[Ichthyology • 2026] Hemitrygon ariakensis • Redescription of Hemitrygon akajei with Description of the cryptic stingray species (Myliobatoidei: Dasyatidae) from the Northwest Pacific

Hemitrygon ariakensis  

 Furumitsu & Yamaguchi, 2025. 

 

DOI: doi.org/10.1007/s10228-025-01048-5 

Researchgate.net/publication/398875566

Abstract

We redescribe Hemitrygon akajei (Bürger in Müller and Henle 1841) based on the lectotype and newly collected specimens, and describe Hemitrygon ariakensis sp. nov. from western Japan. Owing to their considerable morphological similarity and sympatric distribution, these two species have been subject to longstanding taxonomic confusion, with one remaining unrecognized as a cryptic species for over 160 years prior to the availability of molecular evidence. The red stingray H. akajei was originally described from six syntypes, including juveniles that likely represented multiple species, including the cryptic one. Species identification in Hemitrygon is complicated not only by interspecific morphological resemblance but also by marked ontogenetic changes between juveniles and adults. Herein, we describe the external morphology of both species across developmental stages to aid in their distinction. Hemitrygon akajei and Hemitrygon ariakensis sp. nov. can be distinguished by the following combination of characters: arrangement of denticles on dorsal surface of disc and posterior part of tail; shape, size, and arrangement of thorns on dorsal tail anterior to caudal spine; presence or absence of transverse groove on ventral surface of disc; coloration of ventral tail fold; shape of outer marginal color band on ventral disc; morphology of clasper and prepelvic processes of pelvic girdle; and number of prespine separate centra. Stingrays are important fishery resources and key mesopredators in Japanese coastal ecosystems, influencing populations of other fishery species. The ability to distinguish these two species will facilitate more accurate ecological research, inform species-specific conservation strategies, and promote effective biodiversity management. Such taxonomic resolution is essential for understanding coastal ecosystem dynamics. 

Keywords: Taxonomy, New species, Cryptic species, Western Japan, Ariake Bay

Fresh specimens of Hemitrygon ariakensis sp. nov.
a, b Holotype (FFNU-P-02129, 363.3 mm DW, male, mature); c, d paratype (FFNU-P-02126, 154.4 mm DW, male, immature); e, f paratype (FFNU-P-02141, 545.1 mm DW, female, mature). a, c, e Dorsal view; b, d, f ventral view. Scales indicate 50 mm

Illustrations originally considered Hemitrygon akajei; herein reidentified as Hemitrygon ariakensis sp. nov. based on the morphological characters depicted.
a Original illustration from Bürger’s unpublished manuscript (No. 13; RMNH.ART.256, courtesy of Naturalis Biodiversity Center, CC0 1.0), b illustration from the original description in Müller and Henle (1841), c illustration from the Glover Atlas, illustrated by Hagiwara (1915), in the collection of Nagasaki University Library.

 Keisuke Furumitsu and Atsuko Yamaguchi. 2025. Redescription of Hemitrygon akajei with Description of the cryptic stingray species Hemitrygon ariakensis sp. nov. from the Northwest Pacific (Myliobatoidei: Dasyatidae).  Ichthyological Research. DOI: doi.org/10.1007/s10228-025-01048-5 [19 December 2025]

 Researchgate.net/publication/398875566_Redescription_of_Hemitrygon_akajei_with_description_of_Hemitrygon_ariakensis_sp_nov_from_the_Northwest_Pacific

[Ichthyology • 2025] Etmopterus westraliensis • A New Species of Lanternshark (Squaliformes: Etmopteridae) from Western Australia, with Redescription of Etmopterus brachyurus

 

Etmopterus westraliensis

Ng, White, Liu & Joung, 2025 

DOI: doi.org/10.1111/jfb.70162 

 Researchgate.net/publication/395652184

Abstract

Etmopterus westraliensis is described as a new species based on six specimens collected from Western Australia, eastern Indian Ocean. The new species is assigned to the Etmopterus lucifer group due to its slender, elongate anterior and posterior branches of the flank markings. It shares the following combination of morphological characters with two congeners, Etmopterus brachyurus and Etmopterus samadiae: dermal denticles hook-like, a naked area present on underside of snout, denticles present on dorsal fins in mature individuals, the origin of flank-marking base anterior to a vertical line through origin of the second dorsal fin, caudal-fin base marking thin and slender and a relatively short posterior caudal-fin marking. The new species differs from E. brachyurus in having a longer caudal-fin base marking, ventral portion of caudal-fin base marking much longer than wide, and differs from E. samadiae in having a longer mouth, different shape of the naked area on underside of snout, thinner posterior branch of flank marking, caudal-fin base marking tip tapering and more monospondylous centra. The new species is also distinguished from E. brachyurus and E. samadiae by the mean genetic distance for the NADH2 gene, that is, 0.028 and 0.040, respectively. E. brachyurus is redescribed here based on the holotype together with additional specimens collected from the northwestern Pacific.

  Keywords: deep sea, Etmopterus brachyurus, Etmopterus lucifer group, taxonomy, Western Australia

Etmopterus westraliensis n. sp., fresh condition. 
 Paratype, CSIRO H 9025‐22, immature male 174 mm TL.
Photos copyright: CSIRO, Australian National Fish Collection. 

Etmopterus westraliensis 

Shing-Lai Ng, William T. White, Kwang-Ming Liu and Shoou-Jeng Joung. 2025. Etmopterus westraliensis, A New Species of Lanternshark (Squaliformes: Etmopteridae) from Western Australia, with Redescription of Etmopterus brachyurus. Journal of Fish Biology. DOI: doi.org/10.1111/jfb.70162 [18 September 2025] 

 Researchgate.net/publication/395652184_Etmopterus_westraliensis_a_new_species_of_lanternshark_from_Western_Australia

[Ichthyology • 2025] Mobula yarae • An Integrative Taxonomy Investigation unravels A Cryptic Species of Mobula Rafinesque, 1810 (Myliobatiformes: Mobulidae), from the Atlantic Ocean

 

Mobula yarae   Bucair & Marshall, 

in Bucair, Hinojosa-Alvarez, Marshall, Pate, Francini,  Garrido, Capel, Loboda, Monteiro, Bruno, Vaga, Dove, Hoopes, Perry et Kitahara, 2025.

DOI: doi.org/10.1007/s10641-025-01727-2 

 facebook.com/novataxa 

Abstract

Manta and devil rays comprise a vulnerable animal group with a complex nomenclatural history and a somewhat unresolved taxonomy. The existence of a putative undescribed species of manta ray in the Atlantic Ocean has been proposed for over 15 years. Molecular assessments have been crucial for improving our understanding of the evolutionary history and, therefore, species delimitation of this threatened group. Herein, morphological and molecular data from Western Atlantic specimens support the formal description of a new taxon assigned to the genus Mobula Rafinesque, 1810. Morphologically, this new mobulid species differs from its closest congeners (i.e., Mobula birostris and Mobula alfredi) on the stellate-shaped dermal denticle form and non-bifurcate ramification, the characteristic dorsal surface with V-shaped supra-branchial patches, ventral colour patterns, presence and feature of a caudal bulb with a residual spine, 9 to 13 rows of teeth, and overall morphometrics. Based on nearly complete mitochondrial genome and nuclear data, phylogeny reconstructions recovered the new species as a monophyletic lineage closely related to M. birostris and M. alfredi. To date, the new manta ray species has been recorded only in Atlantic waters, inhabiting oceanic islands and archipelagos as well as coastal and estuarine regions, areas under major threats due to pollution, boat strikes, coastal fisheries, and habitat degradation. Unfortunately, the species has been reported caught as bycatch, being either discarded, shared, or sold, in addition to boat strike and entanglement reports, suggesting that this new mobulid species, like all other mobulids, is likely threatened.

 

Keywords: Biodiversity, Conservation, Manta ray, Mobulids, Systematics

Distinct colouration of manta ray species. Dorsal and ventral colouration pattern of
Mobula birostris a, d, M. alfredi b, e, and Mobula yarae sp. nov. c, f.

Photo credits: Leo Francini a; Guy Stevens | Manta Trust b, e; Rawany Porfilho c; Mauricio Andrade d; and Nayara Bucair f

Order Myliobatiformes.

Family Mobulidae Gill, 1893.

Genus Mobula Rafinesque, 1810.

Mobula yarae sp. nov. Bucair & Marshall

Colour morphs variation on the regular spectrum of Mobula yarae sp. nov.
 Dorsal (column a and b) and ventral (column c and d) colouration pattern disparity. Photo credits/sources: Projeto Mantas do Brasil and Marine Megafauna Foundation database

Nayara Bucair, Silvia Hinojosa-Alvarez, Andrea Denise Marshall, Jessica Pate, Carlo Leopoldo Bezerra Francini, Amana Guedes Garrido, Katia Cristina Cruz Capel, Thiago Silva Loboda, Jhonatas Sirino Monteiro, Carlos Eduardo Malavasi Bruno, Claudia Francesca Vaga, Alistair D. M. Dove, Lisa A. Hoopes, Cameron Perry  and Marcelo V. Kitahara. 2025. An Integrative Taxonomy Investigation unravels A Cryptic Species of Mobula Rafinesque, 1810 (Mobulidae, Myliobatiformes), from the Atlantic Ocean. Environmental Biology of Fishes. DOI: doi.org/10.1007/s10641-025-01727-2  [23 July 2025]

https://www.smithsonianmag.com/smart-news/scientists-identify-a-new-manta-ray-species-just-the-third-known-in-the-world-180987109/

[PaleoIchthyology • 2025] Macadens olsoni • A New euchondrocephalan chondrichthyan (Chondrichthyes: Euchondrocephali) from the middle Mississippian (Viséan) Joppa Member of the Ste. Genevieve Formation at Mammoth Cave National Park, Kentucky, USA and A Reassessment of the lower Mississippian (Tournaisian-Viséan) "Helodus" coxanus Newberry, 1897

 

 Macadens olsoni

Hodnett, Toomey, Sues, Santucci, Tolleson & Tweet, 2025

  Researchgate.net/publication/393776561

Art by Benji Paysnoe

A new euchondrocephalan chondrichthyan, Macadens olsoni gen. et sp. nov., is identified from the Middle Mississippian (Viséan) Joppa Member, Ste. Geneveive Formation from Mammoth Cave National Park, Kentucky. Macadens olsoni shares various morphological traits with the enigmatic taxon “Helodus” coxanus Newberry 1897, from the Lower-Middle Mississippian (Tournaisian) Keokuk Limestone of Iowa. These morphological traits of a lower symphyseal on a narrow mesiodistally elongated base with rounded and blunt cusps are not seen in Helodus and we create a new genus name and combination, Rotuladens gen. nov. coxanus Newberry 1897. Macadens and Rotuladens are proposed as members of unnamed clade with a sister-group relationship with Eugeneodontiformes.

  Proposed reconstruction of the new to science species Macadens olsoni, discovered through fossil research at Mammoth Cave National Park.

Art by Benji Paysnoe

Macadens olsoni gen. et sp. nov.

 

 

John-Paul Michael Hodnett, Rickard Toomey, Hans-Dieter Sues, Vincent L. Santucci, Kelli Tolleson and Justin Tweet. 2025. A New euchondrocephalan chondrichthyan (Chondrichthyes, Euchondrocephali) from the middle Mississippian (Viséan) Joppa Member of the Ste. Genevieve Formation at Mammoth Cave National Park, Kentucky, USA and A Reassessment of the lower Mississippian (Tournaisian-Viséan) "Helodus" coxanus Newberry, 1897. New Mexico Museum of Natural History and Science Bulletin. 100: 87–93. 

 Researchgate.net/publication/393776561_A_NEW_EUCHONDROCEPHALAN_CHONDRICHTHYAN_from_The_middle_MISSISSIPPIAN_of_The_Ste_GENEVIEVE_FORMATION_at_MAMMOTH_CAVE_NP_KENTUCKY_USA

[Ichthyology • 2025] Iago gopalakrishnani • A New Species of Hound Shark, of the Genus Iago (Carcharhiniformes: Triakidae) from the northern Indian Ocean

Iago gopalakrishnani 

Bineesh, Beura, Das, Nashad & Akhilesh, 2025

DOI: doi.org/10.21077/ijf.2025.72.1.152519-03 

Abstract

 Sharks of the genus Iago Compagno and Springer, 1971 (Carcharhiniformes: Triakidae) that commonly occur in the deep waters of the Indo-Pacific, are an interesting group phylogenetically. Currently, three nominal species of Iago are known globally, namely, Iago garricki, I. omanensis and I. mangalorensis. In this study, we describe a new species of hound shark, Iago gopalakrishnani sp. nov. from the deep waters of eastern Arabian Sea, India. Iago gopalakrishnani sp. nov. is distinct in its dark chocolate brown to blackish colouration and low fins; pre-oral length 4.7–6% TL, 22.4-25% head length; first dorsal height 5.8-7% TL, first dorsal length 10.6–14.1% TL, first dorsal base length 6.7-9.8% TL, second dorsal length 8.9-10.9% TL and vertebral counts 117-123. Iago gopalakrishnani sp. nov. is genetically distinct from congeners. COI based analysis of Iago gopalakrishnani sp. nov formed a distinct clade in phylogenetic reconstruction with a genetic distance of 4.5-5.2% when comparing K2P parameters with congeners.

Keywords: Diversity, Genetics, Indian Ocean, Morphology, Sharks, Taxonomy

Iago gopalakrishnani sp. nov.
(a) Holotype dorsal view, Reg. No. MBRCF3164, adult female, 447 mm TL.
(b) Paratype dorsal view, Reg. No. MBRCF3165, adult male, 450 mm TL, (c) Paratype lateral view.

Iago gopalakrishnani sp. nov.
(a) Holotype, Regd. No. MBRCF3164, adult female, 447 mm TL, ventral view of head.
(b) Paratype 1, Regd. No. MBRCF3165, adult male, 450 mm TL, ventral view of head.

 Iago gopalakrishnani sp. nov.

K. K. Bineesh, Sweta Beura, Moumita Das, M. Nashad and K. V. Akhilesh. 2025. Description of A New Species of Hound Shark, of the Genus Iago (Carcharhiniformes: Triakidae) from the northern Indian Ocean. Indian Journal of Fisheries. 72(1); DOI: doi.org/10.21077/ijf.2025.72.1.152519-03 

[Ichthyology • 2025] Neotrygon romeoi • A New Blue-spotted Maskray Species (Myliobatiformes: Dasyatidae: Neotrygon) from Fiji

 

Live colouration of Neotrygon romeoi n. sp. from around Fiji:
(a) Lautoka, mixed rocky and sand habitat (©Leon Perrie, observed 1 July 2023, inaturalist.org); (b) Near South Sea Island, rocky reef, (©Jack Crosbie, 17 August 2023,  inaturalist.org); (c) Drawaqa Island, Yasawas on sand flat with some seagrass in ≃18 m of water, (©Robert Macfarlane, 7 January 2024, modified); (d) Suva foreshore, on seagrass in ≃0.2 m of water (©Tom Vierus, observed 24 March 2022, inaturalist.org); (e) Mana Island, over seagrass (©Floyd E. Hayes, observed 27 March 2018, inaturalist.org).

Glaus, White, O'Neill, Thurnheer & Appleyard, 2025

DOI: doi.org/10.1111/jfb.70094

 Researchgate.net/publication/392529313

Abstract

Neotrygon romeoi n. sp. (Dasyatidae), a new species of blue-spotted maskray from Fiji, previously confused with Neotrygon kuhlii (Müller and Henle 1841) or Neotrygon trigonoides (Castelnau 1873), is described based on nine specimens (310–397 mm disc width) from Fiji. Neotrygon romeoi n. sp. is a large maskray with a broadly angled snout, long claspers in adult males and a median row of thornlets extending from the nape to the tail base. Fresh specimens have a brownish dorsal surface with dark mask-like marking covering across and between the eyes (sometimes indistinct), two large brown to black branchial blotches posterior to the spiracles, numerous black pepper-like spots mainly concentrated in masked area and the branchial blotches, and sometimes having small, dark-edged pale blue to whitish spots. The new species is further characterized by ocellated spots in the medial belt usually absent. Molecular analysis based on 570 bp of partial cytochrome c oxidase subunit 1 (COI) mitochondrial gene also supports that N. romeoi n. sp. is a distinct species from other congeners. The new species, known only from the Fiji Islands, may thus warrant inclusion in Fiji's Endangered and Protected Species Act.

Keywords: Fiji, endemic, new species, Oceania, South Pacific Ocean, species complex

Live colouration of Neotrygon romeoi n. sp. from around Fiji:
(a) Lautoka, mixed rocky and sand habitat (©Leon Perrie, observed 1 July 2023, modified, www.inaturalist.org/observations/171357979); (b) Near South Sea Island, rocky reef, (©Jack Crosbie, observed 17 August 2023, modified, www.inaturalist.org/observations/180044335); (c) Drawaqa Island, Yasawas on sand flat with some seagrass in ≃18 m of water, (©Robert Macfarlane, 7 January 2024, modified); (d) Suva foreshore, on seagrass in ≃0.2 m of water (©Tom Vierus, observed 24 March 2022, modified, www.inaturalist.org/observations/109579248); (e) Mana Island, over seagrass (©Floyd E. Hayes, observed 27 March 2018, modified, www.inaturalist.org/observations/99347812).

Neotrygon romeoi n. sp. 

 Etymology: The epithet is dedicated to the late Romeo Glaus, the father of the first author, in recognition of his lasting inspiration, enduring support and deep respect for nature. 

Vernacular: Fiji Maskray.

Kerstin Glaus, William T. White, Helen L. O'Neill, Sarah Thurnheer and Sharon A. Appleyard. 2025. A New Blue-spotted Maskray Species (Neotrygon, Dasyatidae) from Fiji. Journal of Fish Biology. DOI: doi.org/10.1111/jfb.70094 [09 June 2025]

 Researchgate.net/publication/392529313_A_new_blue-spotted_Maskray_Neotrygon_from_Fiji

[Ichthyology • 2025] Hypanus rubioi • A New Species of the Genus Hypanus (Myliobatiformes: Dasyatidae) from the Eastern Tropical Pacific Ocean

Hypanus rubioi

Mejía-Falla, Navia, Cardeñosa & Tavera, 2025

 

Longnose Pacific Stingray | Raya picuda  ||  DOI: doi.org/10.1643/i2024010 

 Abstract 

A new species of stingray belonging to the genus Hypanus is described in this study based on data collected in the Eastern Tropical Pacific (ETP) region of Colombia. This new species stands out within the genus by its unique spade-shaped disc with a width-to-length ratio ranging from 1.0 to 1.1, whereas its obtuse snout extends 29–30% of the disc width (DW). This species also stands out due to its large size (125 cm DW). Notably, it has three distinctive rows of enlarged denticles on its mid-scapular area, with the central row extending back to the caudal sting. Additionally, it possesses a long tail that measures 2.2–2.5 times the DW, tapering smoothly. Molecular data also revealed significant differences between this new species and its congeners using COI. The phylogenetic analysis recovered Hypanus rubioi, new species, as the sister species to the western Atlantic Longnose Stingray H. guttatus, with an uncorrected genetic distance of 2.27 to 2.94%. The preliminary ecological niche modeling further indicates that this newly described species is likely associated with coastal regions in the ETP, ranging from central Mexico to northern Peru, with backlight and salinity as the most influential variables. These findings contribute to our understanding of the biodiversity within the genus Hypanus and the ecological distribution of this novel species in the ETP. 

Hypanus rubioi, new species

Specimens of Hypanus rubioi, new species, caught in artisanal fishing operations in Charambirá, Colombian Pacific Ocean (courtesy of WCS Colombia, Julian Caicedo).

Hypanus rubioi, new species

Longnose Pacific Stingray

Spanish name: Raya picuda

Etymology.—The name rubioi comes from the professor Efrain Rubio, who worked for many decades as ichthyology teacher at Universidad del Valle. Dr. Rubio was one of the first researchers interested in the fish fauna of the Colombian Pacific. During all these years at Universidad del Valle, he started the ichthyology collection (CIRUV) in addition to training many generations of young ichthyologists interested in the Pacific fishes of Colombia.

P. A. Mejía-Falla, A. F. Navia, D. Cardeñosa and J. Tavera. 2025. New Species of the Genus Hypanus (Dasyatidae) from the Eastern Tropical Pacific Ocean. Ichthyology & Herpetology. 113(1); 44-60. DOI: doi.org/10.1643/i2024010  (18 February 2025) 

  facebook.com/TheWCS/posts/1061124059383455

[PaleoIchthyology • 2025] Clavusodens mcginnisi • Obruchevodid petalodonts (Chondrichthyes: Petalodontiformes; Obruchevodidae) from the Middle Mississippian (Viséan) Joppa Member of the Ste. Genevieve Formation at Mammoth Cave National Park, Kentucky, U.S.A.

Clavusodens mcginnisi 
Hodnett, Egli, Toomey, Olson, Tolleson, Boldon, Tweet & Santucci, 2025

  Netsepoye hawesi  Lund, 1989

DOI: doi.org/10.1017/jpa.2024.40  

home.NPS.gov/maca

Art by Benji Paysnoe.

  

Abstract

Obruchevodid petalodonts are rare small chondrichthyans known from nearly complete to partial skeletons from the Upper Mississippian (Serpukhovian) Bear Gulch Limestone of central Montana and isolated teeth from the Upper Mississippian Bangor Limestone of northern Alabama. New records of obruchevodid petalodonts are presented here from the Middle Mississippian (Viséan) Joppa Member of the Ste. Genevieve Formation at Mammoth Cave National Park, Kentucky. Obruchevodids are here represented by multiple teeth of a new taxon, Clavusodens mcginnisi n. gen. n. sp., and a single tooth referred to ?Netsepoye sp. Clavusodens mcginnisi n. gen. n. sp. is characterized by teeth with pointed mesiodistal and lingual margins and more robust chisel-like cusps on the anterolateral and distolateral teeth. The suggestion that obruchevodid petalodonts evolved to inhabit complex reef-like environments and other nearshore habitats with a feeding ecology analogous to extant triggerfish is explored and discussed.

  Netsepoye hawesi;
(1) Reconstruction of the skeleton of Netsepoye hawesi based on holotype CM 46092 from the Heath Formation of Montana; 
(3) revised reconstruction of the upper and lower dentition of N. hawesi.

 Tentative reconstruction of Clavusodens mcginnisi n. gen. n. sp. (modeled after Netsepoye) feeding on phyllocarid crustaceans on the sea floor of a crinoidal forest from the Joppa Member of the Ste. Genevieve Formation, with the ctenacanth Glikmanius careforum swimming overhead.

Art by Benji Paysnoe.

Systematic paleontology

Class Chondrichthyes Huxley, 1880

Subclass Euchondrocephali Lund and Grogan, Reference Lund and Grogan, 1997

Order Petalodontiformes Patterson, 1965

Family Obruchevodidae Lund, Grogan, and Fath, 2014

Genus Clavusodens new genus

 

Occurrence: Mammoth Cave National Park, Kentucky, Middle Mississippian (upper Viséan) Joppa Member, Ste. Genevieve Formation.

Etymology: Latin, clavus (nail), and dents (tooth); in recognition of the nail-like shape of the distal lateral teeth. 

Clavusodens mcginnisi new species

Etymology: In honor of retired National Park Service superintendent and naturalist David McGinnis for his leadership in paleontological resource stewardship during his 39-year career beginning at Mammoth Cave National Park.

John-Paul M. Hodnett, H. Chase Egli, Rickard Toomey, Rickard Olson, Kelli Tolleson, Richard Boldon, Justin S. Tweet and Vincent L. Santucci. 2025. Obruchevodid petalodonts (Chondrichthyes, Petalodontiformes, Obruchevodidae) from the Middle Mississippian (Viséan) Joppa Member of the Ste. Genevieve Formation at Mammoth Cave National Park, Kentucky U.S.A. Journal of Paleontology. First View. DOI: doi.org/10.1017/jpa.2024.40  

Fossil Research Identifies New Shark Species at Mammoth Cave National Park

The small shark named Clavusodens mcginnisi, or “McGinnis’ nail tooth,” only measured 3-4 inches in length.

https://home.NPS.gov/maca/learn/news/fossil-research-identifies-new-shark-species-at-mammoth-cave-national-park.htm

Non-technical Summary: New records of two species of obruchevodid petalodont chondrichthyans are described from the Middle Mississippian Joppa Member of the Ste. Genevieve Formation from Mammoth Cave National Park, Kentucky. The two species are Clavusodens mcginnisi new genus new species, which had more robust crushing-type teeth for its kind, and ?Netsepoye sp., which is based on a partial tooth. These two records represent the oldest known obruchevodid petalodonts, which previously were known from younger Mississippian-age rocks in Montana and Alabama. Obruchevodid petalodonts were among the most specialized cartilaginous fishes during the Mississippian, potentially adapted to live in complex reef and reef-like habitats.

[Ichthyology • 2024] Sphyrna alleni • A New Hammerhead Shark (Carcharhiniformes: Sphyrnidae) from the Caribbean and the Southwest Atlantic

Sphyrna alleni 

Gonzalez, Postaire, Driggers, Caballero & Chapman, 2024

 

 DOI: 10.11646/zootaxa.5512.4.2

 

Abstract

Hammerhead sharks (Family Sphyrnidae) comprise a monophyletic Miocene radiation of carcharhiniform sharks characterized by their laterally expanded and dorsoventrally compressed head (‘cephalofoil’). The bonnethead shark (Sphyrna tiburo) is currently described as a single amphi-American hammerhead species composed of the subspecies Sphyrna tiburo tiburo in the Western Atlantic Ocean (WA) and S. tiburo vespertina in the Eastern Pacific Ocean (EP). Variation in mitochondrial DNA and cephalofoil shape suggest a species complex, with S. tiburo occurring in the U.S., Mexico, and Bahamas; S. aff. tiburo occurring from Belize to Brazil; and S. vespertina occurring in the EP. Morphometric, meristic, and genetic variation was used to resolve the bonnethead shark complex in the Western Atlantic. Twenty-three specimens (12 S. aff. tiburo from Belize and 11 S. tiburo from U.S.) were subject to sixty-one morphometric measurements and three meristic characters (counts of the number of precaudal vertebrae, lower and upper rows of functional teeth). An allometric formula was used to standardize any effect caused by differences in size of the individuals and data were analyzed with univariate and multivariate statistics. Sphyrna aff. tiburo and S. tiburo have non-overlapping vertebral counts (80-83 and 71-74 respectively) but no morphometric differences were detected. Although not captured in morphometric analysis, the cephalofoil of S. aff. tiburo has a more pointed anterior margin than S. tiburo that together with lobule shaped posterior margins gives the cephalofoil a distinctive shovel-shaped appearance. Concatenated mitochondrial sequences and 12 nuclear microsatellite markers clearly separated S. aff. tiburo and S. tiburo. We conclude that this complex comprises two species in the Western Atlantic, S. tiburo and S. alleni sp. nov., and we provide a description of the latter, which is distinguished by precaudal vertebral counts (80-83), a shovel-shaped cephalofoil with rounded posterior margins, and robust differences in mitochondrial and nuclear genetic markers. We suggest nuclear genetic and meristic examination of EP bonnetheads is needed to update the taxonomical status and redescribe S. vespertina.

Pisces, Shovelbill shark, morphology, mtDNA, nDNA, phylogenetics, species complex, taxonomy

Sphyrna alleni sp. nov.,

Cindy Gonzalez, Bautisse Postaire, William Driggers, Susana Caballero and Demian Chapman. 2024. 2024. Sphyrna alleni sp. nov., A New Hammerhead Shark (Carcharhiniformes, Sphyrnidae) from the Caribbean and the Southwest Atlantic. Zootaxa. 5512(4); 491-511. DOI: doi.org/10.11646/zootaxa.5512.4.2

[Ichthyology • 2024] Leucoraja longirostris • A Remarkable New Skate Species of Leucoraja Malm, 1877 (Rajiformes: Rajidae) from the Southwestern Indian Ocean: Introducing 3D Modeling as an Innovative Tool for the Visualization of Clasper Characters

 Leucoraja longirostris 

Weigmann, Stehmann, Séret & Ishihara, 2024

DOI: 10.3390/biology13060405

Abstract

A remarkable new deep-water skate, Leucoraja longirostris n. sp., is described based on eight specimens caught during different expeditions to the southern Madagascar Ridge in the southwestern Indian Ocean. The new species differs from all congeners by its remarkably long and acutely angled snout (horizontal preorbital length 17.2–22.6% TL vs. 8.5–11.9% TL and 4.2–6.1 vs. 1.7–3.5 times orbit length, snout angle 65–85° vs. 90–150°). Furthermore, it is apparently endemic to the Madagascar Ridge, distant from the known distribution areas of all congeners. In addition to L. fullonica and L. pristispina, L. longirostris n. sp. is also the only species with plain dorsal coloration. Furthermore, the new species is the only Leucoraja species with an external clasper component dike and, besides L. wallacei, the only one with four dorsal terminal (dt) cartilages. The shape of the accessory terminal 1 (at1) cartilage with four tips is also unique within the genus. A new approach for the visualization of the clasper characters is introduced based on 3D models of all skeletal and external features. This enables a much easier and much more precise interpretation of every single clasper component, of the entire structure, and, in particular, the relationship between external features and skeletal cartilages. A new English translation of the first diagnosis of Leucoraja is provided, along with a revised generic diagnosis and a key to the species of Leucoraja in the Indian Ocean.

Keywords: Chondrichthyes; Elasmobranchii; rough skates; systematics; taxonomy; diversity; morphology; clasper features; morphometrics; meristics

Leucoraja longirostris n. sp.

Distribution: the new species is only known from the type specimens, which were all caught on the southern end of the Madagascar Ridge at Walters Shoals at depths of 750–1050 m. The new species occurs much deeper than its western Indian Ocean congeners, which are known only at depths of 480–625 m (L. compagnoi), 484 m (L. elaineae), and 73–517 m (L. wallacei), respectively. Furthermore, the new species is the only species of Leucoraja in the western Indian Ocean known from seamounts or ridges, whereas its congeners in the area are only known from the outer continental shelf and upper continental slope.

 

Conclusions: 

The conservation status of Leucoraja skates reveals that five of the 14 assessed species are threatened, including L. melitensis (Critically Endangered), L. circularis and L. ocellata (Endangered), L. fullonica and L. wallacei (Vulnerable), while one species (L. leucosticta) is Near Threatened, six species (L. erinacea, L. garmani, L. lentiginosa, L. naevus, L. pristispina, and L. yucatanensis) are Least Concern, and two species (L. compagnoi and L. elaineae) are Data Deficient. The recognition of a new species, Leucoraja longirostris n. sp., provides new insights into the morphological variation within the genus Leucoraja and constitutes a very unusual and remarkable addition to this skate genus. Nevertheless, the very restricted distribution of the new species raises concerns over its ability to sustain fisheries and it may be susceptible to capture in longline and, particularly, deep-water trawl fisheries. Very little information is available about fisheries operating in the area of the Madagascar Ridge, but this deep-water skate is likely unable to withstand intensive fishing pressure due to its potentially slow life history characteristics and low productivity. Walters Shoals was previously heavily fished, and this pressure may recur in the future. As fisheries targeting Orange Roughy (Hoplostethus atlanticus Collett, 1889) and Alfonsino (Beryx decadactylus Cuvier, 1829) have typically used mid-water trawls off the bottom, the new species may have a benthic refuge. However, further research is needed investigating its distribution, life history, population size and trends, and threats. This is essential for improved data collection and research, and for more effective conservation and management policy decisions.

 Simon Weigmann, Matthias F. W. Stehmann, Bernard Séret and Hajime Ishihara. 2024. Description of a Remarkable New Skate Species of Leucoraja Malm, 1877 (Rajiformes, Rajidae) from the Southwestern Indian Ocean: Introducing 3D Modeling as an Innovative Tool for the Visualization of Clasper Characters. Biology. 13(6); 405. DOI: doi.org/10.3390/biology13060405

 

Simple Summary: Skates of the genus Leucoraja Malm, 1877, are small to medium-sized skates that usually have a short, obtusely angled snout. Until now, 14 valid species of this genus have been identified mostly in the Atlantic, but also in the Indian Ocean. In the 1970s and 1980s, a total of eight specimens of an unusual skate species were collected by researchers working on the Madagascar Ridge, an elevated area of seabed in the southwestern Indian Ocean. Despite their long snouts, the specimens could unambiguously be assigned to the genus Leucoraja due to the typical features of their claspers. Comparisons with congeners clearly indicated that these remarkable specimens represent a species new to science. It can easily be distinguished from all 14 congeners by the long and acutely pointed snout. Furthermore, it appears to occur only on the Madagascar Ridge, distant from the known distribution areas of all congeners, and shows several unique aspects in its clasper morphology. Due to the importance of the clasper features, 3D modeling is introduced as a new tool for the visualization of clasper characters. The newly described species is named Brown longnose skate.

[Ichthyology • 2024] Harriotta avia • A New rhinochimaerid (Chimaeriformes: Rhinochimaeridae) described from the Southwest Pacific

Harriotta avia 

 Finucci,  Didier, Ebert, Green & Kemper, 2024 

 

 Australasia Narrow-nosed Spookfish  ||  DOI: 10.1007/s10641-024-01577-4

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Abstract

Harriotta avia sp. nov., a new species of long-nose chimaera (Holocephali: Chimaeriformes: Rhinochimaeridae), is described from specimens collected off New Zealand in the Southwest Pacific Ocean. The species is distinguished from its congeners by a combination of the following characters: elongated, narrow and depressed snout up to 56% BDL; long, slender trunk; beak-like vomerine tooth plate; large eye, length 8–12% BDL and height 5–7% BDL; long dorsal spine reaching slightly beyond apex of the dorsal fin; and slender rod-like pelvic claspers. The skin is deciduous, and uniform chocolate brown when intact. Harriotta avia sp. nov. is also distinguished from other Harriotta species based on DNA sequence divergence of the NADH2 gene. Harriotta avia sp. nov. is reported from the New Zealand-Australian region. Conclusions here show that Harriotta raleighana, a presumed globally distributed species, likely comprises several species and the genus Harriotta warrants a revision with specimens representing all ocean basins.

Keywords: Holocephali, Integrated Taxonomy, Morphology, Genetics, New Zealand, Australia

 

Harriotta avia sp. nov.

Etymology: The species name is derived from the Latin noun avia (grandmother), in memory of June Thomas who proudly supported her granddaughter’s (BF) science career. The proposed English common name is the Australasia Narrow-nosed Spookfish.

Brittany Finucci, Dominique Didier, David A. Ebert, Madeline E. Green and Jenny M. Kemper. 2024. Harriotta avia sp. nov. – A New rhinochimaerid (Chimaeriformes: Rhinochimaeridae) described from the Southwest Pacific. Environmental Biology of Fishes. DOI: 10.1007/s10641-024-01577-4

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[Ichthyology • 2024] Chimaera supapae (Holocephali: Chimaeriformes: Chimaeridae) • A New Species of Chimaera from the Andaman Sea of Thailand

Chimaera supapae

Ebert, Krajangdara, Fahmi & Kemper, 2024

  Raffles Bulletin of Zoology. (72); 

 twitter.com/LostSharksGuy

Abstract

A new species of shortnose chimaera is described from a single specimen collected at 772–775 m depth in the Andaman Sea (07.54° N; 96.99° E) off Thailand. The species is distinguished from its congeners by the combination of the following characteristics: massive head with short snout; eyes relatively large, horizontally oval, eye length 32.2% head length; thin body with a relatively long trunk 40% body length (BDL), deciduous skin; uniformly dark brown; preopercular and oral lateral line canals sharing a common branch; posterior margin of pectoral fins slightly convex; long dorsal spine 27% BDL, longer than the first dorsal fin. The new species is morphologically close to Chimaera macrospina from Australia but differs in the length of the ventral caudal lobe, snout-vent length, and pectoral fin anterior margin length. It can be distinguished from C. macrospina and other Chimaera species based on the DNA sequence divergence of the mitochondrial ND2 gene. 

Key words. Chondrichthyes, eastern Indian Ocean, SE Asia, morphology, genetics, taxonomy

Lateral view of Chimaera supapae, new species, holotype (PMBC 30399),
immature male, 508 mm TL, 276 mm BDL (Before preservation).

Chimaera supapae, new species 

Andaman shortnose chimaera

Diagnosis. Chimaera supapae can be distinguished from all other chimaeroids by the following combination of characters: massive head with a short snout; eyes relatively large, horizontally oval, eye length 32.2% head length; thin and relatively long trunk 40% BDL, deciduous skin; uniformly dark brown, without any spots or stripes; preopercular and oral lateral line canals sharing a common branch; posterior margin of pectoral fins slightly convex; long dorsal spine 27 % BDL, longer than first dorsal fin.

Etymology. The epithet supapae is named to honor the late Professor Supap Monkolprasit (1934–2013), for her extensive work on the cartilaginous fishes of Thailand. She was the Dean of Faculty of Fisheries, Kasetsart University, Thailand during the years 1991–1995, but devoted her entire life to the study of cartilaginous fishes in Thailand.

Distribution. Known only from the type location ___ in the Andaman Sea off Thailand, eastern Indian Ocean at 772–775 m depth (Fig. 1).

David A. EBERT, Tassapon KRAJANGDARA, FAHMI and Jenny M. KEMPER. 2024. Chimaera supapae (Holocephali: Chimaeriformes: Chimaeridae), A New Species of Chimaera from the Andaman Sea of Thailand.  Raffles Bulletin of Zoology. (72); 84–90.

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