Trapania circinata
Gosliner & Fahey, 2008
Order: NUDIBRANCHIA
Suborder: DORIDINA
Superfamily: ANADORIDOIDEA
Family: Goniodorididae
DISTRIBUTION
Known only from the Marshall Islands.
PHOTO
Upper: Legan Island, Kwajalein Atoll, 30m, Marshall Islands, Pacific, 13 August 2007, Crawling on sand. Length: 17mm. Photographer: Scott and Jeanette Johnson. Lower: CASIZ 116803. Radular morphology. Scale =20 µm.[From Gosliner & Fahey 2008: Fig. 33C].
The body is translucent white and the oral tentacles and rhinophore clubs are black. The extra-rhinophoral processes and the much larger extra-branchial processes are translucent whitish with scattered back specks. The rhinophores stalks and the basal half of the gills are also translucent with black specks, while the upper half of the gills are edged with black. The sole animal was 10 mm long alive.
Gosliner & Fahey mention the similarity in the radular morphology of T. circinata and T. naeva and in fact, apart from the absence of dark spots on the body, they would be difficult to distinguish from each other. In their description of T. circinata they describe the oral tentacles as white, but from their published photo the oral tentacles are clearly black [or dark brown]. From another of Scott Johnson's photos already on the Forum [#6326] the white tentacles at the front are the tentacular foot corners not the oral tentacles. This animal has previously been considered a colour form of T. darvelli on the Forum but the radular morphology of the two species is quite different.
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Gosliner, T.M. & Fahey, S.H. (2008) Systematics of Trapania (Mollusca: Nudibranchia: Goniodorididae) with descriptions of 16 new species Systematics and Biodiversity, 6 (1): 53-98
Rudman, W.B., 2008 (March 13) Trapania circinata Gosliner & Fahey, 2008. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/trapcirc
Related messages
Re: Trapania darvelli? from the Marshalls
March 13, 2008
From: Scott Johnson
Concerning message #6326:
Hi Bill,
I've been meaning to send these additional photos of what is now Trapania circinata. We found this second specimen last year and were able to get better photos of it. These new photos of an obviously healthier specimen show that both the anterior and extra branchial process are white with black spots. The middle right photo shows the reproductive system fairly clearly through the translucent white body wall.
Locality: Legan Island, Kwajalein Atoll, 30m, Marshall Islands, Pacific, 13 August 2007, Crawling on sand. Length: 17mm. Photographer: Scott and Jeanette Johnson.
Scott
uwkwaj@yahoo.com
Dear Scott,
Thanks for the rapid update. The original animal looked like it was rather sick in the photo and I must say I wasn't sure whether the black spots were just an indication that the extra-branchial processes had expanded almost to breaking point. This specimen shows they are apparently a valuable characteristic of the species. I will replace the old photo on the Fact Sheet with this more 'normal' view.
Best wishes,
Bill Rudman
Trapania darvelli? from the Marshalls
March 5, 2002
From: Scott Johnson
Note added 12 March 2008: This species has been named Trapania circinata . The animal photographed here has been designated the holotype of the species. CASIZ 116803.
Hi Bill,
I apologize for the poor photos. My focus was apparently not working the day I shot these. This is the sole specimen I've seen here at Kwajalein, Marshall Islands, of what appears to be Trapania darvelli. It was found at night exposed on dead coral on a lagoon pinnacle. I cannot put my hands on the details right now, but the specimen was small, probably around the 10 mm range.
Scott
johnson@kmr.ll.mit.edu
Johnson, S., 2002 (Mar 5) Trapania darvelli? from the Marshalls. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6326Thanks Scott,
It certainly matches the colour of Hong Kong animals of T. darvelli.
Best wishes,
Bill Rudman
