Mesodorylaimus bomdillaensis, Tauheed, Uzma & Ahmad, Wasim, 2010

Tauheed, Uzma & Ahmad, Wasim, 2010, Four new species of the genus Mesodorylaimus Andrássy, 1959 (Nematoda: Dorylaimida) from India, Zootaxa 2642, pp. 19-35 : 31-34

Mesodorylaimus bomdillaensis n. sp.

( Fig. 7 , 8 )

Measurements: Table 4 .

Description. Female: Body slightly curved ventrad upon fixation, tapering towards both extremities but more so towards the posterior end. Cuticle with fine transverse striations, 1.0–1.5 µm thick at mid body and 2.5–3.0 µm on tail. Lateral hypodermal chords about one-third of body width at mid body. Lateral, dorsal and ventral body pores indistinct.

Lip region offset by slight depression, about three times as wide as high and about one-third as wide as body width at neck base. Lips rounded, amalgamated; labial and cephalic papillae not interfering with the labial contour. Amphids stirrup-shaped, their aperture occupying about half of the lip region width wide. Odontostyle 1.25 times the lip region width long, its aperture about one-third of its length. Guiding ring ‘double’ weak, at 0.87 times lip region width from anterior end. Odontophore simple, rod-like, 1.25–1.3 times the odontostyle length. Nerve ring encircling the anterior slender part of pharynx, at 42–46.5% of neck length from anterior end. Pharyngeal expansion gradual; expanded portion occupying about 35–39% of total neck length. Cardia elongate conoid, two-thirds to three-fourths of the corresponding body width long. Pharyngeal gland nuclei located as follows: D = 67%; AS 1 = 20–25%; AS 2 = 35–39%; PS1 = 70–72%; PS2 = 76–79%.

Genital system didelphic-amphidelphic; both branches almost equally developed. Ovaries reflexed, short, not reaching or surpassing the oviduct–uterus junction, measuring 28–33 µm (anterior) and 26–39 µm (posterior); oocytes arranged in single row except near the tip. Oviduct joining the ovary subterminally, measuring 40–44 µm (anterior) and 39–53 µm (posterior). It consists of a long slender part with prismatic cells and a slightly wider pars dilatata with obscure lumen. Oviduct-uterus junction slightly demarcated. Sperm not present either in uterus or oviduct. Uterus a short tube with obscure lumen, measuring 15–18 µm (anterior) and 15–17 µm (posterior), or about as long as the corresponding body width. Vulva transverse, slitlike. Vagina extending inwards for about slightly more than one-third of the corresponding body width; pars proximalis vaginae 5 µm long, with convex walls, encircled by circular musculature; pars refringens vaginae with two divergent usually well separated rectangular sclerotized pieces, each measuring 1 x 2–3 µm and with a combined width (cw) = 4–5 µm; pars distalis vaginae short, 2–3 µm long with slightly curved walls and a circular structure at the inner core. A well developed anteriorly directed tongue-like projection observed at the intestine-prerectum junction. Prerectum length 1.6–1.9 anal body widths; rectum about 1.4–1.6 times anal body width long. Tail elongate, filiform, 12.7–13.6 times anal body width long, gradually tapering on both sides to a pointed terminus, with no distinct hyaline part. Caudal pores two pairs, one on each side.

Male: Not found.

Type habitat and locality. Soil around the roots of ginger, from Coila vati, Bomdilla, district West Kameng, Arunachal Pradesh, India.

Type material. Holotype female on slide Mesodorylaimus bomdillaensis n. sp. /1; paratype females on slide Mesodorylaimus bondillaensis n. sp. /2–3; deposited with the nematode collection of the Department of Zoology, Aligarh Muslim University, Aligarh. A paratype female deposited with the nematode collection of the Universidad de Jaén, Spain.

Diagnosis and relationships: Mesodorylaimus bomdillaensis n. sp. is characterized by having 0.73–0.81 mm long body; lip region offset by slight depression, ‘double’ guiding ring; stirrup-shaped amphid; 10 µm long odontostyle; pharyngeal expansion gradual; amphidelphic female genital system; transverse vulva; tongue-like structure at intestine-prerectum junction and tail long filiform with pointed terminus.

In the presence of long filliform tail and small body size, the new species comes close to M. chamoliensis Ahmad, 1995 ; M. pusillus ( Cobb, 1893) Andrássy, 1959 ; M. longicaudatus Ahmad and Araki, 2003 ; and M. loofi Ahmad, 1993 but differs from the former in having ‘double’ guiding ring (vs single); rounded lip region (vs flat lip region); longer and differently shaped cardia (vs short conoid to hemishpherical, 10–18 µm); tongue-like structure present at the intestine-prerectum junction (vs tongue-like structure absent).

From M. pusillus , the new species differs in having ‘double’ guiding ring (vs single); shorter odontostyle (vs twice lip region widths long); pharyngeal expansion gradual (vs sudden); slightly shorter prerectum (vs more than twice anal body widths long), and longer tail (vs c = 5.6–6.7, c’= 9–11).

It differs from M. longicaudatus , in having smaller and robust body (vs L= 1.13–1.36 mm, a = 40–49); shorter odontostyle and odontophore (vs odontostyle 12–13 µm, odontophore 14–15 µm); ‘double’ guiding ring (vs single); smaller expanded part of pharynx (vs pharynx 98–111 µm), longer and differently shaped cardia (vs hemispheroid, 9–12 µm), shorter prerectum (vs 38–56 µm); tongue-like structure present in intestine-prerectum junction (vs absent); smaller tail (vs tail 264–316 µm long, c’= 14.8–16.5) and without distinct hyaline part in tail (vs hyaline part 42–43%).

From M. loofi , the new species differs in having; smaller body (vs L = 1.2–1.5 mm); lip region offset by slight depression (vs lip region almost continuous), shorter odontostyle and odontophore (vs odontostyle 13– 14 µm; odontophore 16–21 µm); smaller pharynx (vs 263–290 µm); tongue-like structure present at intestineprerectum junction (vs absent); smaller tail (vs c = 4.9–6.7; c’ = 10–13.8) and absence of male (vs present).

Etymology: The new species is named M. bombillaensis because it was collected from Bomdilla.

Figures

FIGURE 7. Mesodorylaimus bomdillaensis n. sp. A: Entire female. B: Anterior region. C: Anterior end showing amphid. D: Expanded part of pharynx. E: Female genital system. F: Vulval region. G: Female posterior region.

FIGURE 8. Mesodorylaimus bomdillaensis n. sp. A: Anterior region. B: Expanded part of pharynx. C: Pharyngointestinal junction. D: Female genital system. E: Vulval region. F: Intestinal tongue. G: Female prerectum. H. Female posterior region.

Tables

TABLE 4. Morphometrics of Mesodorylaimus bomdillaensis n. sp. All measurements in µm (except L) and in the form: mean standard deviation (range).

Characters n L (mm) a	Holotype 0.8 32.5	Paratype females 7 0.78±0.03 (0.73–0.81) 32.13±0.28 (31.9–32.5)
b	4.5	4.50±0.22 (4.2–4.7)
c c`	4.1 13.1	4.12±0.004 (4.12–4.13) 13.14±0.35 (12.71–13.57)
V G1 G2 Lip region width Lip region height	44.7 7.6 7.0 8 3	44.07±0.67 (43.2–44.8) 7.29±0.37 (6.7–7.6) 6.8±0.18 (6.6–7.0) 8.0 3.0
Amphid aperture	4	4.0
Odontostyle length Odontophore length	10 12.5	10.0 12.7± 0.25 (12.5–13.0)
Guiding ring from ant. end	7	7.0
Nerve ring from ant. end Neck length	75 179	73±2.1 (70–75) 167±9.4 (151–179)
Expanded part of pharynx	65	62.4±3.9 (55–65)
Cardia length	19	16.8±1.5 (15–19)
Body width at neck base Body width at mid body	24.5 25	23.5 ±0.87 (22–24.5) 24±0.8 (23–25)
Body width at anus	15	14.4±0.5 (14–15)
Anterior genital branch Posterior genital branch	62 57	55±3.4 (52–62) 55.4±4.83 (50–65)
Vaginal depth	11	11±0.3 (11–12)
Vulva from anterior end	364	342±16.2 (325–364)
Prerectum length Rectum length Tail length	29 24 197	26±2.2 (23–29) 22±1.7 (20–24) 188±7.8 (178–197)