Opisthobranch of the Week Data
Baba & Abe (1970) described the species based on three specimens from Toyama Bay and Fukui (both locales are on the Japan Sea coast of Honshu Island, Japan). The Japanese name of this attractive little arminoid is Koyanagi-umiushi.
Janolus toyamensis is considered to be very rare on Okinawa as I have seen and collected only a single individual. The animal was collected during a mid-morning SCUBA excursion and it was found in a area of mixed sand and coral rubble, crawling on the upper surface of a slab of rubble. The above featured animal clearly shows the presence of parasitic copepod ova, occupying a major portion of the mid-dorsal aspect of the notum (quite a few of the cerata have been autotomized in this view). I've also included a second image of the same animal and its attached copepod ova prior to the loss of the cerata as seen above.
At the current time (early-July, 2006) there are three described species of Janolus from Okinawan waters (J. toyamensis, featured above, J. savinkini., & J. mirabilis), although I'm aware of several apparent different specimens of Janolus from Okinawan waters which are either undescribed species, or at least, unknown to myself. seven of these unknown Janolus species have been previously featured on these pages as:
Janolus sp. 1 Janolus sp. 2 Janolus sp. 4 Janolus sp. 5 Janolus sp. 6 Janolus sp. 7 Janolus sp. 8