Mylonchulus lacustris
Creators: name: Tahseen, Qudsia
name: Asif, Mohammad
name: Mustaqim, Malka
name: Ahlawat, Shikha
name: Bert, Wim
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Nematoda
Adenophorea
Dorylaimida
Mononchidae
Mylonchulus
Mylonchulus lacustris

description: Mylonchulus lacustris (Cobb in Cobb, 1915) Andrássy, 1958
(Figs. 4–6)
= Mononchus lacustris Cobb in Cobb, 1915
= Mononchus (Mylonchulus) lacustris Cobb in Cobb, 1915 (Cobb, 1917)
= Mononchus (Mylonchulus) brachyuris macrodenticulatus lacustris Cobb in Cobb, 1915 (Micoletzky, 1922) = Mylonchulus sarmini (Azmi, 1991) Ahmad & Jairajpuri, 2010
= Mylonchulus yassini (Elbadri, Khan, Moon, Lee & Choo, 2008) Ahmad & Jairajpuri, 2010 = Mylonchulus lacumurus (Saha, Lal & Singh, 2004) Ahmad & Jairajpuri, 2010
Measurements. Table 3.
Description. Adult: Body medium-sized, ventrally curved upon fixation, more strongly curved in posterior region. Cuticle smooth, 2–3 µm thick at various body regions. Body pores indistinct. Lip region offset from adjoining body, more than 3 times as wide as high. Labial papillae slightly projecting above labial contour. Amphids cup-shaped with oval aperture, 4 µm across, located 10 µm from anterior end, ahead of dorsal tooth. Buccal cavity oblong, goblet-shaped with parallel walls and narrow base about 1.6–2 times as long as wide with heavily sclerotised vertical and oblique plates. Vertical walls comprising of a dorsal tooth bearing wall and two sub-ventral denticulate walls each with 7 transverse rows of denticles (n= 6) and a prominent sub-ventral tooth. One individual possessed 6 irregular or dispersed denticulate rows (Fig. 4 C) in the buccal cavity. Dorsal tooth medium-sized, 8– 9 x 5–6 µm in dimension, anteriorly directed, with tip located at 5–6 µm from anterior end of buccal capsule or at ca 74–80% from its base. Pharyngeal sleeve surrounding buccal cavity base at 1/3–1/4 of its length. Pharynx cylindroid, muscular, 28–29% of body length. Ventral pharyngeal wall with conspicuous bead-like (Fig. 6 G) appearance (in individuals belonging to Ghazipur population). Orifices of pharyngeal glands: DO located at ca 65–67%, SV1O1 and SV1O2 at ca 79–82%, SV2O1 and SV2O2 at ca 91–93% of pharyngeal length from anterior end. Nerve ring surrounding pharynx at 28–31% of pharyngeal length from anterior end. Excretory pore inconspicuous, in few specimens observed at ca 36–39% of pharyngeal length. Pharyngo-intestinal junction nontuberculate. Rectum ca 0.8–1.2 times anal body diameters long. Tail conoid, with slight ventral curvature, gradually tapering to a cylindroid part before ending in a rounded terminus. Caudal glands well developed, arranged in tandem, or slightly deviated from linear pattern; spinneret terminal.
Female: Reproductive system didelphic, amphidelphic with reflexed ovaries. Anterior genital branch a little longer than posterior in most specimens; each ovary with a very large proximal oocyte and small oocytes in double rows present distally. Vagina one-third of corresponding body width with well-developed, almond-shaped pars refringens. Vulva a transverse slit, slightly posterior to middle of the body, vulval lips occasionally protruding (in Aligarh population).
Male: Not found.
Locality and habitat: Aligarh population: The sample containing M. lacustris was collected from a small ditch (alluvial soil) at the outskirts of Aligarh, Uttar Pradesh, India, at 27°53ʹN 78°05ʹE coordinates. Ghazipur population: The sample containing M. lacustris was collected from a pit at Ghazipur, Uttar Pradesh, India, at 25°35ʹN 83°34ʹE coordinates. Udaipur population: The sample containing M. lacustris was collected from a field at Udaipur, Rajasthan, India, at 24°35'11"N 73°43'20"E coordinates.
Characters (n) M. lacustris (2) M. lacustris (3) M. lacustris (2) M. hawaiiensis (10) M. hawaiiensis (3) Aligarh population Ghazipur population Udaipur population Dehradun population Keetham population Voucher specimens. Two females on slide Mylonchulus lacustris (Cobb in Cobb, 1915) Andrássy, 1958 no. AL/1–2 deposited in the Nematode Collection, Department of Zoology, Aligarh Muslim University, Aligarh, Uttar Pradesh, India.
Three females on slide Mylonchulus lacustris (Cobb in Cobb, 1915) Andrássy, 1958 no. Ghz/1-2 deposited in the Nematode Collection, Department of Zoology, Aligarh Muslim University, Aligarh, Uttar Pradesh, India. Two females on slide Mylonchulus lacustris (Cobb in Cobb, 1915) Andrássy, 1958 no. Ud/1-2 deposited in the Nematode Collection, Department of Zoology, Aligarh Muslim University, Aligarh, Uttar Pradesh, India.
Salient characters. Small to medium-sized species with buccal cavity goblet-shaped, about 1.6–2.0 times as long as wide; dorsal tooth large, situated in anterior half of buccal cavity; subventral wall usually bearing seven transverse rows of denticles; subventral teeth prominent; female genital system amphidelphic; tail conoid with slight ventral curvature, gradually tapering to a cylindroid part before ending into a rounded terminus.
Remarks. Justifying its name, the species M. lacustris has been widely reported from moist or limnic habitats (Andrássy, 2006). The species comes close to M. minor. Mulvey (1961) differentiated them on the basis of the shape and size of buccal cavity and the subventral tooth. Cobb (1917) redescribed and illustrated the species and emphasized on the ventrally arcuate tail with three caudal glands arranged in tandem. The three M. lacustris populations in the present study, showed a large, goblet-shaped buccal cavity usually with seven tranverse rows (Fig. 4 D, 6F) of rasping denticles apud Jairajpuri, 1970b. However, one specimen of Aligarh population possessed five (Fig. 5 C) rows (apud Andrássy 2006). In an unusual case a large denticle was observed in between the small rasping denticles (Fig. 6 D). The individuals of the Ghazipur and Udaipur populations possessed large and slender ovaries, however, in one individual of Ghazipur population the posterior ovary was markedly reduced (Fig. 6 I). The arrangement of caudal glands was usually in tandem, however, a slight deviation from the pattern was observed in a few specimens of the Udaipur population (Fig. 4 L) very similar to that reported in a population from Thailand apud Buangsuwon & Jensen (1966).
description: Published as part of 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, pp. 301-335 in Zootaxa 3646 (4) on pages 311-316, DOI: 10.11646/zootaxa.3646.4.1, http://zenodo.org/record/249406