Axonchium Cobb, 1920

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 : 2-4

Genus Axonchium Cobb, 1920

Syn. Axonchium ( Hypaxonchium Coomans & Nair, 1975 ) Axonchium ( Poraxonchium Coomans & Nair, 1975 ) Diagnosis. Small to large-sized ( 1.1–3.6 mm) nematodes; body almost straight to open C-shaped upon fixation.

Cuticle usually smooth which appears finely transversely striated at higher magnification; lateral chords with or

without distinct glandular bodies. Lip region offset, lips separate, conoid with demarcated inner portion.

Odontostyle short fusiform or cylindroid; guiding ring usually simples; odontophore rod-like with thickened walls,

usually equal to odontostyle length. Pharynx long, anterior slender part muscular; both parts separated by a

constriction or a short-isthmus-like narrowing; basal expanded part of pharynx usually very long, enclosed in

weakly to strongly developed sheath of nearly straight muscles. Cardia long, muscular. Female genital system

mono-opisthodelphic, anterior genital branch varying in length, mostly with degenerate, non-functional ovary.

Vulva transverse, rarely longitudinal or oval; vagina usually wide and with longitudinally striated walls; pars

refringens vaginae absent. Males with well-developed massive, straight to ventrally arcuate spicules; sclerotised,

rod-like lateral guiding pieces with distal bifid ends and spaced ventromedian supplements. Tail broadly rounded or

convex-conoid, similar in sexes.

Type species: A. amplicolle Cobb, 1920

= Dorylaimus (Axonchium) amplicollis ( Cobb, 1920) Micoletzky, 1922 = Discolaimium pakistanicum Timm & Bhuiyan, 1963 = A. amphidium Thorne, 1964

= A. mauritiense Williams, 1958

Other species:

A. bihariense Popovici, 1990

A. bulbosum Williams, 1958

A. camelliae Dhanam and Jairajpuri, 1998

A. cephalatum (Schuurmans-Stekhoven, 1951) , Andrássy, 1986 = Dorylaimus cephalatus Schuurmans-Stekhoven, 1951 = Eudorylaimus cephalatus (Schuurmans-Stekhoven, 1951) Andrássy, 1959

A. cingulatum Nair, 1973

A. covercolli Dhanam and Jairajpuri, 1998

A. dubium Siddiqi, 1995

A. elegans Jairajpuri, 1964

A. geminum Coomans and Nair, 1975

A. heynsi Nair, 1973

A. hosakodii Dhanam and Jairajpuri, 1998

A. khasianum Rehman, Jairajpuri and Ahmad, 1985

A. labiatum Thorne, 1939

A. latespiculatum Nair, 1973

A. manalicum Ali, Jairajpuri and Coomans, 1975

A. meghalayense n. sp.

A. metobtusicaudatum (Sch.- Stekhoven and Teunissen, 1938) Nair and Coomans, 1973 = Dorylaimus metobtusicaudatum Sch. - Stekhoven and Teunissen, 1938 = Eudorylaimus metobtusicaudatus (Sch.- Stekhoven and Teunissen, 1938) Andrássy, 1959 = A. gossypii De Coninck, 1962

A. monohysteroides ( Altherr, 1974) Andrássy, 1990

= Discolaimium monohysteroides Altherr, 1974

A. neoeletum Rehman, Jairajpuri and Ahmad, 1985

A. nitidum Jairajpuri, 1964

A. noreasum n. sp.

A. parasaccatum Rehman, Jairajpuri and Ahmad, 1985

A. perplexans Siddiqi, 1995

A. phukani Rehman, Jairajpuri and Ahmad, 1985

A. propinquum (De Man, 1906) Thorne, 1939

= Dorylaimus tenuicollis var. propinqua De Man

A. sabulum ( Yeates, 1967) Coomans and Yeates, 1967

= Discolaimium sabuli Yeates, 1967

A. saccatum Jairajpuri, 1964

A. shamimi Baqri and Khera, 1976

A. siddiqii Coomans and Nair, 1975

A. sinclairi Heyns and Furstenberg, 1993 A. subeletum Gambhir and Dhanachand, 1990 A. thoubalicum Dhanachand and Jairajpuri, 1981 A. tochigiense Khan and Araki, 2002 A. transkeinse Nair, 1973

A. vallum Ahmad and Jairajpuri, 1982 A. variable Coomans and Nair, 1975

Remarks. The shape and size of vagina, degree of development of anterior genital branch, the shape and size of spicules and the number and arrangement of ventromedian supplements are most important diagnostic characters for species delimitation in this genus. Both male and female genitalia are highly diversified in this group. In no other nematode genus has such a level of diversity in these structures been recorded.