Author: Rudman, 1990

Order: Nudibranchia  Family: Chromodorididae

Maximum Size: 80 mm

Sightings: Sunshine Coast

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Glossodoris vespa Rudman, 1990

Some species of sea slug have a very limited geographical range or distribution. There may be a number of reasons for this. Perhaps their food source itself is limited in distribution, perhaps they are a “recently” evolving species due to particular selection pressures in that region/habitat or perhaps their type of development does not allow for a broader distribution of their larvae.

Glossodoris vespa is a large (up to 80 mm) species of nudibranch with a restricted distribution, reportedly endemic to just the Southern Queensland waters of Australia. It is a most distinctive species and cannot be confused with any other. It is moderately common in its area of distribution.

The shape of the mantle is elongate oval with the posterior end of the foot observable with that portion being equal to one quarter, up to one third, of the mantle length. The edge of the mantle overlaps the body and is somewhat undulating with often a single, approximately central, significant fold on each side. The mantle colour is black but with very fine and close-set white speckling, such that the general impression is of a dark blue colour instead. There may be a few white or even yellow insignificant spots that are a little larger but these appear to be randomly positioned. The mantle carries a narrow black marginal band then a wider, single, vivid-yellow submarginal band to its edge on both the dorsal and ventral surfaces. The body and dorsum of the foot are of the same colour as the mantle. The foot too, often has a yellow submarginal band, but there, the yellow is not as vivid nor as wide.

The rhinophores are similarly coloured as the notum but the gills are somewhat translucent and have a black line running up both the anterior and posterior surfaces. There is no contrasting colour to any of the pocket rims. The simple gills are located posteriorly on the dorsum. They form an arc anteriorly around the anus with each end curving around to form a small spiral on both sides, thus leaving the posterior open.

The defensive glands are small and not readily observable being positioned as an uninterrupted line just inside the yellow submarginal band.

The spawn is laid as a cream-coloured upright, but inwardly sloping spiral of two to three whorls. Development is direct, after a long embryonic period, with well-formed juvenile slugs hatching and crawling onto their food source where the spawn was originally laid. The vestigial shell is left behind in the egg capsule. There is a range of direct types of development. In this case the development of Glossodoris vespa may also be referred to as ametamorphic-direct whereby there is only a vestigial appearance of veligal larva features while in the egg capsule. This means there is not a fully developed veliger larva that would then require metamorphosis into the slug form prior to hatching.

Glossodoris vespa preys on sponges like all the Chromodorididae family.

In the 2012 Chromodorididae review by Johnson and Gosliner, Glossodoris vespa was not sequenced, however it was hypothesized then to remain within the Glossodoris genus. This aligned with Rudman’s earlier view that Glossodoris needed splitting up but that Glossodoris vespa seemed to affiliate with the Glossodoris cincta group and Glossodoris hikuerensis. However, its feeding preference would seem to indicate that perhaps it should have been transferred as it would appear to feed upon the same type of sponge as Ardeadoris rubroannulata which was transferred from Glossodoris.

Rudman named this nudibranch vespa because of its wasp-like black and yellow colouration. If you want to find and photograph this species for your nudibranch image collection you’ll have to visit the offshore reefs of SE Queensland.

Prior to Rudman’s description it had been called Casella sp. – Willan & Coleman, 1984.

David A. Mullins – July 2020

References:
– Willan, R.C. & Coleman, N. (1984). Nudibranchs of Australia, Neville Coleman, AMPI: 28-29

– Rudman, W. B., (1990). The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: further species of Glossodoris, Thorunna and the Chromodoris aureomarginata colour group. Zoological Journal of the Linnean Society 100: 263-326.

– Rudman, W. B., (1998, May 26). Glossodoris vespa Rudman, 1990. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/glosvesp and associated messages.

– Wilson, N.G. (2002) Egg Masses of Chromodorid Nudibranchs (Mollusca: Gastropoda: Opisthobranchia). Malacologia, 2002, 44(2): 289-305.

– Johnson, R.F., Gosliner, T.M. (2012). Traditional taxonomic groupings mask evolutionary history: A molecular phylogeny and new classification of the chromodorid nudibranchs. PLoS One 7 (4): e33479.

– This Species Profile has been modified from:
– A previously published article in Dive Log Magazine’s – Critter ID with NudiNotes Column, Issue: #377 (December 2019): 12 by David A. Mullins.