Dumontia oregonensis n. fam., n. gen., n. sp., a cladoceran representing a new family of `Water-fleas' (Crustacea, Anomopoda) from U.S.A., with notes on the classification of the Order Anomopoda

摘要

Dumontia oregonensis, a cladoceran representing a new family in the Order Anomopoda is described from rain pools in the Agate Desert, Oregon, U.S.A. The proposed family, Dumontiidae, is the newest family within Anomopoda that is not just a reshuffling of already-known species. The general appearance of this novel cladoceran is similar to that of members of the family Macrothricidae. However, a detailed examination of the trunk limbs, particularly of the second pair of limbs, showed that the new species lacks the scraper-setae typically observed in all members of the recently erected suborder Radopoda, to which macrothricids belong. Instead, limb morphology suggests a closer relation of Dumontiidae to the family Daphniidae. Dumontiidae appears to be a `missing' link between the suborder Radopoda and the `non-radopodid' anomopods. The families Daphniidae, Ilyocryptidae, Bosminidae, Moinidae and the new Dumontiidae are similar in that they lack of typical radopodid setae on the second pair of trunk limbs. Further studies on the limb morphology of non-radopodid cladocerans are required to solve the phylogenetic relationships among the members of the order Anomopoda.