Axonchium parasaccatum Rahman, Jairajpuri & Ahmad, 1985

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 : 20-23

Axonchium parasaccatum Rahman, Jairajpuri & Ahmad, 1985

( Figs. 9–10 )

Measurements. Table 5 .

Description. Female: Cuticle 4–5 µm thick at mid body and 10–12 µm on tail. Lateral chords about one-sixth as wide as body width at mid body.

Lip region offset, about one-fifth of body width at neck base. Amphids cup-shaped, their aperture about twothirds of lip region width. Odontostyle about one lip region width long. Odontophore 1.2–1.3 times the odontostyle length. Anterior part of pharynx muscular, separated from the posterior expanded part by a deep constriction, the latter occupying about 56–69% of total neck length. Cardia clavate, less than half of the corresponding body width long.

Anterior genital branch represented by a long uterine sac, 2.8–4.7 times the corresponding body width, filled with sperms. Posterior branch well developed; ovary reflexed, not reaching the oviduct-uterus junction, measuring 100–130 µm; oviduct 100–120 µm, consisting of a long slender part with prismatic cells and a slightly wider pars dilatata with clear lumen, its inner part more refractive, being encircled by a muscular ring. Uterus measuring 60–110 µm, demarcated into distal expanded part with clear lumen and proximal narrower part with obscure lumen. Vagina slightly bent posteriad, extending inwards about half of the corresponding body width; pars proximalis vaginae 20 µm long, surrounded by circular muscles; pars refringens vaginae absent; pars distalis vaginae well developed 10 µm long with rounded walls. Prerectum 6.4 anal body widths long. Rectum about one anal body width long. Tail short hemispheroid, 0.8 times anal body width in length. Caudal pores two on each side.

Male: Spicules arcuate, ventrally curved, with straight and narrow distal ends, 1.4–1.5 times cloacal body width long. Lateral guiding pieces rod-like, with distal bifurcated ends, about one-third of the spicules length. Supplements, an adcloacal pair and five ventromedians arranged in two groups of three and two, starting above the range of spicules. Prerectum 6.5–7 times cloacal body width long. Rectum about one cloacal body width. Tail similar to female, 0.8–0.9 times the cloacal body width long. Caudal pores two on each side.

Habitat and locality. Soil around the forest trees (unidentified) from Kaziranga National Park, Assam, India. GPS coordinate 26.64071/93.39958; latitude 26o36’N, longitude 93o28’E.

Remarks. Rahman et al. (1985) described this species from Arunachal Pradesh, India. The present population conforms well to the original description except for having a slightly longer and more robust body (vs L = 1.8–2.03 mm; a = 47–51) and five ventromedian supplements (vs four). A paratype female and a male of this species available in the Department of Zoology, Aligarh Muslim University were also examined. Though they fit the original description, the shape of spicule was slightly different from the original illustration ( Fig 4 J of Rahman et al, 1985). It has been redrawn from the original specimens ( Fig 9 M). This species is closely related to A. saccatum Jairajpuri, 1964 and A. metobtusicaudatum ( Schuurmans Stekhoven & Teunissen, 1938) Nair & Coomans, 1973 . From the former, it differs in having posteriorly directed vagina (vs straight), larger and differently shaped spicules (vs spicules with broad and truncate distal ends) and fewer ventromedian supplements (vs 9–11), and from the latter in having a more posteriorly located vulva (vs 50–53%), in the shape of spicules (vs distal ends more thickened and provided with posterior projection) and lateral guiding pieces (vs rod-like with bifid ends), and in the number of ventromedian supplements (vs 6–8).

Figures

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).

FIGURE 9. Axonchium parasaccatum Rahman, Jairajpuri & Ahmad, 1985. 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 10. Axonchium parasccatum Rahman, Jairajpuri & Ahmad, 1985. 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: Ventromedian supplements. I – J: Male posterior end. (Scale bars A – C = 10 µm; D – J = 20 µm).

Tables

TABLE 5. Morphometrics of Axonchiun parasaccatum Rahman, Jairajpuri and Ahmad, 1985 (All measurements in µm (except L) and in the form: mean ± standard deviation (range).

Characters	Females	Males	Paratype female	Paratype male
n: L (mm) a b c	2 2.4, 2.2 42.6, 42.4 2.6,2.7 67.5, 66.1	4 2.27±0.05 (2.2–2.3) 47.8±3.81 (45–53.4) 3.07±0.37 (2.6–3.5) 64.15±2.4 (62–66.7)	1 2.0 43 2.4 74.8	1 2.0 45 2.7 61.0
c`V G1 G2 Lip region width Lip region height	0.8, 0.8 55.2, 54 6.5, 9.5 10.6, 11.1 12, 11 5, 5	0.87±0.05 (0.8–0.9) - - - 11.5±0.58 5	0.75 60.3 5.0 9.8 12 5	0.85 10 5
Amphid aperture Odontostyle length Odontophore length	7, 7 13, 13 15, 15	7 13.25±0.5 (13–14) 15	10 15	10 15
Guiding ring from anterior end Nerve ring from anterior end Neck length	11, 10 145, 130 905, 830	10.5±0.58 (10–11) 143±12.58 752±84.1 (655–860)	840	765
Expanded part of pharynx Cardia length Body width at mid body	625, 575 20, 18 57, 53	470±84.3 (365–570) 17.7±2.06 (15–20) 48.7±3.8 (43–51)	580 20 49	525 15 46
Body width at neck base Body width at anus/cloaca Anterior genital branch Posterior genital branch Vaginal depth Vulva from anterior end	57, 53 45, 42 160, 235 260, 250 36, 40 1310, 1210	49.6±4.93 (44–53) 39.5±0.6 (39–40) - - - -	48 36 100 200 1220	45 40
Prerectum length Rectum length Tail length	290, 270 45, 43 36, 34	266±8.19 (260–280) - 36.2±0.96 (35–37)	240 35 27	45 34
Spicules length Lateral guiding pieces Ventro median supplements	- - -	63.7±5.68 (55–65) 21.2±0.96 (21–23) 5		55 17 5