Nematology, 2009, Vol. 11(4), 541-550

Nematodes of the order Rhabditida from India. Description ofDiplogasteroides uriceus sp. n. and Rhabditidoides papillatus sp. n.

(Diplogastrina)Md MAHAMOOD and Irfan AHMAD ∗

Department of Zoology, Aligarh Muslim University, Aligarh 202 002, India

Received: 20 September 2007; revised: 22 September 2008Accepted for publication: 22 September 2008

Summary – Two new species of diplogastrid nematodes from India are described and illustrated. Diplogasteroides uriceus sp. n.has a medium-sized body, monoprodelphic reproductive system lacking a post-uterine sac, anteriorly directed muscular vagina andvulva located far posterior; long, slender, arcuate spicules; gubernaculum with proximal thread-like flexible part and nine pairs ofgenital papillae of which four pairs are precloacal and five pairs postcloacal. The new species resembles D. crassus but can be mosteasily differentiated by the structure of the cheilorhabdions, shape and structure of the gubernaculum, arrangement of the genitalpapillae and the complete absence of a bursa. The new species also resembles D. proprius but can be differentiated by stoma structure,more anteriorly located vulva, longer spicules, gubernaculum shape and tail form. Rhabditidoides papillatus sp. n. is characterisedby the presence of three pairs of post-deirids in the lateral fields, posteriorly curved tubular stoma, amphidelphic female reproductivesystem, strongly developed, arcuate spicules with bilobed capitulum and a slender gubernaculum provided with a sleeve distally andanteriorly directed bifid ends proximally. It can be distinguished from R. stigmatus by the structure of the spicule head, gubernaculumshape and arrangement of the genital papillae; from R. mastigurus by spicule structure and the gubernaculum shape; and from R.quercophilus by a more slender female body, stoma structure, absence of a male bursa, spicule form and arrangement of the genitalpapillae.

Keywords – free-living nematodes, morphology, morphometrics, new species, taxonomy.

De Man (1912) described Diplogasteroides de Man,1912 with D. spengelii de Man, 1912 as its type species.Andrássy (1984) accepted three species under the genusDiplogasteroides and considered Rhabditolaimus Fuchs,1915, Masseyus Paramonov, 1964 and Fuchsnema An-drássy, 1984 as valid genera. Sudhaus (1995) clarifiedthat the type species of Rhabditolaimus was R. halleriand synonymised Fuchsnema with Rhabditolaimus. Later,Sudhaus and Fürst von Lieven (2003) accepted that thetype species of Rhabditolaimus was R. leucarti Fuchs,1914 and not R. halleri Fuchs, 1915, as had been sug-gested by Sudhaus (1995). Nevertheless, they (l.c.) con-sidered Rhabditolaimus Fuchs, 1915, PseudodiplogasterTakaki, 1941, Dirhabdilaimus Paramonov & Turlygina,1955, Diplogasteroides (subgenus NeodiplogasteroidesRühm, 1956), Masseyus and Fuchsnema as synonyms ofDiplogasteroides, accepting 27 nominal species in theprocess. However, Andrássy (2005) distinguished Fuch-

∗ Corresponding author, e-mail: ahmadirfi@gmail.com

snema from Rhabditolaimus by the prodelphic gonad andextreme posterior position of the vulva. We believe that allmonophyletic groups should be placed under one genusand, hence, accept the classification proposed by Sudhausand Fürst von Lieven (2003).

Rahm (1928) proposed Rhabditidoides Rahm, 1928for the species R. longicauda Rahm, 1928. Andrássy(1984) accepted four species under the genus Rhabdi-tidoides, viz., R. mastigurus (Steiner, 1943) Andrássy,1984, R. longicauda, R. longispiculus (Meyl, 1954) An-drássy, 1984 and R. stigmatus (Steiner, 1930) Andrássy,1984. Sudhaus and Fürst von Lieven (2003) moved R.longispiculus to Diplogasteroides, transferred Rhabdito-laimus leptosoma Völk, 1950 and Diplogasteroides quer-cophilus Heindl-Mengert, 1956 to Rhabditidoides andlisted six species under the genus. In the present paperone new species of Diplogasteroides and one of Rhabditi-doides are proposed.

© Koninklijke Brill NV, Leiden, 2009 DOI:10.1163/138855409X12465362560476Also available online - www.brill.nl/nemy 541

M. Mahamood & I. Ahmad

Materials and methods

Nematodes were extracted by sieving and decantationand modified Baermann funnel techniques and fixed inhot 4% formaldehyde solution. Following fixation theywere transferred to glycerin/alcohol (5 parts glycerin : 95parts 30% alcohol) and dehydrated slowly over a periodof 3 weeks in a desiccator. Morphological observationsand drawings were made using an Olympus BX 50 DICmicroscope and photographs taken with an Olympus C5050 digital camera.

Diplogasteroides uriceus* sp. n.(Figs 1, 2)

MEASUREMENTS

See Table 1.

DESCRIPTION

Female

Body tapering gradually anteriorly, more rapidly inpost-vulval region. Cuticle with fine transverse and lon-gitudinal striations. Lateral fields with two lines. Am-phidial apertures oval, at level of gymnostom. Lip region5-7 μm diam., continuous with body contour. Lips six,separate, labial papillae well developed. Stoma long, tubu-lar. Cheilostom cuticularised somewhat barrel-shaped,cheilorhabdial flaps protruding beyond labial contour.Posteriorly, cheilorhabdions overlapping anterior part ofgymnostom. Gymnostom long, tubular, cuticularised,walls anisotopic, dorsal wall shorter than subventrals.Stegostom anisomorphic. Dorsal tooth supported by twopointed smaller teeth at base. Subventral walls lackingtooth, teeth or denticles. Procorpus muscular, median bulbovoid. Isthmus gradually expanding to form ovoid basalbulb. Corpus 56-62% of total pharyngeal length. Nervering encircling isthmus at midpoint. Hemizonid slightlyanterior or at level of nerve ring. Excretory pore lo-cated posterior to hemizonid. Intestinal lumen with darkgranules. Reproductive system monoprodelphic, posteriorbranch completely absent. Ovary reflexed, flexure on rightside of intestine, oocytes small, numerous, arranged inmultiple rows in germinal zone. Oviduct long, narrow,gradually expanding posteriorly to form a spermatheca,

* The specific epithet is derived from the high content of uricacid in the sample from which it was isolated.

mostly filled with sperm. Uterus with muscular and glan-dular regions. Uterine lumen narrow in glandular region.Vagina muscular, anteriorly directed with cuticularised lu-men. Vulva located far posterior; vulval lips slightly orvery strongly protruding; posterior lip usually larger thananterior. Vulva located 0.7-1.2 vulval body diam. fromanus. Phasmids ca one anal body diam. posterior to anus.Rectum 1-2 anal body diam. long. Tail slender, elongate,2.8-5.2 times vulva-anus distance long.

Male

Body smaller than female, strongly curved in posteriorregion in fixed specimens. Anterior region similar to thatof female except for presence of four cephalic setae.Shape and position of amphidial apertures as in female.Testis single, ventral, proliferation zone reflexed on right-hand side of body. Spicules slender, arcuate, 1.8-2.5anal body diam. long. Gubernaculum 39-46% of spiculelength, slender, with sleeve in distal part. Proximally witha thread-like appendage. Nine pairs of genital papillaecomprising four precloacal and five postcloacal pairs.Genital papillae formula: v1, v2, (v3, v4)/ad, ph, (v5, v6,v7), pd. Tail divisible into two parts, a conoid anterior partand a narrower, elongate, posterior section.

TYPE HABITAT AND LOCALITY

Collected from chicken manure in Haldwani, UttarPradesh, India.

TYPE MATERIAL

Holotype female, ten paratype females and ten paratypemales on slides Diplogasteroides uriceus sp. n./1-8; de-posited in the nematode collection of the Department ofZoology, Aligarh Muslim University, Aligarh, India.

DIAGNOSIS AND RELATIONSHIPS

Diplogasteroides uriceus sp. n. is characterised by amedium-sized body; monoprodelphic reproductive sys-tem lacking a post-uterine sac; anteriorly directed mus-cular vagina and posteriorly located vulva; long, slender,arcuate spicules; gubernaculum with proximal thread-likeflexible part and nine pairs of genital papillae, four pairsof which are precloacal and five pairs postcloacal.

The new species resembles D. crassus Körner, 1954in body posture, in having a monoprodelphic gonad,absence of a post-uterine sac, in the general shape ofstoma and in general morphometric values. However, the

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Fig. 1. Diplogasteroides uriceus sp. n. A: Female (entire); B: Male (entire); C: Anterior end (lateral); D: Anterior end (dorsoventral);E: Pharyngeal region; F: Female reproductive system (entire); G: Female anal region; H: Male posterior end showing retractedfilamentous part of gubernaculum; I: Male posterior end showing extended filamentous part of gubernaculum.

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Fig. 2. Diplogasteroides uriceus sp. n. A: Anterior end (dorsal view); B: Anterior end (lateral view); C: Vulva (not protruded); D:Vulva (protruded); E: Male posterior end (arrow indicates straight filamentous part of gubernaculum); F: Male posterior end (arrowindicates curved filamentous part of gubernaculum). (Scale bars: A-F = 20 μm.)

new species can be differentiated by the structure ofthe cheilorhabdions (long and posteriorly overlapping thegymnorhabdions vs small with a distinct space betweencheilorhabdions and gymnorhabdions), shape and struc-ture of the gubernaculum (with a proximal flexible thread-like process and distally with a band-like sleeve vs prox-imal flexible thread absent and sleeve differently shaped)and in the arrangement of the genital papillae (v2 ca half a

spicule length anterior to cloaca and (v3, v4) grouped to-gether precloacally vs v2d only slightly anterior to cloacaand v4 ad-cloacal). In addition, smaller differences oc-cur in female body length (L = 0.68-0.86 mm vs 0.91-1.14 mm), length of spicules (47-54 vs 33-44 μm), femalea ratio (17.7-23.2 vs 14.1-15.6), arrangement of genitalpapillae (v3, v4 pre-cloacal, placed close to each other onthe subventral wall vs v3 lateral and pre-cloacal, v4 post-

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Table 1. Morphometrics of Diplogasteroides uriceus sp. n. and Rhabditidoides papillatus sp. n. Measurements are in μm and in theform: mean ± s.d. (range).

Character Diplogasteroides uriceus sp. n. Rhabditidoides papillatus sp. n.

Female Male Female Male

Holotype Paratypes Paratypes Holotype Paratypes Paratypes

n – 10 10 – 8 10L 834 777 ± 68 675 ± 40 783 856 ± 83 700 ± 66

(687-864) (623-732) (733-952) (627-861)a 19.1 20.2 ± 1.5 22.7 ± 2.2 32.3 29.7 ± 3 29.7 ± 2.7

(17.7-23.2) (19.5-25.9) (26-35) (24.5-34.1)b 5.9 5.6 ± 0.3 5 ± 0.2 5 5.5 ± 0.5 4.9 ± 0.3

(5.1-6.1) (4.6-5.4) (4.6-6.4) (4.5-5.8)c 6.7 6.5 ± 1.1 10.2 ± 1.5 3.8 3.9 ± 0.4 4.1 ± 0.2

(5.3-9.6) (7.7-12.5) (3.5-4.4) (3.6-4.5)c′ 6 8 ± 1.6 2.8 ± 0.7 15 13.7 ± 1.9 8.3 ± 1.2

(4.6-11.2) (2.2-4.5) (10.6-15.6) (6.6-9.7)V 82.2 79.5 ± 2.2 – 42.3 42.5 ± 1.6 –

(76.3-84.4) (41.1-46.5)Max. body diam. 44 38 ± 3 30 ± 3.5 24 29 ± 2 23 ± 2

(36-45) (28-35) (24-31) (21-29)Length of stoma 14 15 ± 0.5 14 ± 0.5 17 18 ± 1 17 ± 1

(15-16) (13-15) (16-19) (16-18)Pharynx 140 138 ± 8 133 ± 8 154 154 ± 10 139 ± 7

(126-151) (121-148) (138-170) (128-149)Excretory pore from anterior end 113 112 ± 8 108 ± 7 117 123 ± 8 114 ± 7

(99-121) (96-114) (110-136) (102-123)Hemizonid from anterior end 108 108 ± 7 102 ± 6 112 118 ± 8 109 ± 6

(98-118) (91-109) (106-131) (98-118)Nerve ring from anterior end 109 106 ± 9 97 ± 6 108 110 ± 7 101 ± 4

(94-108) (87-108) (96-121) (92-107)Median bulb length 18 18 ± 1 17 ± 1 20 20 ± 2 18 ± 1

(16-20) (15-19) (18-25) (16-19)Basal bulb length 20.3 21 ± 2.5 19 ± 1 19 21 ± 2 18 ± 1

(19-25) (17-22) (19-23) (17-19)Anterior gonad length 298 324 ± 40 – 99 116 ± 18 –

(258-367) (92-139)Posterior gonad length – – – 94 113 ± 15 –

(90-138)Vulval body diam. 35 33 ± 3.5 – 24 29 ± 2 –

(27-37) (24-32)Vulva to anus distance 25 37 ± 6 – 247 276 ± 37 –

(21-45) (227-325)Rectum 17 21 ± 3.5 21 ± 2 19 20 ± 2 15 ± 1

(17-27) (17-24) (17-22) (14-17)Tail 123 121 ± 21 67 ± 10 204 216 ± 30 168 ± 17

(73-152) (55-87) (165-252) (147-199)Anal/cloacal body diam. 20 15 ± 1 24 ± 2.5 14 16 ± 1 20 ± 1

(14-17) (19-26) (14-17) (17-24)Phasmids from anus/cloaca 15 14.5 ± 1.5 12 ± 2 19 23 ± 2 24 ± 1

(13-17) (10-16) (19-25) (23-27)

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Table 1. (Continued).

Character Diplogasteroides uriceus sp. n. Rhabditidoides papillatus sp. n.

Female Male Female Male

Holotype Paratypes Paratypes Holotype Paratypes Paratypes

Testis – – 310 ± 25 – – 288 ± 31(274-363) (245-347)

Spicule length (arc) – – 50 ± 2 – – 25 ± 1(47-54) (23-27)

Gubernaculum length – – 21 ± 1 – – 15 ± 1(19-22) (13-17)

cloacal) and in the form of the male tail (complete absenceof bursa vs presence of sub-terminal bursa).

The new species also resembles D. proprius (Andrássy,1973) Sudhaus & Fürst von Lieven, 2003, which was alsocollected from a chicken house, in a value, body length,shape of spicules and arrangement of genital papillae.However, the present species can be differentiated fromD. proprius by the structure of stoma (cheilostom over-lapping gymnostom vs no overlap, dorsal tooth present ona prominent bulge vs stegostomal bulge not prominent),position of vulva (V = 76-84 vs 87-88), length of spicules(47-54 vs 40 μm), shape of gubernaculum (with a distalsleeve vs without) and in the shape and length of the fe-male tail (elongate slender vs conoid, c = 5.3-9.6 vs 17-18).

Rhabditidoides papillatus* sp. n.(Figs 3, 4)

MEASUREMENTS

See Table 1.

DESCRIPTION

Female

Body almost straight in fixed specimens, tapering to-wards both extremities. Cuticle with fine transverse andlongitudinal striations. Cuticular surface divided intoblocks. Punctations present, arranged in both transverseand longitudinal rows. Lateral fields with three lines.Deirids at level of nerve ring or slightly posterior. Threeadditional pairs of post-deirids present – first pair slightly

* The specific epithet refers to the presence of post-deirids in thelateral fields.

posterior to level of cardia, second pair far posterior tovulva at level of ovary of posterior gonad and third slightlyanterior to level of rectum. Lip region continuous withbody contour. Lips fused, labial papillae small, protrud-ing only slightly from labial contour. Amphidial aper-tures oval, at junction of cheilostom and gymnostom.Stoma tubular, longer than wide, ventro-dorsally curvedin posterior region. Cheilorhabdions weakly cuticularised,cheilorhabdial flaps extending up to anterior end. Gym-nostom anisotopic and anisomorphic, subventral wallsmore strongly curved and longer than dorsal. Stegostomanisomorphic, dorsal wall with large, ventrally directed,flap-like tooth, surface weakly cuticularised. Subventralwalls plate-like, without armature. Procorpus muscular,median bulb with large valve plates. Isthmus long, basalbulb ellipsoidal. Corpus 60-66% of pharyngeal length.Nerve ring encircling isthmus in mid-region or in ante-rior half. Hemizonid at level of nerve ring with excretorypore located slightly posterior to hemizonid. Intestinalcells large, granular, lumen generally narrow. Reproduc-tive system amphidelphic, anterior branch on right, pos-terior on left side of intestine. Ovaries reflexed, oocytesarranged in more than one row in germinal zone. Oviductnarrow, spermatheca irregularly lobular in form, gener-ally wider than uterus, offset. Uterus with glandular andmuscular parts. Vagina thick-walled, almost half vulvalbody diam. Vulval opening circular, radially ridged. Rec-tum 1.0-1.8 anal body diam. long. Phasmids situated 1.2-1.8 anal body diam. from anus. Tail long, filiform, 0.6-0.9times vulva-anus distance long.

Male

Body strongly curved in posterior region. Anteriorregion similar to that of female except for four smallcephalic papillae. Testis ventral, flexure on right-handside of body. Spicules well developed, arcuate, capitulum

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Fig. 3. Rhabditidoides papillatus sp. n. A: Male (entire); B: Female (entire); C: Female showing position of post-deirids; D: Anterior end(dorsoventral); E: Anterior end (lateral); F: Pharyngeal region; G: Female reproductive system (anterior tract); H: Female posteriorend; I: Male posterior end.

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Fig. 4. Rhabditidoides papillatus sp. n. A: Anterior end (lateral); B: Anterior end (dorsoventral); C: Lateral field (arrows indicatepost-deirids); D: Lateral lines; E: Female reproductive system (anterior tract); F: Vulva; G: Female posterior end; H: Male posteriorend. (Scale bars: A-C, E-H = 20 μm; D = 30 μm.)

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bilobed. Gubernaculum slender, proximal end anteriorlydirected, bifid, 46-61% of spicule length. Sleeve present atdistal end. Nine pairs of genital papillae comprising threepairs precloacal, six pairs postcloacal. Genital papillaeformula: v1, v2, v3d/v4, (ad, v5, v6, ph), pd, v7. Genitalpapillae v1, v2 within range of retracted spicules. GP v4far posterior to cloaca. Phasmids situated posterior to v6and v7 at junction of conoid and filamentous parts of tail.Tail comprising two parts; a short conoid part and a longfilamentous section.

TYPE HABITAT AND LOCALITY

Farmyard manure from Gursai, Mendhar, Poonch,Jammu and Kashmir, India.

TYPE MATERIAL

Holotype female, eight paratype females and ten para-type males on slides Rhabditidoides papillatus sp. n./1-8;deposited in the nematode collection of the Department ofZoology, Aligarh Muslim University, Aligarh, India.

DIAGNOSIS AND RELATIONSHIPS

Rhabditidoides papillatus sp. n. is characterised by,in addition to the deirids, the presence of three pairs ofpost-deirids in the lateral fields, posteriorly curved tubu-lar stoma, lobular uterus, arcuate spicules with bilobed ca-pitulum, slender gubernaculum with a distal sleeve andanteriorly directed bifid proximal ends and nine pairs ofgenital papillae.

The new species resembles R. stigmatus in body mor-phometrics, general shape of stoma and number of geni-tal papillae. However, the new species can be differenti-ated by the structure of spicule head (bilobed vs round),shape of gubernaculum (narrow with anteriorly directedproximal bifid ends vs broad with anteriorly curved fineproximal end) and arrangement of the genital papillae(two pairs vs three pairs precloacal; GP v4 far posteriorto cloaca vs GP v4 just posterior to cloaca). Post-deiridshave not been reported in R. stigmatus and therefore theirpresence or absence needs to be confirmed.

The present species also resembles R. mastigurus inmorphometric values but can be differentiated from itin the spicule structure (head bilobed vs round) and inthe shape of gubernaculum (proximally bifurcate vs notbifurcate; distal sleeve present vs absent). The pharyngealcollar shown in the diagram of Steiner (1943) is doubtful.

It further resembles R. quercophilus (Heindl-Mengert,1956) Sudhaus & Fürst von Lieven, 2003 in body length

and morphometric values and in gubernaculum shape.However, it can be differentiated by a more slender femalebody (a = 26-35 vs 15), stoma structure (cheilostom andgymnostom without any thickening vs both cheilostomand gymnostom with a thickening), male tail lacking arudimentary bursa vs rudimentary bursa present, shapeand form of spicules (head bilobed vs round; blade slenderwith a blunt distal tip vs blade broad proximally, slenderdistally with a finely pointed tip) and in the arrangementof the genital papillae (v2 and v3d far from each other vsv2 and v3d nearly at same level).

Acknowledgement

Financial assistance from the Ministry of Environmentand Forests, Government of India, New Delhi throughAICOPTAX is gratefully acknowledged.

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