Observations on the anatomy of Hermaea variopicta (Opisthobranchia: Ascoglossa)



The alimentary system, reproductive system and central nervous system of Hermaea variopicta (Costa) are described for the first time. Its gut resembles that of Hermaea bifida (Montagu), type species of the genus; the radula is considered in detail. Its diaulic reproductive system is described in morphological and functional terms. The central nervous system has three ganglia on the visceral loop. The anatomical evidence supports the opinion of Lemche & Thompson (1974) that Hermaeopsis Costa, former genus of H. variopicta, should be discarded. However, the division of the genus Hermaea into two subgenera, Hermaea and Placida, is not recommended. H. variopicta appears to be more primitive than H. bifida. In the discussion, the origin of hermaeid and stiligerid lines from a common ancestral stock is suggested, to which is added a new theory of the evolution of stiligerid penial styles.