Tylolaimophorus constrictus Sauer, 1968

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 : 327-328

Tylolaimophorus constrictus Sauer, 1968

After Sauer (1968)

MEASUREMENTS

Holotype female: L = 1.55 mm; a = 29; b = 10; V = 53 %.

12 paratype females: L = 0.84-1.55 mm; a = 22-29; b = 7.3-10.0; body width = (45) µm; spear = 13-14 µm; pharynx = (130) µm; tail = (38) µm; c = 21-34; c’ = (1.2); V = 52-60.

12 paratype males: L = 0.90-1.29 mm; a = 24-32; b = 7.0-13.6; body width = (38) µm; spear =? µm; pharynx = (100-130) µm; tail = (45) µm; c = (22); c’ = (1.4); spicules = 27-33 µm; gubernaculum = (8) µm.

DESCRIPTION

Female. Body cylindrical, ventrally arcuate when relaxed by heat. Fine, faint annulation of the cuticle visible at the head end. Lateral field near one quarter body width. Lip region cap-like, offset by a deep constriction which bisects the oval amphid apertures. Individual lip lobes project slightly to give a hexagonal appearance in face view. Spear typical of the genus, with an arch-like, projecting, dorsal sector and rod-like ventral sector which joins the ventral side of the pharynx. No anterior projection of the ventral sector. The sclerotized tubular structure surrounding the vestibule is symmetrical in the dorso-ventral view, and asymmetrical in lateral view, with the distal end of the spear closer to the dorsal wall. Short slender pharynx, expanding to a pyriform basal bulb. Nerve ring situated near the mid-point of the pharynx. Three distinct glands at the base of the pharynx. Vulva a small transverse slit posterior to middle of the body. Vagina broad with thick cuticular lining, extending almost halfway into the body. Gonads paired, opposed, reflexed, the ovaries relatively short. Rectum less than half as long as the anal body diameter with thick cuticular lining. No extension of the intestine into the caudal cavity. Blunt tail, longer than anal body diameter, tapered dorsally to a rounded terminus.

Male. Similar to female. Spicules arcuate, more or less parallel sided and thin in lateral view, with a proximal ventral process. Conspicuous musculature surrounding the spicules. Gubernaculum simple, trough-like, ridged be- tween the spicules. A series of widely spaced ventromedian supplements beginning within range of the spicules present. Up to nine supplements seen in some specimens, but these are often rudimentary and difficult to distinguish. Usually at least four supplements visible.

DIAGNOSIS AND RELATIONSHIPS

Tylolaimophorus constrictus has been compared with T. pugio , T. cylindricus , T. bulgaricus , and T. pileatus . Considering their size, T. constrictus and T. pugio belong in the T. cylindricus group. T. constrictus has the curved spicules with conspicuous surrounding musculature typical of the group, but the spicules are not as strongly curved as in other species, they are narrower proximally, and the strong proximal process projects ventrally directly from the ventral wall. Only T. bulgaricus and T. pugio have a number of supplements comparable to T. constrictus . Only T. constrictus , T. pileatus , and T. digitatus have the lip region offset by constriction. In T. pileatus , the amphid apertures are posterior to the constriction; in T. constrictus , the constriction passes across the apertures; however, the apertures are not anterior to the spear point as in T. pileatus which seems to be unique in the location of the spear. T. pugio is distinguished from species of similar size by the cephalated, dagger-like spicules lacking conspicuous surrounding musculature, and resembling those of the group of smaller species. In general morphology, it is close to T. constrictus . Females of T. constrictus and T. pugio are readily separated by the presence or absence of the lip region constriction. The cuticular lining of the rectum is thick in these species, as in T. pileatus . The intestine is said to extend into the caudal cavity in T. cylindricus and T. pileatus , but not in T. bulgaricus , T. constrictus , or T. pugio .

DISTRIBUTION

Described from soil in a peach orchard, Boeill Creek, New South Wales, Australia ( Sauer 1968).