Australonannopus aestuarinus gen. nov., sp. nov. (Crustacea, Harpacticoida), an aberrant Cletoid from Australian brackish waters

Abstract

The new species is described and figured in both sexes from a numerous population found near Hobart, Tasmania; isolated individuals have also been found in brackish waters in New South Wales. The new genus Australannopus is defined, and is shown to be unique among the Cletodidae in that (l) the fourth feet have no trace whatever of an endopod in either sex, and (2) the secondary sexual characters of the male are shown by the exopod of P2, instead of by the endopod of P3 as in all other genera. Three cletodid genera have been described since the most recent key (Lang 1965) to the genera of this fami1y; the way in which they and Australonannopus fit into this key is discussed. Australonannopus is shown to occupy a rather isolated position within the family, although its nearest relative is possibly Nannopus; A. aestuarinus is so far the only known species.