Sporonchulus ibitensis (Carvalho, 1951) Andrássy, 1958

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 : 327-330

Sporonchulus ibitensis (Carvalho, 1951) Andrássy, 1958

( Fig. 14 )

= Mononchus ibitiensis Carvalho, 1951

= Sporonchuloides ibitiensis (Carvalho, 1951) Mohandas & Prabhoo, 1982

Measurements. Table 1

Description. Adult: Body ventrally curved upon fixation. Cuticle smooth, 2–3 µm thick. Body pores indistinct. Lip region rounded, almost continuous with adjoining body, more than 2.5 times as wide as high. Lips amalgamated, labial sensillla papilliform, not raised above the body contour. Amphids cup-shaped with slit-like aperture, 3–4 µm across, located at level of dorsal tooth apex. Buccal cavity barrel-shaped, tapering at base, about 1.8 times as long as wide with thick vertical and oblique plates. Dorsal wall bearing a medium-sized, dorsal tooth of 6 × 4 µm dimension, located at 6 µm from anterior end of buccal capsule or at 70% from its base, opposed by four longitudinal rows of 24 subventral teeth. Posterior-most pair occasionally larger and separated by a wider gap from anterior ones. Pharyngeal sleeve surrounding buccal cavity at 1/3–1/4 of its length from base. Pharynx cylindrical, muscular, 24% of body length. Orifices of pharyngeal glands: DO located at 58%, SV1O1 and SV1O2 at 69%, SV2O1 and SV2O2 at 96% of pharyngeal length from anterior end. Pharyngo-intestinal junction nontuberculate with cardial flaps of variable lengths. Nerve ring at about 35% of pharyngeal length. Excretory pore slightly posterior to nerve ring, at about 40% of the pharynx length. Intestine with narrow lumen. Rectum 1.1 times anal body diameter long. Tail conoid, slightly ventrally arcuate, tapering to a narrow rounded terminus. Caudal glands weakly developed, arranged in tandem, spinneret terminal, short, narrow and relatively inconspicuous.

Female: Reproductive system didelphic, amphidelphic with reflexed ovaries. Ovary with a large proximal oocyte and oocytes of increasingly smaller size arranged in two rows towards the distal end. Long ovarian sac present associated with each ovary ( Fig. 14 G, I). Oviduct attached subterminally to the ovary, without distinct pars dilatata. Crustaformeria and uteri well developed. Vagina about one-third of corresponding body diameter with well developed globular pars refringens. Vulva slightly posterior to mid-body with simple vulval lips.

Male: Not found.

Locality and habitat: Soil samples containing Sporonchulus ibitensis were collected from a field in Ghazipur district, Uttar Pradeshat 25°34'46"N 83°34'24"E coordinates.

Voucher specimens. One female on slide Sporonchulus ibitensis (Carvalho, 1951) Andrássy, 1958 no. GZ/1 deposited in the Nematode Collection, Department of Zoology, Aligarh Muslim University, Aligarh, Uttar Pradesh, India.

Salient characters. Medium-sized species with buccal cavity barrel-shaped, about 1.7 times as long as wide; dorsal tooth medium-sized, situated in anterior half of buccal cavity; subventral walls bearing two vertical rows of total 24 denticles; posteriormost subventral teeth larger and separated by a wider gap from anterior teeth; female genital system amphidelphic; pars refringens vaginae globular; tail conoid, ventrally arcuate gradually tapering to a narrow, rounded terminus; caudal glands arranged in tandem; spinneret terminal, short, narrow and inconspicuous.

Remarks. This species has been reported from India, Sri Lanka, Nigeria, Zaire, Brazil, Argentina, Malaysia, and Cameroon (Mulvey, 1963; Jairajpuri & Khan, 1982). The only specimen reported here conforms to the species S. ibitensis in morphological and morphometric values. However, a difference was noted in the dorsal tooth that had a flattened anterior with apex directed forward [vs apex directed anteriad apud Fig. 4 , Mulvey (1963)]. Besides other differentiating features, the pars refringens vaginae were observed to be more or less globular in the present specimen ( Fig. 14 H) compared to the trapezoid pars refringens vaginae found in the populations of S. vagabundus ( Fig. 12 O; 13L).

Figures

FIGURE 4. Mylonchulus lacustris (Cobb in Cobb, 1915) Andrássy, 1958 female (Udaipur population). A – D: Anterior end with buccal armature. E: Anterior end showing amphids. F: Pharyngeal region; G: Pharyngo-intestinal junction. H: Anterior genital branch. I: Posterior genital branch. J: Vulval region. K, L: Posterior body region. (Scale bar = 10 µm).

FIGURE 12. Sporonchulus vagabundus Jairajpuri, 1971 (Sonbhadra population). A, F – H: Anterior end with buccal armature. B – E: Subventral wall. I: Anterior end showing amphids. J – L: Pharyngo-intestinal junction. M, N: Anterior genital branch. O: Vulval region. P, Q: Posterior genital branch. R – U: Posterior body region. (Scale bar = 10 µm).

FIGURE 14. Sporonchulus ibitensis (Carvalho, 1951) Andrássy, 1958. A – D: Anterior end with buccal armature (posterior subventral tooth indicated by arrow). E: Anterior end showing amphids. F: Pharyngo-intestinal junction. G: Anterior genital branch (ovarian sac indicated by arrow). H: Vulval region. I: Posterior genital branch (ovarian sac indicated by arrow). J: Posterior body region. (Scale bar = 10 µm).