Hypselodoris cf. maritima (Baba, 1949)

Mehrotra, Rahul, A. Caballer Gutierrez, Manuel, M. Scott, Chad, Arnold, Spencer, Monchanin, Coline, Viyakarn, Voranop & Chavanich, Suchana, 2021, An updated inventory of sea slugs from Koh Tao, Thailand, with notes on their ecology and a dramatic biodiversity increase for Thai waters, ZooKeys 1042, pp. 73-188 : 73

Hypselodoris cf. maritima (Baba, 1949) Figure 11E, F

Material examined.

Three specimens 14-30 mm, TT; two specimens 15-25 mm, SWP; one specimen 20 mm, SR.

Ecology.

On rocks and rubble within coral reef. Depth 5-25 m.

Distribution.

Hypselodoris maritima is recorded from Japan ( Baba 1949), Vietnam ( Martynov and Korshunova 2012), Taiwan ( Su et al. 2009), the Philippines, Indonesia, Hong Kong, Papua New Guinea, and Australia ( Gosliner et al. 2008). The species is also recorded as being present in Thailand by Gosliner et al. (2008) but no confirmed records of this or similar species outside of Koh Tao have been found in the literature.

Remarks.

Initially recorded as H. maritima from Koh Tao ( Mehrotra and Scott 2016), further observations have shown variation in external morphology that diverges from the original description. In general, the dorsal surface is always white with scattered and slightly raised spots. While many individuals bear the deep blue to black 'longitudinal streaks’ along the central dorsal surface, in others these are broken lines or even entirely disconnected spots of varying sizes. Rhinophore clubs range from entirely orange to white with orange apices, stalks always translucent white. The blue marginal band is always separated from the yellow submarginal band by the same white as the dorsum, and both bands are often broken or rows of pigmented spots, matching variation in the dark pigmentation. There are always deep blue-black spots between marginal and submarginal bands/rows, that may vary in size and often extend to the mantle edge. While closer examination may reveal individuals from Koh Tao and the nearby pinnacles to be more than one species, the population is here treated as a single variable species.

Figures

Figure 11. A Hypselodoris cf. juniperae 6 mm B Hypselodoris cf. kanga 40 mm C Hypselodoris katherinae 15 mm D Hypselodoris cf. lacuna 10 mm E, F Hypselodoris cf. maritima 20 mm (E) and 25 mm (F) G Hypselodoris tryoni, right specimen 35 mm (photograph by Kirsty Magson) H Mexichromis mariei 15 mm (photograph by Pau Urgell Plaza) I Mexichromis multituberculata 30 mm (photograph by Pau Urgell Plaza) J Mexichromis trilineata 8 mm K Verconia cf. hongkongiensis 6 mm L Asteronotus cespitosus 120 mm (photograph by Emily Palmer).