Costasiella usagi Ichikawa, 1993

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

Costasiella usagi Ichikawa, 1993 Figure 4B

Material examined.

Three specimens 2-6 mm, LB.

Ecology.

In soft sediment habitats beyond the coral reef where it feeds predominantly on Avrainvillea longicaulis and less commonly on Vaucheria sp. An individual of the species has been observed to be naturally captured and ingested by the free-living coral Heteropsammia cochlea with subsequent investigations suggesting the species may represent viable prey for the coral in soft sediment habitats ( Mehrotra et al. 2019). Depth 10-18 m.

Distribution.

Across the Indo-Pacific including India ( Dixit et al. 2017), Singapore ( Jensen 2009), Japan ( Ichikawa 1993), Malaysia, the Philippines, Papua New Guinea, Australia, and Guam ( Gosliner et al. 2008). Known from the Gulf waters of Thailand ( Mehrotra and Scott 2016).

Figures

Figure 4. A Costasiella cf. kuroshimae 6 mm B Costasiella usagi 6 mm C Limapontiidae sp. 3 mm D Plakobranchus noctisstellatus 21 mm (photograph by Pau Urgell Plaza) E Plakobranchus ocellatus 32 mm F Plakobranchus papua 27 mm G Plakobranchus papua 21 mm on Holothuria edulis H Elysia aowthai 12 mm I Elysia asbecki 15 mm J Elysia cf. marginata 70 mm K Elysia mercieri 12 mm L Elysia obtusa 9 mm.