). Insect walking traces can still be common, together with tetrapod tracks in middle and late Permian dry playa red beds [170,171,172]; insect remains, however, are almost missing. After a long gap in the fossil record, blattoids with up to 7 cm forewing lengths first re-appeared with phyloblattids such as Aissoblatta Handlirsch, 1904 [173] in the Kungurian of the East European Platform, in the late Permian of China [174], in the late Permian of Jordan (Figure 20G), and in the early Wuchiapingian marine Kupferschiefer of the Mansfeld mining area of central Germany, close to the base of the Zechstein in Europe [5].

Forewing lengths of up to 9 cm are only known from the modern Megaloblatta of tropical Middle and South America [17]. Concerning the gigantism of Paleozoic arthropods, the increased oxygen content of the atmosphere during the Carboniferous up to a peak in the late Permian [175,176,177] is frequently discussed as a potential driver [178,179,180,181]. However, as indicated by the discoveries of the largest terrestrial arthropod of the Late Paleozoic, Arthropleura, the matter of fact seems less schematic [182,183,184]. Our observations do not fit the Late Paleozoic rise and fall of the atmospheric oxygen content. Similarly, Schachat et al. provided evidence that atmospheric oxygen is not the primary constraint on arthropod body size, based on their revised Phanerozoic oxygen curve and detailed analysis of Late Paleozoic arthropod diversities and dimensions [185].

6. Conclusions

• Large-winged blattoid insects appear suddenly in the Euramerican fossil record in the Middle Pennsylvanian (Moscovian, middle to late Atokan) without any so far known forerunners. The families Necymylacridae Durden, 1969, and Gyroblattidae Durden, 1969, comprise the largest pre-Cenozoic blattoids, with forewing lengths of up to 7 cm, besides scarce Late Pennsylvanian/early Permian species of the Mylacridae genus Opsiomylacris, which reaches forewing lengths of up to 7.5 cm.
• In contrast to necymylacrids, the gyroblattids display a particular habitat preference, as concluded from their occurrences in North America, North Africa, and Europe. They are found in coal-bearing sequences, particularly in inter-seam fine clastics, roof shales, and lacustrine laminites. As a rule, they are associated with meso- to xerophilous gymnospermous plants, such as Dicranophyllum, Lesleya, Taeniopteris, and Pterophyllum, and several walchian conifers, peltasperms, or cordaitaleans as well. These relationships with floral elements are reflected in the vast North American basins, e.g., the Narragansett, Illinois, and Appalachian basins, where gyroblattids first occurred, but also in the tiny basins of the European and North African Variscids, where they persisted until the Stephanian B/C (middle Gzhelian).
• We hypothesize that gyroblattids lived mainly outside the basin centers that usually maintained ever-wet conditions. Instead, they may have existed in well-drained hinterland areas from where they immigrated with increasing seasonality during the Late Pennsylvanian. Gyroblattids likely followed meso- to xerophilous vegetational elements and preferably colonized relatively small basins, which offered more diverse edaphic conditions caused by the spatial tightness of erosional and depositional areas on a small scale.
• The large-winged gyroblattids and necymylacrids disappeared in the fossil record already in the latest Pennsylvanian (middle Gzhelian, middle Virgilian). At that time, more drought-resistant floras started to spread and increasingly dominated biomes with stronger seasonality and longer periods of dryness. Other blattoid insects adapted to these climate conditions with increasing elytrification, especially species of the genus Opsiomylacris in the early Permian. The increasing size reduction in phyloblattids is possibly linked to these environmental processes.
• To understand the insect‘s interactions with their environment and insect evolution in the permanently developing biosphere, more than venation-pattern descriptions and sophisticated statistics centered on taxonomic data are needed. The thorough revision of the fossil record is crucial to improving the reliability of any popular biodiversity estimation based on fossil taxa. In respect thereof, we revise all gyroblattid species and reduce the genera number from 12 to 1 and the species number from almost 20 to only 2. Concerning several historical finds, we provide photographs combined with appropriate drawings for the first time.