Halgerda onna
Fahey & Gosliner, 2001
Order: NUDIBRANCHIA
Suborder: DORIDINA
Superfamily: EUDORIDOIDEA
Family: Dorididae
DISTRIBUTION
Known only from Okinawa.
PHOTO
(CASIZ 104720), 17 mm. Photo taken by R. Bolland. (From Fahey & Gosliner, 2001: Fig. 1B).
The ridges and tubercles are quite reduced and differe from most species of Halgerda in being the same translucent white colour as the background colour of the mantle. Another unusual feature is the yellow pigment on the notum is not associated with the ridges but is scattered randomly along the flat midregion of the mantle. Halgerda onna has black lines on both the anterior and posterior sides of the gill branches. The rhinophore club appears to be balck and the stalk white. It is described from a single small animal, 17 mm long found by Bob Bolland. It has also been seen on Guam by Clay Carlson. It is named after the village in Okinawa nearest to where it was found by Bob Bolland.
Reference:
• Fahey, S.J. & Gosliner, T.M. (2001) The phylogeny of Halgerda (Opisthobranchia, Nudibranchia) with the description of a new species from Okinawa. Zoologica Scripta, 30(3): 199-213.
Rudman, W.B., 2001 (October 10) Halgerda onna Fahey & Gosliner, 2001. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/halgonna
Related messages
Information on Halgerda onna
October 16, 2001
From: Shireen Fahey
Dear Bill,
Here is some information on, Halgerda onna, one of the new species of Halgerda that Terry Gosliner and I have just published.
PHOTO: (CASIZ 104720), 17 mm. Photo taken by R. Bolland. (From Fahey & Gosliner, 2001: Fig. 1B).
This new species of Halgerda is unusual for a couple of reasons. First, Halgerda onna has ridges and low tubercles that are the same color as the white notum. Most other Halgerda have different colored ridges and/or tubercles than the background color. Another unusual feature is the yellow pigment on the notum that is not associated with the ridges. It's scattered randomly along the flat centerline of the animal. Halgerda onna has dark lines on both the anterior and posterior sides of the gill branches. The rhinophores are white with black on the tips. It's a very small animal, 17 mm and is named for the village in Okinawa nearest to where it was found by Bob Bolland. This species has also been seen in Guam (Thank you Clay Carlson)!
Reference:
Fahey, S.J. & Gosliner, T.M. (2001) The phylogeny of Halgerda (Opisthobranchia, Nudibranchia) with the description of a new species from Okinawa. Zoologica Scripta, 30(3), 199-213.
Shireen
sfahey@mailbox.uq.edu.au
Fahey, S., 2001 (Oct 16) Information on Halgerda onna. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5478Thanks Shireen,
Bill Rudman
