Stiliger berghi Baba, 1937

Location: Wannai, Osezaki, Shizuoka, Japan
Date: 2018/01/29
Length: 5mm
Depth: 5.0m
Water temperature: 13.0℃

Description

A small species, about 2.5 mm in length. Body elongated and aeolidiform, ending in a well-defined, sharply pointed tail. The head is abruptly truncated in front and lacks oral tentacles. The simple rhinophores are slender, passing forward and outward. A single row of 7–9 distant branchial papillae lies on each side of the back, with large and small papillae arranged alternately and the smallest at the front. Each papilla is fairly long, lanceolate, and houses a single liver-diverticulum that detaches readily after preservation. The back, sides, and papillae are quite smooth. The foot is elongated, abruptly rounded in front, and tapers to the pointed tail.

Coloration

Ground colour translucent white over the body and foot. Dark (chocolate-brown) mottles of irregular shape are scattered over the back, sides, and branchial papillae. The liver, which sends branches into the papillae, is brown to olive-coloured. Each rhinophore is marked with a dark ring near the tip.

Distribution

Type locality: Tomioka, Amakusa, Japan (February 1935 and 1937, 15 specimens collected on Zostera seagrass).

Etymology

The original description (Baba, 1937) states: "I propose to call it S. (S.) berghi, after the late Prof. Rudolf Bergh, who has contributed to our knowledge of the Japanese Nudibranchia." A trans-generational dedication from Baba to Rudolf Bergh (1824–1909, the Danish opisthobranch authority and namesake of the genus Berghia Trinchese, 1877).

Remarks

Described as Stiliger (Stiliger) berghi in the original paper. A sacoglossan (Caliphyllidae lineage). Distinguished from previously described Sacoglossa species by the peculiar arrangement of branchial papillae, the coloration, and the shape of the radular teeth.