Gastropteron chacmol from the Bahamas

January 20, 2004
From: Colin Redfern

Dear Bill,
During the past couple of years I have occasionally collected examples of a species of Gastropteron from Abaco, Bahamas. All have patches of white, but some have many small spots of orange and purple-brown on the parapodia, with the flagellum almost completely white (A). On others (B & C) the color is mostly composed of much larger and less numerous purple spots, with purple and white spots on the flagellum.

I am grateful to Terry Gosliner for taking time to examine the anatomy of these animals, including the three specimens in the attached photos. He has informed me that the internal anatomy is entirely consistent with that of G. chacmol.
The Abaco material demonstrates a considerable variability in color for this species. On the other hand, Anne DuPont's animals from the Exumas appear very similar to the photographed specimens in Gosliner (1989, pl. 1I) which accompanied the description of G. chacmol.

Specimens in the attached photos were all dredged from areas of sand and scattered grass.
Photo A: 4mm. Lee side of Whale Cay, Abaco, Bahamas in 3m. August 20, 2002.
Photo B: 4.5mm. Lee side of Guana Cay, Abaco, Bahamas in 3.5m. August 19, 2002.
Photo C: 4mm. Lee side of Johnny's Cay, Abaco, Bahamas in 3.5m. August 22, 2003.

• Gosliner, T. M. 1989. Revision of the Gastropteridae (Opisthobranchia: Cephalaspidea) with descriptions of a new genus and six new species. The Veliger, 32(4): 333-381.

Best wishes,

Redfern, C., 2004 (Jan 20) Gastropteron chacmol from the Bahamas. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Colin,
As Terry Gosliner has reminded me Anne Dupont's animals are indeed almost identical to Terry's photo of G. chacmol in his original description. As Terry suggests, I suspect that all previous records of G. rubrum from the western Pacific for which there is colour information, are really G. chacmol. I am very interested in these animals of yours. If they do turn out to be G. chacmol it indeed cautions us from describing more new species of this group until we have a better idea of colour variation within existing species.
Best wishes
Bill Rudman

Rudman, W.B., 2004 (Jan 20). Comment on Gastropteron chacmol from the Bahamas by Colin Redfern. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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