Ereptonema arcticum n.sp.

(Fig. 16).

Dimensions of 44 females: L = 0.28 -0.34 mm; a = 16-18; b = 3.4- 3.8; c = 7.0- 8.9; V = 7 - 1548 - 536 - 1 0.

Female, holotype: L = 0.30 mm; a = 16; b = 3.7; c = 8. 1; V = " SO10.

Male not found.

Body straight in death except the tail being curved to ventral side. Anteriorly the body is subcylindroid till the anterior third of the neck, then convex to just anterior to the base of the cervical expansions; anterior to this point the outline of the inner tissues becomes concave. Transverse striae very fine, 0.8 (x apart, except on the ventral side of the tail where they are 1.2 y. apart.Lateral field with two distinct longitudinal lines. The structure of the cephalic ornamentations appears much similar to that of E.fimbriatum Anderson, 1966, but the fringe along the anterior margins is shorter and the expansions bear cornua much longer than the fringe. Cuticular expansions with coarse annulation. Stoma expanded somewhat anteriorly, but not globular. Depth of stoma 11 jx. Amphids round, 1.5 [x in diameter, located anterior to the base of the expansions. Isthmus of oesophagus as thick as corpus. The nerve ring surrounds the oesophagus just before its middle. Deirids conspicuous, behind nerve ring. Tail 3.6-4.6 anal body diameters long; its cuticle thickened dorsally as in E.fimbriatum. A pair of subventral setae halfway the tail, a subdorsal pair just before the terminus.

Holotype: Female on slide WT 1144. Paratypes: 31 females (three with end-on view of head) on slides WT 1145-1164; nine females deposited with Dr. A. Morgan Golden, Beltsville, Maryland, U. S.A.; six females with Dr. R. V. Anderson, Ottawa, Canada.

Type habitat and locality: Sample 70; the species is dominant here. Found also in samples 16, 17, 19, 21, 34, 53, 54, 55, 60, 62, 65 and 69.

This species is close to E.fimbriatum, the only other species of the genus. It differs by the cornua protruding distinctly beyond the fringe, by the shorter fringe, by the shape of the anterior part of the mouth cavity and by the presence of only two pairs of caudal setae (four in E.fimbriatum).