Sunday, June 13, 2010

New Sharks and Rays!

Check this out!

It's a whole list of newly described Elasmobranchs from Borneo.
It includes some very cool finds like a new Wobbegong and a new River Shark - but the one paper that personally fascinates me most starts on page 141.

It re-affirms the Eagle Ray Aetobatus ocellatus as a valid species.

ABSTRACT.— Aetobatus narinari is generally considered to have a circumglobal distribution but some have suggested that it consists of more than one cryptic species. Recent molecular studies have provided evidence of a species complex, with an Indo–West/Central Pacific clade and a Western Atlantic clade.

This paper investigates the nomenclature of the Indo–West Pacific species and provides a redescription of Aetobatus ocellatus (Kuhl, 1823).
Aetobatus ocellatus is very similar morphologically to Aetobatus narinari but differs in having a slightly longer tail and a different dorsal coloration. A major taxonomic revision of the A. narinari complex is required to determine the number of species present, their distributional ranges and effective field characters. The conservation status of members of this complex needs to be evaluated.

The comparison of Aetobatus ocellatus with A. narinari from the Western Atlantic revealed that they are very similar morphologically... The major difference between these species is the background coloration of the dorsal surfaces.

Aetobatus ocellatus has a dark greenish, greyish to almost blackish (sometimes with a pinkish tinge) background colour, whereas all Western Atlantic specimens of A. narinari have a much paler, medium yellowish brownish (fawn) background colour.

This is a direct confirmation of Mahmood's paper that postulated
Based on combined genealogical concordance and genetic distance criteria, we recommend that the Western/Central Pacific lineage be recognized as a distinct species from lineages in the Central Atlantic and Eastern Pacific.
How cool is that!

As to the conservation status, it looks grim.
The IUCN describes the global status of the Spotted Eagle Ray A. narinari as being Near Threatened. Impressively thorough as always (read it!), the report then adds that the fishing pressure in Southeast Asia and Africa, i.e. the range of A. ocellatus, is particularly heavy, warranting a listing as Vulnerable.

Not good - but still, always fascinating to observe Taxonomy in action!

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