Gastropteron vespertilium
Gosliner & Armes 1984

Superfamily: PHILINOIDEA
Family: Gastropteridae




Has anyone a photo of this species I could add to the Forum?

The ground colour is a grayish or purplish black with occasional blue grey spots on parapodia. There is a bright yellow [occasionally blue or green] line present on the edge of the parapodia and the siphon. The flagellum on the visceral hump is translucent white. Known only from Tampa Bay, Florida, where the specimens reached aproximately 5 mm in length.

Another similarly coloured species, Gastropteron chacmol Gosliner 1989, is also known from the Caribbean. It has a background colour of red to plum, with a bright yellow border to gills and siphon. From the single record of G. vespertilium, it appears to differ in the background colour and the width of the yellow parapodial border which appears much wider in G. chacmol.

They both have yellow eggs and their anatomy seems to be very similar, although from the descriptions, the cerebral ganglia in G. chacmol are close together while in G. vespertilium they are separated by a short commissure. I have no idea whether that difference is significant.

  • 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.
Authorship details
Rudman, W.B., 2005 (February 19) Gastropteron vespertilium Gosliner & Armes 1984. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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