Marine molluscs. Part 2. Opisthobranchia

Abstract

This second part of the "Marine Molluscs" series deals with the subclass Opisthobranchia. Some sea slugs, as opisthobranchs are commonly termed, are amongst the largest and most ecologically important gastropods in New Zealand's coastal waters. Opisthobranchs in general, and nudibranchs in particular, are rare in both time and space so some species go unseen for many years. For example the aeolid Babakina aaprinsulensis is still only known from a single specimen that was collected at Goat Island Bay in 1965. It never ceases to amaze us how such rare species ever succeed in finding a mate. Because of their scarcity and general difficulty of collection, opisthobranchs are not well understood taxonomically. Their systematics are incomplete and even within the Leigh area a dozen undescribed species are known. We have departed from the names employed by Powell (1979) in several instances in this work to bring the taxonomy up to date. However reference is always given back to Dr. Powell's "New Zealand Mollusca". As if to reflect the increasing knowledge of opisthobranchs in New Zealand several species are included here which have been described since. Dr. Powell completed the research for his manual.