What is Lobiger viridis?

November 9, 2001
From: Bill Rudman

To help in the on-going discussion about Lobiger viridis, L. souverbii and L. sagamiensis, here is some background information on L. viridis.

PHOTOS: UPPER: L. viridis (as L. picta, from Pease, 1868, Pl.10, fig. 3. LOWER: Unpublished page from Kelaart's field notes, Ceylon. Natural History Museum, London.

The species was described by Pease from a specimen collected and illustrated in Tahiti by Andrew Garrett. Garrett either had an aberrant specimen, or his sketch was inaccurate, because he described it with 4 rhinophores. As he also sketched a number of aplysiids at the same time, which he correctly gave 4 head tentacles, I suspect his drawing was an error. The nomenclature is somewhat tangled because Pease published three accounts of this same animal. In 1861 (p246) he gave a full description of the external features under the heading "Lobiger ---- ?". In 1863 (p510) he published a short communication noting changes and errors in his previous contributions and named the species Lobiger viridis. In a somewhat puzzling later move (1868) he published a nearly identical description of the same animal calling it Lobiger picta. There is no mention of blue or black lines on the mantle.

Nevill & Nevill (1869) apparently unaware of Pease's name, described a species from Ceylon and also named it Lobiger viridis. This species was based on a shell and renamed by Pilsbry (1896) L. nevilli. It is probably a synonym of Pease's species. The only record I know of a Lobiger from Ceylon, is some unpublished sketches in a notebook of Kelaart's from the early 1800s, which is now in the Natural History Museum, London. As you will see from the drawing it has the deeply indented parapodial flaps apparently chracteristic of Indo-West Pacific animals. In Kelaart's painting [see inset] the reddish pink tips of the branches of the parapodial lobes are very similar to those in Masayoshi Chikako's photos from Japan.

Concerning the presence of black or blue lines on the mantle, Marshall & Willan (1999) note that Heron Id sometimes have dark lines and aometimes do not.

References:
• Pease, W.H. (1861): Descriptions of new species of Mollusca from the Pacific Islands. Proceedings of the Zoological Society of London, for 1861: 242-247.
• Pease, W.H. (1863) Letter. On errors and omissions in former communications. Proceedings of the Zoological Society of London, for 1863: 510.
• Pease, W.H. (1868) Descriptions of marine Gasteropodae, inhabiting Polynesia. American Journal of Conchology, 4(2): 71-80. (Pls. 7-10)

Rudman, W.B., 2001 (Nov 9) What is Lobiger viridis?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5652

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