Okenia pellucida Burn, 1957

セスジイバラウミウシ Okenia pellucida
Photographed by
新屋 亮(Ryo Shinya)
Location
Banya, Amamioosima, Kagoshima, Japan
Date
2020/06/06
Length
??mm
Depth
9.0m
Water temperature
25.0℃

MORPHOLOGY

The live slugs are about 10 mm. in length; the three preserved slugs examined are 7, 7, 6 mm. long. Live coloration (pi. X) is translucent yellowish, the viscera darker; everywhere except upon the sole with an anastomosing pattern of dark brown lines, even between the branchiae and on the inner and outer sides of the branchial stems. In one specimen, these lines are thicker and more numerous, and con sequently the animal appears to be darker. The rhinophores have a chocolate-brown band at the third quarter and white tips. The branchiae are wholly transparent. Preserved animals retain the brown patterning of lines.
The body (PL X) is slender throughout and higher than wide at the pericardial eminence anterior to the branchiae. The notum is set off from the sides and the long tail by a notal brim bearing seven to ten simple conical papillae along each side. The two papillae in front of the rhinophores are somewhat longer than the others. The middle line of the notum bears three papillae between the rhinophores and branchiae and often a smaller papilla behind the branchiae. On each side of the middle line anterior of the branchiae stands another series of one to three papillae. The oral tentacles are distinct and ear-shaped as in O. distincta Baba (1940: 195, fig. 3). The rhinophores are long and tapering, with seven to twelve cup-like lamellae projecting from the rear edge of the upper half. Branchiae six, simply pinnate and standing in a small circle on the notum.

DISTRIBUTION

New Zealand, Australia, Hawaii, Japan, Palmyra Atoll, Malaysia, United Arab Emirates

References