Enchodelus minor, Gagarin & Gusakov, 2014

Gagarin, Vladimir G. & Gusakov, Vladimir A., 2014, Enchodelus minor sp. n. and Mesodorylaimus vietnamicus sp. n. (Nematoda, Dorylaimida) from small freshwater bodies of Vietnam, lnternational Journal of Nematology 24 (1), pp. 23-30 : 24-26

Enchodelus minor sp. n.

( Figs l, 2 )

Measurements. See Table l.

Female. Body short, medium thickness. Cuticle very finely transversely striated. Its thickness 0.8 - 1.0 μm at mid-body, at tail 2.8 -3.2 μm thick. Lips high. Labial region offset from adjacent body. Odontostyle thin and slender, 1.0 - 1.1 times as long as the labial region diameter; its aperture about 25 % its total length. Odontophore approximately 1.5 times as long as the odontostyle, with round elongate flanges. Guiding ring double. Amphidial fovea cup-like, wide, situated at the base of lips. Oesophagus slender, long, occupying comparatively one third ofthe total body length; expanding at 40 -45 % of its length; oesophageal gland nuclei indistinct. Cardia small, muscular, surrounded by intestinal tissue. Rectum length equal to slightly less than anal body diameter. Prerectum 5.4 - 7.2 times as long as anal body diameter.

Reproductive system didelphic, amphidelphic; ovaries antidromous. Bends of ovaries comparatively long. Vulva transverse slit-like, slightly postequatorial; lips not sclerotized and not protruding outside the body contour. Vagina comparatively short, with thick muscular walls, extending inwards to less than one third of corresponding body diameter. Uterus spacious. Eggs in uterus not observed. Tail subcylindrical, its terminus rounded. Cuticle at tail strongly thickened. Saccate bodies at tail absent.

Male. Not found.

Diagnosis and relationship: Only females found. Body 478 - 542 μm long. Cuticle very finely striated, 0.8 - 1.0 μm thick at mid-body, 2.8 -3.2 μm thick at tail. Labial region high, offset from adjacent body. Odontostyle thin and slender, 1.0 - 1.1 times as long as the labial region diameter. Its aperture about 25 % of its length. Guiding ring double. Odontophore approximately 1.5 times as long as the odontostyle, with round-elongate flanges. Oesophagus slender, long, occupying approximately one third of total body length. Vulva a transverse slit, slightly postequatorial. Vagina short, with thick muscular walls. Tail subcylindrical, its terminus rounded. Saccate bodies at tail absent.

The genus Enchodelus Thome, 1939 now contain about 25 valid species ( Andrássy, 2009; Pedram et al., 201 1; Elshishka et al., 2012). Of those only one species, E. parvııs Loof, 1971 , has the body length less than 1 mm. E. parvus was described on five females from grassy-moss biocenosis at Spitsbergen ( Loof, 1971). E. minor sp. n. is close to E. parvus but differs from it in the shorter body (L = 478 -542 μm vs L = 590-790 μm in E. parvııs ), comparatively longer oesophagus and tail (b = 2.7 -3.3, c = 26.6 -30.8 vs b = 3.9- 4.7, c = 37 -45 in E. parvus ), comparatively longer prerectum (5.1 -7.2 anal body diameter long vs only 2 anal body diameter long) and absence of saccate bodies at tail ( Loof, 1971).

Type locality and habitat: Vietnam, Dong Nai (Dong Nai) Prov., Cat Tien ( Cat Tien ) National Park , a stagnant part of a nameless forest stream (N 1 1 ° 26.260, E 107 ° 25.636), altitude 124 m, gray clay with pebbles and coarse plant residues, depth 0.1 m, water temperature 27.6 ° C, dissolved oxygen 2.0 mg/ 1, pH 6.8, conductivity 208 μS/sm.

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Table l. Morphometric data of Enchodelus minor sp. n. (all measurements are in μm).

Type specimens: Collected on 14 May 2012 (V. A. Gusakov).

Holotype: Female, inventory slide 102/26, deposited in the Helminthological Museum, RAS, Institute of Ecology and Evolution, Center of Parasitology, Russian Academy of Sciences, Moscow, Russia.

Paratypes: Seven females, in the same inventory slide 102/26 as holotype.

Additional locality: Except the type locality E. minor sp. n. has been found in one more water body of the Cat Tien National Park: a temporary pond near a forest road (N 11 ° 26.381, E 107° 25.556), altitude 140 m, gray clay with pebbles and coarse plant residues, depth 0.25 m, water temperature 27.7 ° C, dissolved oxygen 2.6 mg /1, pH 6.8, conductivity 230 μS/sm. Collected on 14 May 2012 (V. A. Gusakov).

Figures

Fig. 2. Light micrographs of Enchodelus minor sp. n. Holotype female. A - general view; B f head; C — anterior body end; D — vulva region; E, F - posterior body end. (Scale bars: A, C = 20 μm; F = 10 μm; B, D, E = 5 μm)