Partial revision of the<i>aduncus</i>‐like species of<i>Pleuroxus</i>Baird, 1843 (Chydoridae, Cladocera) from the southern hemisphere with comments on subgeneric differentiation within the genus

Abstract

The aim of this study is to revise the aduncus‐like species of the genus Pleuroxus Baird, 1843 (Chydoridae, Cladocera) from the southern hemisphere and test the accuracy of subgeneric differentiation within this genus according to Frey (1993a Frey, D. G. 1993a. Subdivision of the genus Pleuroxus (Anomopoda, Chydoridae) into subgenera worldwide.. Hydrobiologia, 262: 133–144. [Crossref] , [Google Scholar]). Pleuroxus wittsteini Studer, 1878 Studer, T. 1878. Beiträge zur Naturgeschichte wirbelloser Tiere von Kerguelensland.. Archiv für Naturgeschichte, 44: 102–121. [Google Scholar] from the Kerguelen archipelago is re‐examined with special attention to thoracic limbs. Forgotten P. carolinae (Methuen, 1910 Methuen, P. A. 1910. On a collection of freshwater Crustacea from the Transvaal.. Proceedings of the General Meetings for Scientific Business of the Zoological Society of London for, 1910: 148–166. [Crossref] , [Google Scholar]) from the mountains of South Africa is redescribed in detail; it is a species having nine to ten setae in filter plate II, and six to seven setae in filter plate IV, which is a plesiomorphic, non‐oligomerized state. Brief descriptions are also provided for P. scopuliferus (Ekman, 1900 Ekman, S. 1900. Cladoceren aus Patagonien, gesammelt von der schwedischen Expedition nach Patagonien 1899.. Zoologische Jahrbücher, Abteilung für Systematik, Geographie und Biologie der Tiere, 14: 62–84. [Google Scholar]) and P. varidentatus Frey, 1993 Frey, D. G. 1993a. Subdivision of the genus Pleuroxus (Anomopoda, Chydoridae) into subgenera worldwide.. Hydrobiologia, 262: 133–144. [Crossref] , [Google Scholar]. A new species, P. hardingi sp. nov., is reported from high altitudes of the Bolivian Andes; this species was previously misidentified as P. aduncus by Harding (1955 Harding, J. P. 1955. Percy Sladen Trust Expedition. XIX. Crustacea: Cladocera.. Transactions of the Linnean Society of London, 1: 329–354. [Crossref] , [Google Scholar]). A key for identification of aduncus‐like species in the southern hemisphere (except Australia and New Zealand) is proposed. Frey's (1993a Frey, D. G. 1993a. Subdivision of the genus Pleuroxus (Anomopoda, Chydoridae) into subgenera worldwide.. Hydrobiologia, 262: 133–144. [Crossref] , [Google Scholar]) system for differentiation of the subgenera of Pleuroxus is found to be vulnerable in view of the new data. New studies, most probably using genetic methods, are needed for the construction of a consistent phylogenetic tree for the genus.