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Diversity
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Recent Advances in Ecology, Evolution and Biodiversity of the Chondrichthyan...
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Recent Advances in Ecology, Evolution and Biodiversity of the Chondrichthyan Fauna

A special issue of Diversity (ISSN 1424-2818). This special issue belongs to the section "Animal Diversity".

Deadline for manuscript submissions: 31 May 2024 | Viewed by 12177

Special Issue Editor

Dr. Simon Weigmann

E-Mail Website1 Website2
Guest Editor
1. Elasmo-Lab, Elasmobranch Research Laboratory, 22609 Hamburg, Germany
2. Department of Ichthyology, Leibniz Institute for the Analysis of Biodiversity Change (LIB), 20146 Hamburg, Germany
Interests: sharks; batoids; elasmobranchs; biodiversity; taxonomy; systematics

Special Issue Information

Dear Colleagues,

Climate change, the overexploitation of resources and the loss of biodiversity are important issues of global scientific and public interest. The loss of biodiversity and decline in populations are particularly alarming in sharks and rays, with more than one-third of species being threatened by overfishing. Considering the various negative influences on chondrichthyan populations, it is important to improve our knowledge of the biodiversity, ecology and evolution of chondrichthyans. Biodiversity research encompasses a number of disciplines, of which taxonomy is the most fundamental. Consequently, the adequate definition and differentiation of species as a key example of taxonomic research represents one of the most important fields of research in which serious deficiencies must be resolved. A better knowledge of biodiversity, ecology and evolution also provides an important basis for the selection and establishment of protected marine areas and fisheries management measures.

This Special Issue provides an opportunity to highlight new research on the biodiversity, ecology and evolution of cartilaginous fishes. We invite manuscripts focusing on taxonomic, systematic, ecological, evolutionary and conservation aspects, with the aim to build a platform to advance our knowledge of this ancient and unique, but highly threatened class of fishes.

Dr. Simon Weigmann
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Diversity is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • chondrichthyes
  • elasmobranchii
  • sharks
  • rays
  • chimaeras
  • biodiversity
  • ecology
  • evolution
  • taxonomy
  • systematics

Published Papers (5 papers)

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Research

21 pages, 3351 KiB  
Article
A Faunistic Revision of Longnose Skates of the Genus Dipturus (Rajiformes: Rajidae) from the Southern Southwestern Atlantic Ocean, Based on Morphological and Molecular Evidence
by Daniel Enrique Figueroa, Mauro Belleggia, Gabriela Andreoli, Silvina Izzo, Nelson Bovcon, Marcos Pérez-Losada, Agustín María De Wysiecki, Jorge Horacio Colonello and María Inés Trucco
Diversity 2024, 16(3), 146; https://doi.org/10.3390/d16030146 - 25 Feb 2024
Viewed by 1034
Abstract
The identity of longnose skates (Dipturus-Zearaja-like skates) in the southern cone of the Americas has been a topic of extensive debate. This study employs a comprehensive analysis encompassing morphometrics, claspers, and the examination of COI and NADH2 sequence data [...] Read more.
The identity of longnose skates (Dipturus-Zearaja-like skates) in the southern cone of the Americas has been a topic of extensive debate. This study employs a comprehensive analysis encompassing morphometrics, claspers, and the examination of COI and NADH2 sequence data to conclusively demonstrate the existence of only two longnose skate species in the southwestern Atlantic Ocean, extending south of 35 °S. Notably, Dipturus argentinensis Díaz de Astarloa, Mabragaña, Hanner and Figueroa, 2008 is revealed as a junior synonym of D. trachyderma (Krefft and Stehmann, 1975). Dipturus leptocaudus (Krefft and Stehmann, 1975) remains a northern valid species, but the specimen from the Falkland Islands (Malvinas) is recognized as a misidentification of D. trachyderma. Zearaja flavirostris (Philippi, 1892) and Dipturus lamillai Concha, Caira, Ebert and Pompert, 2019 are confirmed as junior synonyms of Zearaja brevicaudata (Marini, 1933). These findings contradict the previous report of six species within the same region over the last decade and underscore the presence of D. trachyderma and Z. brevicaudata south of 35 °S in the southwestern Atlantic. Additionally, this study notes the occurrence of only one specimen of Z. chilensis (Guichenot, 1848) in the Falkland Islands (Malvinas), suggesting an unusual frequency of this eastern Pacific skate in the southern Southwest Atlantic. Given that clasper morphology serves as the key distinguishing trait between Dipturus and Zearaja species, we provided a detailed analysis of the clasper characteristics of the Atlantic D. trachyderma, unequivocally situating it within Dipturus. The diagnostic characteristics include: (i) the presence of cartilage with the distal portion referred to as the sentinel, a feature absent in Zearaja; (ii) longer ventral terminal cartilage with the distal end referred to as the funnel, compared to Zearaja; and (iii) a non-spatulate distal lobe, a distinctive trait specific to Dipturus. Full article
(This article belongs to the Special Issue Recent Advances in Ecology, Evolution and Biodiversity of the Chondrichthyan Fauna)
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75 pages, 27568 KiB  
Article
The Indo-Pacific Stingray Genus Brevitrygon (Myliobatiformes: Dasyatidae): Clarification of Historical Names and Description of a New Species, B. manjajiae sp. nov., from the Western Indian Ocean
by Peter R. Last, Simon Weigmann and Gavin J. P. Naylor
Diversity 2023, 15(12), 1213; https://doi.org/10.3390/d15121213 - 12 Dec 2023
Viewed by 3870
Abstract
Members of the genus Brevitrygon are small, locally abundant tropical stingrays (family Dasyatidae) occurring in soft sedimentary habitats of inner continental shelves of the Indo-West Pacific from the Red Sea to Indonesia. Formerly members of the genus Himantura, whose members lack dorsal [...] Read more.
Members of the genus Brevitrygon are small, locally abundant tropical stingrays (family Dasyatidae) occurring in soft sedimentary habitats of inner continental shelves of the Indo-West Pacific from the Red Sea to Indonesia. Formerly members of the genus Himantura, whose members lack dorsal and ventral skin folds on the tail (typical of most dasyatid genera), folds are present or rudimentary in some Brevitrygon. Important to artisanal fisheries and known to consist of at least five species, these fishes are possibly the most frequently misidentified of all stingrays. Most were inadequately described in the 19th century, and they are often taxonomically confused due to morphological similarity, ontogenetic variability, and sexual dimorphism. Their nomenclatural history is complex with four of the known species represented within the type series of one species, B. walga (Müller & Henle). Also, the type of the species with which B. walga is most often confused, B. imbricata (Bloch & Schneider) from off southern India and Sri Lanka, is in very poor condition. A lectotype has been designated for B. walga (confined to the Bay of Bengal). The genus also contains B. heterura (Bleeker) from the Indo-Malay Archipelago, B. javaensis (Last & White) from off southern Indonesia, and a new species, B. manjajiae sp. nov., from the western Indian Ocean. The former species are redescribed and redefined based largely on a combination of morphometrics, tail morphology, squamation, and molecular data. Molecular divergences were detected within lineages of B. heterura, B. walga and B. manjajiae sp. nov., requiring further investigation. Full article
(This article belongs to the Special Issue Recent Advances in Ecology, Evolution and Biodiversity of the Chondrichthyan Fauna)
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22 pages, 10333 KiB  
Article
Additions to the Taxonomy of the Antarctic Dark-Mouth Skate Bathyraja arctowskii (Dollo, 1904), with Descriptions of the Syntypes and Morphology of Teeth, Dermal Denticles and Thorns
by Simon Weigmann and Thomas Reinecke
Diversity 2023, 15(8), 899; https://doi.org/10.3390/d15080899 - 30 Jul 2023
Cited by 1 | Viewed by 1310
Abstract
The taxonomy of the enigmatic dark-mouth skate, Bathyraja arctowskii (Dollo, 1904), from the Southern Ocean was finally resolved after more than 100 years of ambiguity in 2021. This species is the smallest known species of the species-rich deep-water skate genus Bathyraja Ishiyama, 1958, [...] Read more.
The taxonomy of the enigmatic dark-mouth skate, Bathyraja arctowskii (Dollo, 1904), from the Southern Ocean was finally resolved after more than 100 years of ambiguity in 2021. This species is the smallest known species of the species-rich deep-water skate genus Bathyraja Ishiyama, 1958, which attains a total length of only about 61 cm and appears to be a wide-ranging and locally common species in the Southern Ocean. It differs from its congeners in the small adult size, dark-pigmented mouth cavity and underside of nasal curtain, lack of thorns on upper disc, as well as small and slender egg cases. Although the identity of this species was unambiguously clarified, the syntype egg cases could not be examined due to the COVID-19 pandemic. This examination has now become possible, and detailed data of the syntypes are provided in the present paper for the first time, together with hitherto unknown details of tooth, dermal denticle and thorn morphology. Furthermore, a lectotype and two paralectotypes are designated from the syntypes. Full article
(This article belongs to the Special Issue Recent Advances in Ecology, Evolution and Biodiversity of the Chondrichthyan Fauna)
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12 pages, 2123 KiB  
Article
Photophore Morphogenesis and Extraocular Encephalopsin Expression during the Embryogenesis of Smalleye Pygmy Shark (Squaliolus aliae)
by Laurent Duchatelet, Hsuan-Ching Ho and Jérôme Mallefet
Diversity 2022, 14(12), 1100; https://doi.org/10.3390/d14121100 - 11 Dec 2022
Cited by 3 | Viewed by 1785
Abstract
Bioluminescence is a common phenomenon in marine organisms, especially in deep water where faint blue light remains. Among elasmobranchs, three families display the ability to emit light, the Etmopteridae, the Dalatiidae, and the Somniosidae. Luminous sharks have thousands of minute light organs, called [...] Read more.
Bioluminescence is a common phenomenon in marine organisms, especially in deep water where faint blue light remains. Among elasmobranchs, three families display the ability to emit light, the Etmopteridae, the Dalatiidae, and the Somniosidae. Luminous sharks have thousands of minute light organs, called photophores, that are mainly present ventrally and produce light. The main function of shark luminescence is counterillumination to camouflage the shark silhouette by mimicking the residual ambient light and avoiding being spotted by predators underneath. To perform counterillumination efficiently, luminescence needs to be finely adjusted. A new type of control was recently demonstrated via extraocular photoreception at the level of the light organ. An encephalopsin (i.e., opsin 3) was shown to be expressed in the vicinity of the photophore of an Etmopteridae species, Etmopterus spinax. This opsin was also demonstrated to be expressed concomitantly with the photophore development (i.e., when photophores become able to produce light) during E. spinax embryogenesis. To understand the photophore morphogenesis of different shark families, we analyzed the smalleye pygmy shark, Squaliolus aliae, with a photophore formation which represents the first report on the Dalatiidae family. Since Dalatiidae and Etmopteridae are phylogenetically closely related, the photophore morphogenesis was compared with an Etmopteridae representative, Etmopterus spinax. The results also reveal that Squaliolus aliae shares similar encephalopsin expression pattern as in Etmopterus spinax, which further supports evolutionary conservation of photophore morphogenesis as well as its own encephalopsin-based light perception across the two luminous shark families. Full article
(This article belongs to the Special Issue Recent Advances in Ecology, Evolution and Biodiversity of the Chondrichthyan Fauna)
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22 pages, 1850 KiB  
Article
Catch Composition, Seasonality, and Biological Aspects of Sharks Caught in the Ecuadorian Pacific
by Jesús Briones-Mendoza, Diego Mejía and Pol Carrasco-Puig
Diversity 2022, 14(8), 599; https://doi.org/10.3390/d14080599 - 28 Jul 2022
Cited by 3 | Viewed by 3017
Abstract
Although sharks have a fundamental role in maintaining the balance of aquatic ecosystems, exerting a great influence on lower levels of the food chain, their populations are declining worldwide due, to a large extent, to overfishing. Of the 64 species registered in Ecuador, [...] Read more.
Although sharks have a fundamental role in maintaining the balance of aquatic ecosystems, exerting a great influence on lower levels of the food chain, their populations are declining worldwide due, to a large extent, to overfishing. Of the 64 species registered in Ecuador, from January to December 2019, 19 species were recorded in Manta from the 15,455 captured individuals, with the family Carcharhinidae being the most abundant in the catches (69.4%), and the most abundant species was Prionace glauca (57.9%). Regarding threatened species, such as Carcharhinus longimanus, Sphyrna lewini, and Sphyrna zygaena, a greater presence of immature specimens was observed in landings. However, information on the composition and biological aspects of shark species in the Ecuadorian Pacific is very scarce. Therefore, research on the characteristics of life history (age, growth, and maturity) are of utmost importance for the stock assessments that are being exploited, especially in developing countries, where this information is lacking, causing inadequate management of fishery resources. Full article
(This article belongs to the Special Issue Recent Advances in Ecology, Evolution and Biodiversity of the Chondrichthyan Fauna)
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