Delatylus, Yu & Munawar & Gu & Ye, 2018

Yu, Qing, Munawar, Maria, Gu, Jianfeng & Ye, Weimin, 2018, Delatylus andersoni n. gen., n. sp. (Nematoda: Neotylenchidae) Isolated from White Pine (Pinus monticola) Lumber from USA and Intercepted in Ningbo, China, Journal of Nematology 50 (1), pp. 69-76 : 71

Delatylus n. gen. *

Description

Neotylenchidae : Female body ranges from nonobese to semiobese and from straight to dorsally curved when heat relaxed; lateral fields raised; lip region moderately high, continues with body contour; the head with six sectors; four submedian and two smaller ones laterally; oral aperture elongated; amphidal apertures round and not dorsally displaced; stylet tylenchoid type, with three distinct knobs of equal size, slopped posteriorly, cone is slightly shorter than the shaft, with 4 to 5 guide rings (one or two on the cone, three always on the shaft); pharynx typical of other neotylenchoid: without a median bulb, and glands free in the cavity; pharyngo-intestinal junction located immediately posterior to the nerve ring; excretory pore posterior to the nerve ring; intestinal lumen widens immediately after the pharyngo-intestinal junction, with a broad rectum; the genital system consists of ovary, oviduct, quadricolumella, uterus, and the vagina without a discernible spermatheca (one specimen was observed with a degenerate spermatheca); vagina is directed anteriorly; vulva not protruding, a long transverse slit, about one-body width; anus located about the third distance between the vulva and the tail terminus.

Type species by monotype: Delatylus andersoni n. sp.

Etymology

The name combines elements from the genus names Hexatylus and Deladenus.

Diagnosis and relationships

Delatylus . n. gen. is distinguished from Hexatylus, Deladenus, Gymnotylenchus, Fergusobia, and Rubzovinema , the genera of the family Neotylenchidae by a combination of the body shape, the head framework, the numbers of guide rings on the stylet, the absence of spermatheca, the anterior directed vagina, the nonprotruding vulva, and the relative proximity of vulva to the anus. The new genus differs from Hexatylus ( Shepherd et al., 1983) by its semiobese and dorsally curved mature females in a heat-relaxed state vs. nonobese and straight or ventrally curved ones, the six-sectored lip region vs. eight, the elongated oral aperture vs. the round one, the immediately broadened intestine after the pharyngo-intestinal junction vs. a narrow tube, the absence of male, the absence of spermatheca, and the closer proximity between the vulva and the anus; from Deladenus by its semiobese and dorsally curved mature females in a heat-relaxed state vs. nonobese and straight or ventrally curved ones, the 4 to 5 guide rings vs. 2 to 3 on the stylet, vulva not protruding, the vagina directed anteriorly, and the diminished or absent spermatheca; from Gymnotylenchus by its wide vulva opening vs. a narrow one and the diminished or absent spermatheca vs. a normal one; from Fergusobia by its nonobese juveniles, the diminished or the absent spermatheca and the non-offset lip region vs. an offset one, and the six unequal sectored head framework vs. six equal sectored ( Taylor and Davies, 2008); from Rubzovinema by its semiobese and dorsally curved mature females upon heat relaxation vs. nonobese vermiform, stylet with distinct knobs vs. indistinct and minute knobs, the excretory pore posterior to the nerve ring vs. anterior and the spermatheca diminished or absent vs. the one present ( Siddiqi, 2000).

Key to genera of Neotylenchidae (based on non-entomophagous forms)

1. Juveniles and adults obese……….……………… …………………………….. Fergusobia

Juveniles and young adults not obese, mature adults obese……………… Delatylus n. gen.

Juveniles and adults not obese……………… …………………………………………….2

2. Males without bursa or gubernaculum………… ………………………….Gymnotylenchus

Males if present with bursa and gubernaculum…..……………………………………….3 3. Spermatheca present in female. ……………… ……………………………………………4

Female without spermatheca…………………… ………………………………..Hexatylus

4. Vulva position over 93% ……………………… ……………………………….Deladenus

Vulva position between 83.3 and 92.5%………… …………………………………………Rubzovinema