Gastropteron from the west Atlantic

January 20, 2004
From: Bill Rudman

Following my forgetfulness over Gastropteron chacmol I have had a look for species of the family which have been described from the west Atlantic. Up until 1960, specimens were incorrectly identified as the east Atlantic species Gastropteron rubrum [see Marcus & Marcus, 1960]. I think I am correct in assuming that the since then 3 species have been recognised from the western Atlantic

• Gastropteron vespertilium Gosliner & Armes 1984. Ground colour grayish or purplish black with occasional blue grey spots on parapodia. A bright yellow [occasionally blue or green] line present on edge of parapodia and siphon. Flagellum translucent white. Known only from Tampa Bay, Florida.

• Gastropteron chacmol Gosliner 1989. Background colur to red to plum, with a bright yellow border to gills and siphon. Described from Yucatan Peninsula, Mexico but also known from Florida, Bahamas, Venezuela.

• Gastropteron hamanni Gosliner 1989 Uniformly yellow with a maroon apex to the siphon. Known from a single specimen, 4mm long. Turks & Caicos Ids

Two of these species. G. chacmol and G. vespertilium seem very similar in most respects. Both have a dark background colour deep red to plum in G. chacmol and grayish or purplish black in G. vespertilium, and both can have a yellow parapodial border. They both have yellow eggs and the only locality from which G. vespertilium has been reported falls within the distribution of G. chacmol. The anatomy of both species is very similar, the only difference I can see in the descriptions is that in G. chacmol the cerebral ganglia are close together while in G. vespertilium they are separated by a short commissure. I have no idea whether that difference is significant. As with some Indo-West Pacific species it would seem worthwhile to build up more information on colour variability within poplations of G. chacmol and G. vespertilium. If they are distinct species, and occur sympatrically [= in same geographic region], then its going to be important to find some way of distinguishing between them.

If anyone knows of other named species from the western Atlantic could they please let me know.

• Gosliner, T.M. & Armes, P.T. (1984) A new species of Gastropteron from Florida (Gastropoda: Opisthobranchia). The Veliger, 27(1): 54-64.
• 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.
• Marcus, Ev. & Marcus, Er. (1960)Opisthobranchs from American Atlantic warm waters. Bulletin of Marine Science of the Gulf and Caribbean, 10(2): 129-203.

Best wishes
Bill Rudman

Rudman, W.B., 2004 (Jan 20) Gastropteron from the west Atlantic. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/11964

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