Mylonchulus vasis Yeates, 1992

Tahseen, Qudsia, Asif, Mohammad, Mustaqim, Malka, Ahlawat, Shikha & Bert, Wim, 2013, Descriptions of ten known species of the superfamily Mononchoidea (Mononchida: Nematoda) from North India with a detailed account on their variations, Zootaxa 3646 (4), pp. 301-335 : 321

Mylonchulus vasis Yeates, 1992

( Fig. 10 )

Measurements. Table 2

Description. Adult: Body ventrally curved, C-shaped upon fixation. Cuticle smooth under light microscope, 2–3 µm thick; body pores indistinct. Lip region slightly demarcated, broader than adjoining body about 2.5–2.6 times as wide as body width at the neck base. Labial papillae well developed, slightly protruding above the labial contour. Amphids cup-shaped with oval-shaped aperture near the base of the lips. Buccal cavity funnel-shaped or conical with narrow tapering base nearly half as wide as the diameter of buccal cavity anteriorly. Dorsal tooth massive, 11 × 7 µm in dimension, anteriorly directed with tip located at ca 6–7 µm from anterior end of buccal capsule or at ca 62–70% from its base. Subventral walls usually with four transverse rows of rasping denticles; first row with regularly arranged denticles, others with more or less dispersed arrangement. One specimen ( Fig. 10 E) with five transverse denticule rows. Subventral teeth posterior to the rows of denticles. Pharynx muscular, cylindroid with thick, wide lumen. Orifices of the pharyngeal gland DO located at ca at 50–55%, SV1O1 and SV1O2 at ca 64–68% and SV2O1 and SV2O2 at ca 94–97% of pharyngeal length from the anterior body end. Nerve ring surrounding pharynx at ca 28–32% of pharyngeal length from the anterior end. Excretory pore not discernible. Pharyngo-intestinal junction non-tuberculate with cardial flap of variable lengths. Intestinal lumen wide, made of large polygonal cells. Rectum 0.8–1.0 times anal body diameter. Tail short cylindrical with digitate posterior part and rounded to slightly swollen, blunt terminus. Caudal glands well developed, tandem in arrangement, rarely grouped; spinneret terminal.

Female: Genital system didelphic, amphidelphic; ovaries reflexed with conspicuous constriction between the large proximal oocyte and the rest of the oocytes. Oviduct leading to a prominent crustaformeria. Uterus devoid of any intra-uterine eggs or sperms in the present specimens. Vagina extending inward up to 1/4 of corresponding body diameter. Vulva a transverse slit without protruded lips.

Male: Not found.

Locality and habitat. Soil sample containing M. vasis was collected from around the roots of wild trees from district Sonebhadra, Uttar Pradesh, India, at 24°41'3"N 83°4'0"E coordinates.

Voucher specimens. Five females on slide Mylonchulus vasis Yeates, 1992 no. BS01/1-4 deposited in the Nematode Collection, Department of Zoology, Aligarh Muslim University, Aligarh, Uttar Pradesh, India. One female deposited at USDANC, Beltsville, MD, USA.

Salient characters. Small to medium-sized species with buccal cavity goblet-shaped, about 2 times as long as wide; dorsal tooth large, situated in anterior half of buccal cavity; subventral wall bearing four transverse rows of denticles; subventral teeth present; female genital system amphidelphic; tail conoid, ventrally arcuate with rounded to blunt, slightly swollen terminus; caudal glands in tandem; spinneret terminal

Remarks. The species M. vasis was reported from New Caledonia Island close to Australia. The presence of the species in the Indian subcontinent is slightly intriguing in view of the discontinuity of habitats and many geographical barriers in between. Nevertheless, the features of the present population totally conformed to the species. Besides similar morphometric characteristics, the main feature viz., four rows of subventral rasping denticles was also observed in present specimens with the exception of one individual possessing five rows. The other feature, shape of the tail also corresponded with the tail shape of M. vasis apud Yeates (1992) .

Figures

FIGURE 10. Mylonchulus vasis Yeates, 1992. A – G: Anterior end with buccal armature. H: Anterior end showing amphids. I, J: Pharyngo-intestinal junction. K: Female genital system. L: Anterior genital branch. M: Vulval region. N: Posterior genital branch. O: Intestinal region. P – R: Posterior body region. (Scale bar = 10 µm).