Siphopteron quadrispinosum & S. leah

January 16, 2004
From: Bill Rudman

Following Nils Anthes' recent message I have restudied the descriptions of Siphopteron quadrispinosum Gosliner, 1989 and S. leah Klussmann-Kolb & Klussmann, 2003 and come to the conclusion that they are most probably the same species. Their colour pattern and radular morphology are both very similar, if not identical, and there are no other species in the family with similar characteristics. The one feature which separates them is that Siphopteron quadrispinosum has 4 large spines in a secondary penial sac and S. leah has 2. If we look at the family broadly, these two species are the only two in the family in which the prostate and penial ducts are so deeply separated and which have these large spines. At this stage I would think it more reasonable to assume that the number of penial spines may be variable or that the specimen examined by Klussmann-Kolb & Klussmann was aberrant. Gosliner described his species from both Hawaiian animals and animals from Papua New Guinea. Klussmann-Kolb & Klussmann discuss the similarities between Siphopteron quadrispinosum and S. leah and suggest that the colour differences between Hawaiian and Papua - New Guinean species suggest that Gosliner had two species in his description, and the Paua New Guinean were possibly S. leah.

However in Gosliner's description he examines and illustrates the reproductive organs of both populations and shows they both have 4 spines.

I therefore consider that the animals at present on the Forum as Siphopteron sp. 3 are S. quadrispinosum and that S. leah is a synonym. Although the animal from Japan in Nishina Masayoshi's message is more heavily marked than others from elsewhere in the Pacific on the Forum, if you look at both Nils Anthes photo from the Great Barrier Reef and my photo from New Caledonia, there is a remnant of the orange-red line which runs across the parapodia in the Japanese specimen which clearly links the colour patterns of these three.

In an earlier comment on photos from Scott Johnson of Hawaiian animals, I mentioned that the structure of the siphon looked abnormal. On further examination I think the apparent peculiarity is an illusion caused by the angle at which the animal has been photographed.

• Klussmann-Kolb, A. & Klussmann, A. (2003) A new species of Gastropteridae (Gastropoda, Opisthobranchia, Cephalaspidea) from tropical Northeast Australia. Zootaxa, 156: 1-12

Best wishes
Bill Rudman

Rudman, W.B., 2004 (Jan 16) Siphopteron quadrispinosum & S. leah. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/11935

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