Mylonchulus amurus Khan and Jairajpuri, 1979

Nusrat, Tabinda, Anjum, Ashher & Ahmad, Wasim, 2013, Mononchida (Nematoda) from Silent Valley National Park, India, Zootaxa 3635 (3), pp. 224-236 : 230-232

Mylonchulus amurus Khan and Jairajpuri, 1979

( Fig. 3 E–H)

= Pakmylonchulus amurus (Khan and Jairajpuri, 1979) Khan and Sayeed, 1987

Measurements: Table 2 .

Female: Buccal cavity goblet-shaped, thick-walled, uniformly tapering to its base, 1.6–1.7 times as long as wide; dorsal tooth large, claw-like, anteriorly directed, its tip at 76–80% from base of stoma; ventro-sublateral walls provided with five transverse rows of denticles; subventral teeth absent. Amphidial aperture at level with dorsal tooth apex. Female genital system amphidelphic. Sphincter present at oviduct-uterus junction. Vulva transverse; vagina thick-walled extending inward about two-fifths to one-third of the corresponding body width; pars proximalis vaginae 8.0–9.5 μm long and triangular; pars refringens vaginae triangular in shape, measuring 3–4×1.5–2 μm, cw 5–6 μm; pars distalis vaginae short with circular walls, measuring 2–4 μm. Tail short conoid, ventrally arcuate, 1.2–1.4 anal body widths long. Caudal glands well developed, grouped; spinneret terminal.

Male: Not found.

Habitat and locality: Soil around the roots of forest trees from Mukkali, Silent Valley National Park, Palakkat, Kerala State, India.

Remarks: Khan and Jairajpuri (1979) described M. amurus from several localities at high altitudes in North India. This species is characterized by having a buccal cavity without subventral teeth and an amphidelphic female genital system. Khan and Saeed (1987) proposed a new genus Pakmylonchulus for this species. Andrássy (1993) synonymised Pakmylonchulus with Mylonchulus and transferred back P. amurus to its earlier position as M. amurus . The present population from South India conforms well with those described by the original author except for having a slightly larger buccal cavity (25–26 x 15 vs 22– 25 x 10–16 µm) and slightly lower c value (c = 21–28 vs 28–42). This is the second report of this species after its original description.

Interestingly, while describing M. amurus , the original authors compared it only with M. hawaiiensis (Cassidy, 1931) Andrássy, 1958 , a species possessing subventral teeth in their buccal cavity. They probably overlooked three already known species of Mylonchulus ( M. insolitus Andrássy, 1968 ; M. exacutus Jensen & Mulvey, 1968 ; and M. ubis Clark, 1961 ) possessing buccal cavity without subventral teeth and amphidelphic gonads. Khan and Sayeed (1987) while proposing the new genus Pakmylonchulus also did not refere these species and restricted their genus Pakmylonchulus only to P. amurus . Three further species, M. oceanicus Andrássy, 1986 ; M. ananasi Yeates, 1992 and M. aequatorialis Orcelli & Vinciguerra, 2007 were later described as possessing a buccal cavity without subventral teeth and amphidelphic female genital system. M. amurus differs from these six species in definite morphological features. From M. ananasi , M. ubis , M. oceanicus and M. aequatorialis , it differs in having terminal spinneret (vs spinneret sub-dorsal in all the above species), while in M. exacutus and M. insolitus the spinneret is absent. In addition to this obvious difference, there are several other morphological and morphometric difference between M. amurus and the above six species (cf. key to species of Mylonchulus by Ahmad & Jairajpuri (2010)).

Figures

FIGURE 3 A – D: Clarkus sheri (Mulvey, 1967) Jairajpuri, 1970. A: Anterior end. B: Female genital branch (anterior). C: Vulval region. D: Female posterior end. E – H: Mylonchulus amurus Khan & Jairajpuri, 1979. E – F: Anterior region. G: Vulval region and posterior genital branch. H: Female posterior region (scale bars A, C – G = 20 µm; B = 50 µm; H = 10 µm).