Goniobranchus roboi (Gosliner & Behrens, 1998)

Location: Monshita, Osezaki, Shizuoka, Japan
Date: 2022/07/15
Length: 25mm
Depth: 26.0m
Water temperature: 23.0℃

Description

A medium-sized chromodorid, 17–50 mm long. Easily distinguished by the magnificent, bright blue blocks of colour which appear in series separated by black areas of pigment. The blue blocks are squarish or rectangular in shape with edges that are rounded to varying degree. The dorsal yellowish-orange surface is interrupted in many areas where circles or irregular patches of blue to lavender are visible. Usually a large patch is present behind each rhinophore, and dark brown or wine-coloured blotches may cover the dorsal surface. The areas bordering the rhinophore and gill sheaths are orange and may bear spots of bright blue, lavender, black or wine. The lamellae and rachis of the rhinophores and the longitudinal edges of the gill plumes are dark blue to black; in one specimen the gill plumes are entirely blue-black. The foot bears the same pattern as the mantle margin, blue with black stripes radiating from near the median line. There are 5–6 elongate, unipinnate gills and the rhinophores bear 19–22 lamellae. As in G. hintuanensis, G. roboi raises and lowers its anterior end when actively crawling (R. Bolland, pers. comm.).

Distribution

Type locality: Horseshoe Cliffs, 1 km NW of Onna Village, Okinawa, Ryukyu Islands, Japan, 26°30′N, 127°50.9′E (Holotype CASIZ 079346, collected 31 August 1991 at 47 m depth by Robert F. Bolland). Known from Lord Howe Island, New South Wales, Australia (Coleman 1989); Murion Island, Western Australia (Debelius 1996, as Hypselodoris vibrata); and Okinawa, Ryukyu Islands, Japan (present study). Found at relatively deep reef habitats (37–50 m).

Etymology

The species is named for Robert Bolland, friend and enthusiastic nudibranch biologist. The first two letters of his first and last names produce "robo," synonymous with RoboCop — a fictitious personality equally as daring and adventurous as their friend Bob Bolland.

Remarks

Originally described as Chromodoris roboi; transferred to Goniobranchus in a molecular revision based on molecular phylogeny. Not a member of the Chromodoris quadricolor complex. The most similar species in colour pattern are G. vibratus (Pease, 1860) — with white pustules on a yellow-orange notum and a white marginal region with triangular dark blue interruptions — and G. aureopurpureus (Collingwood, 1881) — with a white body bearing dark blue mantle margin intrusions and orange spots. G. roboi has long been confused with G. vibratus (Debelius 1996, fig. 239 misidentified). Diagnostic differences: G. roboi has only 5–6 gills which do not vibrate, while G. vibratus has 8–10 vibratile gills (Kay & Young 1969); G. roboi has a vestigial rachidian tooth, apparently absent in G. vibratus; the radula of G. roboi bears 8–11 denticles on middle laterals (vs. up to 4 in G. vibratus).

Photographed by Yukio Seki

Description

Distribution

Etymology

Remarks

References

A Kindle field guide by the site author

Seasonality

Shooting Locations

Photos of Goniobranchus roboi

Same Genus Nudibranchs

Similar Colors Nudibranchs

Academic Database