Description of Crassolabium costaricense sp. n. (Nematoda: Dorylaimida: Dorylaimidae) from Costa Rica

A new species of Crassolabium, C. costaricense sp. n., collected from natural habitats in Costa Rica, is described and illustrated. The new species is characterised by its body length of 1.26 (1.22-1.30) mm in the female and 1.28 (1.16-1.37) mm in the male, lip region nearly continuous and 13.5 (12.5-14.5) μm broad in the female and 13.1 (12.5-14.0) μm broad in the male, odontostyle 17.3 (15.5-19.0) μm long in the female and 18.1 (17.0-19.0) μm long in the male with the aperture occupying 33-42% its length, neck 302-334 μm long, pharyngeal expansion 120-142 μm long or occupying 40-45% of total neck length, uterus tripartite and 163 (134-176) μm long or 2.6-3.1 times the corresponding body diam., pars refringens vaginae well developed, vulva transverse (V = 57.1 (56.0-58.0)), tail short and rounded in female (17.9 (17.0-19.0 μm) long; c = 70.3 (67.0-72.0); c′ = 0.56 (0.50-0.60)) and more conoid in males (21.6 (17.0-23.0) μm long; c = 60.4 (56.0-77.0); c′ = 0.65 (0.50-0.70)), spicules 47 (44-49) μm long, and presence of 8-10 closely spaced ventromedian supplements with an hiatus. Its molecular (LSU D2-D3) characterisation supports an evolutionary relationship with members of the Dorylaimidae.