Species in Disguise: A New Species of Hornshark from Northern Australia (Heterodontiformes: Heterodontidae)

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).

Automated summary

A new species of hornshark, Heterodontus marshallae n. sp., has been identified in northwestern Australia. It was previously thought to be the same species as H. zebra from the Western Pacific, but genetic and morphological differences, as well as differences in egg case morphology and coloration, have confirmed it as a distinct species. The H. marshallae n. sp. is endemic to northwestern Australia and inhabits deeper waters than H. zebra.