Qudsianematidae Jairajpuri, 1963

Gusakov, Vladimir A. & Gagarin, Vladimir G., 2017, An annotated checklist of the main representatives of meiobenthos from inland water bodies of Central and Southern Vietnam. I. Roundworms (Nematoda), Zootaxa 4300 (1), pp. 1-43 : 24-25

Family Qudsianematidae Jairajpuri, 1963

66. * Chrysonema distinctum (Jana & Baqri, 1985) Andrássy, 1990 — {50} (0, 4, 0, 0; 1) Population structure and abundance. Ten juveniles and 16 females (10 x10 3 /m2). Ecology and distribution. Possibly an amphibiont. The species of this genus parasitize roots of plants, including aquatic macrophytes ( Gagarin 2001). Rare species. Previously not recorded outside India ( Vinciguerra 2006).

Remarks. Males are unknown ( Andrássy 1990).

67. * Chrysonema limigenus (Siddiqi, 1969) Andrássy, 1990 — {29} (0, 4, 0, 0; 1) Population structure and abundance. Three juvenile specimens, one gravid female and two males (qualitative sample).

Ecology and distribution. Ecology similar to the species described above. Previously reported only from India (Asia), Poland (Europe) and Surinam (South America) ( Vinciguerra 2006).

68. * Crassolabium Yeates, 1967 sp.— {68} (0, 0, 0, 9; 1)

Population structure and abundance. Two juvenile specimens and one female.

Ecology and distribution. Representatives of this genus mainly inhabit diverse terrestrial biotopes, but some occur in the water as well ( Peña-Santiago & Ciobanu 2011).

Remarks. Two species from forest soils are known in Vietnam: C. aenigmaticum Vu, Ciobanu, Abolafia & Peña-Santiago, 2010 and C. vietnamense Vu, Ciobanu, Abolafia & Peña-Santiago, 2010 ( Vu et al. 2010). The specimens we found resemble the widespread C. ettersbergense (de Man, 1885) Peña-Santiago & Ciobanu, 2008 but we could not observe all the morphological details in the single adult female found. Our specimen clearly differs from C. aenigmaticum and C. vietnamense by smaller body size, odontostyle and in some other characteristics.

69. * Epidorylaimus leptosoma ( Altherr, 1963) Andrássy, 1986 — {55, 59, 66, 69, 70} (0, 0, 15, 27; 7) Population structure and abundance. 2 to 3 juveniles and 2 to 14 females at each site (up to 6 x10 3 /m2). Ecology and distribution. Most likely an amphibiont. Rare species. Found in soil in Europe ( Switzerland) and, until this study, not noted anywhere else ( Altherr 1963; Vinciguerra 2006). In Vietnam, found only in small forest water bodies.

70. * Labronemella papillata ( Khan, Ahmad & Jairajpuri, 1995) Gusakov & Gagarin, 2015 — {50, 66} (0, 4, 0, 9; 3)

Population structure and abundance. At site 50—a large number (over 50) of juveniles, 12 females and 12 males (28 x10 3 /m2); at the second locality—only one male.

Ecology and distribution. Amphibiont. Described from soil in India ( Khan et al. 1995), but our finding a large population in one of the Vietnamese water bodies indicates the ability of this species to occupy aquatic environments as well. Until recently, recorded only from India ( Vinciguerra 2006).

Remarks. Initially, this species was assigned to the genus Labronema Thorne, 1939 as L. papillatum Khan, Ahmad & Jairajpuri 1995 ( Khan et al. 1995). Later, Andrássy (2009b) transferred it to Crassolabium based on the fact that females of L. papillatum have a transverse vulva, a characteristic of the genus Crassolabium (in Labronema , the vulva is longitudinal). However, Andrássy did not consider the presence of inner liplets in this species, which are absent in the species of Crassolabium . Indeed, the presence of inner liplets and a transverse vulva are distinctive features of the genus Labronemella ( Andrássy 2009b) . On this basis, after analyzing the Vietnamese material we considered Crassolabium papillatum ( Khan, Ahmad & Jairajpuri 1995) Andrássy, 2009 as a species of Labronemella (Gusakov & Gagarin 2015b) .