Mesodorylaimus vietnamicus Gagarin & Gusakov 2014, sp. n.
Creators: name: Gagarin, Vladimir G.
name: Gusakov, Vladimir A.
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Nematoda
Enoplea
Dorylaimida
Dorylaimidae
Mesodorylaimus
Mesodorylaimus vietnamicus

description: Mesodorylaimus vietnamicus sp. n.
(Figs 3, 4)
Measurements: See Table 2.
Male. Body comparatively short and thick. Cuticle smooth,
1.0 - 1.5 μm thick at mid-body, without longitudinal ridges; cuticular pores not seen. Lips roundish. Labial papillae small, hardly visible. Labial region comparatively high, offset from adjacent body. Amphidial fovea cup-like, occupying 67 -80% of the corresponding body diameter and situated at the base of lips. Odontostyle straight, comparatively short, 1.0 - 1.1 times as long as the labial region diameter. Its aperture 30 -35 % of its total length. Odontostyle width at its base twice more than cuticle thickness at the corresponding body level. Odontophore rodlike, 0.7 -0.8 times as long as the odontostyle. Guiding ring simple. Oesophagus muscular, expanding about the middle ofits length. Oesophageal gland nuclei indistinct. Nerve ring situated at 40 -45 % of the total oesophagus length. Cardia conoid, muscular, surrounded with intestinal tissue.
Testes paired, opposed. Spicules robust, bent ventrally, 1.3 - 1.5 times as long as the cloacal body diameter. Lateral guiding pieces spindle-shaped, 9 -11 μm long. Precloacal ventro-median Supplements in the shape of small papillae. In addition to one adcloacal pair, a series of 12 - 14 regularly spaced supplements are present; the series measuring 73 -86 μm long. Prerectum comparatively short, 2.5 -3.4 times cloacal body diameter long. Intestine-prerectum junction located in the series of ventro-median supplements. Tail short, conoid-rounded, with 3 -4 pairs of cuticular pores.
Table 2. Morphometric data of Mesodorylaimus vietnamiens sp. n. (all measurements are in μm).
Female. General appearance similar to that of males except for the tail region. Structure of cuticle and anterior body end as in males. Cuticle smooth, thin. Labial region high, offset from adjacent body. Amphidial fovea cup-like, situated at the base of lips. Odontostyle straight, comparatively short. Guiding ring simple. Oesophagus muscular, expanding about the middle of its length. Cardia conoid, muscular, surrounded by intestinal tissue. Prerectum and rectum 2.1 -2.8 times and 1.0- 1.2 times as long as the anal body diameter, respectively.
Reproductive system didelphic, amphidelphic; ovaries antidromous. Both ovaries situated at the left of intestine, comparatively long. Vulva pre-equatorial, in the shape of transverse slit. Vulva lips not sclerotized and not protruding outside the body counter. Wrinkles and folds of cuticle in the vulva region absent. Oocytes numerous, ﬁrst in two rows, then in a single row. Vagina with muscular walls, extending inwards to half of the corresponding body diameter. Pars proximalis vaginae 13 - 15 μm long, with weakly sigmoid contour; pars refringens vaginae consisting of welldeveloped, head arrow-shaped or triangular with light sclerotizations; pars dislalis vaginae short. Uterus spacious, with spindle-shaped spermatozoa. Tail long, with broad basal conical portion and narrow cylindrical posterior portion. Length of cylindrical posterior tail portion 73 -80% of total length tail. Tail terminus round. Caudal pores two pairs, one subdorsal, the other subventral.
Diagnosis and relationship. Body 950 - 1137 μm in males, 952 - 1332 μm in females. Cuticle thin, smooth, without longitudinal ridges. Labial region high, offset from adjacent body. Amphidial fovea cup-like, occupying 67 -80 % of the corresponding body diameter. Odontostyle straight and comparatively short, 1.0 - 1.1 times as long as the labial region diameter. Its aperture 30 - 35% of its length. Vulva pre-equatorial, in the shape of transverse slit. Cuticular wrinkles and folds in the vulva region absent. Spicules robust, bent ventrally, 34 -36 μm long. In addition to adcloacal supplement, a series of 12 - 14 regularly spaced supplements are present. Prerectum 2.1 -2.8 anal body diameters long in females, 2.5-3.4 cloacal body diameters long in male.
Intestine-prerectum junction in males located in the region of series of ventro-median supplements. Tail in females long, with broad basal conical portion followed by narrow cylindrical posterior portion. Tail in males short, conoid-rounded.
Mcsodorylaimus vietnamiens sp. n. comes close to M. ornaıivulvaıis Abolaﬁa & Pena-Santiago, 1997 and M. parasubrilis (Meyl, 1957). From the former species it differs in the comparatively thicker body (a = 18-29 vs a = 29.8- 43.6 in M. ornalivıılvalis). shorter spicules (34-36 Wh long vs 40-54 μm long in M. ornaıivıılvaıis), greater number of precloacal Supplements in males (13-IS vs 8-10 in M. ornuıivulvaıis) and absence of cuticular wrinkles and folds in the vulva region in females (Abolaﬁa & Peña-Santiago, 1997). From M. parasııbtilis it differs in the longer body (females L = 952 - 1332 μm, males L = 846- 1185 μm vs females L í 0.8 - 1.0 mm, males L = 0.7 -0.8 mm in M. parasubtílís), comparatively shorter tail in females (c = 7.8- 10.6 vs c = 6- 8 in M. parasııbtilis), shorter odontostyle (10- 12 long vs 12 - 14 long in M. parasubtilis), shorter spicules (34 -36 μm long vs 40 μm long in M. parasubtilis), greater numbers of precloacal Supplements (13 -15 vs 8) and comparatively longer prerectum in females (2.1 -2.8 anal body diameters vs 1.5 anal body diameters in M. parasubtilis) (Meyl, 1957).
Type locality and habitat: Vietnam, Dong Nai (Dong Nai) Prov., Cat Tien (Cát Tien) National Park, a nameless small shallow forest lake (N 11 ° 27.311, E l 07 °20.l 21), altitude 131 m, white clay with plant residues, depth 0.25 m, water temperature 27 ° C, dissolved oxygen 2 mg / 1, pH 6.2, conductivity 40 μS/sm.
Type specimens: Collected on 12 May 2012 (V. A. Gusakov).
Holotype: Male, inventory slide 102/27, deposited in the Helminthological Museum, RAS, Institute of Ecology and Evolution, Center of Parasitology, Russian Academy of Sciences, Moscow, Russia.
Paratypes: Fiﬁeen males and 15 females situated in the same inventory slide 102/27 as holotype.
description: Published as part of Gagarin, Vladimir G. & Gusakov, Vladimir A., 2014, Enchodelus minor sp. n. and Mesodorylaimus vietnamicus sp. n. (Nematoda, Dorylaimida) from small freshwater bodies of Vietnam, pp. 23-30 in lnternational Journal of Nematology 24 (1) on pages 26-30, DOI: 10.5281/zenodo.8161318