Rostral Cartilage Research Articles

An enigmatic chondrichthyan spine from the Visean of Indiana, USA that resembles a median rostral cartilage of Squaloraja (Holocephali, Chimaeriformes)

Squaloraja is a genus of chimaeriform fishes known from the Early Jurassic. It has a dorsoventrally flattened body and a long median rostral cartilage. Males have a lance-like tenaculum that articulates with a central groove on the dorsal face of the median rostral cartilage. The genus is the only member of the family Squalorajidae, itself the only family in the suborder Squalorajoidei of the order Chimaeriformes. Phylogenetic analyses suggest a divergence of the Squalorajoidei from other Chimaeriformes in the Mississippian, implying the existence of a ghost lineage of more than 130 My. A spine that resembles a median rostral cartilage of a male Squaloraja was found in the St. Louis Formation (Visean) of Indiana, USA. As in Squaloraja, the dorsal face has a long narrow groove that would have articulated with a long narrow tenaculum. The spine is designated as the holotype of Sulcacanthus schachti, n. gen. et sp. Sulcacanthus is tentatively assigned to the Squalorajoidei based on morphology, but the possibility of convergence cannot be eliminated. A holocephalan tenaculum from the same locality might belong to the same taxon as the median rostral cartilage but could also belong to the suborder Myriacanthoidei.

A batoid hembryo (Chondrichthyes: Batoidea), from the marine upper Cenomanian (Late Cretaceous) Sannine limestone of Hjoula, Lebanon

ABSTRACT Here, a fossil egg case that contains a well-preserved embryo is described. The embryo is characterised by (i) a rostral cartilage, (ii) some ribs, (iii) and a well-developed stinger; (iv) absence of thoracolumbar synarcual. This represents an unique combination of characters which demonstrate that the batoid that produced the egg case was a completely new form, possibly a stem–Myliobatiformes, which remains undetermined in the absence – to date – of any comparable adult specimen. SEM morphological analysis demonstrates that the wall of the fossil egg case was multilaminate, made up of collagen fibres (with a thickness of 2–4 μm): an ultrastructure that has been positively compared to the egg case of living Rajiformes (Raja asteria) and Myliobatifirmes (Hemitrygodon akajeri). The egg case also contains a mass that is interpreted as the remains of yolk sac, internally organised in platelets with a diameter of 25–35 μm. Since in living Myliobatiformes the egg cases disappears from inside the uterus before the end of the embryogenesis, the described fossil is interpreted as an embryo that was prematurely emitted by the pregnant mother, such as an abortion of a batoid dated to the Late Cretaceous.

A taxonomic revision of Northeast Pacific softnose skates (Rajiformes: Arhynchobatidae: Bathyraja Ishiyama)

Softnose skates (Rajiformes: Arhynchobatidae: Bathyraja Ishiyama) are the most diverse skate genus, with 54 species, and are readily distinguishable from other genera in the family by their poorly calcified, flexible rostral cartilages. Six Bathyraja species are considered valid in the eastern North Pacific, including: B. abyssicola, B. aleutica, B. kincaidii, microtrachys, B. spinosissima, and B. trachura. Similar to other skate genera, eastern North Pacific Bathyraja lack a robust species-specific identification, which leads to issues with setting catch limits and creating management plans. This study identifies and formally redescribes the eastern North Pacific softnose skate species based on morphometric and meristic measurements and includes an Alaskan species, Bering Skate, B. interrupta due to its close morphological relationship to B. kincaidii. A lectotype for B. interrupta is designated. Multivariate tests determined that significant differences existed between the study species. Parsimonious phylogenetic trees showed that B kincaidii represents the basal condition, with B. abyssicola and B. aleutica being the most derived species in the study. The formerly synonymized species B. interrupta and B. kincaidii were shown to be separate, as were the previously synonymized species B. microtrachys and B. trachura. Improved Bathyraja species identification will hopefully assist fisheries managers in developing conservation policies easing the impacts of deep-sea fishing expansion.

Paleobiology and paleobiogeography of sclerorhynchid sawfishes (Chondrichthyes, Batomorphii)

Sclerorhynchid sawfishes are a monophyletic group of Cretaceous selachians. They resemble modern sawfishes in the outer morphology and by having a hypertrophic rostral cartilage armed with lateral rows of spines. Generally, sclerorhynchid sawfishes were inhabitants of warm, shallow tropical and subtropical marine environments. Teeth of the oldest sclerorhynchid sawfishes from Spain are presented. They belong to Onchopristis Stromer and come from the lower Barrernian of eastern Spain. The paleobiology and paleogeographic pattern of sclerorhynchid sawfishes is reviewed and discussed.

The skeletal remains of the euryhaline sclerorhynchoid †Onchopristis(Elasmobranchii) from the ‘Mid’-Cretaceous and their palaeontological implications

AbstractWe present the first known cranial remains of the fossil batoid †Onchopristis numidus. Based on two exceptionally well-preserved specimens collected from the ‘Kem Kem Beds’ (Albian–Cenomanian), south-east Morocco, an almost complete description of the rostral and cranial portions of the genus †Onchopristis is provided, together with new observations regarding the development and arrangement of the rostral denticle series for this genus. The comparison between the rostrum length of the specimens of †O. numidus with those of extant pristids, reveals a relatively large batoid species with an estimated total length between two and four metres. Overall, the cranial morphology of †Onchopristis resembles that of other sclerorhynchoids. Its robust hypertrophied rostrum, with the characteristic wood-like mineralization covering the inner layer of tessellate cartilage at the centre of the rostrum, in addition to the thick lateral layers of densely porous cartilage on the sides of the rostral cartilages, resembles that observed in †Ischyrhiza and †Schizorhiza, and differentiates †Onchopristis from other sclerorhynchoids (e.g. †Libanopristis, †Micropristis and †Sclerorhynchus). Aiming to determinate the phylogenetic relations of †Onchopristis within sclerorhynchoids, a cladistic analysis was carried out based on the remains described here; its results suggest a new taxonomic arrangement within the sclerorhynchoids.

Anatomy, taxonomy and phylogeny of the Eocene guitarfishes from the Bolca Lagerstätten, Italy, provide new insights into the relationships of the Rhinopristiformes (Elasmobranchii: Batomorphii)

Abstract We here re-evaluate the skeletal anatomy and the systematic position of the two Eocene guitarfish species represented by almost complete and articulated material from the Konservat-Lagerstätten of Bolca in Italy. The analyses of morphometric, skeletal and dental features of ‘Rhinobatos’ dezignii and ‘R.’ primaevus allow them to be excluded from the living guitarfish genus Rhinobatos and assigned to the new genera †Pseudorhinobatos gen. nov. and †Eorhinobatos gen. nov., respectively. The placement of these new genera within the rhinopristiform family Rhinobatidae is based on the possession of a series of morphological features (e.g. pectoral fins fused to head forming a wedge-shaped pectoral disc; rostral cartilage extending to the tip of the snout; nuchal cartilages and horn-like processes of nasal capsules absent; teeth with Rhinobatos-like morphology displaying smooth enameloid, central uvula and two lateral uvulae) that unambiguously exclude their assignment to any other rhinopristiform family. A new morphology-based phylogenetic analysis that includes the two new fossil genera, described herein, provides novel insights into the relationships of the Batoidea and recovers the Rhinopristiformes as a paraphyletic group. This indicates that the monophyly of extant taxa could be the result of the extinction of crucial taxa.

First record of Gorgona guitarfish (Pseudobatos prahli) off the Baja California peninsula with updated key to the guitarfishes of the North Eastern Pacific.

The Gorgona guitarfish is a poorly documented ray found in the Eastern Pacific. It can be distinguished from its congeners due to its distinctive coloration and rostral cartilages. Here I document an extensive northern range expansion of almost 2000 km based on a juvenile specimen caught off the Baja California Peninsula. This specimen also represents the smallest documented individual of this species, along with the first quantitative morphometric data reported since the 1995 description. Additionally, an updated key to the guitarfishes of the North Eastern Pacific is included.

Bathyraja (Arctoraja) sexoculata sp. nov., a new softnose skate (Rajiformes: Arhynchobatidae) from Simushir Island, Kuril Islands (western North Pacific), with special reference to geographic variations in Bathyraja (Arctoraja) smirnovi.

A new species of softnose skate (Arhynchobatidae), Bathyraja sexoculata Misawa, Orlov, Orlova, Gordeev and Ishihara is described on the basis of five specimens collected from off the east coast of Simushir Island, Kuril Islands, located in the western North Pacific. The specimens conformed to the genus Bathyraja by having the anteriormost pectoral-fin skeleton almost reaching the snout tip, and a slender unsegmented rostral cartilage. Within Bathyraja, the new species belongs to the subgenus Arctoraja (currently with four valid species) due to the relatively short tail (79-86% of disc width), high count of predorsal caudal vertebrae (more than 86), and large strong nuchal and scapular thorns. It is most similar to Bathyraja (Arctoraja) smirnovi, distributed in the Seas of Japan and Okhotsk, in having tail thorns not extending to the nuchal area, median thorns discontinuous from the nape to the tail, and no mid-dorsal thorns. However, B. sexoculata can be distinguished from B. smirnovi by the following characters: three pairs of white blotches on the dorsal disc surface (vs. blotches absent, or a pair of white or dark blotches in B. smirnovi), dark blotch around cloaca, dark bands along mid ventral line of tail (vs. dark blotch and band usually absent ventral disc surface in B. smirnovi), 86-93 predorsal caudal vertebrae (vs. 80-87 in B. smirnovi), and a unique mitochondrial DNA cytochrome c oxidase subunit I sequence. Proportional measurements, including disc width, disc length, head length, preoral length, prenarial length, internarial distance, eye diameter, and tail length, also differ between the two species. For the referential purpose, geographical variations of B. smirnovi distributed in the Seas of Japan and Okhotsk are analyzed and clarified based on morphological and genetic data. Significant morphological and genetic differences were found between local populations in the Seas of Japan and Okhotsk.

Revision of the Eocene ‘Platyrhina’ species from the Bolca Lagerstätte (Italy) reveals the first panray (Batomorphii: Zanobatidae) in the fossil record

The fossil-Lagerstätte of Bolca (Italy) is well known for the diversity and exquisite preservation of its bony and cartilaginous fishes documenting tropical shallow-water marine environments associated with coral reefs in the western Tethys during the early Eocene. In this study, the taxonomic, systematic and phylogenetic position of two batoid species traditionally assigned to the living thornback ray genus Platyrhina is re-evaluated. †Platyrhina bolcensis Heckel, 1851 is recognized as a separate species of the Platyrhinidae because of its plate-like antorbital cartilage with an irregular outline and a small horn on the nasal capsules. Also, the rostral cartilage does not reach the anterior border of the disc. Support for the placement of this species within the new genus †Eoplatyrhina gen. nov. is based on a combination of morphological and meristic features (e.g. nasal capsules at right angles to the rostrum; large space between the hyomandibulae and mandibular arch; approximately 132 vertebral centra; 15–16 rib pairs; 81–87 pectoral radials; 18–21 pelvic radials; short, straight and stout claspers; 40–50 caudal-fin radials; thorns absent). A second species, †Platyrhina egertoni (De Zigno, 1876), is more closely related to the living panray Zanobatus than Platyrhina and is assigned here to †Plesiozanobatus gen. nov. because of a combination of characters that support its placement within the family Zanobatidae (tail stout and short, distinctly demarcated from disc; two dorsal fins and complete caudal fin; small dermal denticles and scattered thorns covering disc and tail; rostral cartilage absent; nasal capsules without horn-like processes; mesopterygium absent). The systematic position of a third taxon, †Platyrhina gigantea (Blainville, 1818), is currently impossible to establish due to the poor preservation of the only known specimen, and therefore we propose to consider it a nomen dubium. Palaeoecological and biogeographic features of the Eocene platyrhinids and zanobatids from Bolca are also discussed.http://zoobank.org/urn:lsid:zoobank.org:pub:B4C7A979-7972-409B-B489-A6DDD5E35FE5

A new genus and species of catshark (Carcharhiniformes: Scyliorhinidae) from eastern Indonesia.

A new genus and species of catshark is described based on a single specimen collected off Ambon in the Maluku Islands of eastern Indonesia. Akheilos suwartanai belongs to the subfamily Schroederichthyinae which differs from the other catsharks in a combination of: similar sized dorsal fins, supraorbital crests present, pseudosiphon present on claspers, broad subocular ridges under eyes, posterior nasal flaps present, tips of rostral cartilage fused into a rostral node. It represents the first record of this subfamily outside of the Americas. Akheilos differs from the other genus in the subfamily, Schroederichthys in a combination of: clasper groove not fused dorsally, ventral lobe of caudal fin produced, more intestinal valve turns, anal fin slightly larger than second dorsal fin, and in colour pattern.

Revision of Eocene electric rays (Torpediniformes, Batomorphii) from the Bolca Konservat-Lagerstätte, Italy, reveals the first fossil embryo in situ in marine batoids and provides new insights into the origin of trophic novelties in coral reef fishes

The Eocene electric ray †Titanonarke Carvalho, 2010 from the Bolca Konservat-Lagerstätte, north-eastern Italy, is redescribed in detail based upon new material from recent excavations. This taxon exhibits a combination of features (large voids between the pectoral and the axial skeleton filled in life by electric organs, anteriorly directed fan-shaped antorbital cartilages, lack of dermal denticles, long prepelvic processes, and rounded basibranchial copula with a small caudal tab) that clearly supports its assignment to the order Torpediniformes. The analysis of new material also demonstrates that the previous apparent absence of typical narcinoid characters used to diagnose †Titanonarke was the result of taphonomic biases. †Titanonarke shares at least three synapomorphies (presence of a rostral fontanelle, low number of ribs, and rostral cartilage connected to the antorbital cartilage through lateral appendices) with the extant genera Benthobatis, Diplobatis, Discopyge and Narcine, with which it forms a clade (family Narcinidae) recognized herein as unquestionably monophyletic. Moreover, based upon a single specimen of †Titanonarke that exhibits a unique combination of morphometric and meristic features, a new species of Eocene numbfish, †T. megapterygia sp. nov., is recognized. The presence of several specimens representing different ontogenetic stages of at least two species of numbfishes suggests a close association of this taxon with shallow-water habitats corresponding to coral reefs as hypothesized for the Monte Postale palaeoenvironment. The occurrence of a fossilized marine batoid embryo is reported here for the first time. Moreover, the analysis of the gut contents suggests that the dietary adaptations of †Titanonarke can be related, at least in part, to an opportunistic strategy in the context of abundant larger foraminifera in the Monte Postale palaeobiotope, suggesting that this kind of feeding mode, known to occur in present-day reefs, already was realized 50 million years ago.http://zoobank.org/urn:lsid:zoobank.org:pub:EDD6E170-CA64-4FFB-8DD1-AED2D61D5504

The impacts of comparative anatomy of electric rays (Batoidea: Torpediniformes) on their systematic hypotheses

The Comparative anatomy of the 11 recognized genera within Torpediniformes is described, systematically categorized, and illustrated in a comprehensive photo-atlas. Data are compiled into a character matrix and cladistically analyzed using parsimony to test hypotheses about the previously recognized subfamilies, while reconstructing the possible evolutionary history of Torpediniformes. Results are consistent with the previous rank-based classifications, regardless of the parsimony criteria used to generate the phylogenetic hypothesis, with one notable exception: a monophyletic Narcininae was never recovered. Torpedinoidea (=Hypnos + Torpedo) is supported by the presence of long, slender, flexible jaw cartilages, absence of a large rostral fontanelle, presence of suprascapular antimeres that are each shorter than the scapular process of the scapulocoracoid, antorbital cartilages that articulate on the anterior aspect of the nasal capsules and absence of a frontoparietal fontanelle. Subfamilial names Hypninae and Torpedininae are redundant with the genus names Hypnos and Torpedo and are not adopted here. Narcinoidea (=nontorpedinoid torpediniforms) is supported by unambiguous character transformations to the presence of a divided lower lip, labial cartilages, laterolingually compressed palatoquadrates, bifurcated antorbital cartilages, a rostral fontanelle, ventrally projecting nasal capsules, a dorsal rim of the synarcual mouth posterior to occipital condyle, posteriorly positioned lateral stays, and obtuse anterior margins of lateral stays. Narkidae is supported by unambiguous character transformations to the presence of an uncovered eye that protrudes above dorsal surface, a shared rim between the spiracle and the eye, an anterior nasal turret that projects ventrally, a nasal curtain that covers the upper lip and dentition when the mouth is closed, tab-like prepelvic processes, a mesopterygium that is shorter than propterygium but longer than metapterygium, a slender median rostral cartilage, and a basibranchial cartilage with an anterior margin that is depressed medially and a posterior margin that tapers.

Chondrocranial Morphology of the Salmon Shark,Lamna ditropis, and the Porbeagle,L. nasus(Lamnidae)

Adult chondrocranial morphology is poorly documented in modern lamniform sharks. Here it is described for the two extant species of Lamna, L. nasus and L. ditropis. Several features are noted and discussed, including hypercalcification of the rostral cartilages, the ethmoidal region associated with ligamentous jaw attachments, and the configuration of the postorbital region. The small polygonal blocks of calcified cartilage (tesserae) that typically line the chondrichthyan endoskeleton are greatly thickened in the rostral bars of Lamna, forming radial columns; furthermore, concentric banding of the columnar calcification in the rostrum of L. ditropis suggests periodic accretion of new calcified tissue below the perichondrium. The postorbital region in Lamna is notable for lacking a postorbital process, and in having the supraorbital shelf continuing posteriorly as a supra-otical shelf, which extends as far as the hyomandibular fossa. The orbit in Lamna is apparently not drained in the usual elasmobranch m...

An Immunohistochemistry Study of Sox9, Runx2, and Osterix Expression in the Mandibular Cartilages of Newborn Mouse

The purpose of this study is to investigate the spacial expression pattern and functional significance of three key transcription factors related to bone and cartilage formation, namely, Sox9, Runx2, and Osterix in cartilages during the late development of mouse mandible. Immunohistochemical examinations of Sox9, Runx2, and Osterix were conducted in the mandibular cartilages of the 15 neonatal C57BL/6N mice. In secondary cartilages, both Sox9 and Runx2 were weakly expressed in the polymorphic cell zone, strongly expressed in the flattened cell zone and throughout the entire hypertrophic cell zone. Similarly, both transcriptional factors were weakly expressed in the uncalcified Meckel's cartilage while strongly expressed in the rostral cartilage. Meanwhile, Osterix was at an extremely low level in cells of the flattened cell zone and the upper hypertrophic cell zone in secondary cartilages. Surprisingly, Osterix was intensely expressed in hypertrophic chondrocytes in the center of the uncalcified Meckel's cartilage while moderately expressed in part of hypertrophic chondrocytes in the rostral process. Consequently, it is suggested that Sox9 is a main and unique positive regulator in the hypertrophic differentiation process of mandibular secondary cartilages, in addition to Runx2. Furthermore, Osterix is likely responsible for phenotypic conversion of Meckel's chondrocytes during its degeneration.

Comparative morphology of rostral cartilages in extant mackerel sharks (Chondrichthyes, Lamniformes, Lamnidae) using CT scanning

A comparative study of rostral morphology of extant mackerel sharks (Lamniformes, Lamnidae) is presented. Based oncomputed tomography (CT) scans of fresh specimens, 3D reconstructions, dried museum chondrocrania and the availableliterature, detailed morphological descriptions of the rostral cartilages are provided for the type species of all three extantlamnid genera, namely Carcharodon carcharias (Linnaeus, 1758), Isurus oxyrinchus Rafinesque, 1810 and Lamna nasus(Bonnaterre, 1788), and compared with those of I. paucus Guitart Manday, 1966 and L. ditropis Hubbs & Follett, 1947.Despite intraspecific variation, the rostral cartilages of all extant lamnids present significant differences that allow genus-and species-level identification, which is especially of use to identify fossil rostral nodes of these particular taxa. The maindifferences were found to be in overall calcification of the rostrum (Lamna > Isurus > Carcharodon), general configura-tion of the rostral open space, position of the base of the lateral rostral cartilages, (non-)abutting lateral cartilages, (absent)rostral keels and shape of the rostral node. In cross section, the base of the rostral node is rounded in Lamna, Y-shaped in Isurus and uncalcified in juvenile and subadult Carcharodon (tesserae absent).

The taxonomic value of rostral nodes of extinct sharks, with comments on previous records of the genus Lamna (Lamniformes, Lamnidae) from the Pliocene of Lee Creek Mine, North Carolina (USA)

ABSTRACT Mollen, F.H. and Jagt, J.W.M. 2012. The taxonomic value of rostral nodes of extinct sharks, with comments on previous records of the genus Lamna (Lamniformes, Lamnidae) from the Pliocene of Lee Creek Mine, North Carolina (USA). Acta Geologica Polonica, 62 (1), 117-127. Warszawa. Shark rostral nodes from the Yorktown Formation (Zanclean, early Pliocene) of Lee Creek Mine, North Carolina (USA), previously assigned to the genus Lamna Cuvier, 1816, have been reinterpreted using a preliminary identification key for extant Lamniformes based on rostral morphology. In addition, the fossil rostral nodes have been compared in detail with Recent material of both the porbeagle, Lamna nasus (Bonnaterre, 1788) and the salmon shark, Lamna ditropis Hubbs & Follet, 1947. Despite the fact that the rostra compared relatively well with those of Recent Lamna, the Lee Creek Mine specimens proved to differ significantly in having near-parallel lateral rostral cartilages that join the rostral node individually, instead of abutting ones. Based on this observation, we here propose to strike the genus Lamna from the Lee Creek Mine faunal list, so long as no other diagnostic material is forthcoming. These partially preserved rostra are likely to have belonged to extinct taxa within the families Lamnidae or Otodontidae, both of which have been documented from the Yorktown Formation on the basis of isolated teeth of at least three species, Cosmopolitodus hastalis (Agassiz, 1838), Megaselachus megalodon (Agassiz, 1835) and Parotodus benedenii (Le Hon, 1871).

Bathyraja leucomelanos, a new species of softnose skate (Chondrichthyes: Arhynchobatidae) from New Caledonia

A new species of softnose skate (Arhynchobatidae) is described, based on a single adult male measuring 895 mm TL that was collected at a depth of 953–1,022 m on the Coriolis Bank off western New Caledonia in the southwestern Pacific Ocean. The specimen conforms to the genus Bathyraja in having the rostral cartilage continuous with the neurocranium and very slender and uncalcified over its length. Bathyraja leucomelanos sp. nov. differs from its congeners through a combination of the following characters: distinctive coloration of the disc with white dorsal and black ventral surfaces, dorsal surface of the disc entirely covered with dermal denticles, ventral surface naked, anterior portion of the anterior margin of the disc straight, snout long and very broad with orbit about 6.0 times in preorbital length, orbit 0.73 times interorbital width, mouth 6.8% TL, tail 0.88 times precloacal length, accessory terminal 2 cartilage of the clasper having an expanded disc-shaped tip, and alar thorn tip undulating. Molecular barcoding from the COI sequence reveals that this new species is genetically close to B. spinicauda from the North Atlantic Ocean.

A role for FoxN3 in the development of cranial cartilages and muscles in Xenopus laevis (Amphibia: Anura: Pipidae) with special emphasis on the novel rostral cartilages.

The origin of morphological novelties is a controversial topic in evolutionary developmental biology. The heads of anuran larvae have several unique structures, including the supra- and infrarostral cartilages, the specialised structure of the gill basket (used for filtration), and novel cranial muscle arrangements. FoxN3, a member of the forkhead/winged helix family of transcription factors, has been implicated as important for normal craniofacial development in the pipid anuran Xenopus laevis. We have investigated the effects of functional knockdown of FoxN3 (using antisense oligonucleotide morpholino) on the development of the larval head skeleton and the associated cranial muscles in X.laevis. Our data complement earlier studies and provide a more complete account of the requirement of FoxN3 in chondrocranium development. In addition, we analyse the effects of FoxN3 knockdown on cranial muscle development. We show that FoxN3 knockdown primarily affects the novel skeletal structures unique to anuran larvae, i.e. the rostralia or the fine structure of the gill apparatus. The articulation between the infrarostral and Meckel's cartilage is malformed and the filigreed processes of the gill basket do not develop. Because these features do not develop after FoxN3 knockdown, the head morphology resembles that in the less specialised larvae of salamanders. Furthermore, the development of all cartilages derived from the neural crest is delayed and cranial muscle fibre development incomplete. The cartilage precursors initially condense in their proper position but later differentiate incompletely; several visceral arch muscles start to differentiate at their origin but fail to extend toward their insertion. Our findings indicate that FoxN3 is essential for the development of novel cartilages such as the infrarostral and other cranial tissues derived from the neural crest and, indirectly, also for muscle morphogenesis.

Hongeo, a new skate genus (Chondrichthyes: Rajidae), with redescription of the type species

Hongeo gen. nov. is proposed following examinations of several individuals, including adult males, of the type species Raja koreana, previously described from a single adult female specimen from the southern coast of the Korean Peninsula. A number of external (including claspers, squamation, and ampullary and lateral line canal systems) and skeletal characters are newly described. The phylogenetic position of R. koreana among 26 nominal rajid supraspecific taxa plus 2 unnamed supraspecific taxa of Rajidae and 3 outgroups was estimated. According to a strict consensus tree of 20 equally parsimonious trees of 139 steps (CI = 0.626; RI = 0.850; RC = 0.532; HI = 0.374), Hongeo gen. nov. is defined by the two derived character states: rostral cartilage continuous with neurocranium and stout proximally, but very slender and uncalcified distally; and anterior fontanelle broad, extending forward onto the basal part of rostral cartilage slightly beyond the leading edge of nasal capsules. The new genus also differs from all other supraspecific taxa of Rajidae in the following combination of characters: dorsal surface of tail with a row of distinct thorns along midline in both sexes; most thorns directed anteriorly; a pair of longitudinally elongated black blotches having undulated contours on middle of dorsal surface of disc; three groups of outer buccal ampullae and tubules; three groups of nasal ampullae and tubules; hyoidean ampullae and tubules on ventral surface posteriorly extending past cloaca; rostral shaft narrow with filamentous cartilage at base; scapulocoracoid comparatively short and high with dorsoventrally elliptical anterior fenestra and expanded postventral fenestra; external margin of mesopterygium of pectoral fin slightly undulated, not sinuous, and not fused with pectoral radials; and clasper component eperon and pent present.

Dipturus wuhanlingi, a new species of skates (Elasmobranchii: Rajidae) from China

Dipturus wuhanlingi, a new rajid species, is described from an immature male and female collected from the southern East China Sea and off Haimen, Shantou, in the South China Sea, respectively. The specimens conform to the genus Dipturus in having the combination of the following characters: a long rostral cartilage (length more than 60% of dorsal head length), greatly depressed and laterally expanded mesocondyle, and a total length greater than 55 cm when adult. Dipturus wuhanlingi is distinct from all other Dipturus species in the following combination of characters: a pair of scapular thorns, three or four nuchal thorns, an irregular row of lumbar thorns along the dorsal midline of the disc, a single row of tail thorns in both sexes, pores of ampullae of Lorenzini extending to just anterior to the pelvic girdle, anterior fenestra of scapulocoracoid strongly horizontally elliptical, mesocondyle located at about the middle between the procondyle and metacondyle, and three pairs of obturator foramina on the pelvic girdle.