Axonchium

Naz, Tabbasam & Ahmad, Wasim, 2012, Description of two new and five known species of the genus Axonchium Cobb, 1920 (Nematoda: Dorylamida) from India with diagnostic compendia and keys to species of the genera Axonchium and Syncheilaxonchium Coomans & Nair, 1975, Zootaxa 3264, pp. 1-37 : 32-33

Key to species of the genus Axonchium based on females

(modified after Coomans & Nair, 1975)

1 Lips completely amalgamated............................................................................ 2

- Lips incompletely separated or well separated............................................................... 3

2 Body length 1.2–1.4 mm; anterior uterine branch present.............................................. perplexans

- Body length 1.5–1.6 mm; anterior uterine branch absent.............................................. tochigiense

3 The inner portion of the lips deeply offset and appearing as subspherical liplets............................... labiatum

- 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; numerous body pores............................................................................................... 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................................... geminum

- Body length 2.6–3.8 mm; odontostyle 10.5–15 µm; uterus with ‘Z’ organ.................................. variabile

6 Vulva broad, length wise oval; vaginal lumen adjacent to vulva very wide; pharyngeal constriction short isthmus-like.................................................................................................. propinquum

- 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................. cingulatum

- Constriction or sphincter-like structure at the intestino-prerectal junction absent..................................... 8

8 Anterior genital branch less than three-fourths of the corresponding body width long................................ 9

- Anterior genital branch usually long, very rarely slightly less than the body width long............................. 12

9 Vagina straight, vaginal cuticle wide with rounded or spheroid walls...................................... bulbosum

- 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 portion..................................................................................................... nitidum

- Body rather stout (body width 41–58 µm); lips with a deep notch in the middle separating the outer and inner portion..... 11

11 Expanded part 74–80% of total pharyngeal length; anterior uterine branch rudimentary; tail hemispherical with clavate end and three caudal pores on each side................................................................... .. camelliae

- Expanded part 55–73% of total pharyngeal length; anterior uterine branch a simple sac; tail convex-conoid to bluntly rounded and two caudal pores on each side................................................................ amplicolle

12 Posterior genital branch with ‘Z’ organ............................................................ bihariense

- Posterior genital branch without ‘Z’ organ................................................................. 13

13 Vagina with a constriction in the middle................................................................... 14

- Vagina gradually widening towards the uterus.............................................................. 21

14 Vagina wall appears somewhat darker than and offset from the body cuticle................................ saccatum

- Vaginal cuticle not differentiated from the body cuticle....................................................... 15

15 Body length 1.0– 1.6 mm ............................................................................... 16

- Body length 1.8–2.8 mm ............................................................................... 18

16 Vagina straight; anterior uterine branch a simple sac without proximal constriction......................... thoubalicum

- Vagina straight or slightly to completely directed posteriad; anterior uterine branch provided with a proximal constriction.. 17

17 Body almost straight; vaginal wall distinctly thickened than the body cuticle, vaginal sphincter well developed...... phukani

- Body slightly ventrally arcuate; vaginal wall almost of same thickness as the body cuticle, vaginal sphincter weakly developed............................................................................................. neoeletum

18 Vagina straight, anterior uterine sac without a proximal constriction...................................... khasianum

- Vagina bent posteriad; anterior uterine sac with a proximal constriction.......................................... 19

19 Body length 2.1–2.8 mm; middle tubular part of uterus very narrow.......................................... heynsi

- Body length 1.8–2.2 mm; middle tubular part of uterus wide................................................... 20

20 Body almost straight; vaginal lumen becoming cross-shaped within the sphincter; anterior uterine branch 2–3 times body width long................................................................................. transkeiense

- Body curved ventrad; vaginal lumen narrow and straight; prerectum 6–8 times anal body width long; anterior uterine branch 3–4 times body width long................................................................... parasaccatum

21 Lip region distinctly wide (13–15 µm); odontophore relatively long (18–20 µm) more than 1.5 times the odontostyle length............................................................................................... .. sinclairi

- Lip region narrow (less than 12 µm); odontophore less than 1.5 times the odontostyle length......................... 22

22 Body almost straight.................................................................................. 23

- Body ventrally arcuate................................................................................ 24

23 Lip region high, with conoid lips; cardia more or less heart-shaped; tail broadly conoid, shorter than anal body width...................................................................................................... abulum

- Lip region low, with small offset inner portions of the lips; cardia cylindrical; tail cylindroid, longer than the anal body width......................................................................................... latespiculatum

24 Body 2 mm or less; cardia rounded to heart-shaped........................................................... 5

- Body more than 2 mm long; cardia linguiform; posterior uterus with very narrow tubular part................. manalicum

25 Vagina completely directed posteriad.................................................................... 26

- Vagina slightly inclined posteriad....................................................................... 27

26 Lip region with incompletely separated lips and amalgamated inner parts................................... siddiqii

- Lip region with separated lips and well separated inner parts....................................... noreasum n. sp.

27 Anterior part of pharynx slender, separated from the posterior expanded part by an isthmus-like constriction................................................................................................... meghalayense n. sp.

- Anterior part of pharynx moderately to highly muscular, separated from the posterior expanded part by constriction, no isth- mus-like structure.................................................................................... 28

28 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................................................ cooverkolli

- Anterior part of pharynx quite muscular, separated from the posterior expanded part by a very distinct constriction,; tail not clavate............................................................................................. 29

29 Prerectum 10–13 times anal body width long; tail bluntly rounded, slightly clavate.......................... hosakodii

- Prerectum less than 10 anal body widths long; tail rounded or hemispheroid...................................... 30

30 Expanded part of pharynx 60% or less of total neck length; tail obtusely rounded.............................. elegans

- Expanded part of pharynx more than 60% of total neck length; tail hemispherical or broadly rounded.................. 31

31 Body length 1.3–1.4 mm .......................................................................... shamimi

- Body more than 1.5 mm long........................................................................... 32

32 Body length 1.5–1.6 mm; odontostyle 7–9 µm; anterior genital branch without a proximal constriction.............. eletum

- Body length 1.6–1.9 mm; odontostyle 10.5–12 µm; anterior genital branch with a proximal constriction................ 33

33 Lip region with well separated lips; odontostyle 1.1–1.3 times lip region width long............................. .. metobtusicaudatum

- Lip region with incompletely separated lips; odontostyle one lip region width long............................. vallum