Tergiposacca perspicua Fernández-Simón & Moles, 2023

Location: Ebisuno Beach, Nanki kushimoto, Wakayama, Japan
Date: 2023/12/29
Length: 10mm
Depth: 5.0m
Water temperature: 18.0℃

Description

The overall body is translucent — the most striking feature of this species — with the white viscera clearly visible through the body wall. Rhinophores and oral tentacles are conical, smooth, and transparent. The jaws are white and visible by transparency. Cerata are elongate, cylindrical, and isodiametric (uniform width along their length); the digestive gland inside is beige and granulose, also visible by transparency. The subterminal ring of each ceras is transparent and the terminal tip is white. The propodium is rounded. A small species, around 7 mm in length.

Distribution

Type locality is the pier at Magoodhoo, Faafu Atoll, Maldives, at 1 m depth. Records from the Maldives, the Philippines, the Marshall Islands, and New Caledonia.

Etymology

The specific epithet perspicua is the feminine form of the Latin perspicuus ("translucent"), referring to the overall absence of body coloration in this species.

Remarks

A member of the family Fionidae. The type specimens were collected from under a rock.

Until this description, the genus Tergiposacca contained only T. longicerata Cella et al., 2016, known from the Philippines in three color morphotypes. T. perspicua differs from the type species in its almost colorless, translucent appearance, and is genetically distant from the orange morphotype of T. longicerata (around 80% COI divergence), supporting recognition as a new species. The systematic position of the other color morphotypes (burgundy, brown) reported from the Maldives and the western Pacific awaits further molecular and morphological assessment.

No formal Japanese vernacular name has yet been proposed; the species is currently referred to by the katakana transliteration Tājiposakka peruspikua.