Description of five new and six known species of the genus Basirotyleptus Jairajpuri, 1964 (Nematoda: Dorylaimida: Tylencholaimoidea) from the Western Ghats, India

Five new and six known species belonging to the genus Basirotyleptus collected from the Western Ghats, India, are described and illustrated. Basirotyleptus conicaudatus sp. nov. is characterized by having 0.42–0.44 mm long body; odontostyle 9.5–10.0 μm, odontophore 11.5–12.0 μm; pharyngeal bulb pear-shaped, 14–15% of total neck length; female genital system mono-opisthodelphic; tail conoid with acute terminus. Basirotyleptus constrictus sp. nov. is characterized by having 0.38–0.49 mm long body; perioral disc distinct; odontostyle 9–10 μm, odontophore 14–15 μm; pharyngeal bulb pear-shaped, 15–17% of total neck length; female genital system mono-opisthodelphic; tail rounded to conoid. Basirotyleptus goaensis sp. nov. is characterized by having 0.73–0.87 mm long body; odontostyle 13.0–14.5 μm, odontophore 15.0–17.5 μm; pharyngeal bulb pyriform, 16–18% of total neck length; female genital system mono-opisthodelphic; tail rounded. Basirotyleptus neocaudatus sp. nov. is characterized by having 0.31–0.44 mm long body; odontostyle 7.5–9.5 μm, odontophore 10–13 μm; pharyngeal bulb pear-shaped, 14–19% of total neck length; female genital system monoopisthodelphic; tail conoid with acute terminus. Basirotyleptus siddiqii sp. nov. is characterized by having 0.36 mm long body; odontostyle 7.5–8.0 μm, odontophore 10.0–10.5 μm; pharyngeal bulb pear-shaped, 15–16% of total neck length; female genital system mono-opisthodelphic; tail conoid. Six known species viz., B. basiri, B. pini, B. nindei, B. ethiopicus, B. acus, B. minutus are also described and illustrated. Along with light microscopic study, line drawings, compendium and key to species of Basirotyleptus are also provided.


Introduction
The genus Basirotyleptus is a soil-inhabiting nematode taxon proposed by Jairajpuri (1964) with B. basiri as its type species from Assam, India, under the family Leptonchidae Thorne, 1964. Simultaneously, Siddiqi & Khan (1964) proposed a genus Trichonchium with Trichonchium archium as its type species and T. eximium another species also from Assam, India. Thorne (1964) in his monographic work proposed two new genera Belonenchus with B. penetrans and Poncenema with P. striata as type species from Puerto Rico.  synonymized Trichonchium archium Siddiqi & Khan, 1964 with B. basiri hence the genus Trichonchium became a junior synonym of Basirotyleptus due to priority of publications of the later. They  added two more species B. pini and B. coronatus from India and also provided a key for the identification of species. Sauer (1966, from Australia), Jairajpuri (1966, from India) and Hussain & Khan (1968, from India) added a species each to this genus. Siddiqi (1969) synonymized the genera Belonenchus Thorne, 1964and Poncenema Thorne, 1964with Basirotyleptus and Siddiqi (1970 added five new species and also revised the key for identification of species. Goseco et al. (1974) restudied the type material of all the known species, added two new species, B. lieberi and B. acus from Indiana, and also provide a key for the identification of species. Ahmad & Jairajpuri (1979) further added two new species B. upicus and B. soueastus from India and Malaysia respectively, whereas, Jana & Baqri (1981) added a new species B. minimus from India. Siddiqi (1982Siddiqi ( , 1983 proposed two new genera Coronatyleptus and Aculonchus from Colombia with several species and transferred Basirotyleptus bunocephalus Siddiqi, 1970 to the genus Glochidorella Siddiqi, 1982 based on the presence of basal knobs of the odontophore. Khan (1987) further added a species B. minutus from India. Jairajpuri & Ahmad (1992) in their monographic work synonymized Coronatyleptus and Aculonchus with Basirotyleptus and split the genus into five subgenera viz., Coronatyleptus, Aculonchus, Trichonchium, Opisthotyleptus and Basirotyleptus, on the basis of presence or absence of labial disc, flanges at the base of odontophore and female genital system to facilitate proper grouping and easy identification. Siddiqi (1995) added several new species from Tropical rain forests of Colombia and Cameroon and Siddiqi (1997) added a species from West Indies. Dhanam & Jairajpuri (1999) added a new species B. indicus from India. Peña-Santiago (2006) accepted Aculonchus Siddiqi, 1982 as a separate genus but did not accept the subgenera as proposed by Jaiarjpuri & Ahmad (1992). Andrássy (2009) in his book not only accepted Aculonchus as a valid genus but also considered Trichonchium as separate genus from Basirotyleptus with T. eximium (Siddiqi & Khan, 1964) as its type because of the presence of prodelphic female genital system. However, Trichonchium has not been considered here as a valid genus. Jairajpuri & Ahmad (1992) doubted the validity of the genus Punctoleptus Khan, 1987 and considered it a possibly synonym of Basirotyleptus which Andrássy (2009) finally synonymized it with the later. An action which is fairly acceptable here.
In the ongoing study on the nematode fauna of Western Ghats of India, several populations representing the genus Basirotyleptus were collected from different localities. On detailed study, they were found to represent five new and six known species, which are described in this paper.

Material and methods
During the course of present study, the soil samples were collected from different localities of the Western Ghats of India. The nematodes were extracted from soil samples following Cobb's (1918) sieving and decantation and modified Baermann's funnel techniques. The extracted nematodes were fixed in hot triethanolamine-glycerol fixative, dehydrated by the slow evaporation method (Seinhorst 1959), and mounted in anhydrous glycerine. Permanent mounts were prepared using the paraffin wax ring method (de Maeseneer & d'Herde 1963). The measurements were taken using an ocular micrometer, line drawings were made using a drawing tube, and photographs were taken with a Nikon DS digital Camera attached with Nikon Eclipse 80i microscope. Raw photographs were edited using Adobe ® Photoshop ® .
Type and others specimens are deposited in the nematode collection of the Department of Zoology, Aligarh Muslim University (AMU/ZD/NC), as well as in the nematode collection of the Zoological Survey of India, Kolkata, India.
List of abbreviations a = body length / greatest body diameter b = body length / neck length c = body length / tail length c' = tail length / body diameter at anus or cloaca G1 = length of anterior genital branch × 100 / body length G2 = length of posterior genital branch × 100 / body length L = total body length n = number of specimens V = distance of vulva from anterior end × 100 / body length

Male
General morphology similar to that of female except for posterior region being more ventrally curved. Genital system diorchic, testes opposed, sperm cell spindle-shaped. In addition to adcloacal pair situated at 6 µm from cloacal aperture, there is single ventromedian supplement located at 25 μm from adcloacal pair, beyond the range of spicules. Spicules typically dorylaimoid, curved ventrad, slightly robust, 5.0 times as long as wide and 1.3 times as long as cloacal body diameter, dorsal contour regularly convex, ventral contour bearing a moderately developed hump and hollow, curvature 132º, head occupying 20% of total spicules length, median pieces 10.6 times as long as wide or occupying about 37% of the spicules maximum width, reaching the spicules tip, posterior end 2.5 μm wide. Lateral guiding pieces distinct, rod-like, about 5.0 times as long as wide or about one-fourth of the spicules length. Prerectum 3.0 and rectum 1.4 times cloacal body diameter long. Tail short rounded to conoid, about as long as the cloacal body diameter, with a pair of caudal pores on each side. Jairajpuri (1964) proposed the genus Basirotyleptus with B. basiri as its type species from Jorhat, Assam, India. Siddiqi & Khan (1964 recorded this species from Assam and Madhya Pradesh respectively. Furstenberg (1980) described this species from Malaysia, whereas, Shamim et al. (2014) from Pakistan. The morphometrics of present populations conform well with the type population except in having slightly lower c (35-47 vs 45-58) ratio and presence of male (vs absent). The present populations also conform well with Siddiqi & Khan (1964) population except in having slightly shorter body (0.45-0.54 vs 0.59-0.67 mm); lower b (4.0-4.9 vs 5.4-6.4) and c (36-47 vs 47-56) ratios and presence of male (vs absent). The present specimens also conform well with Madhya Pradesh population described by  except in having short and robust body (0.45-0.54 vs 0.68-0.71 mm, a = 22-29 vs 29-31); slightly shorter odontostyle (10.5-12 vs 13-14 µm); lower b (4.0-4.9 vs 6.3-6.5) and c (36-47 vs 58-61) ratios and smaller spicules (20 vs 25-26 µm). The morphometrics of present populations agree well with the Malaysia population except in having slightly longer odontostyle (10.5-12.0 vs 7 9.3-10.5 µm); longer rectum (11.5-20.0 vs 10-11 µm) and presence of male (vs absent). The present populations conform well with the Pakistan population except in having shorter body (0.45-0.54 vs 0.63-0.78 mm); lower b (4.0-4.9 vs 5.0-6.8), lower c (35-47 vs 56-69) ratios and slighter higher c' (0.7-1.0 vs 0.5-0.7) ratio. These differences are considered here as intraspecific variability. This species is recorded here for the first time from the Western Ghats.  Fig. 2, Table 2 Basirotyleptus pini Siddiqi & Khan, 1965: 641-645.

Description
Female Small sized nematodes, slightly curved ventrad or open C-shaped upon fixation; tapering gradually towards both extremities but more so towards anterior end. Cuticle with two distinct layers, 1.0-1.5 µm thick at anterior region, 2.0-2.5 µm at midbody and 2.5-3.5 μm on tail. Outer cuticle thin, smooth or with very fine transverse striations; inner layer thick, its outline irregular, loose, finely striated, with radial refractive elements. Lateral chords occupying about 30-35% of midbody diameter. Lateral body pores distinct; 1-2 in neck region; 2-3 at neck to vulval region and 5-9 at post-vulval region. Dorsal and ventral body pores indistinct. Lip region cap-like, offset by deep constriction, 2.1-2.5 times as wide as high or about two-fifths to one-half of the body diameter at neck base. Lips rounded, amalgamated, angular, projected, inner part elevated. Labial and cephalic papillae distinct and slightly raised above the labial contour. Amphids stirrup-shaped, their aperture about one-half to three-fifths as wide as lip region diameter. Stoma a long, slender truncate cone, slightly sclerotized in the perioral region. Odontostyle slender, solid, needle-like, 1.3-1.5 times the lip region diameter long. Odontophore simple, sclerotized, slightly swollen at base surrounded by pharyngeal tissue, 1.0-1.1 times the odontostyle length. Guiding ring simple, refractive, at 1.2-1.3 times the lip region diameter from anterior end. Pharynx consisting of a slender anterior part, expanding gradually into a short, pear-shaped basal bulb, with a perceptible thickening at the posterior part of its inner lining, occupying about 14-17% of total neck length. Nerve ring at 50-59% of neck length from anterior end. Cardia short, rounded to conoid, about one-fifth to one-third of the corresponding body diameter long.

Remarks
In the presence of simple odontophore and anterior uterine sac, this species also comes close to Basirotyleptus basiri Jairajpuri, 1964 but differs in having outer and inner cuticle finely striated (vs distinctly striated), lip region offset by deep constriction (vs slight constriction) and shorter anterior uterine branch (two-fifths to two-thirds vs always more than midbody diameter long). Siddiqi, 1970 Fig. 3, Table 3 Basirotyleptus nindei Siddiqi, 1970: 203-205.

Description
Female Small sized nematodes, slightly curved ventrad upon fixation; tapering gradually towards both extremities but more so towards anterior end. Cuticle with two distinct layers, 1.0-1.5 µm thick at anterior region, 2.0-2.5 µm at midbody and 2.5-3.0 μm on tail. Outer cuticle thin with transverse striation, inner layer thick, distinctly striated, loose, its outline irregular, with distinct radial refractive elements. Lateral chords occupying about 30-35% of midbody diameter. Lateral body pores distinct; 1-2 in neck region; 1-2 from pharyngeal base to vulva; 4-7 in post-vulval region. Dorsal and ventral body pores indistinct. Lip region cap-like, offset by slight constriction, 1.8-2.1 times as wide as high or about one-third to two-fifths of the body diameter at neck base. Lips rounded, amalgamated; inner part elevated, forming a perioral disc. Labial and cephalic papillae distinct but not interfering with labial contour. Amphids duplex, stirrup-shaped, their aperture about one-half to three-fifths as wide as lip region diameter. Stoma Rectum length 14.4 ± 1.8 (12.5-18.5) Tail length 9.5 ± 0.68 (9.0-11) a long, slender truncate cone, slightly sclerotized in the perioral region. Odontostyle very slender, solid, thin needle-like, 1.4-1.8 times the lip region diameter long. Odontophore simple, sclerotized, about 1.0-1.2 times the odontostyle length. Guiding ring simple, refractive, at 1.0-1.3 times the lip region diameter from anterior end. Pharynx consisting of a slender anterior part, expanding abruptly into a short, pear-shaped basal bulb, with a perceptible thickening at the posterior part of its inner lining, occupying about 13-16% of total neck length. Nerve ring at 55-62% of neck length from anterior end. Cardia short, rounded to conoid, about one-fourth to one-third of the corresponding body diameter long.

Not found.
Remarks Siddiqi (1970) described B. ethiopicus from the Malawi. Goseco et al. (1974) in their revision of the genus Basirotyleptus made a detailed study of the type material and added a population from Indiana. The morphometrics of present populations conform well with the type population as well as Indiana population except in having slightly wider lip region (6.0-7.5 vs 5.0-6.0 µm); narrower lateral chords (30-35% vs more than 50% of mid body diameter) and slight differently shaped cardia (rounded to conoid vs rounded). These slight differences are considered as intraspecific variability. This species is reported here for the first time from the India.

Description
Female Small sized nematodes, slightly curved ventrad or open C-shaped upon fixation; body cylindrical, tapering gradually towards both extremities but more so towards the anterior end. Cuticle with two distinct layers, 1.0-1.5 µm thick at anterior region, 1.5-2.0 µm at midbody and 2.0-2.5 μm on tail. Outer cuticle thin, with fine transverse striations; inner layer thick, striated, loose, its outline irregular, with distinct radial refractive elements. Lateral chords occupying about 28-35% of midbody diameter. Lateral body pores distinct; 1-3 in neck region; 1-2 from pharyngeal base to vulva and 3-8 post-vulval region. Dorsal and ventral body pores indistinct. Lip region cap-like, offset by constriction, 2.0-2.3 times as wide as high or about one-third to two-fifths of the body diameter at neck base. Lips rounded, amalgamated; inner part slightly elevated. Labial and cephalic papillae distinct but not interfering with labial contour. Amphids duplex, stirrup-shaped, their aperture about one-half to three-fifths as wide as lip region diameter. Stoma a long, slender truncate cone, slightly sclerotized in the perioral region. Odontostyle very slender, solid, thin needle-like, sometimes slightly dorsally bent, 1.2-1.6 times the lip region diameter long. Odontophore simple, sclerotized, about 1.0-1.1 times the odontostyle length. Guiding ring simple, refractive, at 1.2-1.4 times the lip region diameter from anterior end. Pharynx consisting of a slender and slightly muscular anterior part, expanding gradually into a short pear-shaped basal bulb, with a perceptible thickening at the posterior part of its inner lining, occupying about 14-18% of total neck length. Nerve ring at 51-60% of neck length from anterior end. Cardia rounded to conoid, about one-fifth to one-fourth of the corresponding body diameter long.

Male
Not found. Goseco et al. (1974) described this species from the Indiana. The morphometrics of present populations conform well with the type population except in having a slightly longer odontostyle (10.0-11.5 vs 8 µm), slightly shorter odontophore (11-13 vs 14.4 µm); shorter pharyngeal bulb (15-20 vs 22 µm); longer vagina (8.5-11.5 vs 13 µm) and presence of anterior uterine sac in some specimens (vs anterior uterine sac absent). This species is reported here for the first time from India.

Remarks
During the present study, two populations representing eighteen specimens were collected from the Western Ghats, India. Although in some specimens of the present populations a very small anterior uterine sac was present, other morphometric values completely overlapped to with those in B. acus, and therefore these specimens are considered as B. acus. Furstenberg (1980) redescribed B. pini  based on two populations comprising twenty eight females from Australia and mentioned that Australian specimens correspond well with European Journal of Taxonomy 791: 1-57 (2022) 20 type population of B. pini except for the absence of anterior uterine sac in some specimens. Some doubt exists on the correct identity of the Australian population as it shows some morphological differences i.e., differently shaped odontostyle (odontostyle very slender, thin needle-like vs slender, simple needle-like); differently shaped lip region (lip region low, flat, offset by slight constriction vs lip region comparatively higher, angular, offset by deep constriction), labial papillae not interfering with labial contour (vs labial papillae interfering with labial contour, forming a liplets-like structure), and absence of anterior uterine sac in some specimens (vs anterior uterine present in every specimen). The morphometrics of Furstenberg (1980) population is quite comparable to B. acus except in the presence of anterior uterine sac in some specimens (vs absent in the type population). With the addition of present populations, which have specimens both with or without sac, B. pini apud Furstenberg, 1980 is considered here as B. acus. Khan, 1987 Figs 6-7, Table 6 Basirotyleptus minutus Khan, 1987: 177-179.

Description
Female Small sized nematodes, slightly curved ventrad upon fixation; body cylindrical, tapering gradually towards both extremities but more so towards the anterior end. Cuticle with two distinct layers, 1.0 µm thick at anterior region, 1.5 µm at midbody and 2.0-2.5 μm on tail. Outer cuticle thin, with fine transverse striations; inner layer thick, finely striated, loose, with radial refractive elements. Lateral chords occupying about 26-30% of midbody diameter. Lateral, dorsal and ventral body pores indistinct. Lip region cap-like, offset by constriction, 2.3 times as wide as high or about one-third of the body diameter at neck base. Lips rounded, amalgamated, slightly angular; inner part slightly elevated. Amphids duplex, cup-shaped, their aperture about one-half to three-fifths as wide as lip region diameter. Stoma a long, slender truncate cone, slightly sclerotized in the perioral region. Odontostyle slender, solid, needlelike, 1.4 times the lip region diameter long. Odontophore simple, sclerotized, with basal flanges, about 1.3-1.4 times the odontostyle length. Guiding ring simple, refractive, at 1.3 times the lip region diameter from anterior end. Pharynx consisting of a slender anterior part, expanding abruptly into a short pyriform bulb, with a perceptible thickening at the posterior part of its inner lining, occupying about 18% of total neck length. Nerve ring at 52-55% of neck length from anterior end. Cardia rounded to hemispheroid, about one-fourth of the corresponding body diameter long.
Genital system monodelphic-opisthodelphic. Ovary reflexed, measuring 43-59 μm; oocytes arranged in single row except near tip. Oviduct joining the ovary subterminally, measuring 55-84 μm, consisting of a slender distal portion and a well-developed pars dilatata. Oviduct-uterus junction marked by distinct sphincter. Uterus a short tube with wide lumen, measuring 27-30 μm. Anterior genital branch reduced to a very small sac, about one-fifth midbody diameter long. Sperm cell absent. Vagina cylindrical, extending inwards, 10.0-10.5 μm or about one-half (50-55%) of midbody diameter; pars proximalis vaginae 6.5 × 4.5-5.0 μm, encircled by circular muscles; pars distalis vaginae 4.0 μm with slightly curved walls; pars refringens absent. Vulva apparently a transverse slit. Prerectum 3.1-3.2 and rectum 0.9-1.0 times anal body diameter long. Tail short, rounded to conoid, 0.8 times anal body diameter long, with a pair of caudal pores on each side.   Tail length 10, 10 Male Not found. Khan (1987) described Basirotyleptus minutus from Tamil Nadu, India. The morphometrics of present specimens conform well with the type population except in having differently shaped amphids (duplex, cup-shaped vs simple, stirrup-shaped) and slightly longer pharyngeal bulb (19-20 vs 16 µm). In original description of B. minutus, the size of odontostyle (10-14 µm) and odontophore (8.0-10.0 µm) does not correspond with the figure (Khan 1987: fig. 2b, e). The figure depicts the odonotostyle as shorter than the odontophore which is generally true with other Basirotyleptus species. There might be error in his measurements. In our present specimens the length of odontostyle (10 µm) is shorter than odontophore (13-14 µm) with a combined length of 23-24 µm, which overlaps with type population (18-24 µm). However, in the other characters the present population agrees well with the type population.

Etymology
The new species is named Basirotyleptus conicaudatus sp. nov. because of its conoid tail.

Type habitat and locality
Soil samples collected from around the roots of shrubs (unidentified) from Chalakudy, Thrissur, Kerala State.

Female
Small sized nematodes, curved ventrad upon fixation; body cylindrical, tapering gradually towards both extremities but more so towards the anterior end. Cuticle with two distinct layers, 1.0 µm thick at anterior region, 1.5 µm at midbody and 2.0 μm on tail. Outer cuticle thin, smooth to finely transversaly striated; inner layer thick, loose, finely striated, radial refractive elements distinct. Lateral chords occupying about 28-30% of midbody diameter. Lateral, dorsal and ventral body pores indistinct. Lip region caplike, offset by constriction, 2.0-2.1 times as wide as high or about two-fifths of the body diameter at neck base. Lips rounded, amalgamated, inner part slightly elevated. Labial and cephalic papillae distinct but not interfering with labial contour. Amphids stirrup-shaped, their aperture about three-fifths as wide as lip region diameter. Stoma a long, slender truncate cone, slightly sclerotized in the perioral region. Odontostyle short, slender, solid, needle-like, 1.1-1.2 times the lip region diameter long. Odontophore simple, sclerotized, with basal flanges, about 1.2 times the odontostyle length. Guiding ring simple, refractive, at 0.9-1.0 times the lip region diameter from anterior end. Pharynx consisting of a slender anterior part, expanding abruptly into a short, pear-shaped basal bulb, with a perceptible thickening at the posterior part of its inner lining, occupying about 14-15% of total neck length. Nerve ring at 53-56% of neck length from anterior end. Cardia rounded to conoid, about one-fifth of the corresponding body diameter long.

Male
General morphology similar to that of female except for posterior region being more ventrally curved. Genital system diorchic, testes opposed, sperm cell spindle-shaped. In addition to adcloacal pair at 6.5 µm from cloacal aperture, there is single ventromedian supplement located beyond the range of spicules, 25 μm from adcloacal pair. Spicules typically dorylaimoid, curved ventrad, slender, five times as long as wide and 1.4 times as long as cloacal body diameter, dorsal contour regularly convex, ventral contour bearing a moderately developed hump and hollow, curvature 135º, head occupying 22% of total spicules length, median pieces about ten times as long as wide or occupying 37% of the spicules maximum width, reaching the spicules tip, posterior end 2.5 μm wide. Lateral guiding pieces distinct, rod-like, about 5.0 times as long as wide or about one-fourth of the spicules length. Prerectum 3.5 and rectum 1.5 times cloacal body diameter long. Tail short, convex-conoid with acute terminus, 1.2 times cloacal body diameter long, with a pair of caudal pores on each side.

Etymology
The new species is named Basirotyleptus constrictus sp. nov. because of its pharyngeal bulb separated by constriction.

Type habitat and locality
Soil samples collected from around the roots of shrubs and forest trees (unidentified) from Bhagamandala, Kodagu, Karnataka State.

Description Female
Small sized nematodes, slightly curved ventrad or open C-shaped upon fixation, tapering gradually towards both extremities but more so towards anterior end. Cuticle with two distinct layers, 1.0-1.5 µm thick at anterior region, 1.5-2.0 µm at midbody and 2.0-2.5 μm on tail. Outer cuticle thin, with fine transverse striations; inner layer thick, finely striated, loose, its outline irregular, with distinct radial refractive elements. Lateral chords occupying about 25-30% of midbody diameter. Lateral, dorsal and ventral body pores indistinct. Lip region cap-like, offset by constriction, 1.8-2.1 times as wide as high or about two-fifths to one-half of the body diameter at neck base. Lips rounded, amalgamated; inner part elevated, forming a perioral disc-like structure. Labial and cephalic papillae clear but not interfering with labial contour. Amphids stirrup-shaped, their aperture about one-half to three-fifths as wide as lip region diameter. Stoma a long, slender truncate cone, slightly sclerotized in the perioral region. Odontostyle slender, solid, needle-like, 1.2-1.3 times the lip region diameter long. Odontophore simple with basal flanges, about 1.4-1.6 times the odontostyle length. Guiding ring simple, refractive, at 1.0-1.2 times the lip region diameter from anterior end. Pharynx consisting of a slender and slightly muscular anterior part, expanding abruptly into a short, pear-shaped basal bulb, with a perceptible thickening at the posterior part of its inner lining, occupying about 15-17% of total neck length, two parts separated    (12.5-16.5) Tail length 16.5 16.4 ± 1.3 (15.0-18.0) by constriction. Nerve ring at 56-60% of neck length from anterior end. Cardia short, rounded to conoid, about one-fifth to one-third of the corresponding body diameter long.

Etymology
The new species is named Basirotyleptus goaensis sp. nov. because of its type locality Goa.

Type habitat and locality
Soil samples collected from around the roots of shrubs and forest trees (unidentified) from Madgaon, Goa State.

Female
Small sized nematodes, slightly curved ventrad or open C-shaped upon fixation; body cylindrical, tapering gradually towards both extremities but more so towards the anterior end. Cuticle with two distinct layers, 1.0-1.5 µm thick at anterior region, 2.0-2.5 µm at midbody and 2.5-3.0 μm on tail. Outer cuticle thin, finely striated, with distinct rows of punctations; inner layer thick, finely striated, loose, its outline irregular, with distinct radial refractive elements but more so towards posterior region. Lateral chords occupying about 24-32% of midbody diameter. Lateral body pores distinct; 1-3 in neck region; 2-3 from pharyngeal base to vulva; 3-7 in post-vulval region. Dorsal and ventral body pores indistinct. Lip region cap-like, offset by deep constriction, 2.0-2.2 times as wide as high or about onethird of the body diameter at neck base. Lips rounded, slightly angular, separated, inner part elevated. Labial and cephalic papillae distinct and slightly raised above the labial contour. Amphids large, duplex, cup-shaped, their aperture about three-fifths to two-thirds as wide as lip region diameter. Stoma a long, slender truncate cone, slightly sclerotized in the perioral region. Odontostyle slender, solid, needlelike, 1.5-1.6 times the lip region diameter long. Odontophore simple, sclerotized, about 1.1-1.2 times the odontostyle length. Guiding ring simple, refractive, at 1.2-1.3 times the lip region diameter from anterior end. Pharynx consisting of a slender anterior part, expanding gradually into a short pyriform bulb, with a perceptible thickening at the posterior part of its inner lining, occupying about 16-18% of total neck length. Nerve ring at 56-60% of neck length from anterior end. Cardia rounded to conoid, about one-seventh to one-fifth of the corresponding body diameter long.

Etymology
The new species is named Basirotyleptus neocaudatus sp. nov. because of its tail close to B. caudatus.

Type habitat and locality
Soil samples collected from around the roots of grasses (unidentified) from Ranipuram National Park, Kasaragad district, Kerala State.

Other habitat and localities
Soil samples collected from around the roots of grasses (unidentified) from Mukkali forest, Palakkad district and from Muttam, Idukki district, Kerala State.

Female
Small sized nematodes, slightly curved ventrad or open C-shaped upon fixation; body cylindrical, tapering gradually towards both extremities but more so towards the anterior end. Cuticle with two distinct layers, 1.0-1.5 µm thick at anterior region, 1.5-2.0 µm at midbody and 2.0-2.5 μm on tail. Outer cuticle thin, with fine transverse striations; inner layer thick, its outline loose, irregular, distinctly striated, with distinct radial refractive elements. Lateral chords occupying about 25-35% of midbody diameter. Lateral body pores distinct; one at odontostyle-odontophore region; 1-2 in neck region; 2-3 at neck to vulval region and 3-9 at post-vulval region. Dorsal and ventral body pores indistinct. Lip region cap-like, offset by constriction, 2.0-2.3 times as wide as high or about two-fifths of the body diameter at neck base. Lips slightly angular, separated, inner part slightly elevated. Labial and cephalic papillae distinct but not interfering with labial contour. Amphids stirrup-shaped, their aperture about one-half to three-fifths as wide as lip region diameter. Stoma a long, slender truncate cone, slightly sclerotized in the perioral region. Odontostyle slender, solid, needle-like, 1.0-1.4 times the lip region diameter long. Odontophore simple, sclerotized, slightly swollen at base surrounded by pharyngeal tissue, 1.2-1.5 times the odontostyle length. Guiding ring simple, refractive, at 1.1-1.4 times the lip region diameter from anterior end. Pharynx consisting of a slender anterior part, expanding abruptly into a short pearshaped basal bulb, with a perceptible thickening at the posterior part of its inner lining, occupying about 14-19% of total neck length. Nerve ring at 49-64% of neck length from anterior end. Cardia rounded to conoid, about one-sixth to one-third of the corresponding body diameter long.

Male
General morphology similar to that of female except for posterior region being more ventrally curved. Genital system diorchic, testes opposed, sperm cell spindle-shaped. In addition to adcloacal pair at 7 µm from cloacal aperture, there are two irregularly spaced ventromedian supplements, first one located beyond the range of spicules, 19 μm from adcloacal pair and second 15 µm from first. Spicules typically dorylaimoid, curved ventrad, slightly robust, 5.3 times as long as wide and 1.2 times as long as cloacal body diameter, dorsal contour regularly convex, ventral contour bearing a moderately developed hump and hollow, curvature 129º, head occupying 13% of total spicules length, median pieces 12 times as long as wide or occupying 35% of the spicules maximum width, reaching the spicules tip, posterior end 2 μm wide. Lateral guiding pieces distinct, rod-like, about 5.5 times as long as wide or about one-fourth of the spicules length. Prerectum 3.7 and rectum 1.4 times cloacal body diameter long. Tail convex-conoid with acute terminus, about one cloacal body diameter long, with a pair of caudal pores on each side.

Remarks
In the presence of a short body and conoid tail with acute terminus, the new species comes close to B. caudatus Jairajpuri, 1966 and B. conicaudatus sp. nov. but, differs from the former in the absence of liplets (vs present); differently shaped amphids (stirrup-shaped vs cup-shaped); shorter odontostyle (7.5-9.5 vs 12 µm); odontophore longer than odontostyle (vs odontophore shorter than odontostyle, about one-half as long as odontostyle length) and presence of male (vs male absent).

Etymology
The new species is named after late Dr Mohammad Rafiq Siddiqi in recognition of his contribution to nematode taxonomy.

Type habitat and locality
Soil samples collected from around the roots of shrubs (unidentified) from Naduvattum, Nilgiris Hill, Tamil Nadu State.

Female
Very small size, robust nematodes, curved ventrad or open C-shaped upon fixation; body cylindrical, tapering gradually towards both extremities but more so towards the anterior end. Cuticle with two distinct layers, 1.0 µm thick at anterior region, 1.5 µm at midbody and 2.0 μm on tail. Outer cuticle thin, with fine transverse striations; inner layer thick, finely striated, loose, with radial refractive elements. Lateral chords occupying about 22-24% of midbody diameter. Lateral, dorsal and ventral body pores indistinct. Lip region cap-like, low, flat, offset by depression, 2.5 times as wide as high or about two-fifths of the body diameter at neck base. Lips rounded, amalgamated, inner part slightly elevated. Amphids stirrup-shaped, their aperture about two-thirds as wide as lip region diameter. Stoma a long, slender truncate cone, slightly sclerotized in the perioral region. Odontostyle short, slender, solid, needle-like, 1.0-1.1 times the lip region diameter long. Odontophore simple, sclerotized, with basal flanges, about 1.3 times the odontostyle length. Guiding ring simple, refractive, at 1.0-1.1 times the lip region diameter from anterior end. Pharynx consisting of a slender anterior part, expanding gradually into a short pearshaped basal bulb, with a perceptible thickening at the posterior part of its inner lining, occupying about 15-16% of total neck length. Nerve ring at 52-53% of neck length from anterior end. Cardia rounded to conoid, about one-fourth of the corresponding body diameter long.

Discussion
Basirotyleptus is a taxon of soil-inhabiting nematodes, mostly occurring in undisturbed natural soils, and due to the presence of delicate odontostyle, it is considered as fungal feeders (Yeates 2007). The genus Basirotyleptus is quite heterogenous, and has a worldwide distribution, with representatives reported from all continents (except Antarctica). It is one of the most speciose taxon in the superfamily Tylencholaimoidea of the order Dorylaimida (Table 12), but is not yet well studied from the Western Ghats. A total of 12 species (38% of the total described species) has been recorded from India so far, Table 12 (continued on next two pages). Morphometrics of species belonging to the genus Basirotyleptus Jairajpuri, 1964 (all measurements Khan, 1987, B. minutus Khan, 1987and B. indicus Dhanam & Jairajpuri, 1999 from this biodiversity hotspot. In the ongoing study, 18 populations representing the genus Basirotyleptus were collected from different localities in the Western Ghats, India. Based on a detailed taxonomic study, they were found to represent eleven species, six known and five new, making a total of 36 valid species under the genus Basirotyleptus. As a result of this survey, the Western Ghats fauna is now represented by 13 species of the genus Basirotyleptus, which constitutes about 68% of Indian's Basirotyleptus fauna and 36% of the World's Basirotyleptus fauna. Three species (B. acus, B. ethiopicus and B. nindei) were recorded here for the first time from India.