Opisthobranch of the Week Data
Volvatella angeliniana was described from Sesoko Island*, Okinawa, by Ichikawa (1993). The species is based on a single 25mm (body length) specimen collected from 2-3m; Ichikawa described it as being found on Caulerpa racemosa var. clavifera. The above featured animal was found crawling amid a relatively large, dense colony of Caulerpa sp., and when the animal was touched, it immediately exuded an apparent white wispy substance into the surrounding water.
Volvatella angeliniana is considered to be very rare on Okinawa; I've seen and collected a total of five individuals which were found at different times but on the same species of alga (Caulerpa sp.). The only other Volvatella which I've found here in the waters of Okinawa's main island is an undescribed(?) green-shelled animal (Volvatella sp. 1), simultaneously found on the same alga as the above species, and a brown-shelled animal (Volvatella sp. 2). Ichikawa (1993) found two additional Volvatella in waters of the southern Ryukyu Islands (Kuro Island): 1) Volvatella viridis, described by Hamatani (1976) from Japan, and 2), an undescribed species, but different from the green-shelled and brown-shelled specimens I've collected.
*Sesoko Island is the site for the University of the Ryukyus' Sesoko Marine Science Center.