Axonchium Cobb 1920

Key to species of the genus Axonchium Cobb, 1920 (based on females) (modified after Naz & Ahmad 2012) 1. Lips completely amalgamated........................................................................................................... 2 – Lips incompletely separated or well separated.................................................................................. 3 2. Body length 1.2–1.4 mm; anterior uterine branch present..................... A. perplexans Siddiqi, 1995 – Body length 1.5–1.6 mm; anterior uterine branch absent........... A. tochigiense Khan & Araki, 2002 3. The inner portion of the lips deeply offset and appearing as subspherical liplets................................................................................................................................................... A. labiatum Thorne, 1939 – The inner portion of the lips less offset and marked by depression of the contour........................... 4 4. Odontostyle straight and narrow; anterior part of pharynx very narrow; pharyngeal constriction inconspicuous; body pores numerous................................................................................................... 5 – Odontostyle fusiform; anterior part of pharynx quite muscular; pharyngeal constriction very deep or isthmus-like; body pores few............................................................................................................. 6 5. Body length 1.8–2.0 mm; odontostyle 8–10 µm; uterus without ‘Z’-organ........................................................................................................................................... A. geminum Coomans & Nair, 1975 – Body length 2.6–3.8 mm; odontostyle 10.5–15 µm; uterus with ‘Z’-organ............................................................................................................................................ A. variabile Coomans & Nair, 1975 6. Vulva broad, lengthwise oval; vaginal lumen adjacent to vulva very wide; pharyngeal constriction short isthmus-like................................................ A. propinquum (de Man,1921) sensu Thorne 1939 – Vulva transverse, broad or narrow; vaginal lumen narrow; pharyngeal constriction deep or rarely isthmus-like........................................................................................................................................ 7 7. Intestino-prerectal junction marked by a constriction, surrounded by a sphincter-like structure............................................................................................................................ A. cingulatum Nair, 1973 – Constriction or sphincter-like structure at the intestino-prerectal junction absent............................ 8 8. Anterior genital branch less than ¾ of the corresponding body diameter long................................. 9 – Anterior genital branch usually long, very rarely slightly less than the body diameter long.......... 12 9. Vagina straight, vaginal cuticle wide with rounded or spheroid walls.. A. bulbosum Williams, 1958 – Vagina bent posteriad, vaginal cuticle not wide.............................................................................. 10 10. Body slender (body width 27–35 µm); lips with a shallow notch in the middle separating the outer and inner portions..................................................................................... A. nitidum Jairajpuri, 1964 – Body rather stout (body width 41–58 µm); lips with a deep notch in the middle separating the outer and inner portions.............................................................................................................................11 11. Expanded part of pharynx 74–80% of total neck length; anterior uterine branch rudimentary; tail hemispherical with clavate end and 3 caudal pores on each side.................................................................................................................................................... A. camelliae Dhanam & Jairajpuri, 1998 – Expanded part of pharynx 55–73% of total neck length; anterior uterine branch a simple sac; tail convex-conoid to bluntly rounded and 2 caudal pores on each side....................................................................................................................................................................... A. amplicolle Cobb, 1920 12. Posterior genital branch with ‘Z’-organ................................................ A. bihariense Popovici, 1990 – Posterior genital branch without ‘Z’-organ..................................................................................... 13 13. Vagina with a constriction in the middle......................................................................................... 14 – Vagina without constriction, or gradually widening towards the uterus......................................... 24 14. Expanded part of pharynx short, about 39–49% of total neck length; tail bluntly conoid................................................................................................................................................ A. indicum sp. nov. – Expanded part of pharynx long, more than 50% of total neck length; tail hemispheroid............... 15 15. Vagina wall appears somewhat darker than and offset from the body cuticle.................................................................................................................................................... A. saccatum Jairajpuri, 1964 – Vaginal cuticle not differentiated from the body cuticle.................................................................. 16 16. Body length 1.0– 1.7 mm................................................................................................................. 17 – Body length 1.8–2.8 mm................................................................................................................. 21 17. Body almost straight, 1.1–1.3 mm long; anterior uterine sac 1.7–2.3 times corresponding body diameter long; tail obtusely rounded......................................................... A. microspiculum sp. nov. – Body slightly ventrally arcuate or straight, over 1.3 mm long; anterior uterine sac more than 2.3 times the body diameter; tail hemispheroid..................................................................................... 18 18. Vagina straight; anterior uterine branch a simple sac without proximal constriction........................................................................................................... A. thoubalicum Dhanachand & Jairajpuri, 1981 – Vagina straight or slightly to completely directed posteriad; anterior uterine branch provided with a proximal constriction....................................................................................................................... 19 19. Body almost straight; vaginal wall distinctly thicker than the body cuticle, vaginal sphincter well developed................................................................. A. phukani Rahman, Jairajpuri & Ahmad, 1985 – Body slightly ventrally arcuate; vaginal wall almost of same thickness as the body cuticle, vaginal sphincter weakly developed............................................................................................................. 20 20. Odontostyle 8–9 µm............................................. A. neoeletum Rahman, Jairajpuri & Ahmad, 1985 – Odontostyle 11–12 µm......................................................................................... A. tropicum sp. nov. 21. Vagina straight; anterior uterine sac without a proximal constriction.............................................................................................................................. A.khasianum Rahman, Jairajpuri & Ahmad, 1985 – Vagina bent posteriad; anterior uterine sac with a proximal constriction........................................ 22 22. Body length 2.1–2.8 mm; middle tubular part of uterus very narrow................ A. heynsi Nair, 1973 – Body length 1.8–2.2 mm; middle tubular part of uterus wide......................................................... 23 23. Body almost straight; vaginal lumen becoming cross-shaped within the sphincter; anterior uterine branch 2–3 times body diameter long....................................................... A. transkeiense Nair, 1973 – Body curved ventrad; vaginal lumen narrow and straight; anterior uterine branch 3–4 times body diameter long.................................................. A. parasaccatum Rahman, Jairajpuri & Ahmad, 1985 24. Vaginal lumen highly expanded toward the uterus, with diamond-shaped lumen in lateral view....................................................................................................................... A. paracingulatum sp. nov. – Vaginal lumen moderately expanded............................................................................................... 25 25. Lip region distinctly wide (13–15 µm); odontophore more than 1.5 times the odontostyle length.................................................................................................. A. sinclairi Heyns & Furstenberg, 1993 – Lip region narrow (less than 12 µm); odontophore less than 1.5 times the odontostyle length...... 26 26. Body almost straight........................................................................................................................ 27 – Body ventrally arcuate..................................................................................................................... 28 27. Lip region high, with conoid lips; cardia more or less heart-shaped; tail broadly conoid, shorter than anal body diameter.................................. A. sabulum (Yeates, 1967) sensu Coomans & Yeates 1969 – Lip region low, with small offset inner portions of the lips; cardia cylindrical; tail cylindroid, longer than the anal body diameter................................................................... A. latespiculatum Nair, 1973 28. Body more than 2 mm long; cardia linguiform; posterior uterus with very narrow tubular part......................................................................................... A. manalicum Ali, Jairajpuri & Coomans, 1974 – Body 2 mm or less; cardia rounded to heart-shaped........................................................................ 29 29. Vagina completely directed posteriad.............................................................................................. 30 – Vagina slightly inclined posteriad.................................................................................................... 32 30. Lip region with incompletely separated lips and amalgamated inner parts................................................................................................................................................ A. siddiqii Coomans & Nair, 1975 – Lip region with well separated lips and separated inner parts......................................................... 31 31. Vagina about two-thirds of the corresponding body diameter; prerectum 3.5–6.5 times anal body diameter; tail hemispheroid to almost clavate.............................. A. noreasum Naz & Ahmad, 2012 – Vagina large, more than two-thirds of the corresponding body diameter; prerectum 7–12 times anal body diameter; tail bluntly conoid.................................................................... A. nilgiriense sp. nov. 32. Anterior part of pharynx slender, separated from the posterior expanded part by an isthmus-like constriction............................................................................ A. meghalayense Naz & Ahmad, 2012 – Anterior part of pharynx moderately to highly muscular, separated from the posterior expanded part by a constriction, isthmus-like structure absent............................................................................... 33 33. Anterior part of pharynx moderately muscular, separated from the posterior expanded part by a weak constriction; tail broadly rounded, distinctly clavate due to expansion of cuticle......................................................................................................................... A. cooverkolli Dhanam & Jairajpuri, 1998 – Anterior part of pharynx quite muscular, separated from the posterior expanded part by a very distinct constriction; tail not clavate..................................................................................................... 34 34. Prerectum 10–13 times anal body diameter long; tail bluntly rounded, slightly clavate................................................................................................................ A. hosakodii Dhanam & Jairajpuri, 1998 – Prerectum less than 10 times anal body diameter long; tail rounded or hemispheroid................... 35 35. Expanded part of pharynx 60% or less of total neck length; tail obtusely rounded.............................................................................................................................................. A. elegans Jairajpuri, 1964 – Expanded part of pharynx more than 60% of total neck length; tail hemispherical or broadly rounded.................................................................................................................................................... 36 36. Body length 1.3–1.4 mm................................................................ A. shamimi Baqri & Khera, 1976 – Body more than 1.5 mm long.......................................................................................................... 37 37. Body length 1.5–1.6 mm; odontostyle 7–9 µm; anterior genital branch without proximal constriction.................................................................................... A. eletum Dhanachand & Jairajpuri, 1981 – Body length 1.6–1.9 mm; odontostyle 10.5–12 µm; anterior genital branch with proximal constriction................................................................................................................................................... 38 38. Lip region with well separated lips; odontostyle 1.1–1.3 times lip region width long....................................... A. metobtusicaudatum (Sch.Stekhoven & Teunissen, 1938) sensu Nair & Coomans 1973 – Lip region with incompletely separated lips; odontostyle about lip region width long.................. 39 39. Lip region low, bluntly conoid; tail bluntly conoid with rounded terminus.......... A. uniqum sp. nov. – Lip region moderately high, rounded; tail hemispherical........... A. vallum Ahmad & Jairajpuri,1982 Key to species of the genus Axonchium Cobb, 1920 (based on males) (modified after Naz & Ahmad, 2012) 1. Lip region offset with incompletely separated lips........................................................................... 2 – Lip region offset with well separated lips......................................................................................... 4 2.– Body more than 1.5 mm long; odontostyle 10–12 µm; spicules 55–57 µm........................................................................................................................................... A. vallum Ahmad & Jairajpuri, 1982 Body about or less than 1.5 mm long; odontostyle 8–9 µm; spicules less than 40 µm..................... 3 3. Spicules 36–39 µm; ventromedian supplements 7; lateral guiding pieces 13–15 µm............................................................................................................................... A. shamimi Baqri & Khera, 1976 – Spicules 32 µm; ventromedian supplements 2; lateral guiding pieces 10 µm.......................................................................................................................................... A. siddiqii Coomans & Nair, 1975 4. Over 150 lateral and over 80 ventral body pores; 7–10 caudal pores; spicules very stout, 52–71 µm long with almost straight ventral side; anterior pharynx very slender................................................................................................................................................... A. variabile Coomans & Nair, 1975 – Body pores less numerous; up to 4 caudal pores.............................................................................. 5 5. First ventromedian supplement above the range of spicules............................................................ 6 – First ventromedian supplement within the range of spicules......................................................... 16 6. Ventromedian supplements 2............................................................................................................ 7 – Ventromedian supplements 4 or more.............................................................................................. 8 7. Spicules 20–23 µm, regular in shape........................................................ A. microspiculum sp. nov. – Spicules 30–36 µm, proximally slender about two-fifths of the total spicule length, and distal part comparatively robust................................................................... A. noreasum Naz & Ahmad, 2012 8. Tail about 1.2 anal body diameter long; spicules short and stout, with greatest width in distal half and complex median piece without posterior projection; lateral guiding pieces less than 10 µm, very heavily sclerotized, without distal bifurcation...................................... A. latespiculatum Nair, 1973 – Tail one or less than one anal body width long; spicules stout with simple median piece and posterior projection at the distal end; lateral guiding pieces more than 10 µm, with distal bifurcation... 9 9. Spicules longer, 1.7–1.9 cloacal body diameter long, ventromedian supplements 4................................................................................................ A. parasaccatum Rahman, Jairajpuri & Ahmad, 1985 – Spicules 1.5 or less cloacal body diameter long; supplements 4 or more...................................... 10 10. Spicules bent ventrally with bluntly rounded distal ends, inner walls heavily sclerotized.............11 – Spicules arcuate, weakly sclerotized.............................................................................................. 13 11. Spicules 1.2 cloacal body diameter long, proximal end of spicules less thickened, median piece thin at most of its length, swollen near distal end.......... A. thoubalicum Dhanachand & Jairajpuri, 1981 – Spicules 1.2–1.4 cloacal body diameter long, median piece of spicules not swollen near distal end........................................................................................................................................................ 12 12. Body 2.1–2.8 mm long; spicules bent ventrally at right angle, stout with blunt posterior projection at distal end, inner walls of spicules sometimes crenate; 5–10 ventromedian supplements......................................................................................................................................... A. heynsi Nair, 1973 – Body 1.4–1.7 mm long; spicules slightly ventrally curved without posterior projection at distal end, inner walls of spicules uniformly thickened; 4–6 ventromedian supplements................................................................................................................... A. phukani Rahman, Jairajpuri & Ahmad, 1985 13. Body 1.6 mm long; expanded part of pharynx 50–54% of total neck length; lateral guiding pieces with sclerotized bifid tip.................................................... A. hosakodii Dhanam & Jairajpuri, 1998 – Body 1.7–2.0 mm long; expanded part of pharynx more than 60% of total neck length; lateral guiding pieces with bifurcated distal ends........................................................................................... 14 14. Body L-shaped; 6–7 irregularly spaced ventromedian supplements; lateral guiding pieces swollen with diverging distal ends; tail with three caudal pores on each side..... A. transkeiense Nair, 1973 – Body slightly curved ventrad; 5–7 regularly spaced ventromedian supplements; lateral guiding pieces with bifurcated distal ends; tail with two caudal pores on each side................................... 15 15. Spicules 1.2 cloacal body diameter long; prerectum 11–14 cloacal body diameter long; 6–7 regularly spaced ventromedian supplements; tail one anal body width long........................................................................................................................... A. khasianum Rahman, Jairajpuri & Ahmad, 1985 – Spicules 1.5 cloacal body diameter long; prerectum 6 anal body diameter long; 5 regularly spaced ventromedian supplements; tail about 0.7 anal body diameter long.................................................................................................................................................. A. meghalyense Naz & Ahmad, 2012 16. Spicules slender.............................................................................................................................. 17 – Spicules robust................................................................................................................................ 20 17. Lip region 9–10 µm wide; spicules somewhat sickle-shaped, its dorsal contour with irregularly convex bulge at level of hump.............................................................................. A. uniqum sp. nov. – Lip region more than 11–15 µm wide; spicules simple in shape, dorsal contour regularly convex.... 18 18. Spic