NEW SPECIES OF MIOCENE SPIDER CRABS FROM NEW-ZEALAND, AND A PARTIAL CLADISTIC-ANALYSIS OF THE GENUS LEPTOMITHRAX MIERS, 1876 (BRACHYURA, MAJIDAE)

Two new species of Leptomithrax, L. elongatus n. sp. and L. garthi n. sp., are described from North Canterbury deposits of Miocene age. Asso ciated fossils suggest that these crabs lived in a cool temperate, sha llow shelf environment. They bring to six the number of fossil Leptomi thrax species known from New Zealand, which still has five Recent repr esentatives of this genus. In addition, nearby Australia has two fossi l and six Recent species. In total there are now eight fossil (all res tricted to Australasia) and 15 Recent species of Leptomithrax from the western Pacific. The relationships of the eight fossil Australasian s pecies and eight Recent species from Australasia and Japan were invest igated by applying cladistic methods to a set of carapace characters d escribing shape and ornamentation. Using this analysis we tested Jenki n's hypothesis about the phylogenetic relationships of the Australasia n Leptomithrax species. Our cladistic analysis of a set of carapace ch aracters describing shape and ornamentation recognises five major grou pings within Leptomithrax: the ''L. elegans'' and the ''L. griffini'' are known only from the fossil record; and the ''L. longimanus'', ''L. tuberculatus'', and ''L. longipes'' clades are known from both fossil and Recent records. The primary branching events resulting in these c lades occurred around the time of the Eocene-Oligocene boundary.