Axonchium thoubalicum Dhanachand & Jairajpuri, 1981

Nguyen, Duong Thi Anh, Vu, Tam Thi Thanh, Bonkowski, Michael & Pena-Santiago, Reyes, 2014, New data of three rare belondirid species (Nematoda, Dorylaimida, Belondiridae) from Vietnam, with the first record and description of the male of Oxybelondiraparaperplexa Ahmad & Jairajpuri, 1979, Biodiversity Data Journal 2, pp. 1156-1156 : 1156

Axonchium thoubalicum Dhanachand & Jairajpuri, 1981

Materials

Type status: Other material. Occurrence: recordedBy: Nguyen T. A. D; individualCount: 4; sex: 0 male, 4 females; Location: country: Cuc Phuong National Park, Vietnam; stateProvince: Ninh Binh; verbatimLocality: in soil around roots of Parashoreachinensis, karst forest; verbatimElevation: 300-400m; verbatimLatitude: 20°19 ’00’’ N; verbatimLongitude: 105°36 ’30’’ E; decimalLatitude: 20.316666; decimalLongitude: 105.6083333; Event: eventDate: August, 2009; Record Level: collectionID: Cuc Phuong 4.1 (7); Cuc Phuong 4.1 (16); institutionCode: IEBR; collectionCode: Nematode

Description

Specimens examined (n=4): Four females in good condition (Figs 1, 2).

Measurements: See Table 2.

Female: Slender nematodes of medium size. Habitus very weakly curved ventrad upon fixation. Body cylindrical, tapering towards both ends, but more so towards the anterior one. Cuticle bearing fine transverse striations, about 2.0 µm thick at neck region, 2.0 µm at mid-body, and 8-10 µm at tail. Lateral chords 7-8 µm wide or occupying one-fifth of mid-body diameter. Lip region cap-like, offset from adjacent body by a constriction, twice as wide as high and less than one-fifth (16-18%) of body diameter at neck base; lips separate, their inner portion forming liplets; papillae low, hardly protruding. Amphid fovea cup-shaped, its opening at level of the cephalic constriction and occupying 6 µm or ca three-fourths of lip region diameter. Odontostyle fusiform, as long as lip region diameter, with aperture occupying one-third of its total length. Guiding ring simple but distinct, located at 9 µm or 1.1 times the lip region diameter from the anterior end. Odontophore simple, rod-like. Pharynxbipartite, consisting of a slender muscular anterior section, which bears a minute (but perceptible) mucro at its beginning (observed in the four specimens examined); a deep constriction separating both sections; basal expansion nearly cylindrical, occupying 63-71% of total neck length and surrounded by a distinct spiral muscular sheath. Cardia conoid to cylindroid. Genital system mono-opisthodelphic, with the anterior branch reduced to an uterine sac ca twice the body diameter long whereas the posterior one is well developed: reflexed ovary does not reach the oviduct-uterus junction, oocytes first in two rows and then apparently in a single row; oviduct joining the ovary sub-terminally and consisting of a slender portion with prismatic cells and a moderately developed pars dilatata with distinct lumen; conspicuous sphincter between oviduct and uterus; uterus long, tripartite, consisting of a proximal wider region, narrower and longer intermediate section and a nearly sphaerical distal part; vagina 20-23 µm long, extending inwards ca one-half of body diameter, with pars proximalis surrounded by a very perceptible sphincter, pars refringens totally absent and pars distalis well developed; vulva a transverse slit. Prerectum long, 4.7-5.2 anal body widths long. Rectum shorter, 0.8-0.9 times anal body width. Tail short and rounded.

Male: Not found.

Distribution

Axonchium thoubalicum Dhanachand and Jairajpuri 1981 was collected in Cuc Phuong National Park, in soil around roots of Parashorea chinensis in karst forest.

Taxon discussion

This species is known to occur onlyin India, from where it was originally described on the basis of three females and one male, and later reported by Gambhir and Dhanachand (1990), who provided measurements of two females and two males. The Vietnamese material herein examined perfectly fits the general morphology of the type material (females) (unfortunately, male was not collected in Vietnam), especially concerning the genital system. Moreover, the morphometrics of the two Indian populations and the Vietnamese one largely overlap in spite of the few number of available specimens in the three cases. The ranges of several ratios and measurements, however, are significantly widened, for instance c = 50-70 vs 53-55 in type material, V = 47-57 vs 52-54, etc. Thus, no reasonable uncertainty persists on the identity of this material.

Notes

This is the first record of this genus and this species in Vietnam, which might display a Oriental biogeographical range.