Ditylenchus virtudesae Tobar-Jimenez, 1964

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 : 364-367

Ditylenchus virtudesae Tobar-Jimenez, 1964

( Figs 5 & 6 )

Measurements. See Table 4 .

Female. Small sized nematodes. Body cylindrical, straight after heat relaxation, mostly ventrally bent after vulval region. Cuticle with indistinct transverse annulations, under 1 µm wide at mid-body. Lateral field marked by six lines. Head low, anteriorly flat, continuous with body contour, 2–3 µm high and 5–6 µm wide, framework slightly sclerotised; outer margins appearing slightly striated. Stylet relatively robust, conus shorter than shaft (31–44 % of total stylet length); DGO opens 1–2 µm posterior to knobs; knobs well-developed, rounded. Precorpus cylindrical, median bulb ovoid with centrally-located crescentic valves, isthmus slender ending in a pyriform to saccate basal pharyngeal bulb. Pharyngeal bulb always offset. Nerve ring surrounding isthmus, slightly anterior to basal bulb; excretory pore opposite anterior part of basal pharyngeal bulb and immediately posterior to hemizonid. Female reproductive tract monodelphic-prodelphic, ovary 92–175 µm in length, outstretched, with oocytes arranged in single to double rows, Crustaformeria quadricolumellate, with four cells in each column followed by an empty and barely visible spermatheca. Vulva a transverse slit, vagina at right angles with body axis, reaching nearly halfway across body. Post uterine sac 14–31 µm, as long as one to three vulval body diameter and extending about one-fourth to half of the vulva-anus distance. Tail cylindrical to subcylindrical with broadly rounded terminus.

Male. Rare, similar to female but with shorter body. Spicules simple and weakly developed, curved ventrally, gubernaculum simple and short. Bursa 23 µm long, beginning after proximal end of spicule, reaching to near the tail tip (subterminal). Tail subcylindrical with narrower tail terminus than that of female.

Ditylenchus virtudesae was originally described from Granada, Spain, from the rhizosphere of olive trees ( Olea europea L.) by Tobar-Jimenez (1964). As far as we know, there has been no report of this rare species after the original description, making this the second reported occurrence of D. virtudesae . Morphological and morphometric characters of the Iranian population of D. virtudesae completely fit with those in original description, except for slight difference in the tail length which covered by bursa. In original description, bursa covers entire tail, but only reaches to near the tail tip in the Iranian population. However , due to the compelete resemblance in all of other characters, the authors consider this slight difference as intraspecific variation or possibly a mistake in observation of this feature in the type material. Our population was collected from the rhizosphere of pomegranate trees from Siahtalu , a village located east of Gorgan (GPS coordinates: N 36° 85', E 54° 51'), Golestan province, northern Iran. Considering the six lateral lines, relatively robust stylet, weak spicules and cylindrical to subcylindrical tail with broadly rounded terminus, the Iranian population of D. virtudesae is easily distinguishable from all other known species of the genus. It is however, closest to D. mirus Siddiqi, 1963 , but our Iranian population differs from this species by having shorter PUS length (14–31 vs 50 µm), shorter spicules (12 vs 17 µm) and more anterior position of vulva (V = 80–83 vs 83–85). The present study expands the morphometrical and morphological characters of the species, and reports, describes and illustrates D. virtudesae for the second time after Tobar-Jimenez (1964).

Figures

FIGURE 5. Iranian population of Ditylenchus virtudesae, female (A, C – H) and male (B, I). A, B: Entire body; C: Reproductive system; D: Pharyngeal region; E – I: Tail. (Scale bars: A, B = 40 µm; C – I = 10 µm).

FIGURE 6. Iranian population of Ditylenchus virtudesae, female (A – J) and male (K). A: Pharyngeal region; B – D: Anterior end; E: Entire body; F: Mid-body showing lateral lines; H: Gonoduct; I – K: Posterior end. (Scale bars: A – D, F – K = 10 µm; E: 50 µm).

Tables

TABLE 4. Morphometrics of Ditylenchus virtudesae in present study and its comparison with original description. All measurements are in µm and in the form: mean ± s. d. (range).

Character\Source	Iranian population		Tobar-Jimenez, 1964
n	1 9 ♀	2 ♂	1 4 ♀	2 ♂
L	395 ± 35 (329–442)	340, 373	400 (370–450)	430, 420
a	29.1 ± 2.5 (24.5–35)	28, 31	33.9 (29.7–36.7)	31, 32.3
b	4.9 ± 0.4 (4.3–5.4)	4.3, 4.7	4.9 (4.5–5.4)	5.1, 5.2
c	19.3 ± 2 (15.7–22.3)	15.5, 17	19.4 (17.3–21.9)	20.3, 19.8
c'	2.4 ± 0.3 (2–3)	2.2, 2.4	2.8	-
V or T	81.2 ± 1.1 (79.7–83.5)	45, 47	80.8 (79.9–81.7)	45.8, 40
V'	85.7 ± 1.2 (83.8–88.3)	-	-	-
Head high	2.6 ± 1.3 (2–3)	2.5	-	-
Head broad	5.2 ± 0.3 (5–6)	5	-	-
Stylet	8.1 ± 0.5 (7–9)	7, 7.5	7.5(7.3–8.2)	-
m	38.6 ± 0.5 (31.3–50)	40, 43	-	-
MB	45.5 ±2.4 (40–48)	45, 46.3	-	-
Pharynx	81 ± 2.7 (77–85)	80	(116–139)	-
Excretory pore	65 ± 3.9 (60–73)	61, 70	(97–108)	-
Head-Vulva	321 ± 29.5 (265–361)	-	-	-
PUS	23.5 ± 4.6 (14–31)	-	(23–36)	-
PUS/BW	1.8 ± 0.4 (1.1–2.8)	-	(1–1.3)	-
PUS/V-A%	43.2 ± 8.4 (27.1–56)	-	(40–60)	-
Vulva-Anus	55 ± 6 (42–66)	-	-	-
Tail length	20.5 ± 2.1 18–25)	22	-	-
Spicules	-	12	-	11.4
Gubernaculum	-	4, 4.5	-	4.9