OKINAWAN
OPISTHOBRANCH OF THE WEEK

Hermaea zosterae (Baba,1959) 8mm
Photo by Atsushi Ono

Opisthobranch of the Week Data

Taxonomy:

Frequency on Okinawa:
Collection Data:
[brackets indicate range for all Okinawa-collected specimens of the species]


Species Account:

        Baba (1959) described Hermaea zosterae (as Stiliger {Ercolania} zosterae) from a single 3mm long specimen which was collected in December of 1936 from Tomioka, Amakusa, Japan. The following is taken from Baba's original 1959 description:

        Very small, about 3 mm in length. Rhinophores auriculate. Branchial papillae short fusiform, arranged in a single row of 6-7 on each side, very irregular in size. Foot corners rounded. General ground-colour of the animal whitish. Head above marked with a purple-red U-letter, the legs running up into the lower halves of the rhinophores. There is an additional purple-red band on each side of the neck; it is divided into two interrupted stripes which pass down the body to near the tip of the tail. Branchial papillae veined with light olive-green, their tips chrome-yellow, their surface ornamented with 3 longitudinal stripes of purple-red. Rhinophores tipped with opaque white. Radula teeth 6 in the ascending series, and about 13 in the descending series. Each tooth straight on the back, and smooth on the ventral edge.
Loc.: Tomioka, Amakusa, living on Zostera marina.

        Hermaea zosterae is unknown from Okinawa's main island as of early-September, 2002, but the close proximity of Okinawa, as well as the similar opisthofauna to that of the Kerama Islands, suggests the possibility that it is also present here on the main island of Okinawa. The above featured animal was photographed and collected from Agonoura Bay, Zamami Island, one of a series of islands in the Kerama Islands Group, which are located 30 ~ 40 kilometers west of the Okinawa Capitol, Naha. This featured animal was photographed by Atsushi Ono during February of 1999 in 7m of water from a rope. Atsushi's photograph is used here with his kind permission. It should be noted that Atsushi considers the species to be relatively common in the Kerama Islands as he has seen over thirty several individuals (per. comm.). I've included a photograph of a second individual, also photographed in the Keramas by Atsushi.

        Also, Jun Imamoto & Nishina Masayoshi have a series of photographs featuring H. zosterae from Hachijo Island, Japan. In addition, Yasuhiro Shirai also has a series of photos of the species on his Opisthobranchs of The Kii Peninsula site.

Etymology:

Literature Cited:


Page Date: 02 Sep '02
Page Modification Date: 02 Sep '02
Digitally manipulated photo
Copyright © 2002 Robert F. Bolland