taxonID	type	description	language	source
461A87F9FFFCF26CFD95FB8599F182AB.taxon	description	(Figures 1, 2, 7, 8, Tables 1, 3, 4) Description Female. Body slender, medium – sized, less than 1 mm; almost straight after fixation, tapering only very slightly anteriorly, but more posteriorly towards a filiform tail. Cuticle with fine transverse striations. Longitudinal striations fine with equally spaced dot-like punctations (Figure 2 (F )). Lip region more or less flat, continuous with body contour. Lips six, amalgamated with six small papilliform inner labial and six setose outer labial sensilla. Amphidial apertures large, elliptical to square-shaped (Figure 2 (B )), 12 – 13 µm from anterior end of stoma, at the level of dorsal tooth. Stoma 2.5 times longer than wide. Cheilostom longer than wide, spacious, barrel-shaped, cheilorhabdions arched inward anteriorly, cheilorhabdial flaps eight, arched outwards to reveal an open stoma; gymnostom broader than long, isotopic, isomorphic, lacking armature (Figure 1 (D )). Stegostom anisotopic and anisomorphic, dorsal metastegostomal wall with a medium-sized, triangular, anteriorly directed, movable tooth, subventral walls without armature (Figure 1 (D )). Pharynx with slender 56 – 95 µm long, muscular corpus of uniform diameter, expanding slightly into a 12 – 20 µm long median bulb. Corpus lumen prominently sclerotised. Isthmus relatively muscular, 20 – 30 µm long, continuing posteriorly into a basal bulb of 17 – 27 µm × 13 – 15 µm dimension without any valve plate or grinder. Dorsal pharyngeal gland nucleus usually prominent, located near base of basal bulb (Figure 1 (F )). Nerve ring encircling isthmus immediately posterior to median bulb, at 68 – 78 % of pharyngeal length. Hemizonid located near the expanding part of basal bulb, about 74 – 80 % of pharyngeal length. Secretory – excretory pore faintly visible. Cardia well-developed, 3 – 4 µm long, consisting of three flaps, one dorsal and two ventro-sublateral. Intestine composed of dark granulated cells with prominent nuclei, intestinal lumen uniformly wide, 7 – 8 µm without any bacterial pouch. Reproductive system amphidelphic, anterior gonad on right side and posterior on left side of intestine. Both branches almost identical. Ovaries reversed with distal part of ovaries not reaching the level of vulva (Figure 2 (D )). Oocytes arranged in double row in germinal zone and single row in maturation zone (Figure 1 (E )). Oviduct narrow, tubular. Spermatheca thin-walled, without distinct demarcation, filled with rounded to ovoid sperms. Uterus divisible into a distal smaller muscular part and a proximally placed longer, glandular part made up of large cells and narrow lumen. Columella distinct from spermatheca. Vagina narrow, tubular, 5 – 6 µm long about one-fourth of corresponding body diameter. Vulval opening small, elliptical, flushing with body contour. Vulva – anus distance 8.0 – 12.5 times vulval body diameter. Rectum 1.1 – 1.7 times anal body diameter (Figure 2 (I )). Phasmids located at a level, 1.4 – 2.5 anal body diameter posterior to anus. Tail long, filiform 0.6 – 1.7 times vulva – anus distance, divided into two parts, an anterior short conoid part and a posterior longer filamentous part. Male. Similar to female in general morphology but smaller in size (625 – 823 µm). Lip region with four cephalic papillae posterior to outer labial sensilla. Reproductive system monorchic, testis reflexed laterally, on right side of intestine. Spermatocytes arranged in two rows distally followed by single row proximally. Vas deferens a long tube containing spermatocytes transforming into spermatozoa, tapering to an ejaculatory duct. Spicules paired, slender, arcuate, 1.2 – 1.7 times cloacal body diameter long. Manubrium round connected to calomus / lamina complex – that is slightly expanded just posterior to manubrium, and then smoothly tapering to prominent bifid distal tips constituting a fine ventral spur (Figure 2 (H )). Gubernaculum slender, boat-shaped, 56 – 75 % of spicules length, proximally curved and distally with a sleeve (Figure 1 (G )). Tail divided into two parts, an anterior short conoid part and a posterior longer filamentous part. Genital sensilla nine pairs – constituting three precloacal and six postcloacal pairs in the configuration of v 1, v 2, v 3 d / v 4, ad, (v 5, v 6, v 7), ph, pd. Precloacal pair v 1 located above the spicule range, about twice cloacal body diameter anterior to cloaca; v 2 and v 3 d almost at the same level, just anterior to cloacal opening. ad about one cloacal body diameter posterior to cloaca. v 7 larger than v 5 and v 6. Phasmids pore-like, at the level of v 5, 1.7 – 2.1 anal body diameter posterior to cloacal opening. pd subdorsal, far posterior to the v 5 – v 7 group (Figure 1 (G )).	en	Mumtaz, Sabia, Ahmad, Irfan, Tahseen, Qudsia (2025): A new and a known species of the genus Butlerius Goodey, 1929 (Nematoda: Diplogastridae) from India and their relationship with congeners. Journal of Natural History 59 (1 - 4): 171-193, DOI: 10.1080/00222933.2024.2441353, URL: https://doi.org/10.1080/00222933.2024.2441353
461A87F9FFFCF26CFD95FB8599F182AB.taxon	materials_examined	Type material Holotype: Female on slide AMU / ZD / NC / Butlerius indicus sp. n. / 1 deposited in the nematode collection of the Department of Zoology, Aligarh Muslim University, Aligarh, Uttar Pradesh, India. Paratypes: Sixteen females and 13 males on slides AMU / ZD / NC / Butlerius indicus sp. n. / 2 – 14 deposited in the nematode collection of Department of Zoology, Aligarh Muslim University, Aligarh, Uttar Pradesh, India.	en	Mumtaz, Sabia, Ahmad, Irfan, Tahseen, Qudsia (2025): A new and a known species of the genus Butlerius Goodey, 1929 (Nematoda: Diplogastridae) from India and their relationship with congeners. Journal of Natural History 59 (1 - 4): 171-193, DOI: 10.1080/00222933.2024.2441353, URL: https://doi.org/10.1080/00222933.2024.2441353
461A87F9FFFCF26CFD95FB8599F182AB.taxon	description	From B. gerlachi, the new species differs in having smaller female (L = 671 – 970 µm vs 1,000 – 1,140 µm), size of cheilostom (longer than gymnostom, as long as head diameter vs as long as gymnostom, half of head diameter), median bulb (oval, as long as corresponding body diameter vs elongate, almost twice the corresponding body diameter), shape of amphid (broad, elliptical to square-shaped vs stirrup-shaped), shorter pharynx (b = 5.5 – 6.8 vs 4.4 – 4.9), longer tail (c = 2.5 – 5.0 vs 5.9 – 7.6), posterior position of vulva (V = 38 – 49 % vs 51 – 54 %), males having spicules (with bifid distal tip constituting a fine ventral spur vs pointed distal tip), gubernaculum slender (boat-shaped vs broad, keel-shaped) and genital sensilla (9 pairs vs 11 pairs in B. gerlachi).	en	Mumtaz, Sabia, Ahmad, Irfan, Tahseen, Qudsia (2025): A new and a known species of the genus Butlerius Goodey, 1929 (Nematoda: Diplogastridae) from India and their relationship with congeners. Journal of Natural History 59 (1 - 4): 171-193, DOI: 10.1080/00222933.2024.2441353, URL: https://doi.org/10.1080/00222933.2024.2441353
461A87F9FFFCF26CFD95FB8599F182AB.taxon	etymology	Etymology The name of the species is based on its country of origin, ie India.	en	Mumtaz, Sabia, Ahmad, Irfan, Tahseen, Qudsia (2025): A new and a known species of the genus Butlerius Goodey, 1929 (Nematoda: Diplogastridae) from India and their relationship with congeners. Journal of Natural History 59 (1 - 4): 171-193, DOI: 10.1080/00222933.2024.2441353, URL: https://doi.org/10.1080/00222933.2024.2441353
461A87F9FFFCF268FE40FCAE9EF48434.taxon	synonymic_list	Syn. Butleroides Lordello & Zamith, 1959 Butleriellus Meyl, 1960 Mesodiplogasteroides Khera, 1969 Parabutlerius Andrássy, 1984 Monobutlerius Ebsary, 1986 (Continued) The key characters for differentiating the species of Butlerius are given hereunder	en	Mumtaz, Sabia, Ahmad, Irfan, Tahseen, Qudsia (2025): A new and a known species of the genus Butlerius Goodey, 1929 (Nematoda: Diplogastridae) from India and their relationship with congeners. Journal of Natural History 59 (1 - 4): 171-193, DOI: 10.1080/00222933.2024.2441353, URL: https://doi.org/10.1080/00222933.2024.2441353
461A87F9FFEEF26EFE09FEE699368705.taxon	description	(Figures 3 – 8, Tables 2 – 4) Description Females. Body slender, medium-sized, less than 1 mm long, almost straight after fixation, tapering towards both extremities. Cuticle with fine transverse and prominent longitudinal striations forming a corn-cob like pattern. Lateral fields with four fine lines (visible in three out of 17 studied specimens). Lip region continuous with body contour. Lips six, amalgamated, with six papilliform inner labial sensilla, small setose outer labial sensilla. Amphidial apertures elliptical, 4 – 5 µm from anterior end of stoma, at the base of cheilostom. Stoma 1.5 times longer than wide. Cheilostom spacious, barrel-shaped; cheilostomal walls thick, arched anteriorly, cheilostomal flaps eight. Gymnostom broader than long, anisotopic and anisomorphic – with dorsal wall shorter than subventrals. Stegostom anisotopic and anisomorphic. Dorsal metastegostomal wall with a medium-sized movable tooth, subventral walls provided with denticulate ridge. Procorpus muscular, 54 – 72 µm long with zipper-like lumen; median bulb round or ovoid, 16 – 21 µm long, strong muscular with thickened lumen, isthmus narrow, 21 – 37 µm long, conspicuously differentiated from median bulb. Basal bulb small, pyriform, glandular, 18 – 29 × 16 – 18 µm in dimension without any valve plate or grinder. Dorsal gland nucleus usually prominent, located near the base of the basal bulb. Nerve ring encircling isthmus in the middle, at 59 – 71 % of pharyngeal length from anterior end. Hemizonid just below the level of nerve ring and anterior to excretory pore, at 66 – 75 % of pharyngeal length. Excretory pore 69 – 79 % of pharyngeal length, at anterior level of basal bulb. Cardia well-developed, 4 – 5 µm long, consisting of one dorsal and two ventro-sublateral flaps. Intestine composed of dark granulated cells with prominent nuclei, intestinal lumen uniformly wide without any bacterial pouch. Reproductive system amphidelphic, anterior gonad on right side and posterior on left side of intestine. Both branches almost identical. Ovaries reversed. Oocytes with large nuclei, arranged in multiple rows in germinal zone and single row in maturation zone. Distal tips of ovaries not reaching vulva. Oviduct narrow, tubular and short. Spermatheca thin-walled, not distinctly demarcated, usually containing sperms. Uterus divisible into a longer glandular columella made up of large cells around a narrow lumen and smaller muscular uterus proper. Two pairs of large unicellular glands opening into uterus. Vagina narrow, tubular, 11 – 17 µm long about one-third of corresponding body diameter. Vulval opening relatively small, elliptical, flush with body contour or sometimes depressed. Vulva – anus distance 6.4 – 8.0 times vulval body diameter. Rectum 1.2 – 2.0 times anal body diameter. Anal opening wide, crescent-shaped. Phasmids located at about 1.3 – 1.9 anal body diameter posterior to anus. Tail filiform 1.2 – 1.8 times vulva – anus distance long, divided into two parts, a short conoid part and a long filamentous part. Males. Similar to females in general morphology but smaller in size (572 – 728 µm). Anterior region with four small cephalic setae present posterior to circlet of six outer labials. Reproductive system monorchic, testis reflexed laterally, on right side of intestine. Spermatocytes arranged in two rows in anterior reflexed part; vas deferens a long tube with spermatocytes in the stage of transformation into immature spermatozoa, tapering to an ejaculatory duct. Spicules paired, cuticularized, arcuate, 1.4 – 1.6 times cloacal body diameter long. Manubrium oval connecting posteriorly to a calomus / lamina complex, lamina broad with a ventral conoid process, gradually tapering to fine tip with subterminal dorsal protuberance. Gubernaculum 45 – 65 % of spicules length, proximally curved, provided with a small distal sleeve. Tail divided into two parts, a short conoid part and a long filamentous part. Genital sensilla setose in nine pairs constituting two precloacal, one adcloacal and six postcloacal pairs in the configuration of v 1, v 2, v 3 d / v 4, ad, (v 5, v 6, v 7), ph, pd. Precloacal pair v 1 located above the spicule range, more than one cloacal body diameter anterior to cloaca; v 2 adcloacal; v 3 d just anterior and v 4 closely posterior to cloaca; ad less than one cloacal body diameter posterior to cloaca. v 5 larger than v 6 and v 7. Phasmids pore-like, at the level of v 5, 1.3 – 1.7 anal body diameter posterior to cloacal opening. pd subdorsal, far posterior to v 5 – v 7 group.	en	Mumtaz, Sabia, Ahmad, Irfan, Tahseen, Qudsia (2025): A new and a known species of the genus Butlerius Goodey, 1929 (Nematoda: Diplogastridae) from India and their relationship with congeners. Journal of Natural History 59 (1 - 4): 171-193, DOI: 10.1080/00222933.2024.2441353, URL: https://doi.org/10.1080/00222933.2024.2441353
461A87F9FFEEF26EFE09FEE699368705.taxon	materials_examined	Voucher specimens Fifteen females and 12 males on slides AMU / ZD / NC / Butlerius micans / 1 – 9 deposited in the nematode collection of Department of Zoology, Aligarh Muslim University, Aligarh, Uttar Pradesh, India.	en	Mumtaz, Sabia, Ahmad, Irfan, Tahseen, Qudsia (2025): A new and a known species of the genus Butlerius Goodey, 1929 (Nematoda: Diplogastridae) from India and their relationship with congeners. Journal of Natural History 59 (1 - 4): 171-193, DOI: 10.1080/00222933.2024.2441353, URL: https://doi.org/10.1080/00222933.2024.2441353
461A87F9FFEEF26EFE09FEE699368705.taxon	discussion	Remarks The original population of B. micans, 1968 was collected from sludge drying bed of the Champaign – Urbana Sanitary sewage treatment plant at Urbana, Illinois, USA. In the type slides of B. micans, Pillai and Taylor (1968) described a large cheilostom divisible into two parts; anterior composed of eight movable plates and a more strongly cuticularised posterior part. They mentioned a large dorsal tooth on dorsal stegostomal wall but did not give any information about the subventral wall. Later; Mahamood (2014) collected another population of B. micans from farmyard manure at Aligarh, India. He reported a pointed tooth on the right and a denticulate plate on the left subventral stegostomal wall. In our study, SEM observations (Figure 5 (C )), provided for the first time, revealed the morphology of stoma with denticulate ridges on both subventral walls. On comparing the loaned type specimens (Figure 6) with our specimens, sufficient evidence of similarity could be noticed. The morphological characteristics viz., structure of stoma, zipper-like structure in the pharyngeal lumen, shape of spicules, and gubernaculum of our specimens conform well with those studied by Pillai and Taylor (1968). Despite the opacity and flattening of type specimens in the loaned slide, the similarity of stomal armature indicated towards possibility of denticulate ridges on subventral walls. Conspicuous uterine glands (Figure 6 (E )) and the adcloacal male genital sensilla (Figure 6 (F )) could be observed, though not reported by Pillai and Taylor (1968) in the original description and also by Mahamood (2014). However, our population showed minor morphometric differences from the original population in having smaller individuals (L = 667 – 864 µm vs 980 – 1,250 µm in females and 572 – 728 µm vs 790 – 1,100 µm in males) and smaller b value (5.5 – 6.0 vs 6.7 – 8.1) in females. Compared with the population reported by Mahamood (2014), our specimens differ considerably in having thicker bodies (a = 22 – 29 µm vs 34 – 43 µm in females; 17 – 20 µm vs 28 – 34 µm in males), smaller males (L = 572 – 728 µm vs 803 – 997 µm), relatively shorter stoma (10 – 13 µm vs 16 – 20 µm), smaller spicules (23 – 26 µm vs 31 – 35 µm) and adcloacal genital sensilla (present vs absent). The comparative study of the two populations reveal interesting results where their status as cryptic species cannot be overruled considering the geographic distance. However, a thorough testing is required at molecular level to ascertain the status of both our specimen and those from the type locality in USA. We, therefore, intend to take up this task in the future. The present population of B. micans differs markedly from the newly described population of B. indicus sp. n. in having transverse and longitudinal cuticular striations forming a corncob pattern (vs cuticle finely-striated and punctated); amphidial aperture elliptical (vs large square-shaped); stoma with dorsal tooth and subventral serrated ridge (vs dorsal tooth and no subventral armature); males with slender, arcuate spicules with conspicuous ventral triangular process (Figure 3 (h )) (vs spicules plump with ventral conoid process inconspicuous, Figure 1 (g )); lamina gradually terminating into a pointed distal tip provided with a dorsal subterminal protuberance (vs distal end with fine ventral subterminal spur); and nine pairs of genital sensilla (constituting two precloacal, one adcloacal and six postcloacal pairs vs three precloacal and six postcloacal pairs in B. indicus sp. n.). Some outstanding differences between B. micans Pillai and Taylor, 1968, B. butleri; Goodey, 1929 and B. degrissei; Grootaert and Jaques, 1979 in general morphology and morphometric values have been given hereunder. It can be easily differentiated from the closely related species by zipper-like lumen of corpus, structure of stoma and arrangement of genital papillae. It further differs from B. butleri in the number of cheilostomal flaps (8 vs 6), size of stoma (10 – 13 µm vs 21 – 29 µm), shape of dorsal tooth (anteriorly-directed vs ventrally-directed), armature on subventral stegostomal walls (both walls provided with serrated ridge vs right subventral with a small tooth; left a smooth-edged plate) and arrangement of genital sensilla (both v 5 – 7 cluster at the same level vs v 5 – 7 cluster greatly separated, right subventral group at the level of pd). From B. degrissei, it differs in the number of cheilostomal plates (8 vs 6), size of stoma (10 – 13 µm vs 22.4 – 24.5 µm), armature on subventral stegostomal walls (both walls provided with serrated ridge vs lacking armature), female reproductive system (amphidelphic vs monodelphic with a post – uterine sac), shape of spicules (broad lamina vs narrow lamina) and arrangement of genital sensilla (v 2 adcloacal vs v 2 above the spicule range).	en	Mumtaz, Sabia, Ahmad, Irfan, Tahseen, Qudsia (2025): A new and a known species of the genus Butlerius Goodey, 1929 (Nematoda: Diplogastridae) from India and their relationship with congeners. Journal of Natural History 59 (1 - 4): 171-193, DOI: 10.1080/00222933.2024.2441353, URL: https://doi.org/10.1080/00222933.2024.2441353
