Chromodoris cf. balat Bonomo & Gosliner, 2020

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

* Chromodoris cf. balat Bonomo & Gosliner, 2020 Figure 9G

Material examined.

One specimen 25 mm, CB.

Ecology.

Among reef rubble, in particular under dead fungiid coral skeletons, in shallow coral reef areas. Depth 4-8 m

Distribution.

Chromodoris balat is known only from the Philippines ( Bonomo and Gosliner 2020) and a similar species is recorded here for the first time from Thai waters.

Remarks.

Similar to Chromodoris balat in having a striated dorsum with numerous large blotches and a broken yellow-orange marginal line. This species was differentiated from the similar Chromodoris striatella Bergh, 1877 based on these and other features ( Layton et al. 2018; Bonomo and Gosliner 2020). Our specimen is differentiated from C. balat by lacking small yellow, orange, and red spots on the white parts of the dorsal surface, the pale tan-coloured gills with orange spots instead of red-brown as seen in C. balat , and by the blotches being pale grey-brown and indistinct instead of dark and pronounced. The indistinct blotches on the dorsum, the broken yellow-orange marginal band, and the colouration of rhinophores and gills do share a resemblance with C. mandapamensis and C. cf. mandapamensis (the latter of which may be found living alongside C. cf. balat at Koh Tao). Given the difficulties of relying on external features for species delineation in many of these striped and spotted species of Chromodoris ( Layton et al. 2018; Bonomo and Gosliner 2020) we refrain from committing to a species identification until specimens from Koh Tao can be investigated further. Chavanich et al. (2013) recorded C. striatella from both Gulf and Andaman coasts of Thailand; however, in the absence of specimen details from both areas, this distribution record may be called into question in light of the recent findings regarding the complex surrounding C. striatella . Further documentation of Chromodoris species from both coasts may clarify this.

Figures

Figure 9. A Hallaxa iju 10 mm B Hallaxa indecora 8 mm C Cadlinella ornatissima 30 mm (photograph by Mati Pauner) D Ceratosoma tenue 85 mm E Chromodoris mandapamensis 50 mm (photograph by Tine Kvamme) F Chromodoris cf. mandapamensis 7 mm G Chromodoris cf. balat 25 mm (photograph by Elouise Haskin) H Diversidoris aurantionodulosa 30 mm I Diversidoris crocea 8 mm (photograph by Pau Urgell Plaza) J Doriprismatica atromarginata 60 mm K Glossodoris cf. cincta 40 mm L Goniobranchus cf. albonares 5 mm.