Tylenchorhynchus microdorus Geraert, 1966

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 : 39-41

Tylenchorhynchus microdorus Geraert, 1966 .

Dimensions:

Females (n = 25): L = 0.62 mm (0. 58 -0.71); a = 24 (22 -26); b = 5.0 (4.5- 5.7); c = 12.3 (10.6-14.8); V = 56 (54-59); d = 34 (27-38); G2 = 30 (25- 36); spear = 13 jx (12-15).

Males (n = 25): L = 0.61 mm (0.52-0.73); a = 27(23-31);b = 5.1 (4.3 -5.7); c = 10.7 (9. 5 -11.4); T = 55 (47 -62); spear = 14 jx (12-15); spicules = 23 u. (21- 26).

This species strongly resembles T.nanus Allen, 1955 . It is, on the average, longer and less slender, the spear in the male is distinctly longer, and the phasmids lie more posterior, in the Spitzbergen females at 49 % (41-60) of tail length. Moreover the tail is relatively shorter; in the Spitzbergen females it measures 2.8 (2.5-3.5) anal body widths, in the males 3.6 (2.9 -4.8). The lateral field shows the punctation described as differentiating character by Geraert, but it should be noted that occasionally this may be found in isolated specimens of other nematode species as well. It is difficult to say whether in the Spitzbergen females the tail tip is striated or not; at any rate it is not so conspicuously smooth as in T. brevidens , but distinct annules were not visible either. The median bulb lies just anterior to the middle of the oesophagus (47 (43 -49)%). This species seems further to differ from T. nanus by the lower lip region with less than seven annules; in fact, the lip region is conspicuously low, more so than in T. nanus judging after Allen's illustration.

Samples 30 (one specimen), 53 and 54 (dominant in both).

In sample 17 one female was found agreeing generally with T. microdorus , but with a spear length of 17 [x, which might suggest that it belongs to T.nothus Allen, 1955 . Dimensions: L = 0.69 mm; a = 28; b = 5.7; c = 13; V = 27 5229; median bulb at 48 % of neck length; T/ABW = 3.2. The only difference is the anterior position of the phasmids (35 % of tail length) which is different from both nothus and microdorus .