Meeting Abstract

S8-1.7  Saturday, Jan. 5  Callianassidae and related families: steps towards a practical classification POORE, Gary C. B.; Museum Victoria gpoore@museum.vic.gov.au

The Callianassidae sensu lato comprise 15 family or subfamily available names, 42 genus-level names and 256 described species, most erected in the last decade. The numbers of names used has gone up and down over time depending on the whose revision is chosen. In a revision of American species Manning & Felder (1991) recognised 21 genera worldwide in two families. Poore�s (1994) key was to 25 genera in two families. Sakai (2005) catalogued the species in three families, 12 subfamilies and 20 genera. He synonymised 12 genera recognised by earlier authors but compensated by erecting others. A tension exists between authors who differentiate subfamilies and genera based on few species and those (not necessarily different) authors who synonymise higher taxa. While some authors seem able to define genera on the basis of small morphological differences others appear overwhelmed by morphological intergradation and convergence. Part of this conflict derives from attempts to use character states that are continuous or complex as if they were separate and exclusive. For example, much as been made of the shape of maxilliped 3 variously referred to as pediform, subpediform, suboperculiform or operculiform. Also, it is now appreciated that juveniles differ from mature adults in the form of pleopods 1 and 2 and chelipeds. Many species are described on the basis of few individuals of unknown developmental state. This contribution examines the distribution of highly variable morphologies in several anatomical features with high potential for definition of higher taxa. Character states suitable for use in cladistic analysis are selected using defined criteria. The outcome is a new hypothesis of families and genera based on a cladistic analysis.