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todropscience · 10 months

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THREE NEW SHARK SPECIES THIS WEEK!

The second week of July 2023 something extraordinarily beautiful happened, the findings of 3 new species of sharks for were announced

A new angel sharks species was identified, from the western Indian Ocean on the Mascarene Plateau and off southwestern India in 100–500 m depths, the Lea’s angel shark Squatina leae, was recognized to be different genetically and morphologically distinct from its congeneric species Squatina africanae, following unique morphological features. This species was first detected in 1988 after finding three unusual, small sharks, but till today was completely understood. The angel shark is named after one of the author’s fiancee’s late sister, Lea-Marie Cordt.

- Squatina leae, adult male, in dorsolateral.

Angel sharks are “flatter sharks”, possesing distinctly broad, dorsoventrally flattened bodies, a short snout with large mouth and nostrils, eyes on top of the head close to the large spiracles, very large pectoral fins, and a lateral caudal keel. They've evolved to be ambush predators, they lie in wait for prey to pass closely overhead before attacking.

Reference (Open Access): Weigmann et al., 2023. Revision of the Western Indian Ocean Angel Sharks, Genus Squatina (Squatiniformes, Squatinidae), with Description of a New Species and Redescription of the African Angel Shark Squatina africana Regan, 1908. Biology

From North Australia, another species of hornshark is described based on six whole specimens and a single egg case. The painted hornshark Heterodontus marshallae was previously considered to be the same with the zebra bullhead shark another well know bullhead shark from the central Indo-Pacific from Japan to Australia, but genetic and morphological analyses indicated the sharks were different, but looking alike. The painted hornshark is endemic to northwestern Australia and occurs in deeper waters, at 125–229 m below surface.

- Lateral view of two mature female painted hornshark Heterodontus marshallae showing small differences between individuals

The painted hornsharks is named in honour of Dr. Lindsay Marshall www.stickfigurefish.com.au a scientific illustrator and elasmobranch scientist who expertly painted all the sharks and rays of the world for the Chondrichthyan Tree of Life Project.

Reference (Open Access): White et al., 2023 Species in Disguise: A New Species of Hornshark from Northern Australia (Heterodontiformes: Heterodontidae). Diversity.

And from an unidentified shark egg collected from the deep waters of northwestern Australia, in 2011 recently helped researchers identify a new species of deep water cat shark. Called ridged-egg catshark Apristurus ovicorrugatus after its eggs, it was collected in the earlys 90 but remained unknown to date. This sharks presents white eyes, and is small in size, reaching less than a half meter in length. .

- Lateral view of female Apristurus ovicorrugatus before preserved. Photo by CSIRO.

Egg cases belonging to this species had been documented as early as the 1980s, but could not be matched to any species of Australian shark until recently scientists examined a shark specimen of previously uncertain identity in the CSIRO collection.

-egg cases of Apristurus ovicorrugatus. Scale bar is 10 mm

Reference (Open Access) White,et al., 2023 What came first, the shark or the egg? Discovery of a new species of deepwater shark by investigation of egg case morphology. Journal of Fish Biology.

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