Morphological and molecular characterisation of Tylencholaimus notrus Khan, Jairajpuri & Ahmad, 1990 (Dorylaimida, Tylencholaimidae) with first report of the male and new insights into the phylogeny of the genus

Summary Four populations (three Indian and one Chinese) of Tylencholaimus notrus comprising 40 females and one male, are characterised, including morphological description, morphometrics, pictures and molecular (18S-, 28S-rDNA) analyses. The male of the species is reported for the first, being distinguished by its 0.63 mm long body, 22 μ m long spicules, and three irregularly spaced ventromedian supplements. The intraspecific variation of the species is studied by means of a PCA analysis. Tylencholaimus notrus is compared and separated from its closest relatives T. nagauriensis and T. obscurus , from which it differs in small but reliable morphometric features. As derived from the molecular analyses, results herein obtained cannot support the monophyly of the genus Tylencholaimus , probably due to the low number of available sequences yet and/or the existence of mistakes in their assignation. The trees obtained from the analyses of both genes significantly differ to infer the outer relationships of the genus, an indication that further research should be undertaken to elucidate them.