Goniobranchus (=Chromodoris) geminus (Rudman, 1987)
This week we present a couple of fantastic images, by two great photographers, of one of the most beautiful of the chromodorids, Goniobranchus geminus. For those of you wondering about the use of the name Goniobranchus rather than Chromodoris, we direct you to Johnson & Gosliner, 2012. In their "Branchworld shaking" review, the genus Chromodoris was separated on phyllogenetic grounds into a number of previously described genera. In the case of C. gemina, it is now referred to as Goniobranchus geminus. The genus Goniobranhcus was erected by Pease in 1866, the type species being Goniobranchus vibratus. Johnson & Gosliner state - "When Pease designated Doris vibrata as the type species for the new genus Goniobranchus, he should have changed the ending of vibrata to vibratus to reflect the masculine gender of the -us ending. We have made that correction here and changed the gender of all of the species names that require changing (names derived from adjectives) in Goniobranchus."
We all hate to see these names change, but this represents the continuing improvements being made in our understanding of the systematics of marine organisms.
G. geminus is distinguished by its yellow body with four color bands around the mantle edge, the outermost which is white, followed by grayish-purple, and then bluish-white then yellow. The middle of the dorsum bears numerous purple-brown spots ringed with bluish-white. A tan to yellow cloud fills the area between the spots.
This is one of the species known for mantle flapping, as seen dramatically in Lawrence's photo.
The photo above was taken by Lawrence Neal, a journalist based in Bangkok, Thailand. The photo to the left was taken by Dave Cowdery, a retired engineer who resides in Australia . Dave's image was taken in Bima Harbor, Indonesia at a site called Black Rocks.
Rebecca Fay Johnson and T. M Gosliner. 2012. Traditional Taxonomic Groupings Mask Evolutionary History: A Molecular Phylogeny and New Classification of the Chromodorid Nudibranchs. PLoS ONE 7(4): e33479. doi:10.1371/journal.pone.0033479.
Lawrence is a newspaper journalist based in Bangkok, Thailand. He escapes the office as often as he can to go diving in the rich waters of the Indo-Pacific but his regular dive sites are just down the road along the Gulf of Thailand and the Andaman Sea coast. Lawrence uses a Nikon D200 with a 60-mm or 105-mm macro lens in a Nexus housing together with a pair of Inon Z240 strobes and several wet lenses for the really small stuff.
Send Lawrence mail at firstname.lastname@example.org