Mylonchulus lacustris
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publication ID |
https://doi.org/ 10.11646/zootaxa.3646.4.1 |
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publication LSID |
lsid:zoobank.org:pub:DDE05DCD-A443-499D-9F38-8C3B43592694 |
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DOI |
https://doi.org/10.5281/zenodo.5616693 |
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persistent identifier |
https://treatment.plazi.org/id/03C21B03-FF84-FFC2-FF5B-FDB474BE2D91 |
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treatment provided by |
Plazi |
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scientific name |
Mylonchulus lacustris |
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Mylonchulus lacustris (Cobb in Cobb, 1915) Andrássy, 1958
( Figs. 4–6 View FIGURE 4 View FIGURE 5 View FIGURE 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 View 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 View FIGURE 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 View FIGURE 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 View FIGURE 4 D, 6F) of rasping denticles apud Jairajpuri, 1970b. However, one specimen of Aligarh population possessed five ( Fig. 5 View FIGURE 5 C) rows (apud Andrássy 2006). In an unusual case a large denticle was observed in between the small rasping denticles ( Fig. 6 View FIGURE 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 View FIGURE 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 View FIGURE 4 L) very similar to that reported in a population from Thailand apud Buangsuwon & Jensen (1966).
TABLE 3. Morphometrics of females of Mylonchulus lacustris (Cobb in Cobb, 1915) Andrássy, 1958 and M. hawaiiensis (Cassidy, 1931) Andrássy, 1958. Measurements in Μm and in the form: mean ± SD (range).
| Body length 1080±60 (1020–1140) | 962±28 (828–1085) | 970±49 (794–1147) | 880±80 (710–950) | 820±68 (750–890) |
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| Body diameter at vulva 38±2.3 (36–40) | 37±1.1 (35–39) | 41±7 (36–46) | 40±2.9 (35–45) | 37±2.3 (35–39) |
| a 28.5±0.2 (28.3–28.7) | 25±1.3 (23.6–26.3) | 24.4±1.5 (23.3–25.5) | 22.6±1.2 (20.4–24.0) | 21.8±0.4 (21.1–22.8) |
| b 3.4±0.1 (3.4–3.5) | 3.5±0.2 (3.2–3.5) | 3.5±0.2 (3.3–3.7) | 3.2±0.2 (3.0–3.6) | 3.3±0.1 (3.2–3.5) |
| c 24.8±0.5 (24.3–25.3) | 24±1.6 (22.3–25.6) | 26.4±1.2 (25.5–27.3) | 21.6±1.4 (19.1–23.3) | 23.1±1.5 (22.2–24.9) |
| c' 1.7±0.1 (1.6–1.7) | 1.7±0.2 (1.6–2) | 1.3±0.2 (1.2–1.5) | 1.5±0.1 (1.3–1.8) | 1.4±0.1 (1.3–1.6) |
| V 57.5±0.1 (57.3–57.7) | 57±0.8 (56.8–57.5) | 58.9±2.1 (57.4–60.4) | 58.7±0.9 (57.2–60.5) | 59.3±0.9 (58.3–60.1) |
| G1 15.1±2.6 (12.5–17.8) | 10.5±3 (7–12.5) | 12.5±1.4 (11.5–13.5) | 13.5±4 (8.2–14.6) | 12.4±1.6 (11.2–14.3) |
| G2 14.7±3.0(11.6–17.7) | 10.7±0.7 (10.2–11.6) | 12.8±0.3 (12.4–13.2) | 12.2±2.4 (9.4–14.6) | 12.1±1.3 (11.2–14.3) |
| Lip height 8.5±0.5 (8–9) | 6.6±1.2 (6–8) | 6.5±2.1 (5–8) | 9.1±1 (7–10) | 6.6±0.5 (6–7) |
| Lip diameter 20.5±0.4 (20–21) | 20.2±0.5 (20–21) | 22±2.8 (20–24) | 23.3±1 (21–25) | 20±0 (20–20) |
| Stoma length 24.5±0.1 (24–25) | 23±0 (23–23) | 23.5±2.1 (22–25) | 23.5±1.2 (21–25) | 22.3±0.5 (22–23) |
| Stoma diameter 14.5±0.5 (14–15) | 14±0 (14–14)1 | 14.5±0.7 (14–15) | 14.2±0.7 (13–15) | 12.6±0.5 (12–13) |
| Dorsal tooth position 6±0 (6–6) | 5.3±0.5 (5–6) | 6.5±0.7 (6–7) | 6.2 ± 0.5 (6–7) | 5.6±0.5 (5–6) |
| Pharynx length 313.5±23.2 (290–337) | 266.1±19.4 (244–281) | 274.1±53.7 (236–312) | 269.9±16.4 (237–290) | 245.2±19.0 (233–267) |
| Nerve ring from ant. end 95±5 (90–100) | 86.6±5.7 (80–90) | 85.9±14.1 (75–95) | 86.7±5.5 (77–95) | 75±8.6 (70–85) |
| Excretory pore from ant. end 12.5±9.5 (103–122) | 96.6±6.5 (90–103) | 96.1±9.8 (89–103) | 102.1±6.9 (90–115) | 83.3±10.2 (76–95) |
| Rectum length 20.4±1.5 (18–23) | 17.3±1.5 (16–19) | 19.5±1.4 (18–20) | 22.4 ± 1.2 (20–24) | 19.5±1 (18–20) |
| Anal body diameter 20.5±0.4 (20–21) | 22±0 (22–22) | 26±4.2 (23–29) | 26.6±1.1 (24–28) | 24.1±0.4 (24–25) |
| Tail length 43.5±1.3 (42–45) | 40.0±4.3 (37–45) | 37.5±12.4 (29–46) | 41.1±3.6 (36–50) | 35.6±3.7 (33–40) |
| Vulva–anus distance 417±38.3 (390–445) | 372±51(320–422) | 372±116.6 (290–455) | 298±26.9 (245–337) | 299±28.1 (267–320) |
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