Monhystera vietnamica, Tsalolikhin, 2020

Tsalolikhin, S. Ya., 2020, Two new species of free-living nematodes (Nematoda) from Vietnam, Zoosystematica Rossica (Zoosyst. Rossica) 29 (1), pp. 11-16 : 12

Monhystera vietnamica sp. nov.

( Figs 1−4 )

Holotype. Female, Vietnam, Tuyn Quang Prov., Na Hang Distr., Tung Vui Commune , pond in forest, 400 m a.s.l., 22°19′46″N, 105°25′47″E, 16 June 2019, coll. L. Iogansen. Microscope slide No. A-9238 , ZISP.

Paratypes. 9 females, same data as for holotype .

Description. Females. Morphometric description of the holotype and paratypes is given in Table 1 . Cuticle thin, about 1 µm. Space between internal organs with small cristalloid bodies of various sizes. Head not offset from body outline. Labial papillae undetectable. Diameter of amphidial fovea corresponding to 30% of body width. Ocellus present at about 20–26 (23) µm from anterior end. Cheilostome medium-sized, with thin walls. Esophagus muscular, gradually dilating towards its base. Cardium mushroom-shaped. Renette more or less oval, located somewhat below cardium; canal of renette and excretory pore not visible. Reproductive system monodelphic, prodelphic. Oocytes arranged in several rows in germinal zone. Uterus usually containing one or two eggs: 29–36 x 14–23 µm. Vagina very long, cuticularised, noticeably longer than one vulval body diameter. Paravulval gland present. Rectum longer than anal diameter. Tail slender, filiform.

Male not found.

Comparision. The new species Monhystera vietnamica sp. nov. most closely resembles M. uncigubernaculum Zeidan, Jacobs et Geraert, 1989 , which was described from Africa (Zeidan, Jacobs & Geraert, 1989), and M. rolandi Khan et Tahseen, 2006 from India (Khan & Tahseen, 2005). The main differences of the new species from M. uncigubernaculum are the following: vagina 45–52 µm (vs 25–37 µm), rectum/anal body diameter 0.9 (vs 0.7), and tail filiform (vs tail with slightly swollen spinneret). The main differences of the new species from M. rolandi are: ocellus present (vs absence of ocellus), cephalic setae 5 µm (vs 3–4 µm), and tail filiform (vs tail gradually tapering).

Etymology. This species name is a Latinized toponym.

Figures

Figs 1–9. Morphology of Monhistera vietnamica sp. nov. (1–5) and Brevitobrilus larae sp. nov. (6–9). 1, 6, entire body of female; 2, 7, head; 3, esophagus; 4, 8, vulval section; 5, 9, tail. Scale bars: 2, 7 – 5 µm; 3, 4, 5, 8, 9 – 20 µm; 1, 6 – 50 µm.