Evolutionary and taxonomic aspects within the species group Pseudocandona eremita (Vejdovský) (Ostracoda, Candonidae)

Abstract

The contribution deals with evolutionary and taxonomic aspects of the stygobitic ostracod lineage Pseudocandona eremita (Ostracoda, Candonidae). It is based on a comparative study of the morphology of both the carapace and limbs of individuals belonging to eight populations from Romania (three reproducing bisexually, the others by parthenogenesis). Left valves display various outline shapes, classified in two morphotypes, the “dorsally rounded shape” and the “triangular shape”. The intra- and interpopulation shape variability of these valves is described using geometric morphometrics and multivariate statistics. It is shown that the more flat carapace occurs frequently in populations living in gravel-sand habitats. Moreover, variability of 12 morphological limb characters taken on females is quantitatively evaluated by discriminant analysis. The character state of the m process of the male copulatory organ gives the most reliable information for the separation of the three bisexual populations in different species: P. serbani Danielopol, P. danubialis sp. nov. and P. transylvanica sp. nov. Short descriptions of the latter two species are presented. For the five parthenogenetic populations where no particular discriminant trait could be found, a solution of compromise is adopted, i.e. they are temporary assigned to Pseudocandona eremita (Vejdovský, 1882, Thierische Organismen der Brunnenwasser von Prag. Prag) sensu lato.