Re: Lobiger cf. souverbii from Japan
November 8, 2001
From: Kathe R. Jensen
Dear Nishina and Bill,
On reading Nishina's message I can understand why Baba (1974) synonymized his Lobiger sagamiensis Baba, 1952 with L. souverbii. The distinct black lines and the lobed parapodial margins of this specimen are clearly similar to the Caribbean L. souverbii. When I resurrected L. sagamiensis to full specific rank, based on specimens from Hong Kong (1985), my specimens had no trace of lines on the mantle, only a few blue and brownish spots. The differences in radular teeth between L. souverbii (in Florida) and L. sagamiensis (in Hong Kong) are: lateral bristles only on the smallest teeth in L. souverbii and bristles on all teeth in descending limb and ascus, and in some specimens even the teeth in the ascending limb in L. sagamiensis. Also, the attachment of the long, muscular pharyngeal pouch differs.
Looking at the juvenile Lobiger from Japan, I wonder if L. souverbii is a fairly recent speciation in which the juvenile colour pattern and parapodial shape has been retained in the adult. Unfortunately I have not yet had an opportunity to dissect specimens of L. viridis, so I can only compare with literature information (Burn, 1966). The teeth of L. viridis are said to be all non-denticulate and only a few have notched tips (in L. souverbii and L. sagamiensis all teeth have bifid tips); the parapodia have large lateral lobes as in L. sagamiensis, and there are blue-green lines on the mantle. It is possible that it could be one "world-wide" species, but in that case a number of genetically isolated populations seem to occur. This might something for the molecular biologists to look into.
References:
• Baba, K. 1974. Some comments on Lobiger souverbii Fischer, 1856, re-identified of Japan. The Veliger, 16: 253-257.
• Baba, K. 1952.Record of a rare sacoglossan mollusk, Lobiger (Lobiger) sagamiensis n.sp. from Sagami Bay, Japan. Zoological Magazine (Dobutsugaku Zasshi) 61: 337-38
• Baba, K. 1955. Opisthobranchia of Sagami Bay. Supplement. Iwanami Shoten: Tokyo. 59pp. Pls 1-20.
• Burn, R. 1966. The opisthobranchs of a Caulerpan microfauna from Fiji. Proc. Malac. Soc. Lond. 37: 45-65.
• Jensen, K.R. 1985.Annotated checklist of Hong Kong Ascoglosa (Mollusca: Opisthobranchia), with descriptions of four new species. In: The Malacofauna of Hong Kong and Southern China. II. (eds. B. Morton & D. Dudgeon), 77-107. Hong Kong University Press.
Cheers,
Kathe
jensen@ait.ac.th
Jensen, K.R., 2001 (Nov 8) Re: Lobiger cf. souverbii from Japan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5641Thanks Kathe,
I'm sorry I haven't kept up with all your nomenclatural changes - when they are scattered amongst faunal accounts I sometimes miss them.
It seems from what you say that this matter can't really be resolved until the anatomy of Lobiger viridis is re-examined. I have seen blue-streaked animals throughout the Pacific but they are usually mixed in populations where blue streaks may be absent, so it seems the fine structure of the teeth is the important character. In the mean time I will leave all the Indo-West Pacific Lobiger messages together under Lobiger viridis, not because I disagree with you, but because I am not sure how to differentiate them on external characters.
Best wishes,
Bill Rudman
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