New Definition of Neoprotereunetes Fain et Camerik, Its Distribution and Description of the New Genus in Eupodidae (Acariformes: Prostigmata: Eupodoidea) ^†

Simple Summary

The mite genus Neoprotereunetes, long neglected in the literature, is revised according to modern taxonomic standards. Six species from both Arctic and Antarctic locations, previously placed in the genera Protereunetes or Eupodes, are transferred to Neoprotereunetes. The new genus Antarcteupodes is created to accommodate one Antarctic species A. maudae comb. nov, originally described in Protereunetes. An identification key to Neoprotereunetes is provided.

Abstract

The genus Neoprotereunetes Fain et Camerik, 1994 is revised and its definition is extended in order to incorporate some species of the invalid genus Protereunetes Berlese, 1923. The former type species Neoprotereunetes—Ereunetes lapidarius Oudemans, 1906 is redescribed and transferred to Filieupodes Jesionowska, 2010 (Cocceupodidae); Proterunetes boerneri is redescribed and designated the new type species. Two species groups are proposed to embrace Arctic and Antarctic species, respectively. Protereunetes paulinae Gless, 1972 is redescribed, whereas Protereunetes maudae Strandtmann, 1967 is redescribed and designated the type species of the new genus Antarcteupodes gen. nov. A key to the species of Neopretereunetes is provided.

1. Introduction

Superfamily Eupodoidea C.L. Koch, 1842 gathers mostly cosmopolitan, terrestrial, soft-bodied and often-colorful mites. Most of them are mycophagous, but there are also predacious (Rhagidiidae) and phytophagous groups (Penthaleidae and Penthalodidae). Some of them, like Penthaleus major (Dugès, 1834) (Penthaleidae) and Halotydeus destructor (Tucker, 1925) (Penthalodidae), are significant crop pests, whereas Linopodes sp. (Cocceupodidae) is considered an economic pest in mushroom houses [1]. Eupodoidea is divided into nine families: Eupodidae C.L. Koch, 1842; Rhagidiidae Oudemans, 1922; Penthaleidae Oudemans, 1931; Penthalodidae Thor, 1933; Strandtmanniidae Zacharda, 1979; Eriorhynchidae Qin et Halliday, 1997; Pentapalpidae Olivier et Theron, 2000; Dendrochaetidae Olivier, 2008 and Cocceupodidae Jesionowska, 2010 [2]. However, internal relationships among families within Eupodoidea remain uncertain [3].

Family Eupodidae C.L. Koch, 1842 currently includes 11 genera: Eupodes C.L. Koch, 1835; Benoinyssus Fain, 1958; Claveupodes Strandtmann et Prasse, 1976; Caleupodes Baker, 1987; Niveupodes Barillo, 1991; Neoprotereunetes Fain et Camerik, 1994; Aethosolenia Baker et Lindquist, 2002; Xerophiles Jesionowska, 2003; Pseudoeupodes Khaustov, 2014; Pseudopenthaleus Khaustov, 2015 and Echinoeupodes Khaustov, 2017. Genera Linopodes Koch, 1835 and Cocceupodes Thor, 1934 (previously in Eupodidae) along with one new genus Filieupodes (Jesionowska, 2010), were placed by Jesionowska [4] in the separate family Cocceupodidae Jesionowska, 2010, still within Eupodoidea.

Representatives of the genus Neoprotereunetes (as diagnosed herewith) are small, inconspicuous mites. Their bodies are pale white often with dark- to light-green-colored idiosoma, divided by a white medial longitudinal stripe, that apparently being an intestine, showing through the lucent integument. Two pigment eye spots occur on the prodorsum but do not preserve in permanent microscopic slides. These fast-moving mites inhabit soil, mosses, lichens, grasses and mammal nests, and have been observed feeding on algae [5].

The history of the genus is long and complex. The subgenus Protereunetes was erected within the genus Micrereunetes (Tydeoidea: Ereynetidae) by Berlese [6], with the type species M. (P.) agilis and another species, M. (P.) brevipes. Thor [7] raised Protereunetes to the generic rank and placed it in the family Eupodidae. Next, Thor and Willmann [8] included five species in Protereunetes: P. striatellus (C.L. Koch, 1838), P. lapidarius (Oudemans, 1906), P. agilis (Berlese, 1923), P. brevipes (Berlese, 1923) and P. börneri Thor, 1934. Subsequently, Fain [9] redescribed P. agilis and P. brevipes, showing them actually belonging in the genus Ereynetes Berlese, 1883 (Tydeoidea: Ereynetidae), meaning that Protereunetes is a junior synonym of Ereynetes. Regardless of that, in the next twenty years, some new eupodid species were still described in Protereunetes: P. minutus Strandtmann, 1967; P. maudae Strandtmann, 1967; P. crozeti Strandtmann et Davies, 1972 and P. paulinae Gless, 1972. Although Strandtmann [10], noticing the results of Fain’s study [9], transferred P. minutus to the genus Eupodes, he did not sustain his own view in subsequent papers [11,12]. This new combination, however, was widely accepted by subsequent authors, e.g., Goddard [13], Booth et al. [14], Baker [15]. Lastly, Fain and Camerik [16] created a new genus—Neoprotereunetes with the type species Neoprotereunetes lapidarius (Oudemans, 1906)—to bracket those species, which were described in Protereunetes until then and, unlike P. agilis and P. brevipes, belonged to the family Eupodidae. However, Fain and Camerik did not present any firm diagnosis for the new genus and only pointed at inaccurate and outdated definition of Protereunetes of Thor and Willmann [8]. Moreover, thanks to the present study, their designated type species, Neoprotereunetes lapidarius (Oudemans, 1906) appears to be a senior synonym of Filieupodes filistellatus Jesionowska, 2010, from the family Cocceupodidae (Eupodoidea). Neoprotereunetes as a genus-level taxon appeared in the literature only once more, in the revision of the family Eupodidae by Khaustov [17]. Thus, the aims of the present study are: (1) to redescribe Ereunetes lapidarius and correct its systematic position; (2) to provide new definition for the genus Neoprotereunetes; (3) to list species in this genus according to the revised diagnosis; (4) to designate its new type species; and (5) to create an identification key for the species within the genus.

2. Material and Methods

The material of Neoprotereunetes boerneri was extracted from soil samples using a Berlese–Tullgren funnel (photo-eclector) for one day and stored in 75% ethanol. Thereafter, specimens were cleared in lactic acid, mounted in Hoyer’s medium on glass slides and heated for 10–15 days at the temperature of 55 °C. The type material of Eupodes minutus, Protereunetes maudae and Protereunetes paulinae was loaned from collection at Bishop Museum in Honolulu (Hawaii) and the type material of Neoprotereunetes lapidarius was loaned from collection at Naturalis Biodiversity Center in Leiden (the Netherlands) (Figure 1). Mites were studied with a phase contrast (PC) (Olympus BX41, BX50) and differential interference contrast (DIC) (BX51) microscopes and identified using keys of Booth et al. [14], Jesionowska [4] and Khaustov [17], as well as original descriptions. Measurements were obtained from the specimens with the aid of an ocular micrometer and are given in micrometers (μm). The drawings were performed using a drawing tube (camera lucida) and processed in the Corel PHOTO-PAINT X5 program. Micrographs were taken using a Canon D5 Mk. II DSLR camera; pictures were assembled and processed with PICOLAY stacking software [18] or manually in Corel PHOTO-PAINT X5.

Morphological nomenclature for idiosoma and gnathosoma follows Baker and Lindquist [3]; for leg chaetotaxy, a universal Grandjean’s notation system, reviewed by Norton [19] and applied for eupodoids by Lindquist and Zacharda [20] and Baker [21], is used. The spine-like seta on tibia I is treated herein as a famulus, and thus designated by the Greek letter kappa (κ) rather than the Latin letter k, analogically to the famuli on tarsi I and II designated by the Greek letter epsilon (ε). Palpal and leg setal formulae are given from trochanters to tarsi with solenidia and famuli indicated in parentheses. The setae for basi- and telofemora are given separately, even when segment is not divided. The terms “long” and “short” related to dorsal hysterosomal setae mean values equal to or longer than the distance between members of a pair of setae and shorter than this distance, respectively. This excludes lateral hysterosomal setae, i.e., c₂, f₂ and h₂, and also setae f₁ and h₁, which are more tightly clustered at rear part of hysterosoma (caudal bent). Those are longer than remaining hysterosomal setae, and the latter in some eupodid genera (e.g., Benoinyssus, Aethosolenia) differentiated into trichobothria. Eupathidia are treated herein as setae (1) completely hollow, and (2) with a widely open base and designated by the Greek letter zeta (ζ), subtending the name of a seta. When a seta does not fulfill both conditions (e.g., it is partially hollow) it is then designated by “ζ?”. Abbreviations used: ap—subcapitular apodema, cpc—podocephalic canal, LL—lateral lip, LS—labrum, OE—esophagus, tr?—trachea?. Diagnoses and descriptions of taxa refer to adult females if not stated otherwise.

3. Results

3.1. Systematics

Superfamily Eupodoidea C.L. Koch, 1842

Family Eupodidae C.L. Koch, 1842

• Neoprotereunetes Fain et Camerik, 1994

Type species: Protereunetes boerneri Thor, 1934 by new designation.

Diagnosis. Sejugal furrow present. Idiosomal integument with striate-spiculate ornamentation. Internal vertical setae (v₁) inserted in common areolae, on well-delimited naso. Prodorsal trichobothria (sc₁) filiform and pilose. Hysterosomal setae short and pilose. No hysterosomal trichobothria. Coxisternal setal formula: 3–1–4–3. Six (or exceptionally five) pairs of genital setae in single row and none more lateral than others. Three pairs of pseudanal setae. Adanal setae absent. Four pairs of lyrifissures. Palpal setal formula: 0–2–3–9(ω). All legs shorter than body. Femora IV not enlarged. Leg integument with spiculate ornamentation. Tibiae I and II each with two rhagidial organs.

Description. Idiosomal dorsum. Sejugal furrow present. Integument with striate-spiculate ornamentation. Prodorsum bearing four pairs of setae: internal verticals (v₁), external verticals (v₂), internal scapulars (sc₁) and external scapulars (sc₂). Naso basally delimited from prodorsal shield and bearing setae v₁. Setae sc₁ trichobothrial, short, not reaching the posterior edge of naso, pilose. Remaining prodorsal setae short, pilose and inserted in typical areolae. Hysterosoma bearing eight pairs of dorsal setae: internal humerals (c₁), external humerals (c₂), first dorsals (d₁), second dorsals (e₁), internal lumbars (f₁), external lumbars (f₂), internal sacrals (h₁) and external sacrals (h₂). All hysterosomal setae short, pilose, inserted in typical areolae and none of them trichobothrial. Three pairs of dorsal lyrifissures (ia, im, ip) present.

Idiosomal venter. Coxisternal fields integument with weakly striate-spiculate ornamentation. Coxisternal setal formula: 3–1–4–3. Small cavities near outer margin of coxae I-III present. Genital aperture posteroventral, flanked by four or five pairs of aggenital setae (ag_{1-4 or -5}). Genital valves bearing six (or exceptionally five) pairs of genital setae (g_{1-6 (-5)}) of which the anterior first is longer than the second and the second is longer than the remaining ones. All setae g are always in single row and none more lateral than others. Internal genital structures consist of two pairs of genital papillae and four or six pairs of eugenital setae (eu_{1-4 or -6}) set on protuberances. Anal opening terminal, flanked by three pairs of pseudanal setae: ps_1,2 posteriorly (sometimes located terminally or dorsally) and shorter ps₃ anteriorly. No anal setae (an) on anal valves. One pair of ventral lyrifissures (ih) present.

Gnathosoma. Subcapitulum roughly triangular, bearing four pairs of setae: two pairs of pilose subcapitular setae (sbc_1,2) and two pairs of minute smooth adoral setae (or_{1, 2}). Setae sbc₁ usually thinner and shorter than sbc₂, both located along the base of each lateral lip, at antiaxial and paraxial end of subcapitular apodema, respectively. Setae or₁ and or₂ closely clustered at the tip of each lateral lip and often hard to discern. Apex of labrum acuminate. Chelicerae slender, bearing short, smooth dorsal seta cha. Palps four-segmented with weakly barbed supracoxal seta ep. Palpal setal formula: 0–2–3–9(ω). Tarsus laterally flattened, bearing nine setae: dorsal (d), two laterals (l′, l″), sublateral (sl″), anteroculminal (acm), two prorals (p′, p″), ventral (v), basal (ba) and small rhagidial organ ω.

Legs. Legs I and IV longer than II and III, but all shorter than body. Femora I subdivided ventrally, II undivided, III and IV divided. All apoteles with ambulacra, consisting of pad-like empodium with dense setulae arranged in bands on lateral margins and pair of hooked claws with short outgrows on its ventral surface. Integument with spiculate ornamentation. All setae densely pilose except for sparsely pilose v′ on trochanters I and II and weakly barbed supracoxal seta el. Solenidia and famuli. Leg I. Genu with one dorsomedial erect solenidion σ. Tibia with one anterior complex of rhagidial organ φ₁ and spiniform famulus κ, and one medial rhagidial organ φ₂, tandemly or obliquely in separated depressions. Tibial rhagidial organs long and T-shaped or L-shaped, or either short and ellipsoid to almost spherical. Tarsus with two rhagidial organs ω_1,2 and one stellate famulus ɛ, in tandem in confluent or separate depressions. Posterior one two to three times longer than anterior one. Leg II. Genu with or without medial, erect solenidion σ. Tibia with two rhagidial organs φ_1,2 (anterior and medial), tandemly in separate depressions. Tarsus with two or three rhagidial organs and with or without spiniform famulus ɛ, variously arranged. Mostly three rhagidial organs present, in confluent depression arranged alternately, i.e., anterior and posterior rhagidial organs situated antiaxially, whereas the medial one is situated paraxially. However, only two rhagidial organs can be present and situated obliquely in separate depressions or in tandem in confluent depression. Leg III. Genu without solenidion. Tibia with or without proximal rhagidial organ. Tarsus without rhagidial organs. Leg IV without solenidia.

Differential diagnosis. The genus resembles Caleupodes Baker, 1987 in having short dorsal setae, all legs shorter than the body, femora IV not enlarged and two rhagidial organs on both tibiae I and II. It differs from Caleupodes in having integument with striate-spiculate ornamentation (reticulate in Caleupodes), pilose dorsal setae (weakly serrate in Caleupodes), six or five genital setae (seven in Caleupodes) and three pairs of pseudanal setae (two in Caleupodes). Neoprotereunetes also shares some similarities with the genus Pseudoeupodes Khaustov, 2014, i.e., short dorsal setae, legs shorter than body and femora IV not enlarged. It differs from Pseudoeupodes in having five or six genital setae (six in Pseudoeupodes), three pairs of pseudanal setae (two in Pseudoeupodes), two rhagidial organs on both tibiae I and II (one rhagidial organ and one erect solenidion in Pseudoeupodes).

Species belonging to the genus Neoprotereunetes:

• Protereunetes boerneri Thor, 1934
• Protereunetes crozeti Strandtmann et Davies, 1972
• Eupodes exiguus Booth, Edwards et Usher, 1985
• Eupodes minutus (Strandtmann, 1967)
• Eupodes parvus Booth, Edwards et Usher, 1985
• Protereunetes paulinae Gless, 1972

Neoprotereunetes boerneri species group

Diagnosis. Genital region with five aggenital, six genital and six eugenital setae. Tarsus I with 21 setae (additional ventro-lateral antiaxial seta on tarsus I between setae pv″ and v₁″). Tarsus IV with 13 setae. Tibia I with five setae. Genua III and IV each with four setae. Femur I with 13 setae. Arctic and sub-Arctic distribution. Currently the group contains only one species (N. boerneri).

• Neoprotereunetes boerneri (Thor, 1934) comb. nov. (Figure 2, Figure 3, Figure 4, Figure 5, Figure 6 and Figure 7)

Protereunetes börneri [7,8]

Protereunetes boerneri [11,22]

Protereynetes boerneri (sic!) [23]

Neoprotereunetes borneri (sic!) [24]

Diagnosis. Genital region with five pairs of ag and six pairs of g setae. An extra ventro-lateral, antiaxial seta on tarsus I, located between setae pv″ and v₁″. Trochanter IV with one seta. Two rhagidial organs on tarsus II, slantwise in separated depressions. Proximal rhagidial organ on tibia I and II long, at most four times shorter than its segment.

Redescription. Female. Idiosoma 220 long, 113 wide.

Idiosomal dorsum (Figure 2 and Figure 7A). Prodorsal shield 57 long, 82 wide, triangular. Prodorsal integument with weakly striate-spiculate ornamentation, but course of striae hard to retrace. Naso (Figure 2 and Figure 7B) 9 long, 13 wide, rounded. Lengths of prodorsal setae: v₁ 9, v₂ 17, sc₁ ca. 40, sc₂ 16; distances: v₁–v₁ 3, v₂–v₂ 44, sc₁–sc₁ 29, sc₁–sc₁ 64. Hysterosoma tapering caudally, its frontal corners protruding laterally over prodorsum. Hysterosomal integument with striate-spiculate ornamentation. Lengths of hysterosomal setae: c₁ 11, c₂ 19, d₁ 11, e₁ 10, f₁ 12, f₂ 19, h₁ 17, h₂ 17; distances: c₁–c₁ 22, c₁–c₂ 44, d₁–d₁ 37, e₁–e₁ 24, f₁–f₁ 20, f₁–f₂ 20, h₁–h₁ 12, h₁–h₂ ca. 14.

Idiosomal venter (Figure 3 and Figure 7C). Coxisternal fields outlined, with weakly striate-spiculate ornamentation, separated medially by striate-spiculate ornamentation of longitudinal course. Lengths of coxisternal setae: 1a 12, 1b 14, 1c 9, 2b 11, 3a 10, 3b 11, 3c 11, 3d 11, 4a 9, 4b 10, 4c 10; distances: 1a–1a 19, 1b–1b 40, 1c–1c 65, 2b–2b 66, 3a–3a 15, 3b–3b 80, 3c–3c 90, 3d–3d 61, 4a–4a 20, 4b–4b 81, 4c–4c 57. Coxal cavities well defined. Genital region (Figure 4A) with five pairs of aggenital setae: ag₁ 8 long, ag_2-5 7 long, and six pairs and genital setae: g₁ 8 long, g₂ 7 long, g_3-6 6 long. Six pairs of eugenital setae, ca. 6 long, on protuberances (Figure 4B). Sternal (1a, 3a, 4a), genital, aggenital and ps₃ slightly expanded distally. Lengths of pseudanal setae: ps₁ 14, ps₂ 16, ps₃ 10.

Gnathosoma (Figure 4C–G and Figure 7D,E). Subcapitulum (Figure 4C) 66 long, 31 wide, slender, roughly triangular, with spiculate ornamentation. Subcapitular apodema not visible. Setae sbc₂ 8 long, densely pilose, thicker than sparsely pilose sbc₁, 3 long. Chelicerae (Figure 4D) 52 long, 15 wide, with spiculate ornamentation, bearing small smooth dorsal seta cha. Fixed digit with two pointed tips, ventral pointing forward and dorsal slightly curved backward; movable digit sharp, clawlike. Palps (Figure 4E–G and Figure 7D,E) with spiculate ornamentation, spiculate-cuspidate on femorogenu. Palpal femorogenu 30 long, with indication of division dorsolaterally (Figure 4E). Palp tibial seta l′ nearly twice as long as l″. Palpal tarsus 18 long, oval in lateral aspect, triangular in dorsoventral aspect. Setae d, l′, l″, v and ba pilose; setae sl″, acm, p′ and p″ smooth; rhagidial organ ω ellipsoid with proximal stock.

Legs (Figure 5, Figure 6 and Figure 7F–H). Lengths of legs: I 164, II 94, III 108, IV 140. Lengths of leg segments: I: Ts: 47, Tb 30, G 30, F 64, Tr 27; II: Ts 33, Tb 22, G 18, F 40, Tr 22; III: Ts 34, Tb 23, G 19, TF 15, BF 31, Tr 22; IV: Ts 36, Tb 29, G 24, TF 16, BF 39, Tr 29. Integument with spiculate ornamentation, spiculate-cuspidate on basifemur III and from tibia to trochanter of leg IV. Leg setal formulae: I: 1–8+5–6(σ)–5(2φ, κ)–21(2ω, ɛ); II: 1–5+5–4(σ)–5(2φ)–13(2ω, ɛ); III: 1–4+4–4–5(φ)–12; IV: 1–3+3–4–5–13. Leg eupathidial setae: I: Tb: all except v′; Ts: all except (v₃) II: Tb: d, l″; Ts: all except tc″ and it″; III: Tb: d, v′; Ts: it′, (p); IV: G: l′; Tb: d, l′, v′; Ts: tc. Solenidia and famuli. Leg I. Genu with one dorsomedial erect solenidion σ. Tibia with one anterior complex of L-shaped rhagidial organ φ₁, 6 long, plunge into integument basally and spiniform famulus κ, and one medial T-shaped rhagidial organ φ₂, 11 long, obliquely in separated depressions. Tarsus with two rhagidial organs and one stellate famulus ɛ, obliquely in confluent depression. Posterior one (ω₁) T-shaped, 10 long and anterior one (ω₂) L-shaped, 4 long. Leg II. Genu with one dorsomedial erect solenidion σ. Tibia with two rhagidial organs (L-shaped φ₁, 4 long and T-shaped φ₂, 6 long), tandemly in separated depressions. Tarsus with two rhagidial organs (T-shaped ω₁, 10 long and L-shaped ω₂, 4 long), obliquely in separated depressions. Posterior one (ω₁) subtended by spiniform famulus ɛ. Leg III. Tibia with proximal T-shaped rhagidial organ φ, 6 long.

Tritonymph. Body length 214. Four and three pairs of ag and g setae, respectively; eu setae absent. Leg setal formulae: I: 1–6+5–6(σ)–5(2φ, κ)–18(2ω, ɛ); II: 1–5+5–4(σ)–5(2φ)–12(2ω, ɛ); III: 1–4+4–4–5(φ)–10; IV: 1–3+3–4–5–11. Other characters as in adults.

Deutonymph. Body length 198. Coxisternal setal formula: 3–1–3–2. Two pairs of both ag and g setae; eu setae absent. Leg setal formulae: I: 1–5+5–4(σ)–5(2φ, κ)–17(2ω, ɛ); II: 1–3+5–4(σ)–5(2φ)–12(2ω, ɛ); III: 1–2+4–4–4(φ)–10/11; IV: 0–1+3–4–4–11. Other characters as in adults.

For male, protonymph and larva see [11].

Differential diagnosis. N. boerneri resembles N. parvus by presence of two rhagidial organs on tarsus II. It differs from N. parvus in having five pairs of ag setae (four in N. parvus), one seta on trochanter IV (lacking in N. parvus) and long proximal rhagidial organs on tibiae I-III (short on tibia I and II, and lacking on tibia III in N. parvus).

Distribution. Temple Bay, “Grosser Trichter”, Magdalena Bay, Spitsbergen, Svalbard, Norway [7]; Utqiaġvik (formerly Barrow), Anaktuvuk Pass, Wainwright, Alaska, USA [11]; Bolshevik Island, Severnaya Zemlya, Russia [22].

Material examined. Four females, one tritonymph and one deutonymph: Svalbard, Spitsbergen, mountain slope, NW exposition, 150 m a.s.l., 78°14′08″ N 15°20′05″ E, soil in vicinity of little auk (Alle alle) rookery, 17 July 2022, leg. K. Zawierucha, M. Zacharyasiewicz, M. Jastrzębski.

Remarks. The original description lacks some valid diagnostic characters and thus the species is redescribed herewith. The type material of N. boerneri does not exist ([25], 408 p.; correspondence with Dr. Vladimir Gusarov, Natural History Museum, University of Oslo), but the specimens collected from Spitsbergen fully fit the original description and figures by Thor [7].

The species was redescribed by Strandtmann [11] on the basis of specimens collected from tundra and from the nests of brown lemming (Lemmus trimucronatus) in Alaska. The Strandtmann’s material was not available for this study, but no significant differences between the specimens from Alaska and those from Svalbard were found.

N. boerneri possesses a unique character, i.e., one extra ventro-lateral, antiaxial seta on tarsus I, located between setae pv″ and v₁″. An additional tarsal seta is present in yet another eupodid species, Echinoeupodes echinus Khaustov, 2017. In that species additional seta (designted as “vs” by Khaustov [26]) is situated ventrally, between the pair of pv setae, and occurs on tarsi of all four legs. As it is hard to determine whether these two cases deal with homologous setae, the extra seta is marked only with an asterisk (*) in our study (Figure 5B and Figure 7G).

Neoprotereunetes minutus species group

Diagnosis. Genital region with four aggenital, six (or exceptionally five) genital and four eugenital setae. Tarsus I with 20 setae. Tarsus IV with 11 setae. Tibia I with four setae. Genu III with two or three setae. Genu IV with three setae. Femur I with 12 setae. Antarctic and sub-Antarctic distribution.

• Neoprotereunetes crozeti (Strandtmann et Davies, 1972) comb. nov.

Protereunetes crozeti [12,22,27]

Diagnosis. Genital region with four pairs of ag and six pairs of g setae. Trochanter IV with one seta. Tarsus II with three rhagidial organs and without spiniform famulus. Both tarsal rhagidial organs in separate depressions. Proximal rhagidial organs on tibia I and II long, at most four times shorter than its segment. No rhagidial organs on tibia III.

Differential diagnosis. N. crozeti resembles N. minutus by long proximal rhagidial organs on tibiae and lack of famulus on tarsus II. It differs from N. minutus in lacking proximal rhagidial organ on tibia III (present in N. minutus) and in arrangement of tarsal rhagidial organs. On tarsus I, in N. crozeti tip of antiaxial ω₁ and base of paraxial ω₂ overlap, whereas in N. minutus both are situated medially in tandem. On tarsus II, in N. crozeti ω₂ and ω₃ lie side by side and in N. minutus ω₃ is displaced anteriorly in relation to ω₂.

Distribution. Possession Island, Crozet Islands, ATF [12].

Material examined. None.

Remarks. The original description lacks some valid diagnostic characters, but as the type- or any other material was not available for this study, only standardized diagnosis is given. There is no information on type material deposition in the original paper. It is not deposited in Bishop Museum (courtesy of Dr. Jeremy Frank, Entomology Collections Manager at Bishop Museum).

• Neoprotereunetes exiguus (Booth, Edwards et Usher, 1985) comb. nov.

Eupodes exiguus [14,22,27]

Diagnosis. Genital region with four pairs of ag and six pairs of g setae. Trochanter IV with one seta. Tarsus II with three rhagidial organs and spiniform famulus. Both tarsal rhagidial organs in confluent depressions. Proximal rhagidial organs on tibiae I–III short, at least seven times shorter than their segment.

Differential diagnosis. N. exiguus resembles N. parvus by very short, globular proximal rhagidial organs on tibiae, and T-shaped rhagidial organs on tarsi I and II. It differs from N. parvus in number of rhagidial organs on tarsus II (two instead of three) as well as in presence of rhagidial organ on tibia III and seta on trochanter IV (both absent in N. parvus).

Distribution. Signy Island, South Orkney Islands [14]; South Shetland Islands [28].

Material examined. One female and one male: King George Island, South Shetland Islands, 62°05′00″ S, 58°23′28″ W, Grasses near the Comandante Ferraz Antarctic Station, 8 February 2016, leg. D.J. Gwiazdowicz.

Remarks. The original description contains all valid diagnostic characters and thus only standardized diagnosis is given.

• Neoprotereunetes minutus (Strandtmann, 1967) comb. nov.

Protereunetes minutus [29]

Eupodes minutus [10,13,14,22,27,30,31,32]

Diagnosis. Genital region with four pairs of ag and six pairs of g setae. Trochanter IV with one seta. Tarsus II with three rhagidial organs and without spiniform famulus. Both tarsal rhagidial organs in confluent depressions. Proximal rhagidial organs on tibiae I and II at most four times shorter than their segment.

Differential diagnosis. N. minutus closely resembles N. crozeti, by long proximal rhagidial organs on tibiae and lack of famulus on tarsus II. N. minutus, however, possess a proximal rhagidial organ on tibia III (lacking in N. crozeti). Additionally, the arrangement and shape of rhagidial organs is different in these two species. On tarsus I, in N. minutus ω₁ and ω₂ lie parallel, while in N. crozeti they lie in tandem. On tarsus II, in N. minutus ω₃ is displaced anteriorly in relation to ω₂ and in N. crozeti ω₂ and ω₃ lie side by side.

Distribution. Anvers Island, Palmer Archipelago [29]; Signy Island, South Orkney Islands [14]; Dunedin, New Zeland [30]; Marion Island, Prince Edward Islands, South Africa [31]; King George Island, Halfmoon Island, Deception Island, South Shetland Islands [28].

Material examined. Holotype male (Bishop Museum, slide labeled “BBM 7055”): Antarctic Peninsula, Anvers Island, Norsel Point, 64°30′ S 63°30′ W, under stones and mosses, March 17. 1965, Coll. D. Strong; one female: King George Island, South Shetland Islands, 62°05′00″ S, 58°23′28″ W, Grasses near the Comandante Ferraz Antarctic Station, 8 February 2016, leg. D.J. Gwiazdowicz.

Remarks. The redescription by Booth et al. [14] contains all valid diagnostic characters and thus only a standardized diagnosis is given here.

Except the type locality, records published before 1985 are not included as suggested in [14].

Mites collected from subalpine grasslands of Mt. Aso and Mt. Kamegamori in Japan were identified by Shiba [33] as P. minutus. However, the depicted specimen does not fully agree with the original description and figures as well as the holotype of P. minutus. It has shorter rhagidial organs on tibiae I and II and shows rather unusual solenidiotaxy of tibia II (two rhagidial organs and one erect solenidion; see [33], Figure 7e), which does not occur in any other eupodoid species. As the solenidiotaxy of tibiae is not commented in the description and thus cannot be confronted with that figure, this record remains dubious.

Luxton [30] recorded N. minutus from Dunedin, New Zeland and refered this species to Eupodes antipodus (Womersley, 1937). As no nomenclatorial act was established or synonymy commented it is not included here.

• Neoprotereunetes parvus (Booth, Edwards et Usher, 1985) comb. nov.

Eupodes parvus [14,22,27]

Diagnosis. Genital region with four pairs of ag and six pairs of g setae. Tarsus II with two rhagidial organs and spiniform famulus. Both tarsal rhagidial organs in confluent depressions. Proximal rhagidial organs on tibia I and II short, at least seven times shorter than its segment. No rhagidial organs on tibia III. Trochanter IV without setae.

Differential diagnosis. N. parvus resembles N. exiguus by short proximal rhagidial organs on tibiae and T-shaped rhagidial organs on tarsi I and II. It differs from N. exiguus in number of rhagidial organs on tarsus II (two instead of three) as well as in absence of rhagidial organ on tibia III and seta on trochanter IV (both present in N. exiguus).

Distribution. Signy Island, South Orkney Islands, South Shetland Islands, Antarctic Peninsula [14]; King George Island and Ardley Island [28].

Material examined. One female and one male: King George Island, South Shetlands, the Antarctic, 62°09′49″ S 58°27′57″ W, nest of the south polar skua (S. maccormicki), 27, 28, 31 January 2016, leg. D.J. Gwiazdowicz.

Remarks. The original description contains all valid diagnostic characters, and therefore only a standardized diagnosis is given here.

Two subspecies of N. parvus were proposed by Booth et al. [14]: N. parvus parvus from South Orkney Islands and N. parvus grahamensis from South Shetland Islands and Antarctic Peninsula, which differs from nominative subspecies only in body length and lengths of idiosomal setae (see [14]).

• Neoprotereunetes paulinae (Gless, 1972) comb. nov. (Figure 8, Figure 9, Figure 10, Figure 11, Figure 12 and Figure 13)

Protereunetes paulinae [5,22,27]

Diagnosis. Genital region with four pairs of ag and five pairs of g setae. Trochanter IV without setae. Tarsus II with three rhagidial organs and spiniform famulus. Rhagidial organs on tarsi I and II in confluent depression. Proximal rhagidial organs on tibia I and II short, at least seven times shorter than its segment.

Redescription. Holotype female. Idiosoma 268 long, 178 wide.

Idiosomal dorsum (Figure 8 and Figure 13A). Prodorsal shield (Figure 13B) 64 long, 80 wide, triangular. Prodorsal integument with weakly striate-spiculate ornamentation, but course of striae hard to retrace. Naso 10 long, 20 wide, rounded. Lengths of prodorsal setae: v₁ 11, v₂ 20, sc₁ ca. 47, sc₂ 19; distances: v₁–v₁ 3, v₂–v₂ 49, sc₁–sc₁ 34, sc₂–sc₂ 73. Hysterosoma tapering caudally, its frontal corners protruding laterally over prodorsum. Lengths of hysterosomal setae: c₁ 16, c₂ 21, d₁ 16, e₁ 15, f₁ 18, f₂ 22, h₁ 24, h₂ 23; distances: c₁–c₁ 26, c₁–c₂ 65, d₁–d₁ 42, e₁–e₁ 41, f₁–f₁ 30, f₁–f₂ 22, h₁–h₁ 17, h₁–h₂ 19. Prodorsal integument with weakly striate-spiculate ornamentation, hysterosomal ornamentation striate-spiculate.

Idiosomal venter (Figure 9 and Figure 13A). Coxisternal fields outlined with weakly striate-spiculate ornamentation, separated medially by striate-spiculate ornamentation of longitudinal course. Lengths of coxisternal setae: 1a 12, 1b 17, 1c 10, 2b 15, 3a 11, 3b 15, 3c 16, 3d 17, 4a 11, 4b 15, 4c 17; distances: 1a–1a 12, 1b–1b 46, 1c–1c 70, 2b–2b 75, 3a–3a 26, 3b–3b 77, 3c–3c 99, 3d–3d 114, 4a–4a 27, 4b–4b 67, 4c–4c 95. Genital region (Figure 10A and Figure 13C) with four pairs of aggenital setae: ag₁ 10 long, ag₂ 9 long, ag_3-4 6 long, and five genital setae: g₁ 13 long, g₂ 8 long, g_3-4 5 long, g₃ 6 long. Four pairs of eu setae, 6 long, on protuberances. Sternal setae (1a, 3a, 4a), genital, aggenital and ps₃ setae slightly expanded distally. Lengths of pseudanal setae: ps₁ 19, ps₂ 19, ps₃ 14.

Gnathosoma (Figure 10B–E and Figure 13D,E). Subcapitulum (Figure 10B) 51 long, 40 wide, slender, roughly triangular, with spiculate ornamentation. Subcapitular apodema visible under integument. Setae sbc₁ 10 long, sbc₂ 9 long, densely pilose, subequal. Chelicerae (Figure 10C) 60 long, 20 wide, with spiculate ornamentation, bearing small smooth dorsal seta cha; fixed digit with two pointed tips directed forward; movable digit sharp, clawlike. Palps (Figure 10D,E) 92 long, with spiculate ornamentation, spiculate-cuspidate on femorogenu. Palpal femorogenu 36 long. Palpal tibia 20 long, seta l″ 2/3 length of l′. Palpal tarsus 19 long, oval in lateral aspect, triangular in dorsoventral aspect. Setae d, l′, l″, sl″, v and ba pilose; setae acm, p′ and p″ smooth; rhagidial organ ω ellipsoid with proximal stock.

Legs (Figure 11, Figure 12 and Figure 13F,G). Lengths of legs: I 193, II 147, III 149, IV 190. Lengths of leg segments: I: Ts 68, Tb 32, G 29, F 71, Tr 28; II: Ts 43, Tb 25, G 23, F 50, Tr 23; III: Ts 46, Tb 26, G 22, TF 188, BF 35, Tr 25; IV: Ts 48, Tb 37, G 29, TF 25, BF 47, Tr 30. Integument with spiculate ornamentation, spiculate-cuspidate on basifemur III and from tibia to trochanter of leg IV. Leg setal formulae: I: 1–7+5–6(σ)–5(2φ, κ)–20(2ω, ɛ); II: 1–5+5–4(σ)–5(2φ)–13(3ω, ɛ); III: 1–4+4–3–4(φ)–12; IV: 0–3+3–3–5–11. Leg eupathidial setae: I: Tb: (l) Ts: all except (v₃); II: Ts: tc′, (p); III: Tb: d, v″; Ts: (p); IV: G: l′; Tb: d, l′; Ts: (p).

Solenidia and famuli. Leg I. Genu with dorsomedial erect solenidion σ. Tibia with one anterior rhagidial organ φ₁ 3 long, associated with spiniform famulus κ and one medial, globular rhagidial organ φ₂ 1 long, in separate depressions. Tarsus with two T-shaped rhagidial organs: ω₁ 9 long, ω₂ 6 long, and stellate famulus ɛ, tandemly in confluent depression. Leg II. Genu with dorsomedial erect solenidion σ. Tibia with one short dorsodistal rhagidial organ φ₁ 3 long and dorsomedial globular rhagidial organ φ₂ 1 long. Tarsus with three T-shaped rhagidial organs ω₁ 7 long, ω_2,3 5 long, tandemly in confluent depression, subtended by spiniform famulus ɛ. Leg III. Tibia with globular rhagidial organ φ 1 long.

Differential diagnosis. N. paulinae resembles N. parvus by lack of seta on trochanter IV and short, globular proximal rhagidial organs on tibiae I and II. It differs from N. parvus in number of genital setae (five instead of six) and number of rhagidial organs on tarsus II (three instead of two).

Distribution. Hallett Peninsula, Antarctica [5].

Material examined. Holotype female (Bishop Museum, slide labeled “Bishop 7986”): Hallett Peninsula, Cape Hallett, about 1000 m southeast of Hallett Station on a talus slope, 72°20′ S 170°10′ E, loose soil in north shadow of rock, 25 December 1966, leg. E. Gless.

Remarks. Chaetotaxy of holotype differs significantly from that in original description by Gless [5]. The most apparent seems to be the discrepancy in genital chaetotaxy, i.e., six genital setae in original description and undoubtedly five in holotype female (Figure 10A and Figure 13C). On one hand, this can be attributable to misfortunate arrangement of the last pair of eugenital setae (eu₄) which is everted outward the progenital chamber and supplants, (evidently lacking) last pair of genital setae (g₆). On the other hand, the depicted body ventral side of a female and genital region of a male in the original paper (Figures 32 and 33 in [5]) clearly show six pairs of genital setae in both sexes. As no other specimens of N. paulinae are available for this study, it is impossible to decide if it is a both-sided anomaly in holotype or typical state of the species, and thus this character is excluded from the couplet No. 4 of the key.

Species formerly listed as, but not belonging to the genus Neoprotereunetes according to the newly proposed diagnosis:

• Ereunetes lapidarius Oudemans, 1906: a senior synonym of Filieupodes filistellatus Jesionowska, 2010 (Cocceupodidae).
• Protereuntes maudae Strandtmann, 1967: transferred herewith to the new genus Antarcteupodes gen. nov.
• Protereunetes turgidus Shiba, 1978: transferred by Khaustov (2017) to the genus Echinoeupodes Khaustov, 2017.
• Protereunetes villosus Shiba, 1978: probably belongs to the genus Benoinyssus Fain, 1958.
• Protereunetes perforatus Shiba, 1978: resembles Caleupodes reticulatus Baker, 1987, but it differs in body size and form of solenidia.

Species Inquirenda

Protereunetes striatellus (C.L. Koch, 1838): the species description is not sufficient to determine its generic affiliation and the type material most probably does not exist.

• Antarcteupodes Laniecki gen. nov.

Type species: Protereunetes maudae Strandtmann, 1967; monobasic.

Diagnosis. Sejugal furrow present. Idiosomal integument with lightly striate-spiculate ornamentation. Internal vertical setae (v₁) inserted in bothridia, on well-delimited naso. Prodorsal trichobothria (sc₁) filiform and pilose. Hysterosomal setae short, thin and setose. No hysterosomal trichobothria. Coxisternal setal formula: 3–1–3–2. Six pairs of genital setae in single row and none more lateral than others. Three pairs of pseudanal setae. Adanal setae absent. Four pairs of lyrifissures. Palpal setal formula: 0–2–3–8(ω). All legs shorter than body. Femora IV not enlarged. Leg integument with striate-spiculate ornamentation. Tibiae I and II each with one distal rhagidial organ and one proximal erect solenidion.

Description. Idiosomal dorsum. Sejugal furrow present. Integument with lightly striate-spiculate ornamentation. Prodorsum bearing four pairs of setae: v₁, v₂, sc₁ and sc₂. Naso basally delimited from prodorsal shield and bearing short setae v₁ inserted in bothridia. Setae sc₁ trichobothrial, short, not reaching the posterior edge of naso. Remaining prodorsal setae short, setose, inserted in typical areolae and none of them trichobothrial. Hysterosoma bearing eight pairs of dorsal setae: c₁, c₂, d₁, e₁, f₁, f₂, h₁ and h₂. All hysterosomal setae short, thin and setose. Three pairs of dorsal lyrifissures (ia, im, ip) present.

Idiosomal venter. Coxisternal fields integument with weakly striate-spiculate ornamentation. Coxisternal formula: 3–1–3–2; setae 3d and 4c not present. Small cavities near outer margin of coxae I-III present. Genital aperture postero-ventral, flanked by five pairs of aggenital setae (ag_1-5). Genital valves bearing six pairs of genital setae (g_1-6) of which anterior first is longer than second and second is longer than remaining ones. All setae g in single row and none more lateral than others. Internal genital structures consisting of two pairs of genital papillae and six pairs of eugenital setae (eu_1-6) set on protuberances. Anal opening terminal, flanked by three pairs of pseudanal setae: ps_1, 2, posteriorly and shorter ps₃, anteriorly. No anal setae (an) on anal valves. One pair of ventral lyrifissures (ih) present.

Gnathosoma. Subcapitulum roughly triangular, squat bearing four pairs of setae: two pairs of setose subcapitular setae (sbc_1,2) and two pairs of minute smooth adoral setae (or_1, 2). Setae sbc₁ thinner and shorter than sbc₂, both located along the base of each lateral lip, at antiaxial and paraxial end of subcapitular apodema, respectively. Setae or₁ and or₂ closely clustered at the tip of each lateral lip and hard to discern. Apex of labrum acuminate. Chelicerae thick, bearing long, nude dorsal seta cha. Palps four-segmented with weakly barbed supracoxal seta ep. Palpal setal formula: 0–2–3–8(ω). Palparsus laterally flattened, bearing eight setae: d, l′, l″, acm, p′, p″, v, ba and small rhagidial organ ω; seta sl″ not present. Cheliceral and palpal ornamentation spiculate (spiculate-cuspidate on palpal femorogenu).

Legs. Legs I and IV longer than II and III, but all shorter than body. Femora of I and II leg undivided. Femora III and IV divided. All apoteles consist of pad-like empodium with dense setulae arranged in bands on lateral margins and pair of hooked claws with short outgrows on its ventral surface. Integument with striate-spiculate ornamentation. All setae setose except weakly barbed supracoxal seta el. Solenidia and famuli. Leg I. Genu with one dorsomedial erect solenidion σ. Tibia with one anterior complex of short ellipsoid rhagidial organ φ and weakly furcate famulus κ, and one proximal short erect solenidion. Tarsus with two L-shaped rhagidial organs (ω) and one small weakly stellate famulus ɛ, tandemly in separated depressions. Leg II. Genu without solenidion. Tibia with one ellipsoid rhagidial organ φ and one proximal erect solenidion. Tarsus with three L-shaped rhagidial organs and with weakly furcate famulus ɛ, arranged alternately, i.e., anterior and posterior rhagidial organs situated antiaxially, whereas medial one—paraxially, each in separated depression. Leg III. Genu without solenidion. Tibia with proximal erect solenidion φ. Tarsus without rhagidial organs. Leg IV. Genu without solenidion. Tibia with proximal erect solenidion φ. Tarsus without rhagidial organs.

Differential diagnosis. The new genus is similar to Pseudoeupodes Khaustov, 2014 because of legs shorter than body, femora IV not enlarged, short dorsal setae, and number and location of genital setae. It differs from Pseudoeupodes by internal vertical setae located in bothridia (in common areolae in Pseudoeupodes), coxisternal formula: 3–1–3–2 (3–1–4–2 in Pseudoeupodes) and three pairs of pseudanal setae (two in Pseudoeupodes). It resembles also Neoprotereunetes Fain et Camerik, 1994 in having short dorsal setae, same number and location of genital setae, all legs shorter than body, and not enlarged femora IV. It differs from Neoprotereunetes in internal vertical setae located in bothridia (in common areolae in Neoprotereunetes), coxisternal formula: 3–1–3–2 (3–1–4–3 in Neoprotereunetes) and in presence of one rhagidial organ and one erect solenidion on both tibiae I and II (two rhagidial organs in Neoprotereunetes).

• Antarcteupodes maudae (Strandtmann, 1967) comb. nov. (Figure 14, Figure 15, Figure 16, Figure 17, Figure 18, Figure 19 and Figure 20)

Protereunetes maudae [22,27,29]

Redescription. Holotype female. Idiosoma flattened and ruptured along its right margin, 360 long, ca. 220 wide.

Idiosomal dorsum (Figure 14 and Figure 20A). Prodorsal shield 74 long, 100 wide, triangular. Prodorsal integument with weakly striate-spiculate ornamentation, but course of striae hard to retrace. Naso (Figure 20B) 15 long, 28 wide, rounded. A pair of canals, probably representing tracheae (tr?), extending from anterior end of idiosoma to posterior corners of prodorsum (Figure 14). Lengths of prodorsal setae: v₁ 18, v₂ 14, sc₁ ca. 40, sc₂ 18; distances: v₁–v₁ 8, v₂–v₂ 60, sc₁–sc₁ 37, sc₂–sc₂ 92. Hysterosoma roughly rectangular, slightly rounded caudally. Lengths of hysterosomal setae: c₁ 14, c₂ 24, d₁ 14, e₁ 14, f₁ 19, f₂ 20, h₁ 24, h₂ 23; distances: c₁–c₁ 50, c₁–c₂ 78, d₁–d₁ 58, e₁–e₁ 63, f₁–f₁ 52, f₁–f₂ 33, h₁–h₁ 22, h₁–h₂ 27. Prodorsal and hysterosomal integument with lightly striate-spiculate ornamentation.

Idiosomal venter (Figure 15 and Figure 20C). Coxisternal fields outlined, with weakly striate-spiculate ornamentation, separated medially by striate-spiculate ornamentation of longitudinal course. Lengths of coxisternal setae: 1a 14, 1b 16, 1c 10, 2b 13, 3a 12, 3b 15, 3c 15, 4a 10, 4b 15; distances: 1a–1a 27, 1b–1b 69, 1c–1c 97, 2b–2b 82, 3a–3a 39, 3b–3b 92, 3c–3c 122, 4a–4a 42, 4b–4b 104. Coxal cavities weakly defined, half-open. Genital region (Figure 16A) with five pairs of aggenital setae: ag₁ 10 long, ag₂ 9 long, ag_3-4 8 long, ag₅ 7 long, and six pairs of genital setae: g₁ 10 long, g₂ 9 long, g_3-6 7 long. Six pairs of eugenital setae, ca. 10 long, on protuberances (Figure 16B). Genital, aggenital and ps₃ setae slightly expanded distally. Lengths of pseudanal setae: ps₁ 24, ps₂ 19, ps₃ 9.

Gnathosoma (Figure 16C, Figure 17A–C and Figure 20D,E). Subcapitulum (Figure 17A) 47 long, 50 wide. Border between lateral lips and subcapitular base visible under integument. Setae sbc₂ 7 long, setose, thicker than sparsely setose sbc₁ 5 long. Chelicerae (Figure 16C) 70 long, 29 wide, with small smooth dorsal seta cha; fixed digit with two pointed tips directed forward; movable digit sharp, clawlike. Palps (Figure 17B,C and Figure 20D,E) 118 long, with striate-spiculate ornamentation, spiculate-cuspidate on femorogenu. Palpal femorogenu 50 long. Palpal tibia 25 long, seta l″ 2/3 length of two times thicker l′. Palpal tarsus 37 long, ellipsoid in dorsoventral aspect. Setae d, l′, l″, v and ba pilose; setae acm, p′ and p″ smooth; rhagidial organ ω minute, protruding on both tarsi in dorsoventral view. Subcapitular, cheliceral and palpal integument with striate-spiculate ornamentation (spiculate-cuspidate on palpal femorogenu).

Legs (Figure 18, Figure 19 and Figure 20F,G). Lengths of legs: I 247, II 197, III 200, IV 255. Lengths of leg segments: I: Ts 64, Tb 45, G 35, F 88, Tr 35; II: Ts 53, Tb 34, G 30, F 68, Tr 28; III: Ts 53, Tb 37, G 27, TF 30, BF 38, Tr 32; IV: Ts 63, Tb 43, G 35, TF 35, BF 60, Tr 43. Integument with striate-spiculate ornamentation, spiculate-cuspidate on basifemur of leg III and from genu to basifemur of leg IV. Leg setal formulae: I: 1–3+5–4(σ)–5(2φ, κ)–17(2ω, ɛ); II: 1–2+5–4–5(2φ)–11(3ω, ɛ); III: 1–2+3–3–3(φ)–11; IV: 1–2+3–3–4(φ)–9. Eupathidial setae: I: Tb: all; Ts: all and v₂″?; II: Tb: d (only on left leg), l″, v″; Ts: all; III: Tb: d?, v′?; Ts: all and (tc)? (it)?; IV: Tb: d?; Ts: all and tc?, (it)?. Solenidia and famuli as in generic description. Lengths of rhagidial organs: leg I: φ₁ 4, ω₁ 8, ω₂ 5; leg II: φ₁ 4, ω₁ 8, ω₂ 8, ω₃ 8.

Distribution. Victoria Land, Antarctica [29].

Material examined. Holotype female (Bishop Museum, slide labeled “BBM 7056”): Shackleton Glacier area, north of Garden Spur, east side of Massam Glacier, 457 m elevation, 84°33′ S 174°40′ E, 15 December 1964, leg. J. Shoup.

Remarks. The species is characterized by the unique combination of character states, not present in any hitherto described eupodid genus, including the most reduced coxisternal and leg chaetotaxy among the family Eupodidae, and sufficient to represent a separate genus.

Family: Cocceupodidae Jesionowska, 2010

Filieupodes Jesionowska, 2010

Type species: Filieupodes filiformis Jesionowska, 2010 by original designation.

• Filieupodes lapidarius (Oudemans, 1906) comb. nov. (Figure 21, Figure 22, Figure 23, Figure 24, Figure 25 and Figure 26)

Ereunetes lapidarius [34]

Ereynetes lapidarius [35,36]

Micrereunetes (Protereunetes) lapidarius [6]

Protereunetes lapidarius [7,8,11]

Neoprotereunetes lapidarius [16,22]

Filieupodes filistellatus Jesionowska, 2010 syn. nov.

Diagnosis. Naso well delimited. Dorsal hysterosomal setae short. Tarsus I with two parallel rhagidial organs in separate depressions, of which proximal one posterolaterad of distal one. Stellate famulus well removed proximo-laterally from proximal rhagidial organ. Tarsus II with three parallel rhagidial organs in separate depressions, of which medial one posterolaterad of proximal and distal ones. Spiniform famulus well removed laterally from proximal rhagidial organ.

Redescription. Holotype female. Idiosoma 330 long, 200 wide.

Idiosomal dorsum (Figure 21 and Figure 26A). Prodorsal shield (Figure 26B) 74 long, 100 wide, triangular. Prodorsal integument with weakly striate-spiculate ornamentation, but course of striae hard to retrace. Naso 15 long, 28 wide, rounded. Lengths of prodorsal setae: v₁ 34, v₂ 22, sc₁ ca. 50, sc₂ 25. Hysterosoma oval. Hysterosomal integument with striate-spiculate ornamentation. Lengths of hysterosomal setae: c₁ 24, c₂ 40, d₁ 27, e₁ 30, f₁ 40, f₂ 33, h₁ 41, h₂ 27.

Idiosomal venter (Figure 22). Coxisternal fields poorly outlined, with weakly striate-spiculate ornamentation, separated medially by striate-spiculate ornamentation of longitudinal course. Lengths of coxisternal setae: 1a 18, 1b 20, 1c 13, 2b 26, 3a 18, 3b 18, 3c 20, 3d 18, 4a 13, 4b 16, 4c 15. Genital region (Figure 23A and Figure 26C) with four pairs of aggenital setae, ag 9 long, g 10 long and six pairs of genital setae, all ca. 10 long. Two pairs of genital papillae and five pairs of eugenital setae, 8 long, on protuberances. Lengths of pseudanal setae: ps₁ 32, ps₃ 15. Lyrifissures ih not visible.

Gnathosoma (Figure 23B–D and Figure 26D,E). Subcapitulum (Figure 23B) 52 long, 46 wide roughly triangular, with striate-spiculate ornamentation. Subcapitular apodema visible under integument. Setae sbc₂, 9 long, subequal to sbc₁, 12 long, both pilose. Chelicerae (Figure 23C) 60 long, with spiculate ornamentation, bearing pilose dorsal seta cha; fixed digit with blunt tip; movable digit sharp, clawlike. Palps (Figure 23D and Figure 26D,E) with spiculate ornamentation. Palpal femorogenu 29 long. Palpal tibia 33 long, setae l″ and l′ subequal in length. Palpal tarsus 20 long, ellipsoid in dorsoventral aspect. All setae except acm smooth; rhagidial organ ω small, protruding on both tarsi in dorsoventral view. Subcapitular, cheliceral and palpal integument with spiculate ornamentation (spiculate-cuspidate on palpal femorogenu).

Legs (Figure 24, Figure 25 and Figure 26F,G). Lengths of legs: I 315, II 198, III 221, IV 255. Lengths of leg segments: I: Ts 77, Tb 64, G 51, F 112, Tr 27; II: Ts 58, Tb 37, G 24, F 74, Tr 20; III: Ts 62, Tb 37, G 32, TF 29, BF 41, Tr 20; IV: Ts 72, Tb 46, G 51, TF 23, BF 64, Tr 23. Integument with spiculate ornamentation. Leg setal formulae: I: 1–6+5–8–13(2φ)–21(2ω, ɛ); II: 1–5+5–4–5(2φ)–12(3ω, ɛ); III: 1–4–4–4–5–12; IV: 1–3–3–4–5–12. Eupathidial setae: I: G: (l); Tb: all except (l_1-2); Ts: all; II: Tb: d, v′; Ts: all except ft′; III: G: l′; Tb: d, l′; Ts: all; IV: BF d; G: l″; Tb: d, l′; Ts: all.

Solenidia and famuli. Leg I. Tarsus with two parallel T-shaped rhagidial organs in confluent depression and one stellate famulus ɛ well moved antiaxially to the lateral side. Posterior, dorsolateral rhagidial organ (ω₁) reaching half of the length of anterior, dorsal one (ω₂). Tibia with one distal (φ₁) and one medial rhagidial organ φ₂, both T-shaped, tandemly in separated depressions. Leg II. Tarsus with three parallel T-shaped rhagidial organs in separated depressions, of which the smallest anterior one (ω₃) oblique antiaxially and flanked by two bigger posterior ones (ω₁ and ω₂). Spiniform famulus ɛ not visible. Tibia with two T-shaped rhagidial organs (anterior φ₁ and medial φ₂), in separated depressions. Leg III and IV without solenidia.

Differential diagnosis. F. lapidarius is similar to F. shepardi Strandtmann, 1971 because of naso delimited dorsally and the same number of aggenital and genital setae. It differs from F. shepardi in short dorsal hysterosomal setae (long in F. shepardi) and parallel arrangement of rhagidial organs on tarsi I and II (tandem in F. shepardi).

Distribution. Arnhem, Netherlands [34]; nature reserve of halophitic vegetation, Ciechocinek near Toruń, Kujawsko-Pomorskie District; “Zielona Góra” nature reserve, vicinity of Częstochowa, Śląskie District (both [4]); Morasko Campus, Poznań, Wielkopolskie District [37], all latter localities in Poland.

Material examined. Holotype female (Naturalis Biodiversity Centre, slide labeled “RMNH.ACA.P 5507”): Netherlands, Arnhem, under stones, 1903, leg. Dammermann; four females and two males: Poland, Wielkopolskie district, Poznań, Morasko University Campus, 52°27′58″ N 16°55′21″ E, Fresh meadow with often reaped Arrhenatheretum elatioris, 19 February 2019, leg. R. Laniecki.

Remarks. The original description [34], as well as subsequent redescriptions [35,36], lacks some valid diagnostic characters and thus the species is redescribed herewith. Despite high similarity of the holotype of Filieupodes lapidarius and specimens previously identified as F. filistellatus collected in Poland, some differences can be observed. In the original description of F. filistellatus proximal rhagidial organs are present on all tibiae, whereas they were not found on tibiae III and IV in holotype of F. lapidarius. This, however, could be a result of age and condition of the original material (117 years). Because of this, some structures (e.g., lyrifissures, supracoxal setae) are not visible. Moreover, due to the position of the specimen on the slide, some structures could not be entirely distinguished, e.g., some coxisternal and aggenital setae. Those, however, which are visible, fit the setal patterns of F. filistellatus.

The type material of F. filistellatus is lost (courtesy of Prof. Andrzej J. Zawal, former superior of Dr. Katarzyna Jesionowska), and thus only newly collected material along with the original description by Jesionowska [4] were used to compare the species with holotype of N. lapidarius.

3.2. Key to the Species of Neoprotereunetes (Adults)

1. Five pairs of genital setae, tarsus I with 21 setae, femur I with 13 setae, tibia II with five setae, genu III and IV each with four setae, arctic species .................................................... ......... boerneri species group ........................................................................ boerneri (Thor, 1934)

– Five or six pairs of genital setae, tarsus I with 20 setae, femur I with 12 setae, tibia II with four setae, genu III and IV each with three setae, Antarctic or sub-Antarctic species ......... minutus species group ......................................................................................................... 2

2. Tibial proximal rhagidial organs long, at most four times shorter than its segment, famulus ε on tarsus II absent ....................................................................................................... 3

– Tibial proximal rhagidial organs short, at least seven times shorter than its segment, famulus ε on tarsus II present ..................................................................................................... 4

3. Tibia III with proximal rhagidial organs, two anterior rhagidial organs (ω_2, 3) on tarsus II parallel and arranged side by side, both tarsal rhagidial organs in confluent depressions.....................................................................................minutus (Strandtmann, 1967)

– Tibia III without proximal rhagidial organ, two anterior rhagidial organs (ω_2, 3) on tarsus II parallel, but ω₃ displaced anteriorly in relation to ω₂, both tarsal rhagidial organs in separated depressions ................................................ crozeti (Strandtmann et Davies, 1972)

4. Tarsus II with three rhagidial organs of unequal size, tibia III with short ellipsoid rhagidial organ, trochanter IV with one seta ............ exiguus (Booth, Edward et Usher, 1985)

– Tarsus II with three rhagidial organs of equal size, tibia III with small spherical rhagidial organ, trochanter IV without setae .......................................... paulinae (Gless, 1972)

– Tarsus II with two rhagidial organs, tibia III without rhagidial organ, trochanter IV without setae .................................................................. parvus (Booth, Edward et Usher, 1985)

4. Discussion

The family Eupodidae is composed mostly of monotypic genera, e.g., Claveupodes, Caleupodes, Aethosolenia. Two non-monotypic genera, i.e., Pseudopenthaleus and Echinoeupodes, have two species each, but in both cases, only one of them is accurately described. The remaining two non-monotypic genera, i.e., Eupodes and Benoinyssus are highly heterogenous. It is, therefore, hard to establish diagnostic characters at the generic level. We decided not to base generic diagnoses on leg setal patterns until more data on intra-generic variability in this respect will be collected. Body dimensions and shape are also excluded from diagnoses as these characters are contingent on age and condition of an individual as well as specimen treatment and preparation technique and may even change with an age of the slide.

In the present study, six species were classified within the genus Neoprotereunetes. Though the Arctic species differ slightly from Antarctic and sub-Antarctic congeners (mostly in genital and leg chaetotaxy), we decided not to divide them into separate genera or subgenera until the intrageneric variability in eupodid genera is better understood. However, to express these differences, two species groups were proposed: one, boerneri, containing N. boerneri, and another one, minutus, containing N. crozeti, N. exiguus, N. minutus, N. parvus and N. paulinae, based on type or newly collected material as well as original descriptions and redescriptions. Additionally, seven species that were described in or transferred to Protereunetes are not included in Neoprotereunetes. The first one was originally described by Oudemans [34] as Ereunetes lapidarius (Ereynetidae). In [35], the description of this species, with the (then) corrected generic name (Ereynetes), was extended and supplied with pictures by the same author. Next Oudemans [36] moved E. lapidarius to the family Eupodidae, without reference to its generic rank. Subsequently, Thor [7] transferred E. lapidarius to the genus Protereunetes. Finally, this species was designated as a type species of Neoprotereunetes Fain et Camerik, 1994. However, after the present examination of the holotype, it turned out that Neoprotereunetes lapidarius is the senior synonym of Filieupodes filistellatus Jesionowska, 2010 (Cocceupodidae). The second one, P. maudae, described as a congener of N. minutus by Strandtmann [29], is designated as a type species of the new genus Antarcteupodes on the basis of its unique combination of character states, not present in any hitherto described eupodid genus, including the most reduced coxisternal and leg chaetotaxy among the family Eupodidae. The third one, Protereunetes turgidus Shiba, 1978, was transferred by Khaustov [26] to the genus Echinoeupodes Khaustov, 2017. The fourth, Protereunetes villosus Shiba, 1978, possesses long and slender setae f₁ (presumably trichobothrial) and characteristic solenidiotaxy of tarsi I and II (each with two rhagidial organs, of which distal one is much smaller than proximal one), suggesting its affiliation to Benoinyssus Fain, 1958. The fifth species, Protereunetes perforatus Shiba, 1978, resembles Caleupodes reticulatus Baker, 1987 with respect to its reticulated body ornamentation and almost smooth setae. These characters are extremely rare in the family Eupodidae and might suggest a close relationship between these two species. Even if so, P. perforatus slightly differs from C. reticulatus in the solenidiotaxy of tarsus II (three rhagidial organs, instead of two) and the tibiae (one rhagidial organ, instead of two), and also in terms of its much larger body. The last species, Protereunetes striatellus (C.L. Koch, 1838) was originally described in Eupodes and then transferred by Thor and Willmann [8] to Protereunetes. As the description of this species is insufficient to determine its generic affiliation, and the type material probably does not exist, it is considered a species inquirenda. To confirm the above proposals, the type material should be examined, if (or when) available.

In reply to the transfer of Protereuntes (junior synonym of Ereynetes) back to Ereynetidae by Fain [9], Strandtmann [10] moved one of his species (P. minutus) to the genus Eupodes without reference to the second one (P. maudae). Although in subsequent papers Strandtmann was still using the name Protereunetes in relation to eupodoid mites, the usage of Eupodes sensu [10] was widely accepted by other authors [13,14,15]. However, in our opinion, the six species assigned herein to Neoprotereunetes possess a set of characters sufficient to constitute a separate genus. They have short and plumose dorsal body setae (long and lightly plumose in Eupodes); normal setae f₁ (sometimes trichobothrial in Eupodes); all legs shorter than body (legs I and II longer than body in Eupodes); femur IV slender (usually swollen in Eupodes) short and plumose leg setae (long and pilose in Eupodes); two or three L-shaped or T-shaped rhagidial organs on tarsi I and II (always two L-shaped rhagidial organs in Eupodes); two rhagidial organs on tibiae I and II (one rhagidial organ and one erect solenidion in Eupodes). Eupodes is still a highly heterogeneous taxon demanding a major revision. Nevertheless, the abovementioned characters enable the separation of Neoprotereunetes from Eupodes.

According to the Principle of Priority [38], the synonymy of original type species of Neoprotereunetes, namely Ereunetes lapidarius Oudemans, 1906 with Filieupodes filistellatus Jesionowska, 2010 implies that Neoprotereunetes is the valid genus-level name and should replace Filieupodes as its senior synonym.

This, however, does not resolve the problem of the lack of a replacement for the genus-level name Protereunetes—the primary aim of creating Neoprotereunetes by Fain and Camerik [16]. As the descriptions, redescriptions and original figures of E. lapidarius [33,34,35] do not imply that this species belongs to the family Cocceupodidae, only the present examination of the type could demonstrate that. As the type species fixation of the genus Neoprotereunetes was based on a misidentification (even at the time of its inception it did not meet its own diagnosis) for the sake of nomenclatural stability, we suggest retaining the name Filieupodes for the genus in the family Cocceupodidae (in line with the original proposal by Jesionowska [4]) and Neoprotereunetes for the genus in the family Eupodidae (as used by Khaustov [17]).

Thus, because the designation of new type species for Neoprotereunetes becomes necessary, we propose establishing Protereunetes boerneri Thor, 1934 (the oldest known species after E. lapidarius listed by Thor and Willamnn [8]) as the type species of the newly diagnosed genus.

Such practices are justified and encouraged by ICZN [38], as expressed in its initial chapter “Introduction. Development of underlying principles” (p. 14) by the following statement: “Also when individual zoologists discover that the type species had been misidentified when a genus or subgenus was established, they are given the power to fix as the type species either the species actually nominated by the original author or the nominal species in conformity with the name in use”.

The representatives of Neoprotereunetes thus far have been found only in the high latitudes of either hemisphere. The boerneri species group is restricted to the Arctic (Svalbard, Severnaya Zemlya, Arctic Alaska) and sub-Arctic (sub-Arctic Alaska) locations, whereas the minutus species group is restricted to the Antarctic (e.g., Antarctic Peninsula, South Orkney Islands, South Shetland Islands) and sub-Antarctic (Crozet Islands, Prince Edward Islands) locations. Additionally, N. minutus has also been recorded in Dunedin, New Zealand. Apart from the latter, all the locations are characterized by harsh climate and low yearly temperatures that seem to be favorable to eupodoid mites. Among terrestrial Prostigmata, Eupodoidea dominate in the Antarctic (36 species described) are one of the dominating groups in the Arctic.

5. Conclusions

Establishing Neoprotereunetes as a replacement for Protereunetes constitutes an important step in dividing the large and highly heterogeneous eupodid genus Eupodes and contributes to increasing the stability within Eupodidae. Even though Neoprotereunetes displays no unique characters specific only to this genus, it can be easily defined by a combination of characters. This might be one of the reasons that it remained so poorly defined for such a long time.