Halgerda okinawa Carlson & Hoff, 2000 (105mm)
OPISTHOBRANCH OF THE WEEK
Opisthobranch of the Week Data
Frequency on Okinawa:
- Order: NUDIBRANCHIA
- Suborder: Doridina
- Family: Discodorididae
[brackets indicate range for all Okinawa-collected specimens of the species]
- Individual Collection No: RFB #3729-A
- Location: Seragaki, Okinawa (26o 30.4'N, 127o 52.6'E) [all specimens from Seragaki]
- Date: 20 August, 1999 [23 Apr '95(2 indiv), 18 Jul '95, 7 Jul '96, 28 Jul '96, 14 Jan '97, 2 Mar '97, 31 May '97(2 indiv), 10 May '98, 20 Aug '99]
- Depth: 215ft (66m) [175ft, 175ft, 190ft, 200ft, 200ft, 215ft, 220ft, 220ft, 235ft, 240ft, 250ft]
- Water temperature at collection depth: 77.8oF (25.4oC)
- Size: TL 105mm [66mm, 71mm, 86mm, 94mm, 98mm, 100mm, 100mm, 105mm, 110mm, 114mm, 125+mm]
- Specimen deposited: The Australian Museum, New South Wales (as #C370458)
Halgerda okinawa is one of the more recently described species of Halgerda (Carlson & Hoff, 2000), based upon Okinawan material (see also H. diaphana, and H. onna). This is a relatively large and very attractive Okinawan discodorid having the typical ridges and depressions of the notum as seen in most other members of the genus, but Carlson & Hoff (2000) point out that H. okinawa is the only Halgerda species known to them having a color other than the body color as an intrinsic part of the tubercles. The species is also known from Indonesia (Gosliner et al, 1996 [p. 160 as Halgerda sp.]). I've added a second page showing the designated holotype and paratypes of the species.
Halgerda okinawa is considered to be rare on Okinawa as I have collected a total of eleven individuals; the first animal was collected on the 23rd of April, 1995, and the most recent, the above featured animal, collected on the 20th of August, 1999. The above featured animal was found crawling in the open amid coral rubble at the deep reef drop-off during a mid-morning SCUBA excursion. All eleven of the collected animals were found in basically the same environment during mid-morning SCUBA dives.
As of early June, 2016, fourteen described species of Halgerda have been featured on these pages from Okinawa's main island and the Keramas. These fourteen species are:
H. okinawa - The featured animal above
- Carlson & Hoff (2000) chose the specific name in reference to the locality from which the type specimens were collected (seven animals from Seragaki, Okinawa).
- Carlson, C.H. & P.J. Hoff. 2000. Three new Pacific species of Halgerda (Opisthobranchia: Nudibranchia: Doridoidea). The Veliger 43(2):154-163.
- Fahey, S. J. & T. M. Gosliner. 1999. Preliminary Phylogeny of Halgerda (Nudibranchia: Halgerdidae) from the Tropical Indo-Pacific, with descriptions of three new species. Proceedings of the California Academy of Sciences 51(11): 425-448.
- Gosliner, T.M., D.W. Behrens & G.C. Williams. 1996. Coral Reef Animals of the Indo-Pacific. Sea Challengers, Monterey, California. vi + 314pp.
Page Date: 15 May '00
Page Modification Date: 01 Jun '16
Digitally manipulated photo
Copyright © 2016 Robert F. Bolland