Gymnodoris nigricolor Baba, 1960

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

* Gymnodoris nigricolor Baba, 1960 Figure 16B

Material examined.

Two specimens 5-7 mm, SN.

Ecology.

Recorded exclusively from deeper soft sediment habitats, crawling on the substrate. Depth 19-27 m.

Distribution.

Gymnodoris nigricolor is known from the Philippines, Japan, New Caledonia, and the Solomon Islands ( Gosliner et al. 2008). Here recorded as a first for Thai waters.

Remarks.

The present species closely resembles externally the description by Baba (1960) possessing a black (sometimes translucent black) dorsum and rhinophores, and a translucent foot. The gills match the description in being black, small, and club-shaped and arranged in a semi-circle. It should also be noted that the plate supplementing the original description of the species shows gills in a circular arrangement and seemingly plumose rather than reduced and club shaped. While the species is known to be parasite of gobies ( Osumi and Yamasu 1994), all observations from Koh Tao were not in the vicinity of any demersal fish, including any in the family Gobiidae . Ongoing searches of gobies from both soft sediment and coral reef habitats have thus far revealed no observations of parasitic nudibranchs.

Figures

Figure 16. A Gymnodoris sp. 3 12 mm B Gymnodoris nigricolor 5 mm C Gymnodoris cf. nigricolor 6 mm D Gymnodoris sp. 4 9 mm E Plocamopherus tilesii 90 mm F Polycera sp. 12 mm G Tambja amakusana 6 mm (photograph by Richard Brinke) H Tambja pulcherrima 40 mm (photograph by Liam Kelly) I Tambja sp. 4 mm (photo by Kaitlyn Harris) J Thecacera sp. 6 mm K Anteaeolidiella sp. 15 mm L Aeolidiopsis harrietae 17 mm.