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| Heterodontus marshallae White, Mollen, O’Neill, Yang & Naylor, 2023 |
Abstract
A new species of hornshark is described from northwestern Australia based on six whole specimens and a single egg case. Heterodontus marshallae n. sp. was previously considered to be conspecific with H. zebra from the Western Pacific. The new species differs from H. zebra in the sequence of its NADH2 gene, several morphological characters, egg case morphology and key coloration features. Despite the coloration being similar between H. marshallae n. sp. and H. zebra, i.e., pale background with 22 dark brown bands and saddles, they differ consistently in two key aspects. Firstly, the snout of H. marshallae n. sp. has a dark semicircular bar, usually bifurcated for most of its length vs. a pointed, triangular shaped dark marking in H. zebra. Secondly, H. zebra has a dark bar originating below the posterior gill slits and extending onto anterior pectoral fin, which is absent in H. marshallae n. sp. The Heterodontus marshallae n. sp. is endemic to northwestern Australia and occurs in deeper waters (125–229 m) than H. zebra (0–143 m).
Keywords: Heterodontus; taxonomy; species complex; egg case; morphology; genetics
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| Holotype of Heterodontus marshallae n. sp. (WAM P.35408-007, adolescent male, 541 mm TL), fresh: (a) dorsal view; (b) lateral view. |
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| Lateral view of female paratypes of Heterodontus marshallae n. sp., fresh: (a) WAM P.26193-010, juvenile, 355 mm TL; (b) CSIRO H 6581-01, 580 mm TL (image flipped, right side of specimen shown). |
Heterodontus marshallae n. sp.
Diagnosis: A small species of hornshark with the following combination of characters: colour pattern consisting of 22 dark bands and saddles; snout with a semicircular dark bar, usually bifurcated for most of its length; no dark bar below posterior gill slits extending onto anterior pectoral fin; anal fin well separated from caudal fin (anal-caudal space 11.0–13.5% TL); ventral lobe of caudal fin prominent (lower postventral margin 4.7–6.1% TL); dorsal spines long (exposed first dorsal spine length 3.9–4.5% TL); dorsal fins taller in juveniles than adults; symphyseal and anterior teeth pointed, lateral teeth molariform with a longitudinal keel; 20–22 tooth files in upper jaw, 17–19 in lower jaw; total vertebral centra 106–112, precaudal centra 70–76, monospondylous centra 33–37; egg case with narrow, curved, screw-like keels with 1.5 rotations from anterior to posterior margins.
Etymology:
The specific name is in honour of Dr. Lindsay Marshall (www.stickfigurefish.com.au (accessed 10 May 2023)), a scientific illustrator and elasmobranch scientist who expertly painted all the sharks and rays of the world for the Chondrichthyan Tree of Life Project.
The vernacular name proposed is painted hornshark, in allusion to not only the beautiful coloration of the species but also to its namesake, who has painted all the hornsharks in amazing detail.
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| Egg case of: (a) Heterodontus marshallae n. sp., preserved (paratype, NTM S.18275-001); (b) H. zebra, preserved (KAUM-I. 69456); (c) H. portusjacksoni, preserved (CSIRO H 8732-02). |
(This article belongs to the Special Issue Genetic Connectivity, Species Diversity and Conservation Biology of Chondrichthyes)
