Monhysteridae de Man, 1876

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 : 31-32

Family Monhysteridae de Man, 1876

103. Monhysteridae gen. spp.— {22, 31, 33} (5, 4, 8, 0; 4)

Population structure and abundance. Single females of unidentified genera from each site.

104. * Eumonhystera andrassyi (Bíró, 1969) Andrássy, 1981 — {52} (0, 4, 0, 0; 1)

Population structure and abundance. Two juvenile specimens, two females and male (2x10 3/m2). Ecology and distribution. Likely a hydrobiont. To date found only in water (lotic and lentic water bodies). Relatively rare species. Found in several countries of Europe and in China ( Eyualem et al. 2001; Andrássy 2005). Not previously reported from Vietnam.

105. * Eumonhystera barbata Andrássy, 1981 — {65} (0, 0, 0, 9; 1)

Population structure and abundance. Two females.

Ecology and distribution. Amphibiont. Dwells in water bodies and in wet soil. Relatively rare species. Untilrecently, found only in some countries of Europe, Novaya Zemlya Archipelago, Vaygach Island (Arctic, Russia), and in Paraguay ( South America ) ( Gagarin 1997, 2001; Andrássy 2005). Probably the first record for Asia.

Remarks. Males are unknown in this and in the majority of other species of this genus; presumably, reproduction is parthenogenetic ( Andrássy 2005; Coomans & Eyualem, 2006).

106. * Eumonhystera dispar (Bastian, 1865) Andrássy, 1981 — {54} (0, 4, 0, 0; 1)

Population structure and abundance. One gravid female.

Ecology and distribution. Amphibiont, ubiquitous, dwelling in diverse aquatic and terrestrial biotopes. Reported from several countries of Africa and North America , and one of the islands of Oceania. Widespread in Europe and Asia ( Andrássy 2005; Schabetsberger et al. 2009). To date, not reported from Vietnam. According to some workers, this is a cosmopolitan species ( Gagarin 1993; Schabetsberger et al. 2009).

107. * Eumonhystera huruii Peng, Eyualem & Coomans, 2002 — {34} (0, 0, 8, 0; 1)

Population structure and abundance. Single female.

Ecology and distribution. Possibly a hydrobiont. Rare species. Until this study, found only at two locations in one of the rivers of China ( Peng et al. 2002). Our finding marks the third known locality of the species.

108. Eumonhystera vulgaris (de Man, 1880) Andrássy, 1981 — {2} (5, 0, 0, 0; 1)

Population structure and abundance. Single female with egg.

Ecology and distribution. Amphibiont. Cosmopolitan. Found in various aquatic and terrestrial biotopes on all continents, including Antarctica. Already registered in Vietnam ( Andrássy 2005; Nguyen 2007).

109. Eumonhystera Andrássy, 1981 sp.— {62} (0, 0, 0, 9; 1)

Population structure and abundance. One gravid female of an undetermined species (not all morphological features are visible on the mount).

110. ** Monhystera longivaginata Gagarin & Gusakov, 2013 — {4–6, 27, 29, 31} (16, 11, 0, 0; 8)

Population structure and abundance. At sites 5 and 31—8 to 10 females, including those with eggs, and just one male (up to 4x10 3/m2), at the rest of samples—1 to 3 juvenile specimens and females (or gravid females) (up to 1x10 3/m2).

Ecology and distribution. Most likely a hydrobiont. New species ( Gagarin & Gusakov 2013a). To date found exclusively in lakes and reservoirs.

111. Monhystera stagnalis Bastian, 1865 — {14, 58, 63} (0, 4, 8, 9; 4)

Population structure and abundance. One female at site 14, two gravid females at site 58, and one male at the third locality.

Ecology and distribution. Hydrobiont. Prefers aquatic biotopes but may be found sporadically in wet soil near water bodies ( Andrássy 2005; Nguyen 2007). Widespread in Europe , reported from some countries of South America (Columbia), Africa ( Ethiopia and South Africa), and Asia ( Japan) ( Andrássy 2005). According to other sources, cosmopolitan ( Gagarin 1993; Tsalolikhin 2015). Recorded in many regions of northern Vietnam ( Gagarin & Nguyen 2005a; Nguyen & Nguyen 2005; Nguyen 2007).