Ditylenchus sturhani, Karani, Hossein Mirbabaei, Eskandari, Ali, Ghaderi, Reza, Heydari, Ramin & Miraeez, Esmaeil, 2017

Karani, Hossein Mirbabaei, Eskandari, Ali, Ghaderi, Reza, Heydari, Ramin & Miraeez, Esmaeil, 2017, Morphological characterisation of a new and two known species of Ditylenchus Filipjev, 1936 (Nematoda: Anguinidae) from Iran, Zootaxa 4216 (4), pp. 355-368 : 356-360

Description of Ditylenchus sturhani sp. n.

( Figs 1 & 2 )

Measurements. See Table 1 .

Female. Body posture, after fixation and mounting in glycerin, stright to slightly arcuate ventrally. Cuticular annuli about 1 µm wide at mid-body; lateral field with four lines. Head low, not offset, 2–3 µm high and 6–7 µm wide at base, framework very slightly sclerotised; outer margins extending over two body annuli. Head annuli very fine and indistinct. Stylet delicate, conical part smaller than half stylet length; knobs rounded, 2–3 µm wide.

Pharyngeal median bulb oval, 8–9 µm wide, with central sclerotised thickenings of lumen. Basal bulb elongatedcylindrical, offset, sometimes slightly overlapping intestine. Nerve ring surrounding isthmus; excretory pore at level with anterior end of pharyngeal basal bulb, hemizonid located anterior to the pore as one to four cuticular annuli. Female reproductive tract monodelphic-prodelphic, ovary outstretched, oocytes mainly in single row, crustaformeria quadricolumellar followed by an oval to elongated spermatheca packed with large rounded sperm. Vulva a transverse slit with raised lips, vagina at right angle with the body axis, reaches in no halfway across body. Post-uterine sac (PUS) 19–31 µm, as long as one to two vulval body diameters and extending about one-fourth to one-fifth of vulva-anus distance. Tail conical, regularly tapering towards to a finely rounded, rarely dull to pointed tip.

Male. Similar to female, but usually shorter and thinner. Spicules short, simple, curved ventrally, gubernaculum simple, short. Bursa 15–32 µm long, beginning before proximal end of spicule and covering 45–50 % of the tail length.

Type host and locality. Specimens collected from the soil around roots of an unknown grass from Asiab Kharabeh waterfall in Jolfa, East Azarbaijan province, Northwestern Iran (GPS coordinates: 27 30' 11''N, 56 27' 41''E).

Type material. Holotype, 15 female and 3 male paratypes, mounted on glass slides deposited at Department of Plant Protection , College of Agriculture, University of Zanjan, Iran ; further 8 female and 5 male paratypes at Department of Plant Protection , School of Agriculture, Shiraz University, Iran ; and 5 female and 2 male paratypes also at Department of Plant Protection , College of Agriculture and Natural Resources, University of Tehran, Iran .

Diagnosis and relationships. Ditylenchus sturhani sp. n. is characterised by straight to slightly arcuate body 656–865 µm in length, lip region not offset, presence of four incisures in lateral field, slender stylet 10–12 µm in length, pharynx with distinct and well-developed median bulb, basal bulb offset or slightly overlapping the intestine, post-uterine sac 1.0–1.9 vulval body diameter long and conical tail with finely rounded terminus. The new species comes close several species having four lateral lines including D. solani Husain & Khan, 1976 , D. ausafi Husain & Khan, 1967 , D. angustus ( Butler, 1913) Filipjev, 1936 , D. dipsaci , D. drepanocercus Goodey, 1953 , D. obesus Thorne & Malek, 1968 and D. gallaeformans Oliveira, Santin, Seni, Dietrich, Slazar, Subbotin, Mundo-Ocampo, Goldenberg & Barreto, 2013 , but differs from these species in some characters. The new species can be distinguished from D. solani by the more anterior position of the vulva (V = 76–78 vs 80–83), different shape of the pharyngeal glands (cylindrical vs pyriform), lower b ratio (3.7–4.9 vs 6.0–9.0), having a shorter tail (c' = 3.3–4.6 and vs 6–7), smaller PUS (1.0–1.9 vs more than 2 times vulval body diameter, or one-fifth to one-fourth vs more than half of the vulva-anus distance), slightly longer stylet (10–12 vs 8–11 µm) and bursa covering a larger part of the tail (45–50% vs less than 20% of the tail). It differs from D. ausafi by the higher c ratio (13–17 vs 9–10), lower c' ratio (3.3–4.6 vs 5.7) and larger body (656–865 vs 510–610 µm) in females and also in having larger spicules (18–21 vs 12–15 µm) in males, as well as in having elongated pharyngeal basal bulb (vs pyriform) in females and males. In the two other species, D. angustus and D. dipsaci , the tail has a pointed terminus. Furthermore, D. dipsaci is larger (1000–1300 vs 656–865 µm) and has longer spicules (23–28 vs 18–21 µm), and D. angustus has some additional differences in c ratio (18–24 vs 13–17), PUS (2.0–2.5 vs 1.0–1.9 times of the vulval body width) and bursa length (almost 100% vs 45–50% of the tail). From D. drepanocercus , the new species differs by having a longer stylet (10–12 vs 8–9 µm) in females, as well as having longer spicules (18–21 vs 10 µm) in males. From D. obesus , the new species can be distinguished by having a longer stylet (10–12 vs 7–10), lower b ratio (3.7–4.9 vs 5.8–8.0), higher a ratio (30–42 vs 24–31) and different shape of the pharyngeal basal bulb (elongated-cylindrical vs pyriform). The new species has a longer stylet than D. gallaeformans (10–12 vs 6–9 µm) and presents a different tail tip (finely rounded vs usually pointed); also D. gallaeformans has the bursa extending over the entire tail whereas in the new species, it extends to about half of the tail. Safianema indicum ( Sethi & Swarup, 1967) Siddiqi, 1986 shares several morphological and morphometric characters with our population, but pharyngeal glands overlap the intestine for over three body widths (vs offset or slightly overlapping), female tail is slightly longer (c = 10–14 and c' over 5 vs c = 13–17 and c' = 3.3–4.6) and male has a shorter spicules (14 vs 18–21 µm).

Etymology. The species is named in honor of Dr. Dieter Sturhan, the well-known nematologist, recognizing his work on the taxonomy of the genus.

mean ± s.d. (range).

Present study (Iran) Anderson, 1983 Brzeski, 1991 (Poland) Brzeski, 1991 (Bulgaria) (Canada)

Figures

FIGURE 1. Ditylenchus sturhani sp. n. from Iran. Female (A, C – F, H – J) and male (B, G, K, L). A, B: Entire body; C, D: Anterior end; E: Reproductive system; F, G: Pharyngeal region; H – L: Posterior end. (Scale bars: A, B = 100 µm; C, D = 10 µm; E = 25 µm; F – L = 15 µm).

FIGURE 2. Ditylenchus sturhani sp. n. Female (B, D – F, H, I, K, M) and male (C, G, J, L). A: Entire body; B – D: Anterior end; E – G: Posterior part of pharynx (arrow shows pharyngo-intestinal junction); H: Gonoduct; J: Cloacal region; K, L: Posterior end; M: Mid-body showing lateral lines. (Scale bars: A = 50 µm; B – M = 10 µm).

Tables

TABLE 1. Morphometrics of Ditylenchus sturhani sp. n. from Iran. All measurements are in µm and in the form: mean ± s. d. (range).

Character	Female		Male
	Holotype	Paratypes	Paratypes
n	-	19	10
L	7 4 0	736 ± 54.3 (656–865)	655 ± 44.3 (580–727)
a	3 6.9	36.6 ± 3.1 (30.1–42.4)	38.3 ± 2.8 (34.8–41.8)
b	4.4	4.1 ± 0.3 (3.7–4.9)	3.9 ± 0.2 (3.6–4.3)
c	1 5.0	14.9 ± 1.0 (13.0–16.7)	14.4 ± 0.7 (13.4–15.6)
c'	4.0	4.1 ± 0.4 (3.3–4.6)	3.6 ± 0.2 (3.0–3.9)
V	7 6.9	77.1 ± 0.5 (76.4–78.2)	-
Stylet	11.0	10.8 ± 0.3 (10.4–11.6)	10.5 ± 0.1 (10.3–10.7)
Conus	5.0	4.9 ± 0.3 (4.6–5.4)	4.7 ± 0.6 (4.2–5.3)
m (conus/stylet %)	45.9	45.3 ± 1.8 (42.5–47.0)	45.0 ± 5.8 (40.1–51.4)
Pharynx	167	178 ± 13.8 (134–199)	166 ± 7.3 (148–172)
Median bulb	64.0	61.4 ± 3.8 (49.9–66.9)	58.1 ± 3.8 (53.9–67.7)
MB	38.2	34.3 ± 1.5 (32.3–38.2)	35.0 ± 2.1 (32.4–39.9)
Median bulb width	8.7	8.4 ± 0.5 (7.8–9.2)	7.8 ± 0.5 (7.4–8.4)
Excretory pore	111	112 ± 4.7 (103–121)	107 ± 5.7 (98–118)
Hemizonid	107	107 ± 5.2 (97–118)	104 ± 6.2 (93–114)
Head-vulva	569	568 ± 42.8 (510–670)	-
Head-anus	691	686 ± 52.1 (612–808)	614 ± 44.8 (540–677)
Vulva-anus	122	119 ± 10.7 (103–138)	-
Tail length	49.3	49.6 ± 3.7 (42.7–57.1)	45.5 ± 3.2 (40.4–49.9)
Tail/Vulva-anus	0.4	0.4 ± 0.0 (0.3–0.5)	-
Body width	20.1	19.9 ± 1.0 (18.1–21.8)	16.9 ± 0.4 (16.4–17.4)
Vulval body width	19.5	18.2 ± 1.2 (15.8–20.9)	-
Anal body width	12.4	12.3 ± 0.9 (10.7–13.7)	12.7 ± 0.7 (11.9–14.0)
Lip region width	6.6	6.5 ± 0.3 (5.9–6.8)	6.4 ± 0.3 (6.0–6.6)
Lip region height	2.4	2.4 ± 0.2 (2.0–2.7)	2.4 ± 0.2 (2.0–2.7)
PUS	27.5	25.3 ± 3.2 (19.5–31.2)	-
PUS/VBW	1.4	1.4 ± 0.2 (1.0–1.9)	-
Spicules	-	-	19.4 ± 0.7 (18.4–20.6)
Gubernaculum	-	-	4.5 ± 0.5 (3.8–5.4)