Trichotylenchus gorganiensis, 2018

Ghaderi, Reza, Karegar, Akbar & Miraeiz, Esmaeil, 2018, Morphological characterization of Trichotylenchus gorganiensis n. sp. (Nematoda: Dolichodoridae) and photomicrographs of several other species of the subfamily Telotylenchinae Siddiqi, 1960, Zootaxa 4526 (4), pp. 447-480 : 448-449

Description of Trichotylenchus gorganiensis n. sp.

( Figs 1 & 2 )

Measurements. See Table 1.

Female. Body usually open to close C-shaped. Cuticle prominently striated; annuli 1.2–1.8 µm wide at midbody. Lateral fields 7.0–8.4 µm wide at mid-body, occupying 29–40 % of body width; with three longitudinal incisures and two equal bands; outer lines crenate. Lip region conoid-rounded, slightly convex at anterior end; 7.0– 8.6 µm wide at base and 4.3–5.0 µm high, continuous with the body contour; transversely striated with 5–7 annuli which are narrower and finer than other cuticular annuli; perioral disc distinct. Basal and radial plates of the cephalic framework weakly sclerotized, but vestibule wall thick and sclerotized. Stylet slender and attenuated, 2.7– 3.1 times the lip region width; conus 10–12 µm long, as long as or slightly shorter than shaft; knobs relatively weak, 3–4 µm across, directed posteriorly or laterally. Orifice of dorsal pharyngeal gland 2.5–5.0 µm from the base of stylet. Procorpus rather wide, metacorpus ellipsoid with prominent valve plates, located at the middle of pharynx; isthmus slender; basal pharyngeal bulb saccate, offset from intestine or often overlapping the anterior end of intestine very slightly. Secretory-excretory pore located at level of the anterior end of the pharyngeal basal bulb, hemizonid at the same level or one annule anterior to it. Pharyngo-intestinal valve prominent, rounded, two-celled. Ovaries outstretched; the anterior 192–390 µm and the posterior one 161–368 µm long; with single row of oocytes, except in multiplication region. Vulva a transverse slit, flush with the body surface, without epiptygma. Vagina as long as 46–60 % of the corresponding body width. Spermathecae rounded, usually empty or sometimes filled with globular sperm. Rectum about 0.8–1.3 times of the anal body width. Post-anal sac 24–40 µm long, extending 50– 73% of tail length. Tail cylindrical to subclavate, with a truncated or slightly rounded, annulated terminus; striae on tail terminus as wide as or sometimes wider than the other tail striae; some specimens with only two or three deep and coarse striae on tail terminus. Phasmids usually located on posterior half of tail.

Male. Similar to female in general characteristics. Spicules arcuate, distally flanged, equipped with a velum. Gubernaculum hook-shaped, proximal end directed posteriorly. Bursa crenate, enveloping entire tail. Phasmids located 19–24 µm posterior to anus, usually slightly anterior to mid tail region.

Diagnosis and relationships. Trichotylenchus gorganiensis n. sp. is characterized by its large body size (760– 1073 µm), relatively long stylet (22.0–24.5 µm), conoid-rounded lip region bearing 5–7 fine striae and continuous with the body contour, pharyngeal glands offset or slightly overlapping intestine, post-anal sac approximately half of tail length, and cylindrical or subclavate tail with striated tail terminus. The new species comes close to T. astriatus Khan & Nanjappa, 1971 , T. astriatoides Rahaman, Ahmad, Khan & Ahmad, 1992 , T. changlingensis ( Xu, Xie, Zeng, Chen & Zhou, 2011) Geraert, 2011 and T. papyrus ( Siddiqi, 1970) Seinhorst, 1971 . This new species can be separated from T. astriatus by having a relatively longer body (760–1073 vs. 490–680 µm), higher value of a ratio (35–45 vs. 22–33), more head annuli (5–7 vs. 1–4), shape of the stylet knobs (directed posteriorly or laterally vs. anteriorly cupped), and a slightly longer tail (48–66 vs. 35–52 µm) with different shape (cylindrical to subclavate vs. regularly tapering). It can be distinguished from T. astriatoides by having a relatively longer body size (760–1073 vs. 560–680 µm), higher values of a (35–45 vs. 31–35) and c (16–20 vs. 11–13) ratios, smaller value of c´ ratio (2.9–3.7 vs. 3.9–4.8), longer post-anal sac (24–40 µm and 50–73% of tail length vs. 13–16 µm and about 30%), tail shape (cylindrical to subclavate vs. gradually tapering) and spicules length (25–28 vs. 21 µm). It differs from T. changlingensis , by more anterior pharyngeal median bulb (MB = 46–54 vs. 62–68), lip region demarcation (continuous vs. distinctly offset), tail shape (cylindrical to subclavate vs. subconoid), striated tail terminus (vs. unstriated). T. gorganiensis n. sp. differs from T. papyrus in having a smaller c´ value (2.9–3.7 vs. 3.7–4.2), slightly more posterior vulva (55–60 vs. 52–55 %), structure of lateral field (non-areolated vs. regularly areolated), and presence of post-anal sac (present vs. absent).

Type habitat and locality. Specimens recovered from rhizosphere of camel thorn ( Alhagi sp.) on riverside of Gorgan Rood river, near Gorgan, ( GPS coordinates: 36°89'66.7"N, 54°27'50.78"E), Golestan province, northern Iran; September 2015.

Type material. Holotype, eight paratype females and five paratype males were deposited in the nematode collection of the Department of Plant Protection , School of Agriculture , Shiraz University, Shiraz, Iran.

Etymology. The species epithet refers to Gorgan, the Iranian city where the new species was recovered.

Figures

FIGURE 1. Diagnostic characters of Trichotylenchus gorganiensis n. sp. Female (B, C, E, F, H–J) and male (A, D, G). A, B: Entire body; C, D: Head and stylet; E: Vulva, part of reproductive system and lateral field; F: Anterior end and pharyngeal region; G–J: Posterior end. (Scale-bars: A, B = 100 µm; C, D, H–J = 10 µm; E–G = 20 µm).

FIGURE 2. Diagnostic characters of Trichotylenchus gorganiensis n. sp. Female (A–F, H–J, L–N), male (G, H, K) and juvenile (H). A: Anterior end and pharyngeal region; B–D: Head and stylet; E: Pharyngeal basal bulb; F: Lateral field; G: Spicules and gubernaculum; H: Entire body; I–N: Posterior end. (Scale-bars: A = 20 µm; B–G, I–N = 10 µm; H = 100 µm).