Helicotylenchus abunaamai Siddiqi 1972

Kashi, Leila & Karegar, Akbar, 2014, Description of Helicotylenchus persiaensis sp. n. (Nematoda: Hoplolaimidae) from Iran, Zootaxa 3785 (4), pp. 575-588 : 579-580

Helicotylenchus abunaamai Siddiqi 1972

( Fig. 2 )

Measurement (Table 3). Female. Habitus spiral when relaxed. Cuticle usually coarsely annulated, annules 1.5 ± 0.2 (1.1–1.9) µm wide at mid-body. Lateral fields about 5.9 ± 0.8 (4.6–7.2) µm wide (20–30% of body width), without areolation after pharyngeal region. Head usually rounded, slightly obtuse, continuous with body contour, marked with usually four, sometimes three or five distinct annules, 6.8 ± 0.5 (6.1–7.5) µm wide at base and 3.7 ± 0.2 (3.3–4.0) µm high. Cephalic framework sclerotized, its outer margins extending posteriorly 2–3 annules from basal plate. The anterior and posterior cephalids are located 6–7 and 14–15 annules from the anterior end, respectively, not observed in some specimens. Stylet length about 4.0 ± 0.4 (3.2–4.4) times as long as head diameter; conus is 47.0 ± 2.6 (44.2–53.1) % of stylet length. Stylet knobs rounded with usually (approximately 62.5% of specimens) flattened, sometimes (approximately 25%) rounded or (approximately12.5%) concave anterior surfaces, 5.3 ± 0.6 (4.5–6.3) µm across. Orifice of dorsal pharyngeal gland located about one half to less than one stylet length from its base. Median bulb oval, 7.64 ± 0.9 (7.6–10.6) µm wide, distance from anterior end to its center 81.9 ± 4.7 (70.7–87.0) µm. Hemizonid 1–2 body annules anterior to excretory pore. Two ovaries, both functional; length of anterior branch (n = 6) 156 ± 14.9 (137–180) µm and posterior branch 154 ± 17.5 (135–177) µm; length of posterior branch 98.9 ±5.2 (91.8–106) % of the anterior branch, oocytes arranged in a single row, vagina less than one half of the corresponding body diameter. Spermatheca small, rounded, slightly dorsally demarcated from reproductive tubes and without sperm. Tail dorsally curved, almost ventrally straight, variously shape from trapezoid to conical, sometimes with small rounded projection; tail terminus without annules. Phasmids at level of anus or up to six annules anterior and asymmetrical in placement relative to anus in some specimens. Internal incisures of lateral fields at the tail end fused and Y shaped. Caudalids can be seen on some specimens, located at 3–5 annules anterior to anus.

Male. Not found.

The Iranian population was identified as H. abunaamai Siddiqi 1972 because of the very small ventral projection on the tail terminus (less than two annules in length), hemispherical lip region, usually anteriorly flattened or sometimes rounded to concave stylet knobs, position of phasmids (0–6 annules anterior to anus) and fused (Y shaped) internal incisures of lateral fields at the tail end. Measurements agree with those published for H. abunaamai , except for a slightly longer stylet (23.3–26.8 vs. 21.0–22.0 µm) There are no other notable differences between the current population data and those of other populations from Pakistan ( Firoza & Maqbool 1991), Thailand ( Mizukubo et al. 1992) and Malaysia ( Sauer & Winoto 1975) (Table 4). In the some morphological characters (head shape and the small projection at the tail end), this population also comes close to H. exallus Sher, 1966 , H. egyptiensis Tarjan, 1964 , H. elegans Roman, 1965 , H. curvatus Román, 1965 , H. zeidani Elbadri, Moon, Wani, Bukhari, Lee & Choo, 2009 and H. dihysteroides Siddiqi, 1972 .

Sharafat-Ali and his colleagues (1973) synonymized H. abunaamai with H. exallus Sher, 1966 but Sauer and Winoto (1975) considered the monosexuality of H. abunaamai , in contrast to the bisexuality of H. exallus , sufficient justification to maintain these as separate species. Our population also differs from H. exallus in absence of males, smaller c ratio (24.2–33.7 vs. 30–52), higher c´ratio (1.4–1.98 vs. 0.7–1.2), tail shape (more curved ventrally, with Y-shaped termini of the inner lines of the lateral field on the tail vs. usually straight ventrally, with V- or U-shaped termini of internal incisures). It can be separated from H. egyptiensis in tail shape (trapezoid to conical with non-annulated tip, sometimes with small, rounded projection vs. rounded and bearing a sharp projection, usually longer than two annules in length), Y-shaped termini of the lateral field internal incisures on the tail vs. both Y- and V-shaped incisure termini, head shape (mostly rounded vs. mostly obtuse) ( Tarjan 1964); from H. elegans in tail shape (more ventrally curved vs. more straight), longer body (600–779 vs. 430–450 µm) and higher b ratio (5.2–6.1 vs. 4.4–4.6 ( Román 1965); and from H. curvatus in tail shape (less curved ventrally, with Yshaped lateral field internal incisure termini vs. more curved and U- or V-shaped lateral field termini) and smaller c ratio (24.2–33.7 vs. 38–44) ( Román 1965). It also differs from H. zeidani in absence of sperm (vs. presence), annulated head (vs. smooth), usually non-annulated tail tip (vs. annulated), and smaller b ratio 5.8 (5.2–6.1) vs. 8.1 (5.4–10.6)) ( Elbadri et al. 2009); and from H. dihysteroides in the lip region (rounded to slightly obtuse, with distinct annules vs. always rounded and with indistinct annules), smaller body length (695 [600–779] µm vs. 740 [670–840] µm), b ratio (5.2–6.1 vs. 6.1–7.2), b' ratio (3.9–4.6 vs. 4.7–5.8), c ratio (24.2–33.7 vs. 39–55), c' ratio (1.7 [1.4–2.0] vs. 1.2 [1.1–1.4]), tail annules (12 [10–15] vs. 9 [6–11]), phasmid position (3 (0–6) vs. 6–13 annules anterior to anus) and tail terminus shape (usually without annules vs. usually annulated) ( Siddiqi 1972).

This population was collected from a sugarcane farm in Haft-Tappeh, Karoon region, Khuzestan province, soutwestern Iran, where sugarcane has been cultured for more than 40 years. This is the first report of H. abunaamai from Iran.

Figures

FIGURE 2. Helicotylenchus abunaamai Siddiqi, 1972 Female. A: Variations of tail shape, B: Anterior end, C: Pharyngeal region, D: General view, E: Body habitus after fixation.