Axonchium elegans Jairajpuri, 1964

Naz, Tabbasam & Ahmad, Wasim, 2012, Description of two new and five known species of the genus Axonchium Cobb, 1920 (Nematoda: Dorylamida) from India with diagnostic compendia and keys to species of the genera Axonchium and Syncheilaxonchium Coomans & Nair, 1975, Zootaxa 3264, pp. 1-37 : 9-12

Axonchium elegans Jairajpuri, 1964

( Figs. 3–4 )

Measurements. Table 2.

Description. Female: Cuticle 3 µm thick at mid body and 5–7 µm on tail. Lateral chords without distinct glandular bodies, about one-seventh of body width at mid body.

Lip region offset, about one-fifth as wide as body width at neck base; lips separate. Amphids cup-shaped, their aperture occupying 0.8 times the lip region width. Odontostyle about one lip region width long, Odontophore 1.4 times the odontostyle length. Nerve ring at 22.5% of neck length from anterior end. Anterior muscular part of pharynx abutting the posterior expanded part, the latter occupying about 60% of total neck length. Cardia small, rounded, about one-half of the corresponding body width long.

Anterior genital branch represented by a simple uterine sac, 140 µm long. Posterior branch well developed; ovary reflexed, not reaching the oviduct–uterus junction, measuring 78 µm; oviduct measuring 95 µm, consisting of a long slender part with prismatic cells and a slightly wider pars dilatata with wide lumen; sphincter present at oviduct-uterus junction. Uterus 110 µm long, tripartite, having proximal and distal expanded parts with wide lumen and the intermediate convoluted part with narrow lumen. Vagina bent posteriad, extending inwards about half of the corresponding body width; pars proximalis vaginae 15 µm long with almost straight walls, encircled by muscles; pars refringens vaginae absent; pars distalis vaginae 4.5 µm with slightly concave walls. Prerectum six times anal body width long. Rectum about as long as anal body width. Tail obtusely rounded, 0.8 times anal body width long. Caudal pores two on each side.

Male: Similar to female in general morphology except for posterior region being more curved ventrad because of the presence of copulatory muscles. Spicules dorylaimoid, with an unusually wide and blunt distal end, about 1.5 times cloacal body width long. Lateral guiding pieces rod-like with bifid distal ends, about one-third as long as spicule length. Supplements consisting of an adcloacal pair and four spaced ventromedians, starting anterior to the range of spicules. Prerectum 5.6 times cloacal body width long. Rectum about as long as cloacal body width. Tail with a broad, truncate terminus, 1.1 times cloacal body width long. Caudal pores two on each side.

Habitat and locality. From soil around the roots of wild weeds (unidentified), near guest house, IIT Campus, Guwahati, Assam. GPS coordinate 26.24785/91.88965; latitude 26°11'N, longitude 91°44'E.

Remarks. A. elegans was described by Jairajpuri (1964) from Kerala, India. The present specimens from Assam conform well to the type population except for having a longer and more slender body (L = 1.8 mm; a = 56.8 vs L = 1.2–1.3 mm; a = 43–49), shorter prerectum (6 abw vs 8.5) and slightly shorter tail (c = 94 vs 75). Although the present specimens have a longer and slender body compared to the type, but the shape of spicules which is so characteristic for A. elegans is also present in the present male specimen and hence there is no doubt that these two specimens are A. elegans .

A. elegans closely resembles A. eletum Dhanachand & Jairajpuri 1981 , and A. neoeletum Rahman, Jairajpuri & Ahmad, 1985 in having a posteriorly directed vagina, long sac-like anterior genital branch and in tail shape. However, it differs from both these species in the shape of the spicules, lateral guiding pieces and number of ventromedian supplements.

Figures

FIGURE 3. Axonchium elegans Jairajpuri, 1964. A: Entire female. B: Entire male. C: Anterior region. D: Anterior end showing amphid. E – F: Junction between two parts of pharynx. G – H: Pharyngo-intestinal junction. I: Female genital system. J: Vulval region. K: Female posterior end. L: Male posterior region. M: Spicule. N: Lateral guiding piece.

FIGURE 4. Axonchium elegans Jairajpuri, 1964. A – B: Anterior region. C: Anterior end showing amphid; D: junction between two parts of pharynx; E: Pharyngo-instestinal junction; F: Vulval region; G: Female posterior end; H – I: Male posterior end. (Scale bars: A – C = 10 µm; D – I = 20 µm).