Tylenchorhynchus arcticus Mulvey, 1969

P. A. A. LOOF, 1971, FREELIVING AND PLANT PARASITIC NEMATODES FROM SPITZBERGEN, COLLECTED BY MR. H. VAN ROSSEN, Mededelingen Landbouwhogeschool Wageningen 71, pp. 1-86 : 41-43

Tylenchorhynchus arcticus Mulvey, 1969

( Fig. 11 ).

Dimensions:

Females (n = 14): L = 0.99 -1. 25 mm; a = 31- 38; b = 5.9 - 7.6; c = 13 -21; V = 21- 3548- 5522" 33; spear = 34-37 JA.

Males (n = 11): L = 0.88 -1. 22 mm; a = 35-45; b = 5.7- 7.9; c = 14-16; T = 42-49; spear = 32-35 JA.

Body nearly straight in death, only male tail curved slightly to ventral side. Cuticle with peculiar punctation which may be a fixation artefact; composed of two well-demarcated layers. Annulation very fine (1 JA, on tail occasionally even less) but distinct. Lateral field with six longitudinal lines, the inner ones originating about level of base of oesophagus. The lateral field is very indistinct owing to the punctation. Deirids not visible. No longitudinal striation outside the lateral field.

Lip region offset, knob-shaped, with six to seven annules; offset by a deep constriction. Perioral disc slightly raised, not refractive. Internal sclerotization of lips moderately developed, cheilorhabdions more distinct than in many other species of this genus. Spear very thin, with basal knobs directed posteriad. Orifice of dorsal oesophageal gland about 3 JA behind base of spear. Median bulb large, broadly oval, in the male slightly narrower; measuring 17-20 x 12-16 jj. in the female, 16-20 x 10-12 \x in the male. Valves central, distinct, located at 51- 55 % of oesophagus length from head end. Isthmus very long and thin. Terminal bulb large, saccate, slightly overlapping the mid-intestine. The nerve ring surrounds the middle of the isthmus. Hemizonid located slightly anterior to the end of the isthmus; the excretory pore lies 5-10 annules behind the hemizonid.

Female. Vulva transverse. Gonads with round spermathecas filled with sperm. No eggs. Tail conoid with round, almost smooth terminus, its length equal to 2.3 -3.3 anal body widths; with 54 - 74 annules. Phasmids located at 33-48 % of tail length.

Male. Testis outstretched. Spicules tylenchoid, 26-29 jx long. Gubernaculum curved, 9 [x long. Bursa with crenate edge, enveloping tail. Just before the terminus the tail is constricted distinctly on the ventral side, slightly so on the dorsal side, thus resembling the tail of Pratylenchoides ; its length equal to 3.5 -4.7 anal body widths.

Samples 3, 11, 18, 25, 40, 48, 52, 64 and 66.

These specimens differ from the Canadian type specimens by the much strong­ er constriction of the male tail and by the higher number of tail annules in the female, Mulvey's illustration giving 46; however, five paratypes had 60- 70. From Geocenamus this species differs by the absence of a refractive perioral disc.

Figures

FIG. 11. Tylenchorhynchus arcticus Mulvey. A: neck region;B:vulva region; C-D: male tails; E: female tail.