Helicotylenchus crenacauda Sher 1966

Kashi, Leila & Karegar, Akbar, 2014, Description of Helicotylenchus persiaensis sp. n. (Nematoda: Hoplolaimidae) from Iran, Zootaxa 3785 (4), pp. 575-588 : 584

Helicotylenchus crenacauda Sher 1966

( Fig. 3 )

Helicotylenchus pteracercus Singh, 1971 (by Baqri & Ahmad, 1983)

Helicotylenchus indenticaudatus Mulk & Jairajpuri, 1975 (by Lal & Khan, 1993) Helicotylenchus indentatus Chaturvedi & Khera, 1979 (by Baqri & Ahmad, 1983) Helicotylenchus paracrenacauda Phukan & Sanwal, 1981 (by Siddiqi, 1986) Helicotylenchus parapteracercus Sultan, 1981 (by Siddiqi, 1986)

Helicotylenchus pteracercusoides Fotedar & Kaul, 1985 (by Siddiqi, 1986)

Measurements (Table 3). Female. Habitus C-, G- or double-helix shaped when relaxed. Cuticle with coarse annules, 1.6 ± 0.2 (1.0–1.9) µm wide at mid-body. Lateral fields 5.4–8.7 µm wide, 20–30% of body diameter. Lip region continuous with body contour, usually hemispherical, sometimes slightly obtuse, marked with 4–5 distinct annules, 7.2 ± 0.5 (6.0–8.4) µm wide at base and 3.9 ± 0.4 (3.3–4.6) µm high. Cephalic framework strongly sclerotized, outer margins extending posteriorly 2–3 annules from basal plate. Cephalids usually obscure, but when observed, the anterior and posterior ones located 8–9 and 15–16 annules from the anterior end (including lip anniules), respectively. Stylet about 3.6 ± 0.3 (3.0–4.0) times as long as head diameter. Stylet knobs usually rounded, with anterior faces flattened or sloping backward and 5.2 ± 0.3 (4.2–5.9) µm in width. Orifice of dorsal pharyngeal gland located about 31.6%–50.3% of stylet length from stylet base. Median bulb oval, gradually expanding to a width of 11.3 ± 0.9 (9.6–12.7) µm, with moderate valve, distance from anterior end to its center 79.1 ± 5.5 (70.8–97.3) µm. Hemizonid usually indistinct. Two ovaries both functional, length of anterior branch (n = 7) 200 ± 32.6 (167–253) µm and posterior branch 174 ± 23.7 (146–220) µm, length of posterior branch 84.7 ± 0.9 (71.3–95.2)% of anterior branch,, ovaries in single row, spermatheca rounded, in line, and without sperm. Vagina 9.4–12.6 µm long, about 33%–45% of corresponding body diameter. Tail indented terminally, with short to long, variously-shaped ventral projection, in some specimens with cuticular fold. The terminal indentation of the female tail is usually filled with debris. ( Fig. 3 A). Termini of the inner incisures of lateral field on tail usually fused and Yshaped, not observed in some specimens. Caudalid not observed. Phasmids very small, pore-like, located from level with anus to six annules anterior to anus, in some specimens difficult to observe or indistinct.

Male. Not found.

This population, in having an indented terminus, usually with a long ventral projection (two or more annules in length) on the tail end is identified as H. crenacauda Sher 1966 , but differs in the flat to backward-sloping stylet knobs and the presence of a cuticular fold at the tail tip of some specimens. Some nominal species of Helicotylenchus including H. pteracercus Singh 1971 , H. indenticaudatus Mulk & Jairajpuri 1975 , H. paracrenacauda Phukan & Sanwal 1981 , H. pteracercusoides Fotedar & Kaul 1985 and H. indentatus Chaturvedi & Khera 1979 already have been synonymized with H. crenacauda ( Siddiqi 2000, Andrássy 2007). Baqri & Ahmad (1983) synonymized H. indentatus Chaturvedi & Khera 1979 with H. crenacauda after comparison to its paratypes. Because of the similarity in stylet knob shape and the cuticular fold at the tail end, our population is similar to H. indentatus , and was thus designated as H. crenacauda .

H. crenacauda already has been reported from Iran ( Kheiri & Barooti 1985, Pedramfar et al. 2002, Mohammad Deimi & Mitkowski, 2010). In this paper, some new data such as the presence of a cuticular fold at the tail terminus, phasmid position relative to anus (0–5 annules vs. 5–9 annules anterior to anus, respectively, in the present population and in the previous report) were added. Also, the ranges of V and o ratios were extended (Table 3, Fig. 3 ) and the present population is compared with two other populations from South Africa ( Marais 1993) and Thailand ( Mizukubo et al. 1992) (Table 5, Fig. 3 ).

Locality: This population of H. crenacauda was collected from the rhizosphere of rice in Chabok-Sar, Gilan Province, northern Iran.

Figures

FIGURE 3. Helicotylenchus crenacauda Sher, 1966 Female. A: Variations of tail shape, B: Pharyngeal region, C: General view, D: Body habitus after fixation.