Cuthona beta (Baba and Abe, 1964)

Miller, M. C., 2004, An appraisal of the identity of the New Zealand species of the aeolid nudibranch family Tergipedidae (Gastropoda: Opisthobranchia), Journal of Natural History 38, pp. 1183-1192 : 1184

as Cuthona beta (Baba and Abe, 1964) in Miller (1977)

Remarks

The identification of the New Zealand tergipedid specimens as Cuthona beta has remained unchallenged. As far as can be ascertained, Cuthona sibogae (Bergh, 1905) is the only named species which is similar to C. beta in outward appearance, particularly in the coloration being purple all over with yellow or gold tipped cerata (Gosliner et al, 1996, photograph number 623 on p. 176; Marshall and Willan, 1999, Fig. 255 on p. 251). However, C. sibogae is clearly distinguishable in having the small or outer cerata all yellow or gold, the cerata borne on cushions (forming fans), large cnidosacs, the anus at the outer end of the first post-pericardial ceratal row, long rhinophores, tentacle-like foot corners, a long radula (72 teeth), and an unarmed penis. The lack of a penial stylet and the position of the genital aperture are the only features of reproductive anatomy known (Bergh, 1905), consequently other details of this system cannot be compared. Much closer in morphology and colour to Cuthona beta seems to be Cuthona sp.4 (in Gosliner, 1987 p.236). Its coloration is like that of the Japanese specimens in lacking the yellow or gold subapical ceratal band. The striking orange yellow or gold subapical ceratal band present in New Zealand specimens of C. beta seems a distinctive difference between them and specimens from Japanese waters. However, this can be explained as intraspecific variation, the yellow or gold band being absent in some New Zealand specimens.