Burnaia Miller 2001, gen. nov.

Genus Burnaia gen. nov.

Diagnosis

Body long, narrow, oral tentacles moderately long, tapered, rhinophores longish, lamellate almost to base; cerata cylindrical, long, mobile (diverticula loosely spiralled), arranged in horseshoe shaped arches, in single rows; cleioproctic, anus in centre of second arch, renal pore abanal, immediately in front of arch, reproductive apertures at tip of rear limb of ®rst arch; foot narrow, rounded at front end extending as short, blunt lobes; oral glands small, club-shaped; radular tooth a very low, wide arch, blade narrowish, denticles almost uniform; jaw masticatory process complexly denticulate.

Type species. Aeolidia helicochorda Miller, 1988.

Etymology. Named after Robert`Bob’ Burn who has contributed much to our knowledge of opisthobranch molluscs, especially those of Australia. Burnaia is the Latinized form of the Old English noun burna meaning spring, fountain, stream or river.

A decade ago I described a new aeolidiid species, Aeolidia helicochorda Miller, 1988. At that time I assigned this species to Aeolidia on the grounds that it seemed to ®t this genus well enough. My appraisal of the aeolidiid genera here has caused me to change my original view. I feel now that there is indeed su cient diOEerence, and, as a consequence, I have created a new genus for this species. In terms of the principal feature used by me to separate the aeolid genera, the arrangement of the cerata, the horseshoe pattern shown by A. helicochorda is su ciently distinct. This feature certainly separates the new genus from the other two slender-bodied aeolidiid species, Limenandra nodosa Haefel ®nger and Stamm, 1959, and Baeolidia fusiformis Baba, 1949. In the ®rst species there are two short vertical rows in the pre-cardiac group, in the second species three vertical rows (Gosliner, 1979,198 5), the remaining rows being single in both. Gosliner (1979) transferred L. nodosa to the genus Baeolidia. However, on the arrangement of the cerata I return it to its original genus. It is possible too that B. fusiformis has only two pre-cardiac rows, but this needs to be con®rmed by an examination of the branching of the digestive gland. If there are only two rows, then this species could be transferred to Limenandra as had been done by Haefel®nger and Stamm (1959).