Helicotylenchus persiaensis, Kashi, Leila & Karegar, Akbar, 2014

Kashi, Leila & Karegar, Akbar, 2014, Description of Helicotylenchus persiaensis sp. n. (Nematoda: Hoplolaimidae) from Iran, Zootaxa 3785 (4), pp. 575-588 : 576-579

Helicotylenchus persiaensis sp. n.

( Fig. 1 )

Measurements ( Table 2 ). Female. Habitus spiral when relaxed. Cuticle coarsely annulated, annules 1.3 ± 0.2 (1.2– 1.8) µm wide at midbody. Lateral fields 5.0–6.2 µm wide and 20–30% of body diameter. Lip region almost conical, truncate, continuous with body contour, marked by four or five distinct annules, 6.7 ± 0.7 (5.6–8.0) µm wide at base and 3.6 ± 0.5 (3.2–4.5) µm high. Cephalic framework strongly sclerotized, its outer margins extending posteriorly 1–2 annules from basal plate. Cephalids were only observed in three specimens, the anterior and posterior ones 6–7 and 14–15 annules from the anterior end, respectively. Stylet robust, its length 3.7 ± 0.4 (3.1– 4.6) times as long as head diameter. Stylet knobs well developed, with flattened anterior surfaces, 4.4 ± 0.4 (3.9– 5.1) µm across. Orifice of dorsal pharyngeal gland located less than one half of stylet length from knobs. Median bulb oval, gradually enlarging to a width of 8.9–10.0 µm with moderately developed valve; distance from anterior end to its center 76.4 ± 4.2 (67.2–80.4) µm, (82 µm in holotype). Nerve ring 92.4 ± 7.0 (78.4–105.5) µm from anterior end of body. Hemizonid generally distinct, one to three body annules anterior to excretory pore. Hemizonion 7–12 annules posterior to excretory pore, not seen in some specimens. Ventro-lateral overlap of pharyngeal lobe 40.6 ± 7.3 (31.8–50.8) µm long.

Two ovaries equally developed and functional, oocytes arranged in a single row. Length of anterior branch (n=12) 158 ± 19.4 (126–192) µm and posterior branch 144 ± 12.0 (127–167) µm; length of posterior branch 92.6 ±9.2 (70.7–104)% of anterior branch, Spermatheca rounded, 14.9 ± 1.5 (11.8–17.1) µm in diameter, markedly set off dorsally, empty. Vagina with uniformly thin wall, 8.0–10.8 µm long and about 1/3 to 1/2 of the corresponding body diameter. Tail short, dorsally convex-conoid, terminus broadly rounded, smooth or bearing 1–3 very coarse annules; in some specimens with minor projection in ventral, dorsal or lateral side ( Fig. 1 C). Inner incisures of lateral fields terminating in V- or U-shaped pattern on tail. Phasmids conspicuous, one to three annules (two in holotype) anterior to level of anus. Caudalid located three annules anterior to anus in some specimens.

Male. Not known.

Etymology. From “ Persia ” (former name of Iran) and –ensis (a Latin adjectival suffix, meaning “originating in”).

Habitat and locality. Collected from the rhizosphere of zelkova, (Zelkova carpinifolia (Pall.) C. Koch) and maple ( Acer sp.) trees in the forest of Ali-Abad Katool, Golestan province, northern Iran.

Type material. Holotype (code number: ShUNC 001) and eight paratypes (four slides, code numbers ShUNC 0 0 2 - ShUNC 005) deposited in the nematode collection of the Department of Plant Protection, College of Agriculture, Shiraz University (Shiraz, Iran), three paratypes (two slides, code numbers INC 0 0 1, INC 002)) at the National Nematode Collection of the Nematology Department, Iranian Research Institute of Plant Protection ( IRIPP, Tehran, Iran) and three paratypes (two slides, code numbers WT3621, WT3622) at the Wageningen Nematode Collection, Plant Protection Organization (Wageningen, The Netherlands).

Diagnosis. H. persiaensis sp. n. is characterized by its short tail (tail length = 8–11 µm, anal body diameter = 12–16 µm, c = 54.2–79.0, c ′ = 0.6–1.2) with usually smooth terminus or with 1–3 very coarse annules, rarely with minor ventral, dorsal or lateral projection, conical, truncate head with 4–5 distinct annules, stylet 22–26 µm long with anteriorly flattened knobs, relatively short body length (570–730 µm), inner incisures of lateral fields terminating in V- or U-shaped pattern on tail, and absence of males.

Relationships. H. persiaensis sp. n., in most morphometric characters including body length, a, b and V ratios and tail shape, is similar in some respects to H. caipora Monteiro & Mendonca, 1972 , H. martini Sher, 1966 , H. truncatus Román, 1965 , H. lemoni Firoza & Maqbool, 1996 , H. astriatus Khan & Nanjappa, 1972 , H. aquili Khan & Nanjappa, 1972 , H. arachisi Mulk & Jairajpuri, 1975 , H. bihari Mulk & Jairajpuri, 1975 and H. wajihi Sultan, 1981 (see remarks, below, concerning these last three species). However, H. persiaensis sp. n. can be differentiated from these closely related species by a number of characters (Table 3).

H. persiaensis sp. n. differs from H. caipora in its truncate and conical head (vs. hemispherical), higher c and lower c´ratios (Monteiro & de Mendonca 1972) and absence (vs. presence) of males; from H. martini by having greater body length, 4–5 distinct annules on head (vs. smooth), higher c and lower c´ratios and absence of males (vs. presence) ( Sher 1966); from H. truncatus by having smooth terminus or with 1–3 very coarse annules and sometimes with minor projection (vs. equal-sized annules and without any projection), longer body and higher c and b ratios ( Román 1965); from H. lemoni by having longer stylet, higher c ratio and smooth terminus or with 1– 3 very coarse annules and sometimes with minor projection (vs. partly non- annulated and without any projection) ( Firoza & Maqbool 1996); from H. astriatus in its distinctly annulated lip region (vs. smooth), longer stylet with anteriorly flattened knobs (vs. cupped), internal incisures of lateral fields distally fused at the end of tail (U or V vs. Y shaped) and higher c ratio ( Khan & Nanjappa 1972).

H. persiaensis sp. n. differs from H. aquili in its truncate lip region (vs. hemispherical), having anteriorly flattened stylet knobs (vs. concave), fused internal incisures of lateral fields at tail end (U or V vs. Y shaped), position of phasmids relative to anus (0–2 annules anterior vs. 8–11) and offset spermatheca (vs. inline) ( Khan & Nanjappa 1972); from H. arachisi in its truncate and distinctly annulated lip region (vs. hemispherical and indistinctly annulated), having anteriorly flattened stylet knobs (vs. concave), with or without very coarse annules at tail end (vs. striated and sometimes with notch), lower c´and higher c ratios ( Mulk & Jairajpuri 1975); from H. bihari in having 4–5 distinct lip annules (vs. 5–6 indistinct), longer stylet, smooth tail terminus or with very coarse annules (vs. with fine annules), position of phasmids relative to anus (0–2 annules anterior vs. 3–9), and hemispherical tail (vs. convex to sub-cylindrical) ( Mulk & Jairajpuri 1975); from H. wajihi in its truncate head with 4–5 distinct annules (vs. hemispherical, smooth or with 5–6 indistinct annules), greater body length, and higher c and o ratios ( Sultan 1981) (Table 3).

Remarks. Lal and Khan (1997) synonymized H. arachisi , H. bihari and H. wajihi with H. aquili (without studying the type materials for these species), based upon comparison of descriptions, illustrations and their shared common characters: body size, spear length, shape of spear knobs, tail shape and position of phasmids. However, in addition to the characters used to differentiate these taxa when described ( Mulk & Jairajpuri, 1975; Sultan, 1981) there are numerous differences that can still be used to distinguish these species: H. aquili and H. wajihi have smooth tail termini (vs. striated in H. arachisi and H. bihari ), and the dorsal pharyngeal gland orifice is located more posteriorly in H. aquili (O> 33 vs. O = 22–35 in H. wajihi ). Moreover, the head of H. bihari is truncate (vs. hemispherical in H. arachisi , H. wajihi and H. aquili ) (Table 3). Accordingly, the synonymization of these species is not accepted here and we propose the reinstatement of H. arachisi , H. bihari and H. wajihi as valid species.

Figures

FIGURE 1. Helicotylenchus persiaensis sp. n. Female. A: Pharyngeal region, B: Anterior end, C: Variations of tail shape, D: General view, E: Body habitus after fixation.

Tables

TABLE 2. Morphometric data of the females of Helicotylenchus persiaensis sp. n. [All measurements are in µm and in form of mean ± s. d. (range)]

Characters	Holotype Paratypes
n	- 14	CV
L	706 628 ± 49 (570–730)	7.8
a	27.4 27.5 ± 1.7 (25.2–31.4)	6.2
b	6.2 5.8 ± 0.3 (5.4–6.4)	4.9
b'	4.6 4.2 ± 0.3 (3.8–5.0)	7.7
c	73.8 65.8 ± 7.0 (54.2–79.0)	10.7
c'	0.6 0.8 ± 0.2 (0.6–1.2)	25.1
V	61.9 62.5 ± 1.4 (58.8–64.2)	2.3
Stylet length	24.9 25.1 ± 0.8 (23.6–25.9)	3.0
M	49.0 50.8 ± 1.2 (48.5–52.5)	2.3
DGO	10.9 10.2 ± 0.7 (8.9–10.9)	6.9
O	44.0 3 40.3 ± 2.6 (36.5–44.2)	6.5
E.P. pore	111 106.1 ± 6.3 (98.1–117.3)	6.0
Pharynx	115 109 ± 8 (98–119)	7.2
Base of glands	153 149 ± 6 (137–159)	4.0
Anterior end to vulva	437 392 ± 31 (364–463)	8.0
Anterior end to anus	696 618 ± 49 (561–719)	7.9
Tail length	9.6 9.6 ± 0.9 (8.4–11.0)	9.0
Tail annules	8 7.0 ± 1.2 (6.0–9.0)	16.5
Body diameter at midbody	25.8 22.9 ± 2.0 (20.8–26.8)	8.6
Anal body diameter	15.1 13.6 ± 1.0 (12.3–15.9)	7.3