The sexual dimorphism in the chaetotaxy of the antenna in various species of Sclerocypris is studied and described. Relying on larval morphology, a homology between the patterns in the two sexes is deduced and a suitable nomenclature for the apomorphic male condition is proposed. The differences observed are in all probability related to the function of the male antenna during copulation.
Several crustacean groups have produced extensive species flocks in ancient lakes. However, except for the Amphipoda in Lake Baikal, crustacean diversity per se is not significantly higher in ancient lakes than in non-marine aquatic habitats in general. Yet the degree of endemicity in such long-lived habitats is certainly higher in these crustacean groups than in the average of noncrustacean groups. Causality must thus be sought in the evolutionary biology, rather than in the ecology of the groups at issue. Several potential, intrinsic factors, possibly promoting speciation, have been cited, but thus far no singular cause for high crustacean endemicity in ancient lakes could be demonstrated. Plusieurs groupes de crustaces ont produit de vastes ensembles d'especes dans les lacs anciens. Cependant, excepte pour les amphipodes du lac Baikal, la diversite des crustaces en elle-meme n'est pas significativement plus grande dans les lacs anciens que dans les habitats aquatiques nonmarins en general. Pourtant, le degre d'endemisme dans des habitats habites de si longue date est certainement plus eleve dans les groupes de crustaces que dans la moyenne des groupes non crustaces. La cause doit alors etre recherchee dans la biologie evolutive, plutot que dans l'ecologie des groupes concernes. Plusieurs facteurs potentiels, intrinseques, pouvant induire la speciation, ont ete cites, mais pour l'instant, aucune cause particuliere n'a pu etre etablie pour expliquer l'endemisme crustaceen superieur dans les lacs anciens.
We describe Argentocypris sara, a new genus and species from a Patagonian lake in the province of Neuquén, Argentina. The genus and species clearly belong to the tribe Eucypridini, and as such have a rather isolated biogeographical position in South America. The genus can be distinguished from other Eucypridini based on both valve (large external Porenwarzen, anterior selvage and posterior inner list on RV) and soft part features (cylindrical shape of second distal segment of Mx1-palp, length ratio setae d1 = c 3 × d2 on T2, curved attachment of caudal ramus). A study of the literature reveals that several other nominal species can be transferred to this genus. Nevertheless, at least two of these species (A. virgata n. comb. and A. labyrinthica n. comb.) are based on juvenile fossil specimens only and their identity is uncertain. Two other species (A. fontana n. comb. and A. sarsi n. comb.) are based on adult morphology.
The Israeli inland-water ostracod fauna numbers 53 named species belonging to 29 genera and comprising 15 subfamilies. The most diverse genera are Heterocypris and Ilyocypris, while the families Candonidae (most common in the Palearctic) and Cypridopsinae (most common in the Ethiopian) are relatively poorly represented. The fauna are circumtropical and cosmopolitan (21%), Holarctic-Palearctic (49%), Ethiopian and Mediterranean (15%), Oriental (6%), and endemic species (9%). Of the original five endemics described to date, three occur in Lake Kinneret, one has Ethiopian affinities but occurs in a northern river, and the status of the fifth species is still unknown. The Palearctic fauna is most likely Quaternary in origin. Four periods of Ethiopian invasion could be distinguished, two of which (end of Miocene and end of Pliocene) were probably the most important. No truly Tethyan elements (Miocene) could be detected in the extant inland-water ostracod fauna, as the only species with genuine marine affinities is most likely a relict of Pliocene marine transgressions.
We redescribe Strandesia tolimensis Roessler, , originally described from Colombia, and describe three new species, Strandesia lansactohai n. sp., S. velhoi n. sp. and S. nupelia n. sp. from lakes, channels and rivers in the alluvial valley of the upper Paraná River. Mainly valve morphology and shape and size of the attachment of the caudal ramus are used to characterize these species, as other soft parts are uninformative. All populations studied here are parthenogenetic, so male morphologies are not available.
Sequences of the mitochondrial COI-gene are used to construct a phylogeny, as well as a genetic network of specimens, and in both analyses the four species are well-supported. In addition, we also delimit the four species with genetic distances using Birky’s K/θ method and conclude that it supports the identity of the species under consideration.