Nematodes of the order Dorylaimida from Romania. The genus Thonus Thorne, 1974. Part II.

Five Thonus species from Romania are described. Thonus montanus sp. n. is characterised by its body length of 1.56-1.90 mm, cuticle with coarse transverse striations, lip region 15-18 μm diam., odontostyle 20-22.5 μm long, plicate guiding ring, neck 400-553 μm long, pharyngeal expansion occupying 49-56% of total neck length, uterus 1-1.5 body diam. long, pars refringens vaginae with two separate pieces, gland cells present near vagina-vulva junction, vulva a short post-equatorial (V = 54-59) longitudinal slit, and female tail conoid (25-33 μm, c = 54-73, c′ = 0.8-1.2) with abundant blister-like structures and distinct hyaline portion. Thonus tenuistylus sp. n. is characterised by its body length of 1.17-1.56 mm, lip region offset by a more or less, usually well, marked constriction and 16-17.5 μm diam., slender odontostyle 17-20.5 μm long or 1.1-1.3 times lip region diam., neck 275-397 μm long, pharyngeal expansion occupying 42-52% of total neck length, female genital system amphidelphic, uterus bipartite and 1.7-2 body diam. long, pars refringens vaginae with two adjacent pieces, vulva a post-equatorial (V = 50-56) transverse slit, tail conoid-rounded (19-24 μm, c = 48.7-72.9, c′ = 0.8-1.0) and with abundant blister-like structures, spicules 38-43 μm long, and 3-6 widely spaced ventromedian supplements. Thonus sp. is characterised by its slender (a = 37.5) body 1.41 mm long, lip region practically continuous with adjacent body and 11.5 μm diam., odontostyle 10.5 μm long, neck 325 μm long, pharyngeal expansion 138 μm long or ca two-fifths of total neck length, a coarse ring-like structure surrounding cardia, female genital system amphidelphic, uterus ca 2.5 body diam. long, pars refringens vaginae with two adjacent trapezoidal pieces, vulva a transverse slit (V = 52), a pseudocoelomocyte present at mid-body, tail convex conoid (26.5 μm, c = 56, c′ = 1.1) with abundant blister-like structures, and males unknown. Thonus eroshenkoi n. comb. and T. medianus n. comb. are proposed. Thonus kaszabi and T. medianus n. comb. are new records for the Romanian nematode fauna. [ABSTRACT FROM AUTHOR]