Unidentia kiku Korshunova, Fletcher & Martynov, 2025

Location: Gorilla Chop, Okinawa Island (Motobu and Northern area), Okinawa, Japan
Date: 2025/02/02
Length: 12mm
Depth: 10.0m
Water temperature: 21.0℃

Description

A small, elongate sea slug, up to 13 mm long. Background body colour is translucent dark orange with a thin, often interrupted purple line running along the middorsal axis. Along the dorsal edges sit several distinctly elongated elevations bearing clusters of long, thin, mostly finger-shaped (some partly fusiform) cerata. The cerata are variegated, encrusted with small white specks and spots, with subapical purple rings and yellowish tips. Light pinkish to pale brownish branches of the digestive gland show through the body wall into the cerata. Rhinophores are smooth, similar in length to the oral tentacles, irregularly covered with white spots and purple pigment toward the tip. Oral tentacles bear irregular purple pigment over their basal half, overlaid with white spots.

Distribution

Type locality: Sakimotobu beach, Motobu, Okinawa Prefecture, Japan (Holotype KM1077, 13 mm live, 3 m depth, collected 31 October 2021 by Kaoru Imagawa). Currently known only from Okinawa, but likely to occur in other tropical waters.

Etymology

Verbatim from the 2025 revision:

From Japanese kiku (キク), chrysanthemum, to denote the external similarity of this beautiful new species to the flower that is iconic in Japanese culture.

Remarks

U. kiku is the fifth species of Unidentia described in a 2025 revision. Verbatim from the original Remarks:

The new species Unidentia kiku sp. nov. (Fig. 1) clustered together with Unidentia aliciae, Unidentia sp., Unidentia nihonrossija, and U. sandramillenae, constituting a highly supported clade (PP = 1, BS = 100).

COI p-distances from the U. aliciae, undescribed Unidentia sp., U. nihonrossija, and U. sandramillenae clades are 15.5%, 17.0%, 16.0%, and 15.5% respectively. It is readily distinguished externally: from U. sandramillenae by its translucent dark orange ground and variegated coloration (vs. whitish/light purple ground and more uniform coloration), and from the only previously described Japanese Unidentia (U. nihonrossija) which is whitish with reddish-orange, largely non-variegated colouration. The radula is uniserial; central teeth bear distinct denticles; lateral teeth are absent.