Description on Discolaimus pakistanense n.sp. (Nematoda: Dorylaimida) with a compendium of the genus Discolaimus cobb, 1913 from Pakistan

A compendium of the genus Discolaimus, based on the characters: body length, stylet and spicule length, number of supplements, ratios a, b, c, c', and vulva percentage, is presented. These allometric and morphometric characters were derived from the original descriptions. Discolaimus pakistanense n. sp., collected from soil around the roots of wheat plants in Mirpurkhas, Sindh, is described and illustrated. It is characterized by its moderately large and slender body; oesophagus with a conspicuous sheath in the posterior half of the expanded part of oesophagus; a bluntly rounded tail, less than one anal body width; nine supplement arranged in two groups of 3 and 6. It comes close to D. curvus Siddiqi, 2005; D. levinae Furstenberg & Heyns, 1965; D. neomajor Siddiqi, 2005 and D. papilla us Khan et al., 1994 but differs from the former in the body length, in a, b values, vulva percentage, odontostyle length, spicule length and in number of supplements (L = 2.2-2.4 vs 2.4-3.1 mm; a = 42-44 vs 48-55; b = 5.5-6.0 vs 4.0-4.5; V % = 55-57 vs 48-55; odontostyle = 21-24 vs 29-31 mum; in male spicule length = 39 vs 50; supplements = 9 vs 8). It differs from D. levinae in b, c values, vulva percentage and in number of supplements (b = 5.5-6.0 vs 4.1; c = 94-100 vs 73; V % = 55-57 vs 48; supplements 9 vs 11). It differs from D. neomajor in b, c, c' values, vulva percentage, odontostyle length and in presence of males (b = 5.5-6.0 vs 3.84.0; c = 94-100 vs 65-74; c' = 0.6-0.7 vs 0.9-1.0; V % = 55-57 vs 40.8-42.3; odontostyle = 21-24 vs 24-27 mum; presence of males vs absent). It differs from D. papilla us in body length, a, b, c, c' values, odontostyle length and in number of supplements (L = 2.2-2.4 vs 1.7-1.9 mm; a = 42-44 vs 44-47; b = 5.5-6.0 vs 4.2-4.6; c --- 94-100 vs 54-60; c' = 0.6-0.7 vs 1.2-1.3; odontostyle =21-24 vs 18-19 mum; supplements = 9 vs. 15). An up to date list of 41 valid species along with illustrations is also provided.