Mylonchulus hawaiiensis (Cassidy, 1931) Andrássy, 1958

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, Zootaxa 3646 (4), pp. 301-335 : 318-321

Mylonchulus hawaiiensis (Cassidy, 1931) Andrássy, 1958

( Figs. 8 , 9 )

= Mononchus (Mylonchulus) hawaiiensis Cassidy, 1931 (Goodey, 1951) = Mylonchulus bareilliensis Sharma & Saxena, 1980

= Mylonchulus indicus Sharma & Saxena, 1980

Measurements. Table 3 .

Description. Adult: Body medium-sized, ventrally curved upon fixation, more in posterior region. Cuticle smooth 2–3 µm thick; body pores indistinct. Lip region slightly offset, about 2.3–2.8 times as wide as high with labial papillae projecting above labial contour. Amphids cup-shaped with oval aperture, 4–5 µm across, located 10–12 µm from anterior end. Buccal cavity goblet-shaped with narrow base about 1.5–1.8 times as long as wide with heavily sclerotised vertical and oblique walls. Dorsal wall having massive dorsal tooth directed anteriorly, 9– 10 × 6–6 µm in dimension, located at ca 8–9 µm from anterior end of buccal capsule or at ca 69–79 % of its base. Two subventral denticulate walls, each bearing 6 transverse rows of denticles and a subventral tooth posterior to the last row of denticles. Pharynx cylindroid, muscular, ca 27–30% of body length. Pharyngeal sleeve surrounding stoma at 1/3–1/4 of its length from base. Outlets of pharyngeal glands: DO situated at ca 52–58%, SV1O1 and SV1O2 at ca 66–69%; SV2O1 and SV2O2 at ca 87–94% of pharyngeal length from anterior end. Pharynx highly muscular, cylindrical in shape with clear, thick lumen. Nerve ring located at ca 28–32% of pharyngeal length from the anterior end. Excretory pore faintly visible, approximately at ca 36–37% of pharyngeal length from anterior end. Pharyngo-intestinal junction non-tuberculate, with variable cardial flap length Fig. 9 I-L. Intestinal lumen narrow. Rectum length 0.6–0.9 times anal body diameter. Tail abruptly curved ventrally, assuming an ‘L’ shape, often appearing digitate with slightly clavate tip. Caudal glands well developed, arranged in tandem, occasionally grouped; spinneret terminal.

Female: Reproductive system didelphic, amphidelphic with reflexed ovaries each having 7–8 developing oocytes arranged alternately in proximal region and multiple proliferating oocytes at distal end. Vagina about onefourth of corresponding body diameter long with well developed pars refringens. Vulva a transverse slit.

Male: Not found.

Locality and habitat: Dehradun population: The soil sample containing M. hawaiiensis was collected from a ditch at Dehradun, Uttarakhand, India, at 30°20'42"N 77°59'50"E coordinates.

Keetham population: Soil sample containing Mylonchulus hawaiiensis was collected from the bank of Keetham Lake, Agra, Uttar Pradesh, India.

Voucher specimens. Nine females on slide Mylonchulus hawaiiensis (Cassidy, 1931) Andrássy, 1958 , no. DJ29/1-2 deposited in the Nematode Collection, Department of Zoology, Aligarh Muslim University, Aligarh, Uttar Pradesh, India. One female deposited at USDANC, Beltsville, MD, USA.

Two females on slide Mylonchulus hawaiiensis (Cassidy, 1931) Andrássy, 1958 , no. Kee/1-2 deposited in the Nematode Collection, Department of Zoology, Aligarh Muslim University, Aligarh, Uttar Pradesh, India. One female deposited at USDANC, Beltsville, MD, USA.

Salient characters. Small to medium-sized species with buccal cavity funnel-shaped, about 1.5–1.8 times as long as wide; dorsal tooth large, situated in anterior half of buccal cavity; each subventral wall bearing six transverse rows of denticles and a relatively posterior subventral tooth; female genital system amphidelphic; tail conoid, ventrally arcuate, bent at middle with clavate terminus; caudal glands usually arranged in tandem; spinneret terminal.

Remarks. The species M. hawaiiensis has been reported from India, Egypt, Niger, Kenya, South Africa, El Salvador, Argentina, Hawaii, Abuachapan and Costa Rica. The species is widely distributed in India. The present populations showed variations in the size of ovaries ( Fig. 8 I–J; 9M, N, Q, R), cardial flaps ( Fig. 8 G; 9I –L) and the shape of tail ( Fig. 8 K, L; 9S–W); moreover, the spinneret also appeared terminal with a slight shift toward ventral side in some individuals as also illustrated ( Fig. 2 C) by Jairajpuri (1970b). The variations in the body length, shape of tail, and the position of amphids have also been reported by Mulvey (1967), and Jairajpuri & Khan (1982). Earlier the species was synonymised by Mulvey (1961) with M. incurvus (Cobb, 1917) Andrássy, 1958 but he later revalidated it. Bruin & Heyns (1992) also considered it a possible synonym of M. minor .

Figures

FIGURE 2. Prionchulus muscorum (Dujardin, 1845) Wu & Hoeppli, 1929 female. A – D: Anterior end. E – H: Subventral wall with denticulate ridge. I: Body region showing excretory pore. J – L: Pharyngo-intestinal junction. M: Vulval region. N, O: Posterior body region. P: tail tip. (Scale bar = 10 µm).

FIGURE 8. Mylonchulus hawaiiensis (Cassidy, 1931) Andrássy, 1958, (Keetham population). A – F: Anterior end with buccal armature. G, H: Pharyngo-intestinal junction. I: Posterior genital branch. J: Anterior genital branch. K, L: Posterior body region. (Scale bar = 10 µm).

FIGURE 9. Mylonchulus hawaiiensis (Cassidy, 1931) Andrássy, 1958, (Dehradun population). A – G: Anterior end with buccal armature. H: Anterior end showing amphids. I – L: Pharyngo-intestinal junction. M, N: Anterior genital branch. O, P: Vulval region. Q, R: Posterior genital branch. S – W: Posterior body region. (Scale bar = 10 µm).