Opisthobranch of the Week Data
Hermaea noto was previously featured on these pages as Aplysiopis sp. 1 and has now been changed to reflect what I believe to be the correct designation, Hermaea noto. The species is considered to be very rare in the waters of Okinawa's main island as I have seen and collected only the above single individual. This attractive little sacoglossan was collected near the end of a late morning SCUBA dive during spring tide conditions from a rocky cut at the shore's edge; the cut was covered with a dense grown of miscellaneous red algae from which H. noto was found and collected.
Baba described the species (as Stiliger noto) from six specimens collected from Toyama Bay, Japan. Four of the six specimens were collected by Abe from the Noto Peninsula, which makes up in part, the eastern margin of Toyama Bay. The following description is from Baba (1959):
Animal 5-10 mm in length. With a pair of lobiform oral tentacles. Rhinophores auriculate, having an outer longitudinal groove. Branchial papillae long fusiform. They are arranged on back-margins in 9-10 oblique rows with 1-2 papillae in each row. Liver-diverticula ramified in the papillae, but no branching of the albumen gland in these structures. Pericardial prominence ovate; anus and nephroproct not determined. General aspect of the animal black. Head especially marked by having 4 longitudinal bands of intense black; the median part of the head and the eye regions white. Back black. It is somewhat deeper towards the outer edges of the mantle and in the median line behind the pericardial prominence. Upper half of the oral tentacles and of the rhinophores opaque white. The pericardial region also opaque white. The branchial papillae black, the inner and the outer edges towards the end opaque white, their tips yellowish brown; the inner veins of the papillae dark yellow. Sole yellowish white. Radula teeth 10 in the ascending series, and about 38 in the descending spiral series. Each tooth without an indention in the back; the ventral edge smooth (?).
Baba (1959) mentions the close resemblance to Stiliger boodleae BABA, 1938, but suggests that the two may be separated from each other as follows:
1. Rhinophores simple.
2. Descending series of radula not spiral.
3. Radula teeth indented in the middle of the back.
1. Rhinophores Auriculate.
2. Descending series of radula spiral.
3. Radula teeth not indented in the middle of the back.
The above feature animal is very similar to the photographs of two 8mm animals seen in Ono (2004), as well as an on-line image posted by the Takaoka Biological Club.
I've added a second page with an additional image of the above featured animal as well as the drawing from Baba's original publication.