Description of Calcaridorylaimus heynsi n. sp. (Nematoda: Dorylaimidae) from Potchefstroom, South Africa

Calcaridorylaimus heynsi n. sp. is the second species of the genus to be described by both morphological and molecular techniques. Morphologically, it can be distinguished from all known species of Calcaridorylaimus by a combination of the following characters: presence of advulval ornamentations, short body (0.90-1.33 mm), slightly anteriorly positioned vulva (V = 47.6 (45.8-49.8)), short odontostyle in females and males (13.1 (11.5-14.5) mu m and 13.5 (12.0-18.0) mu m, respectively), number of supplements (2 + 9-11), short spicules when measured along the median line (40.4 (38-42) mu m) and pore-like vulval opening. It is closest to C. sirgeli, especially in the presence of advulval ornamentations and the pore-like vulva. Phylogenetic analysis based on partial D2-D3 segment of 28S rDNA sequences showed that C. heynsi n. sp. is in a well-supported sister relation with Mesodorylaimus sp. in a clade with C. cignatus and Mesodorylaimus spp. In the Bayesian tree, using partial sequences 18S rDNA, M. japonicus was the closest taxon to the new species.