Author: Undescribed

Order: Nudibranchia  Family: Tritoniidae

Maximum Size: 40 mm

Sightings: Whitsundays

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Marionia sp. 10 Undescribed

This species bears a close resemblance to the Marionia sp. 10 in NSSI, 2018. The same numbering is purely coincidental.

This first specimen, recorded in the Whitsundays, was approximately 40 mm in length.

The body is long, narrow and high in profile that tapers posteriorly, ending in a short whip-like tail. There appear to be six pair of short, sparsely-branched secondary gill processes situated laterally on the margin of the notum, and spaced down the length of the animal. The notum is covered in small low tubercles. The foot is wider than the body.

The rhinophore stalks arise out of tall sheaths that have small papillae around the rim. The sheaths are angled outwards at ninety degrees to each other. The rhinophore clubs, at the ends of plain stalks, are bulbous with arborescent processes, a single ”finger” protruding from the centre that ends in a small knob. They are mostly white with some brown and red pigmented spots. There appear to be six velar tentacles, the lateral-most on each side are the longest and are branched with the inner four only one third of that length and with minor branching. They are all white in colour with red spotting upon the basal portions.

The overall impression of body colour is red with white patches on the notum and brown to the body sides, however the body is translucent white with the colour being formed by many minuscule opaque red, brown and white spots of varying densities. The the head carries a long white patch that bifurcates to extend anteriorly on to the dorsal surface of rhinophore sheaths. There are four to five irregularly-edged, white patches located down the centre of the notum alternating between each set of gill processes. The secondary gill processes are reddish brown basally and white on the finer branches.

David A. Mullins – August 2023

References:
– Gosliner, T. M., Valde ́s, A ́. & Behrens, D. W. (2018). Nudibranch & Sea Slug Identification – Indo-Pacific, 2nd Edition. New World Publications, Jacksonville, Florida, USA.