Paraxonchium carmenae Peña-Santiago & Jiménez-Millán, 1986 revisited four decades later, with new insights into the phylogeny of the genus Paraxonchium Krall, 1958 (Dorylaimida)

A revised characterisation of the dorylaimid nematode Paraxonchium carmenae is provided, including an updated description, SEM observations and molecular (18S-, 28S-rDNA) analyses. A total of 29 females and 16 males, collected from several mountain natural locations in eastern Andalusia, Spain, are studied. This species is very homogeneous morphologically, but displays wide variations in their morphometrics, although with high coincidence or overlapping when the ranges of different populations are compared. The morphology of the genus Paraxonchium is analysed and discussed, with emphasis on its remarkable interspecific variations. Results of molecular studies show a close relationship of P. carmenae with P. laetificans, the type species of the genus, and tentatively support its monophyly. Nevertheless, neither morphological nor molecular data clear up the uncertainties about its position in the Dorylaimina system.