Costasiella cf. kuroshimae 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 cf. kuroshimae Ichikawa, 1993 Figure 4A

Material examined.

Two specimens 3-6 mm, LB; two specimens 4-6 mm, SN.

Ecology.

In soft sediment habitats, beyond the coral reef where it feeds predominantly on Avrainvillea longicaulis ( Kützing) G. Murray & Boodle, 1889 and less commonly on Vaucheria sp. Depth 10-18 m.

Distribution.

Costasiella kuroshimae is currently known from the Indo-Pacific including the Red Sea ( Yonow 2015), Singapore ( Jensen 2009), Indonesia ( Eisenbarth et al. 2018), Japan ( Ichikawa 1993), Guam ( Jensen et al. 2014b), Madagascar, Tanzania, Malaysia, Papua New Guinea, Palau, and Australia ( Gosliner et al. 2008). Known from the Gulf waters of Thailand ( Mehrotra and Scott 2016).

Remarks.

Due to the original description of the species being entirely based on external features, the identity of numerous similar species and the extent of the variability of the species has remained unclear for several years. Molecular work ( Jensen et al. 2014b) has shown that specimens identified as Costasiella kuroshimae or C. cf. kuroshimae actually make up numerous distinct species that currently await description. Research carried out on specimens from Koh Tao ( Mehrotra et al. 2019) indicates that this species is palatable to some scleractinian corals and, based on natural observations, may be viable prey for the free-living coral Heteropsammia cochlea (Spengler, 1781), in soft sediment habitats.

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.