Opisthobranch of the Week Data
I've not personally seen Herviella albida here in the waters of Okinawa's main island, however Atsushi Ono mentions (pers. comm.) that the above featured animal is the only specimen he's seen in the Keramas* and he of course considers the species to be very rare there. Atsushi reports finding this beautiful little glaucid intertidally on the underside of a rock.
I've previously featured another Herviella species, Herviella yatsui, on these pages. This animal was also photographed and collected by Atsushi from Zamami Island in the Keramas.
Baba (1966) described the species from a single specimen collected from Seto, Kii, Japan on 21 Decembder, 1964. The following is taken from Baba's original description of Herviella albida:
Animal seemingly whitish owing to the lack of black spotting found in the specimens of H. yatsui (or of H. afnis).
Total length 8 mm. General body-form as usual in the genus: cephalic tentacles slender, the rhinophores shorter and simple, the foot-corners rounded, the branchial papillae set in simple oblique rows on either side, showing the formula I (8-6), II (6-6), III (6-6), IV (3-3), V (2-2) and VI (0-1), the genital orifices below the middle of the right liver row, the anus closely behind the first right row of the left posterior liver, and the nephroproct a short distance in front of the anus. Tail injured (?), ending bluntly.
The branchial papillae in this new species elongated fusiform when greatly extended, themselves being more or less flattened dorso-ventrally. The liver-diverticulum within each of these papillae not simple, but forming a light natural swelling in about its mid-length. The contracted papillae shortened fusiform, the swollen part of diverticulum often showing a bulbous appearance to the outside. General colour of diverticulum yellowish brown; on the bulbous portion a local accumulation of melanin pigment granules is marked in the lining epithelium of the diverticulum.
The general integument of body yellowish white, the back more intensively yellowish due to the viscera, the sole colourless. There are scattered opaque white spots over the head and back, but not on sides and papillae. A U-letter of light black on the head. Cephalic tentacles opaque white above, each one having a black longitudinal band on the lower half. Rhinophores opaque white above, yellow tinted below, and each is banded with black in about its half way. A black trapezoid marking between the bases of the rhinophores. The dorso-lateral margins behind rhinophores and between branchial rows are each indicated by a black longitudinal band. Each of the branchial papillae is provided with a broad, subapical band of opaque white below the colourless tip, and a second one further down. There occurs a cluster of colourless gland cells towards the base of each of the papillae.
Remarks: The peculiarities of H. albida may be seen (1) in the absence of black spotting on the body, (2) in the formation of a bulbous swelling in the mid length of the papillar diverticulum, (3) in the possession of slender lateral denticles on the radula teeth, and (4) in having a rather shortened penis stylet. Outwardly this species is more closely akin to H. yatsui than to H. afnis in some other points of the body colouring.
* Keramas = the Kerama Islands Group, located 30 ~ 40 kilometers west of the Okinawa capitol, Naha.