Goniobranchus geometricus (Risbec, 1928) Figure 10C

Material examined.

One specimen 15 mm, KKR.

Ecology.

Locally rare, known only from the reef edge and soft sediment habitats outside the coral reef. Depth 12-25 m.

Distribution.

Widespread throughout the Indo-Pacific including Myanmar (Sanpanich and Duangdee 2019), Tanzania, Madagascar, Guam, Japan, Papua New Guinea (Gosliner et al. 2008), Maldives (Yonow 1994), Indonesia (Yonow 2001), Philippines (Debelius 1996), and Australia (Nimbs and Smith 2016). Known from both Andaman and Gulf waters of Thailand (Chavanich et al. 2013).