Berthella cf. caledonica (Risbec, 1928)

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

* Berthella cf. caledonica (Risbec, 1928) Figure 8J

Material examined.

Three specimens 10-15 mm, TW.

Ecology.

Under coral rubble in shallow coral reef habitats. Depth 6-8 m.

Distribution.

Berthella caledonica is known from New Caledonia ( Risbec 1928), Mariana Islands ( Carlson and Hoff 2003), Hawaii ( Johnson 2002a), Marshall Islands ( Johnson 2002b), Australia ( Cobb 2009), and Japan ( Bolland 2002).

Remarks.

Overall colour variable from pink to light or dark brown, with numerous small, low tubercles across the dorsal surface, often surrounded by a brown ring, and with dark brown apices. A prominent brown mark surrounded by a diffuse ring of translucent white is located centrally on the dorsal surface. While specimens from Koh Tao resemble the description of Berthella caledonica (Risbec, 1928) rather well, records of Berthella africana (Pruvot-Fol, 1956) have also been made from Thailand, with an unclear locality ( Nabhitabhata 2009). Both species share external similarities, in particular the presence of a brown spot or ‘hole’ found centrally on the dorsum, and the need for clarification between both species has been noted ( Gosliner et al. 2008; Rudman 2009b). The present species is most similar to Berthella sp. 1 of Gosliner et al. (2018). With the Gulf of Thailand being distant from the type localities of both species (Morocco for B. africana and New Caledonia for B. caledonica ), and the Pacific range currently known for B. caledonica , the present species is treated as potentially distinct until such a time as closer examinations can be made.

Figures

Figure 8. A Migaya sp. 3 mm B Siphopteron makisig 3 mm C Siphopteron sp. 3 mm (photograph by Will Malsukum) D Philine orca 3 mm E Aplysia kurodai 30 mm (photograph by Geoffrey Chamayou) F Aplysia nigrocincta 9 mm G Bursatella cf. ocelligera 65 mm (photograph by Elouise Haskin) H Stylocheilus longicauda 45 mm (photograph by Kirsty Magson) I Stylocheilus striatus 29 mm J Berthella cf. caledonica 10 mm K Berthella martensi 60 mm (photograph by Paddy Steele) L Pleurobranchus forskalii 130 mm (photograph by Tine Kvamme).