Palythoa heliodiscus (Ryland & Lancaster 2003)

This zooxanthellate species was described in detail recently by Ryland and Lancaster (2003). Superficially similar in appearance to Palythoa mutuki, externally the species can be distinguished by its short tentacles (length <20% of oral disk) and subtidal distribution, compared to primarily intertidal Palythoa mutuki, which also has longer tentacles (~45% of oral disk) (Ryland and Lancaster 2003). Sizes of specimens agree well with specimens seen in other localities (average polyp heights 11.3 mm and 17.0 mm for each specimen, range 7–20 mm; average width 3.9 mm and 4.4 mm for each specimen, range 3.5–5.5 mm; n=2 specimens of 8 and 5 polyps, respectively). Depth of collected specimens (12 and 35 m) also fits well with the description of this species as primarily subtidal in the original description, and from data in Okinawa, Japan (e.g. Reimer 2010).

Regions recorded in this study (Figure 7). West Bali (4), eastern Bali (5), Spermonde Archipelago (9), Tukang Besi Islands (12), Moluccas (14). Previous records. Palythoa heliodiscus has been reported from Australia (Ryland and Lancaster 2003) and is likely widespread in the Indo-Pacific (Ryland and Lancaster 2003 and references within), as well as Japan (Reimer et al. 2006b), Palau (Reimer et al. 2014a), while Palythoa toxica Walsh & Bowers, 1971 has been reported from Hawai’i.