Tylolaimophorus minor ( Thorne, 1939 ) Goodey, 1963

Ghaderi, Reza, Asghari, Ramezan & Eskandari, Ali, 2020, Systematics of the genus Tylolaimophorus de Man, 1880 (Nematoda Diphtherophoridae), with description of T. minor (Thorne, 1939) Goodey, 1963 from Iran, Zootaxa 4755 (2), pp. 322-340 : 331-332

Tylolaimophorus minor ( Thorne, 1939) Goodey, 1963

After Thorne (1939)

After Thorne (1974) After Eroshenko & Tepljakov (1977) After Brzeski (1994)

MEASUREMENTS

Holotype female: L = 0.6 mm; a = 17; b = 6.3; body width = (35) µm; spear =? µm; pharynx = (95) µm; tail = (30) µm; c = 20; c’ = (1.3); V = 50.

? females: L = 0.4-0.7 mm; a = 16; b = 6.1; c = 18; V = 52.

19 females: L = 0.34-0.60 mm; a = 10-23; b = 3.7-6.1; spear = 12-15 µm; c = 12-18; V = 53-64.

77 females: L = 0.38-0.58 mm; a = 13-23; b = 3.9-7.0; spear = 9-12 µm; pharynx = 79-112 µm; tail = 20-33 µm; c = 15-23; c’ = 0.9-1.7; V = 43-61.

DESCRIPTION

Female. Body arcuate ventrad to C shaped. Cuticle up to 1 µm thick, striation only visible on younger specimens and then striae very shallow. Some body pores seen on dorsal and ventral sides. Lip region separated by a shallow depression that may not be observable in older, thickened specimens. Amphidial opening about 3 µm wide or 27-37 % of lip region width. Pharynx with fusiform median swelling and short pyriform basal bulb. Body width at pharynx base 2.2-2.9 times lip region width. Vulva a minute transverse slit. Vagina extending 27-30 % into body. Ovaries symmetrical, reflexed about halfway back to the vulva. Rectum 6-8 µm long or about one-third the anal body diameter. Post-anal intestinal sac extends into tail to varying lengths in most of the examined specimens. Body tapering from a short distance posterior to the anus. Tail dorsally convex-conoid, bluntly rounded at the terminus.

Male. Never described.

DIAGNOSIS AND RELATIONSHIPS

Tylolaimophorus minor has been differentiated from T. cylindricus by its smaller size (0.4-0.6 vs 1.2-2.1 mm) and more tapering tail. It also should be compared with other species which have small body sizes: T. tegmentum differs by a longer spear (15-17 vs 10-12 µm) and the presence of males, and both T. digitatus and T. indicus are bisexual species, have a distended cuticle, rectum with thin walls, and more pointed tails. Thorne (1974) reported a population with the name Triplonchium parvum Thorne, 1939 . Brzeski (1994) suggested that this is, in fact, a population of T. minor , and the error is evident from the reproduction of the tail drawing from the original description of T. minor . Brzeski further noted that Thorne (1939) didn’t use the name T. parvum .

DISTRIBUTION

Described from foothill soil near Salt Lake City, Utah, USA ( Thorne 1939). Recovered in the forests of Tippecanoe County, Indiana, the USA ( Johnson et al. 1972). Also reported from several other localities in the USA: from native sod, windbreaks and forest shrubs and trees in South Dakota, North Dakota and Iowa ( Thorne 1974). It has been recovered from three localities in Russia: in soil and forest litter in the Dalnegorsky region, in forest soil at the edge of the city of Khabarovsk, and in the rhizosphere of Scots pine in Korsakovo on Sakhalin Island ( Eroshenko & Tepljakov 1977), and also from Slovakia: in forests of the Vihorlat Protected Landscape Area ( Hánĕl & Čerevková 2010). Two populations were reported in association with forests ( Quercus dalechampii Ten. ) in Rhodopes, Bulgaria ( Peneva et al. 2011). Two other populations of the species were found during the present study from the rhizosphere of alder and hawthorn trees in Gilan, Northern Iran (see below).