Opisthobranch of the Week Data
I've not personally seen Phyllidia scottjohnsoni here in the waters of Okinawa's main island. Atsushi Ono mentions collecting only a single specimen (pers. comm.) but has seen in excess of ten individuals from a single dive site on a yearly basis off Zamami Island in the Keramas* and considers this animal to be uncommon there. Atsushi reports finding the above featured animal on the face of a cliff wall in twelve meters of water.
Phyllidiopsis loricata is similar in external appearance to Phyllidia scottjohnsoni, however Phyllidiopsis loricata is more elongate and it lacks the black spots in the mid dorsal region so apparent in Phyllidia scottjohnsoni. I've added a link to Bill Rudman's Sea Slug Forum (Rudman, 1999) showing the superficially similar appearing Phyllidiopsis loricata.
The following description of external morphology of P. scottjohnsoni is taken from Brunckhorst (1993):
External morphology. Live specimens ranged in size from 6.5-25 mm. The dorsum of Phyllidia scottjohnsoni has a white coloured background and six to ten, large black spots. Small black dots may occur around the mantle edge. Phyllidia scottjohnsoni is oval in shape and flattened dorsoventrally. Many tiny, irregular tubercles are scattered on the dorsum. Medially, the tubercles may form up to five indistinct, broken, low ridges. The short, cream coloured rhinophores bear seven to nine broad lamellae on the clavus (specimens greater than 15 mm). Ventrally, the hyponotum (except beneath the black spots), gills, foot and pointed oral tentacles are white to cream in colour.
In addition to the above featured animal from the Keramas, I've previously presented on these pages the following members of the genus from Okinawan waters:
* Keramas = the Kerama Islands Group, located 30 ~ 40 kilometers west of the Okinawa capitol, Naha.