OKINAWAN
OPISTHOBRANCH OF THE WEEK
Halgerda tessellata (Bergh, 1880) 19mm
Opisthobranch of the Week Data
Taxonomy:
- Order: NUDIBRANCHIA
- Suborder: Doridina
- Family: Halgerdidae
Frequency on Okinawa:
Collection Data:
- Individual Collection No: RFB #2545
- Location: Horseshoe Cliffs, Okinawa (26o30.0'N, 127o50.9'E) [Horseshoe Cliffs, Seragaki]
- Date: 17 May, 1991 [Jul 87, Apr 89, May 89, Aug 89, Mar 90, Jun 90, Jul 90,
Sep 90, May 91 (2 indiv), Jun 91, Feb 92, May 92]
- Depth: 30ft (9.1m) [10ft (8 indiv), 30ft, 40ft, 100ft, 105ft, 120ft]
- Water temperature at collection depth: Not recorded
- Size: Notum: 19mm [15mm, 16mm, 18mm, 19mm, 20mm, 21mm, 23mm, 24mm, 26mm,
29mm, 30mm, 30mm]
- Specimen deposited: RFB Personal Research Collection
[brackets indicate range for all Okinawa-collected specimens of the species]
Species Account:
Halgerda tessellata is considered to be uncommon on Okinawa; I have collected a total of thirteen individuals, but dozens of others have been seen but not collected over a period of many years of diving here. The triangular, orange colored ridges on the animal's upper surface set this dorid apart from all other opisthobranchs found on Okinawa.
The specific name of this immediately identifiable dorid means "to form a mosaic pattern",
which is quite apparent.
The featured animal was found in 30ft of water on the wall of a surge channel, amid spur & groove formations near drop off at the reef forefront.
Page Date: 26 January '98
Page Modification Date: 26 January '98
Digitally manipulated photo
Copyright © 1998 Robert F. Bolland
