Halgerda diaphana
Fahey & Gosliner, 1999
Order: NUDIBRANCHIA
Suborder: DORIDINA
Superfamily: EUDORIDOIDEA
Family: Dorididae
DISTRIBUTION
Known only from RyuKyu Islands (Okinawa).
PHOTO
UPPER: About 40mm long. 20m depth., Kerama Is. near Okinawa. LOWER: Juvenile, about 5mm long, found at 7m depth underside of a dead coral. Kerama Island. PHOTO: Atsushi Ono.
See message for more details.
White with orange-lined ridges. There can be orange marks between the ridges. The mantle edge has a submarginal orange band and a margin of intense white. The gills and rhinophores are translucent white with closely sprinkled black spots.
Reference:
• Fahey, S. & Gosliner, T.M. (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.
Rudman, W.B., 2000 (March 14) Halgerda diaphana Fahey & Gosliner, 1999. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/halgdiap
Related messages
Re: Two Halgerda species mating
April 10, 2003
From: Atsushi Ono
Dear Bill,
Concerning your question about whether the Halgerda were actually mating. Unfortunately I didn't touch their mantle edges - if the mating continued, I
was going to take a photo with my camera. After 40 minutes these 2 Halgerda had separated. But I believe I can see a part of the genital organs which have scattered dark brown dots. And also the mantle margin above the genital organs swelled out a lot. This was easily visible when I found these 2 Halgerda in the sea - now God knows the truth.
Sincerely,
Atsushi Ono
ononini@cosmos.ne.jp
Ono, A., 2003 (Apr 10) Re: Two Halgerda species mating. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9632Thanks very much Atsushi,
I am sure you saw them mating - its just that scientists like to see something with their own eyes, especially when it is very unusual. Species of Halgerda have these brown-black spots on the inside skin of both the genital opening and the oral tube so when you see them its a good sign that the relevant organ - in this case the genital organs - are everted. It is indeed an interesting observation.
Best wishes,
Bill Rudman
Halgerda - different species mating
April 9, 2003
From: Atsushi Ono
Dear Bill,
I recently came across this amazing mating between different species. In fact I saw a mating between these species about ten years ago too but unfortunately I did not have a camera available. Again I did not have a camera this time, but luckily my diving guests did.
These photos show H. carlsoni and H. diaphana, at Zamami Is. in Kerama Ids, Okinawa, Japan.
About 10m depth, March 2003. Photos by Mitsuo & Ayumi Murakami. These photos were taken by two digital cameras.
Sincerely,
Atsushi Ono
ononini@cosmos.ne.jp
Ono, A., 2003 (Apr 9) Halgerda - different species mating. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9587
Dear Atsushi,
Thanks for the very interesting photos of the 2 species of Halgerda mating. I am afraid the first question people who see the photos will ask is 'Are they really mating? because we can't see the genital organs joined. When I posted the photos of the Hypselodoris bullocki and H. apolegma mating I heard that at least one colleague was not convinced they were mating even though you can see the genital organs everted and joined. So it would be nice to know if you could see the genital organs in contact or whether you touched the animals to see if they were joined together. I think I will need to start a page for cross-species mating so these interesting observations can be cross referenced.
Best wishes
Bill
Re: Three? Halgerda from Japan
March 20, 2000
From: C. Carlson & P.J.Hoff
Bill,
Atsushi's 5mm Halgerda appears to be H. diaphana. The only thing we would question might be the size of the spotting on branchia and rhinophores. I have a number of H. diaphana photos (courtesy of Bob Bolland) and all except the smallest 29mm specimen have fine spotting. The 29mm specimen has larger spots more widely spaced.
I have included two scans of some not so good shots of H. guahan.
Clay & Patty Jo
clay.carlson@kuentos.guam.net
Carlson, C. & Hoff, P.J., 2000 (Mar 20) Re: Three? Halgerda from Japan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/2128Dear Clay & patty Jo,
Thanks for the photos and for clarifying the juvenile photo.
Best wishes,
Bill Rudman.
