ON SOME NEMATODES BELONGING TO THE ORDERS CHROMADORIDA AND ENOPLIDA FROM INDIA

The soil and freshwater nematodes in general, and the non-stylet bearing nematodes in particular, have received little attention in India. In the order Enoplida, one new species of the genus Oncholaimus Dujardin was described by Stewart (1914); Kreis (1936) reported a single specimen of Tobrilus gracilis (Bastian) from Madras and Sukul (1967, 1968, 1968a) described three new species belonging to this order. Khera (1970) described the male of Tripyla (Tripyla) glomerans Bastian from Srinagar and attempted a revision of the genus Tripyla Bastian; he also recorded the occurrence of [ronus ignavus Bastian and Cryptonchus abnormis AUgen from India and reviewed both the genera (in press). There is no record of any species belonging to the order Chromadorida from India. Following is .an account of some nematodes from Rajasthan, Uttar Pradesh, Orissa and Kerala belonging to these two orders. I am grateful to Dr. A. P. Kapur, Director, Zoological Survey of India for providing facilities and to Dr. M. Oostenbrink of Landbouwhogeschool, Wageningen, The Netherlands, for advice regarding the genu~­ Oncholaimium.


INTRODUCTION
The soil and freshwater nematodes in general, and the non-stylet bearing nematodes in particular, have received little attention in India.In the order Enoplida, one new species of the genus Oncholaimus Dujardin was described by Stewart (1914); Kreis (1936) reported a single specimen of Tobrilus gracilis (Bastian) from Madras and Sukul (1967Sukul ( , 1968Sukul ( , 1968a) ) described three new species belonging to this order.Khera (1970) described the male of Tripyla (Tripyla) glomerans Bastian from Srinagar and attempted a revision of the genus Tripyla Bastian; he also recorded the occurrence of [ronus ignavus Bastian and Cryptonchus abnormis AUgen from India and reviewed both the genera (in press).There is no record of any species belonging to the order Chromadorida from India.Following is .anaccount of some nematodes from Rajasthan, Uttar Pradesh, Orissa and Kerala belonging to these two orders.
Remarks.-The nematodes ,collected from Achalgarh have outstretched ovaries, and amphids near the proximal end of the stoma.Loof (1964), while describing A. ruricola, stated that the amphids had shifted forward during the mounting process.The outstretched condition of the ovary, though unique, is being treated as a variation.This would, however, entail emendation in the generic diagnosis as follows: Achro~adora Cobb Emended diagnosis: Cyathulaiminae.Cuticle with transverse striae bearing rows of punctations.Amphids spiral.Head not offset, with six indistinct lips, each with a small apical papilla.At the base of lips a circlet of 10 cephalic setae, 2 lateral, 4 subdorsal and 4 subventrol.Stoma rather funnel-shaped, with a prominent dorsal tooth medially placed and I or 2 smaller subventral teeth situated further back.Oesophagus cylindrical.witha terminal pseudobulb.Caudal glands and terminal duct present.Vulva equatorial; gonads paired, opposed.Male with paired spicules and a large gubernaculum.
Type species: Achromadora ruricola (de Man).Goodey (1951Goodey ( , 1963)), while giving measurements and description of A. ruricola, has stated that male of the species is absent although a diagram of tail of male of this species, based after de Man (1884), has been given in his works.de Man (1880,1884) described both the male and female of this species-measurements and de Manian formula are common to both the sexes and an account of the male has been given.
Distribution.-Rajasthan and U.P. Gondas paired, opposed and reflexed.Both the ovaries short.One egg in each uterus.Vulva slightly pre-equatorial, transversely elliptical, flush with body surface.
Diagnosis and Relationship.-Ofthe various genera belonging to the subfa~ily Cyatholaiminae Micoletzky, the new gen~s comes close to the genera Achromadora Cobb and Ethmolaimus de Man, occupying an intermediate position between the two genera.It resembles the genus Achromadora in the shape and structure of stoma but differs in possessing a stomal capsule and four cephalic setae.The new genus resembles Ethmolaimus in having a stomal capsule surrounding the stoma but differs in the shape and structure of stoma.with irregularly arranged, coarse, rounded punctations dIfferentIated all over the body except laterally; the tail, howe~er, be~rs p~nctations all over.Two circlets of c~phalic setae, anterior ~lrcl~t 'Ylth eIght and posterior with six setae.Amphids large, ~rescentlc, sht-lIke.St?~a fun~el shaped, in two portions: prox~ma~ pqrtlon ~up-sh~ped, comp r1s1 !lg cheIlostom and protostom with longltudlna~ folds ~n chedos~om and w~t~ a large pointed tooth on dorsal" protorhabdlon.; dIstal por.oon, comprIsIng te~o storn, becoming narrow as it proceeds dIstally..A rl~g (whose homologies are not clear), comprising three .plates,at the JU!lctiO~ of protostom and telostom.Oesophagus club-shaped.Oesoph~go-lntesbnal valve cells prominent.Single testis.Gubernaculum and ventral supplements absent.Body elongate, slender, blunt at the anterior extremity, finely pointed posteriorly.Posterior portion of the nematode drawn out, coiled Ventrally, attenuating gradually beyond the cloacal aperture.Tail 500 pm long, filiform.Body cuticle as in generic diagnosis.A few bristles here and there" on the body.Head continuous" 22 pm.wide, with six indistinct lips.Cephalic setae as in genus.Amphids at about two head-widths from the anterior end, immediately behind the posterior circlet of setae.Stoma as in genus, 25 X 18 pm; cheilostom with six longitudinal folds (= cheilorhabdions) in the walls, protostom with three protorhabdions; telostom surrounded by oesophageal collar.Oesophagus 250 pm long without a valvular apparatus.Intestinal wall moderately thick.Caudal glands not observed.Nerve ring surrounds oesophagus anterior to its middle at 105 pm from the anterior end.Excretory pore not seen.
Spicula stout, heavily sclerotized, rose-thorn shaped, ventrally arcuate, tapering towards bluntly pointed tip.Each spicule with a distinctly flanged capitulum bent at right angles to the body of the spicule; the latter also bears longitudinal ridges.
Diagnosis and Relationship.-Ofthe various freshwater genera included in the family Chromadoridae by Goodey (1963), the new genus comes closest to Chromadorella Filipjev in possessing an oesophagus without a distinct bulb-all other genera possess a distinct bulb.The new genus, however, differs from Chromadorella in possessing only a single dorsal tooth.The presence ofa three-piece ring at the junction of prot os tom and teiostom, absence of ventral supplements (latter absent in some species of the genus Hypodontolaimus de Man) and gubernaculum sets the new genus apart from all other genera of Chromadoridae obtained from the freshwater biotope.
Biological Notes.-Thenematode has been found in a freshwater pond near the sea-coast-obviously a vagrant form from maril1:e habitat since the entire group (Chromadoridae) has not been found in ponds away from the sea-coast.
The nematode had a rapid jerky moVement.
Order   Body transparent.Tail conical, ending in a fine point, 160 pm' in length, about eight times the anal body-diameter long.Body cuticle smooth, without setae.Head 22 pm broad.A circlet of six stout cephalic setae at the base of lips, each cephalic seta about 1/4 head-width long.A~phids large, cup-shaped at the base of cephalic setae.Stoma longer than wide, 25 X 10 pm, in three sections, with continuous sclerotized walls: the anteriorrilost section being the largest, between triangular and subglobular in shape 10 X 10 pm; middle section f~nnel-shaped, 8 X 7 pm with three teeth, one dorsal and two subventral; the third section elliptical with finer •walls and two prominent lateral teeth.At the junction of the first two sections the cuticular walls form a ledge towards the lumen of stoma.Stoma enV'eloped by an oesophageal collar.Oesophagus 224 pm long with no valvular apparatus.Three large ovoid oesophago-intestinal gland cells.Intestine and its lumen broad except near the female reproductive system where these are narrowed.Rectum 19 pm in length, about one anal body-diameter long.Nerve ring surrounds oesophagus at about 36% of its length from anterior end.Excretory pore absent.
A circular vulva more or less flush with body surface, surrounded by a rosette of cuticular warts.Eggs large and oval, from unicellular to two-celled stage.
Male.-General structure similar to that of female.Posterior end curved slightly ventrally on thermal death.Tail 104 pm long, four times the anal body-diameter in length.Stoma 20 X 5 pm, the anterior-most section mOst spacious, subglobular, 10 X 5 pm; mid~le section much reduced, more or less cylindrical, 5 X 2 pm, with three usual teeth; the posterior-most section elliptical, 5 X 1.5 pm, with two large lateral teeth.
Cuticular ledge at the junction of the first two sections in the female not evident here.
Two poorly sclerotized spicules possessing a narrow capitulum and a broad body which narrows towards the tip.Gubernaculum strongly sclerotized.Six pre-cloacal, midventral supplements, nearly of the same size.No caudal alae.
Diagnosis and Relationship.-Thenew species comes close to T gracilis (Bastian), T allophysis (Steiner), T a~errans (W" Schneider), T consimilis (W.Schneider) and T vibratus Sukul in possessing cephalic setae which are about 1/4 the head width, a tail without a terminal seta and six supplements nearly of the •same size in the males.
The new species differs from these and other species of the genus as enumerated by Andrassy (1959, 196'4) in possessing six cephalic setae at the base of lips, in having a ledge at the junction of the first two sections of stoma in the female and rosettiform cuticular warts surrounding the vulva.Further, there is sexual dimorphism in the structure of stoma, the middle section of the latter being much wider in female than in male.
Biological Notes.-Alarge, number of female and male nematodes of this species were collected from time to-time from the banks to about a depth of two feet from various tanks of Rajasthan and Kerala.Some nematodes were also collected from the ba~ks• of R. Yamuna near Wazira .. bad Pumping Station, n-elhi where algal matter was found in abundance, while others were recovered ftoJ!l moist soil of' pits, up to four feet.deep, dug up in a dried pond during drought to get water for drinking purposes at Khandwai Talai, a village near Agolai about 32 kni.west of JQdhpur.
These nematodes, as those of the next species, .had .rapid wriggling movements followed by uncoiling and ,coiling mOVenient.All these move .. ments were punctuated by periods of quiescen(:e...The nematodes could anchor themselves to the substratum by me~nSl6f 4:he tip of their tail thus resting or even wriggling in a vertical position.slightly' posterior, of four setae.Each seta about 1/6 the head width long.Amphids large, cup-shaped with ellipsoid opening behind the posterior circlet of cephalic seate.Stoma longer than wide, 18 X 7 pm, in three sections with continuous well sclerotized, walls: the anterior most section being the largest, cup-shaped, 8 X 7 pm; middle section funnelshaped, 5 X 4 pm, with three teeth, one dorsal and two subventral; the• "third section tubular, 5 The anteriormost section 6.0 x4.5 pm, somewhat funnel-shaped; the middle section much reduced, cylindrical-elliptical, 3.5 X 1.5 pm, with three teeth; the posterior-most section cylindrical, 2.5" X 1 pm, with two teeth.Oesophagus 151 pm long.Two somewhat arcuate, spindle-shaped, poorly sclerotized spicules.The capitulum of each of the two spicules connected to one of the upper (shorter) limbs of a Y-shaped accessory piece.Gubernaculum strongly sclerotized, of the shape of a bowling pin with its head recurved ventrally and with a strong diagonal ridge marking its posterior third from the anterior two-third.Six equal, pre-cloacal, mid-ventral supplements.

Tobrnus confusus
Diagnosis and Relationship.-Thenew species is unique in having an accessory piece in addition to the usual spicula and gubernaculum.
I t comes closest to T sexsetiferous n.sp. in the stoma exhibiting sexual dimorphism, in the position of amphids, in the number of teeth in the stoma and in the number of pre-cloacal supplements but differs in having ten cephalic setae, in the absence of a ledge between the first two sections of stoma in the female and cuticular warts around the vulva, in the shape of spicules and gubernaculum, in addition, of course, to the presence of an accessory piec~.
Holotype Owing to the absence of lateral fields, the anteriQr position of amphids, the division of stoma in three sections and the preserice of six cephalic setae in T. sexsetiferous, the diagnosis of the genus Tobrilus, as given by Goodey (1963), is emended as follows :

TobrUus Andrassy
Emended diagnosis: .Tripylidae.Outicle smooth, body tapering behind, but very little in front.Amphids cup-or funnel-shaped with .aflattened oval opening situated near the level of stoma.Head not offset, provided with six, more.or less roundly conical, lips each provided with a very small apical papilla.Six, ten or more stout setae at the base of lips.Stoma in two or' three sections, its walls distinctly sclerotized; the anterior section without teeth or denticles, the posterior section(s) denticulated.Oesophageal collar surrounds the stoma.Oesophagus clubshaped.Three distinct oesophago-intestinal gland cells.Vulva practically equatorial; female gonads didelphic, amphidelphic and reflexed.Testes paired; gubernaculum present.A series of pre-cloacal supplements in male.Tail of both sexes tapering, caudal glands and terminal duct present.A few fine setae irregularly scattered over the body and tail in most of the species.Males unknown in some species.
SUMMARY Ethmodora stagnalis n.g., n.sp.and Chromanema solitarium n.g., n.sp., both belonging to order Chromadorida are described.Two new species of Tobrilus, T sexsetiferous and T confusus (order Enoplida) are described, and the generic diagnosis of Tobrilus Andrassy and Achromadora Cobb emended.Genera Achromadora (order Chromadorida) and Oncholaimium Cobb (order EnopIida) are recorded from India for the first time.

.... tOp.
The genus Achromadora is being recorded for the first time from India.Body slender.~nter!or regi?n not markedly a~tenuated.Tapering 78 pm long, endIng In a spmneret.Body cuticle bears prominent ~ransver~e striae composed of fine punctations.Amphids fine, spiral, Just behlnd the level of the base of stoma.Head not offset, 10 pm wide fla!tened-r~unded in .front,with six partially fused lips, each with a smali apIcal papIlla.A cIrclet of four submedian setae at the base of lips.
X•-} pm, with finer walls and two prominent lateral teeth.Stoma enveloped by an oesophageal collar.Oesophagus 209 pm long with no valvular apparatus.'fhreelarge,ovoid, oesophago-intestinal gland cells.Intestine and its lumen broad except near the fem'ale reproductive systeln where these are narrowed.Rectum 10 pm jn length, being about half the anal body-diameter long.Nerve ring surrounds oesopha gus at abdut 33% of its length from anterior end.Excretory pore absent.Circular vulva, more or less flush with body surface.Male.-Generalstructure similar to that in female.Posterior end curved slightly ventrally on thermal death.Tail 84 pm long, and 4! times the anal body-diameter in length.Stoma 12 X 4.5 pm.