New records of rare males of Cryptocandona vavrai Kaufmann, 1900 (Crustacea, Ostracoda), with further additions to the description of the species

Three males of Cryptocandona vavrai were discovered in geographically distant sites (UK, France, Romania), representing different environments (surface and underground waters). The species may be considered a parthenogen with rare occurrence of single males, the morphology of which was hitherto poorly known. The first complete description of males is given, which, together with comparative descriptions of females from surface waters at the UK site and underground waters at an additional site in eastern France, as well as consideration of the shape and size of the last juvenile stages, permits the presentation of a more complete description and an amended diagnosis of the species. Cryptocandona vavrai takes an intermediate position in the genus, lodged between stygobitic species and the cluster of more primitive C. reducta and C. brehmi. Due to a number of traits (broad calcified inner lamella of the valves, 3rd ramus podomere of the antennule lacking the posterior seta, hook-like shortest terminal seta of the cleaning leg, specific morphology of the male prehensile palps and hemipenis lobes) C. vavrai is fairly easily recognised, although there seems to be considerable intraspecific variation. The comparison between females from surface and underground waters revealed substantial elongation of the apical antennal claws, aesthetascs and the distal claw of the walking leg in the latter population. The major difference recorded among the compared males is the underdevelopment of the external claw z2 on the 3rd endopodial podomere of the antenna in the male from the underground waters in Romania. The revealed variation could indicate that some populations may deserve a separate (sub-specific) taxonomic status. Finally, available data on the distribution and ecology of this species are summarised