Opisthobranch of the Week Data
Costasiella kuroshimae is considered to be very rare in Okinawan waters; I've not seen the animal here on Okinawa although I've collected a series of related, undescribed members of the species from Okinawa's main island. Atsushi Ono mentions (pers. comm.) having seen only two members of the species in the Keramas*, the above featured animal and an additional uncollected 3.5mm individual. The above animal was collected by Atsushi during April of 2000 from a rope in a fish preserve.
In the Ichikawa (1993) publication the species is illustrated via a line drawing with a white head having a brown mark medially behind the eyes and a dark streak across the head just in front of the rhinophores. The tips of the white rhinophores were reported to be black and the cerata described as "generally green with white tips". The description of the species was based on four specimens found in the waters of Kuro Island, in the Yaeyama Islands, during July of 1991. Ichikawa (1993) reports that the species was found on Avrainville [sic] **lacerata var. robustior.
Kathe Jensen (2002) reporting in the Sea Slug Forum, mentions that she has a series of Costasiella species from Singapore. She apparently at one time was to have described these along with Jon Sigurdsson, but that the paper didn't get started due to her following statement:
" . . . this awful paper by Ichikawa appeared. In this paper she describes 6 species of Costasiella based on photos and serial sections. There are so many characters not mentioned in these descriptions that it is impossible to compare these species with others."
* Keramas = the Kerama Islands Group, located 30 ~ 40 kilometers west of the Okinawa capitol, Naha.
** A green alga, Avrainvillea.