Taxonomical efforts in freshwater zooplankton are continuously needed for the delineation of species. Even today, confusion exists in correct identification of several European Cladocera because of poor original descriptions and subtle differences in morphology. In this context, we discuss three of the rarest Alona-like Chydoridae in the Palaearctic and their validity. 1) Alona moniezi, only reported once from Vichy area, France, has a male indistinguishable from that of A. elegans Kurz, 1875 while females show characters of A. elegans and of Coronatella rectangula. We provide a description of this taxon, with intermediate morphology and discuss the possibilities of hybridization. 2) Alona karelica is unusual as one of the few eurythermic species of a predominantly stenothermic A. pulchella-group. We discuss Neotropical A. cf. karelica from Mexico as its closest relative. Both show similarities with the semi-terrestrial A. bromelicola from Nicaragua, forming a small A. karelica-section within the A. pulchella-group. 3) A. weltneri is redescribed based on type material and we confirm it as a member of the A. costata-group. We discuss the three taxa and expand their diagnosis. A. weltneri and A. karelica are both found sporadically, and little is known about their ecology. Their scarcity in the Palaearctic may be linked with specialisation to a peculiar habitat and the possibility that these are true relicts.

I examined ephippial females and males of the Palaearctic Macrothrix hirsuticornis Norman & Brady, 1867 and M.tripectinata Weisig, 1934 (Cladocera: Anomopoda: Macrothricidae). Parthenogenetic and ephippial females, and males of a thirdspecies, M. dadayi Behning, 1941, are redescribed on material from the Ciscaucasian coast of the Black Sea (Russia). A series ofmale characters, useful for species discrimination was found. Ephippia of M. tripectinata and M. dadayi are covered with smallspinules, a unique synapomorphy of these species. Recent progress in Macrothrix systematics allows us to predict that thetaxonomy will improve as more males and ephippial females (currently known only in half the species), yet especially valuablefor systematics, are described.

A revised diagnosis of Mixobates Thor, 1905, is given, including the proposal to rank this taxon as a separate genus. The species so far published from the palaearctic region are revised. Adults of M. caucasicus Tuzovskij, 1990 are described for the first time and the following synonyms are established : M. uncatus Sokolow, 1930 = M. processifer Thor, 1905 ; M. lundbladi Schwoerbel, 1957 = M. incurvatus Láska, 1954. The latter species is for the first time recorded from the Mediterranean area. Four new species are described : M. acutidentatus, M. brachypalpus and M. uncatellus from Russia, and M. maghrebinus from Morocco. A dichotomic key for the determination of the palaearctic species is presented.