Extremalona timmsi gen. nov., sp. nov., a new cladoceran (Cladocera: Anomopoda: Chydoridae) from an acid saline lake in southwest Western Australia

摘要

A new species of Cladocera, Extremalona timmsi gen. nov., sp. nov., was found in acid saline lakes in the southwest of Western Australia. Extremalona gen. nov. belongs to the Coronatella-branch of Aloninae, but differs from all members of the group by the oval body with small high-set head (tip of rostrum located at half-height of the body), the exopodite III with uniform, well-developed setae 4-6 and male antennule with six lateral and nine terminal aesthetascs, and by numerous other characters. In our opinion, Extremalona gen. nov. is one of the ancestral genera of the Coronatella-branch of Aloninae, sharing numerous common features with the elegans-group of Alona s.l. Our data confirm a high level of endemism in Australian Chydoridae and Cladocera in general.