Recent advances in taxonomy and phylogeny of “maxillopodan” crustaceans

Abstract

One of the major crustacean groups, Maxillopoda had accommodated Mystacocarida, Copepoda, Thecostraca, Tantulocarida, Ostracoda, Branchiura, Pentastomida, and some fossil taxa, and was generally defined by some combinations of the following characters: body tagma composed of 5 cephalic, 6 (or 7) thoracic and 5 (or 4) abdominal somites; male gonopore (s) located on the first abdominal somite; uniramous antennules; naupliar eyes with tapetal cells, and so on. However, the monophyly of maxillopodans is totally rejected by a number of genetic analyses, while palaeontological and morphological approaches still recognize not only maxillopodans but also entomostracans as valid taxa. Since this issue is not well documented in Japan, the present paper briefly introduces modern phylogenetic studies on maxillopodan crustaceans, in particular Copepoda and Ostracoda.