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 : 34-35

Key to species of the genus Axonchium based on males

(modified after Coomans & Nair, 1975)

1 Lip region offset with incompletely separated lips............................................................ 2

- Lip region offset with well separated lips................................................................... 4

2 Body 1.5 mm or less long; odontostyle 8–9 µm; spicules less than 40 µm.........................................3

- Body more than 1.5 mm; odontostyle 10–12 µm; spicules 55–57 µm........................................ vallum

3 Spicules 36–39 µm; ventromedian supplements 7; lateral guiding pieces 13–15 µm........................... shamimi

- Spicules 32 µm; ventromedian supplements 2; lateral guiding pieces 10 µm.................................. siddiqii

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............................................................ variabile

- 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 or just in front of proximal end of spicules................. 15

6 Ventromedian supplements only two......................................................... .. noreasum n. sp.

- Ventromedian supplements 4 or more..................................................................... 7

7 Tail about 1.2 anal body widths 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............................................................................................... latespiculatum

- 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.............................................. 8

8 Spicules longer, 1.7–1.9 anal body widths long, ventromedian supplements 4............................. parasaccatum

- Spicules 1.5 or less anal body widths long; supplements 4 or more............................................... 9

9 Spicules bent ventrally with bluntly rounded distal ends, inner walls heavily sclerotized............................. 10

- Spicules arcuate, lightly sclerotized...................................................................... 12

10 Spicules 1.2 anal body widths long, proximal end of spicules less thickened, middle piece thin at most of its length, swollen near distal end.............................................................................. thoubalicum

- Spicules 1.2–1.4 anal body widths long, middle piece of spicule not swollen near distal end.......................... 11

11 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............................................... heynsi

- Body 1.4–1.7 mm long; spicules slightly ventrally curved without posterior projection at distal end, inner walls of spicules uni- formly thickened, 4–6 ventromedian supplements...................................................... phukani

12 Body 1.6 mm long; expanded part of pharynx 50–54% of total neck length; lateral guiding pieces with sclerotized bifid tip................................................................................................ hosakodii

- Body 1.7–2.04 mm long; expanded part of pharynx more than 60% of total neck length; lateral guiding pieces with bifurcated distal ends.......................................................................................... 13

13 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........................................................... transkeiense

- 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............................................................... 14

14 Spicules 1.2 anal body width long; prerectum 11–14 anal body widths long; 6–7 regularly spaced ventromedian supplements; tail one anal body width long.................................................................... khasianum

- Spicules 1.5 anal body width long; prerectum six anal body widths long; 5 regularly spaced ventromedian supplements; tail about 0.7 times anal body width long........................................................ meghalyense n. sp.

15 Spicules slender...................................................................................... 16

- Spicules robust...................................................................................... 18

16 Spicules 50–56 µm long; ventromedian supplements 5–6................................................ sabulum

- Spicules above 70 µm long; ventromedian supplements 7–12.................................................. 17

17 Guiding ring ‘double’; 7–11 irregularly spaced ventromedian supplements; spicules 78–81 µm, ventrally arcuate, head of spic- ule distinctly ventrally curved; lateral guiding pieces arcuate............................................. sinclairi

- Guiding ring ‘single’; 8–12 ventromedian supplements in two groups; spicules 73–79 µm, ventrally arcuate, head of spicule not ventrally curved; lateral guiding pieces slender, straight............................................... dubium

18 Body 1.9–2.0 mm long; spicules 66–70 µm long; lateral guiding pieces rod-like and provided with a distal inward projection............................................................................................. manalicum

- Body 2.2 mm or less long; spicules 55 µm or less long; lateral guiding pieces without distal inward projection........... 19

19 Body 1.2–1.3 mm long; spicules less than 33 µm long....................................................... 20

- Body 1.4–2.2 mm long; spicules more than 39 µm long...................................................... 21

20 Spicules unusually wide at the blunt distal end; lateral guiding pieces with bifid distal ends; tail with two caudal pores on each side........................................................................................... elegans

- Spicules with narrow distal end; lateral guiding pieces with blunt distal ends; tail with three caudal pores on each side................................................................................................... cooverkolli

21 Spicules wide at the distal end.......................................................................... 22

- Spicules with narrow distal end......................................................................... 24

22 Spicules 39–44 µm or 1.0–1.1 anal body width long with very broad and truncate distal end.................... accatum

- Spicules over 1.5 anal body widths long with blunt distal end.................................................. 23

23 Nine ventromedian supplements in two groups of three and six; lateral guiding pieces less sclerotized.............. eletum

- Six to seven irregularly spaced ventromedian supplements; lateral guiding pieces heavily sclerotized............ neoeletum

24 Ventromedian supplements 10–13; lateral guiding pieces slender; prerectum 9.4–12.2 anal body widths long; tail with four caudal pores on each side...................................................................... propinquum

- Ventromedian supplements less than ten; lateral guiding pieces not so slender; prerectum less than ten anal body widths long; tail with two caudal pores on each side.................................................................... 25

25 Prerectum 4.3–7.4 anal body widths long; lateral guiding pieces simple with bifurcated distal ends............. amplicolle

- Prerectum 8.7–9.9 anal body widths long; lateral guiding pieces simple with thickened distal ends....... metobtusicaudatum