Halgerda onna Fahey & Gosliner, 2001

Location: Kitiemon dasi, Nanki kushimoto, Wakayama, Japan
Date: 2019/05/08
Length: 15mm
Depth: 21.0m
Water temperature: 18.0℃

Description

Body ground color is semi-translucent white, with the mantle margin outlined by a thin yellow band. The dorsum bears small scattered tubercles connected by white ridges. Yellow ring-shaped marks and dark brown spots are dispersed across the dorsum. Rhinophores are semi-translucent white with a dark brown patch on the inner side of the stalk; the distal half of the lamellae is dark brown. The secondary gills are white with dark brown rachises. Reaches about 19 mm in length, making this one of the smaller members of the genus.

Distribution

Type locality is Onna Village, Okinawa Island, Japan. Recorded from the western Pacific between Japan (Okinawa) and Guam.

Etymology

The specific epithet onna refers to Onna Village (Onna-son), Okinawa Prefecture, where the holotype was collected by Bob Bolland.

Remarks

The Japanese vernacular name "オンナソンウミウシ" likewise refers to Onna Village. In the molecular phylogeny of a 2023 study, Halgerda is supported as a monophyletic genus within Discodorididae, and Halgerda onna falls outside the newly recognized mesophotic clade, in a separate well-supported lineage.