An annotated checklist of the main representatives of meiobenthos from inland water bodies of Central and Southern Vietnam. I. Roundworms (Nematoda) Author Gusakov, Vladimir A. Author Gagarin, Vladimir G. text Zootaxa 2017 4300 1 1 43 journal article 32584 10.11646/zootaxa.4300.1.1 7eb2410e-8578-432a-88f8-bc129d0a5b08 1175-5326 837117 5FA0C659-9C52-4ABB-9CB6-1FB5CDDDF9F8 Family Ironidae de Man, 1876 1. Ironus gagarini Tsalolikhin, 1987 — {11, 12, 70} (11, 0, 0, 9; 4) Population structure and abundance. 1 to 2 juvenile specimens and/or females at each site. Ecology and distribution. Hydrobiont. Registered in reservoirs and lakes in countries of Central Asia ( Azerbaijan , Kyrgyzstan ) and Europe ( Ukraine ) ( Tsalolikhin 1987 ; Gagarin 1993 , 2001 ), as well as in rivers and small waterbodies in Southeast Asia ( Vietnam, Thailand , Malaysia ) ( Nguyen & Nguyen 2005 ; Tsalolikhin 2009 ). Presumably, this species has wider distribution in the waters of Eurasia, and possibly on other continents (see Remarks). Remarks. Tsalolikhin (2009) presumes that I. gagarini also occurs in North and South America but has been identified there as a similar species, I. longicollis Daday, 1899 . At the same time, Andrássy (2007) considers I. longicollis to be a synonym of I. ignavus Bastian, 1865 . It is thus possible that both before and after the description of I. gagarini , many occurrences of this species have been identified as either I. longicollis or I. ignavus . 2. Ironus ignavus Bastian, 1865 — {23, 24, 31, 36} (11, 4, 8, 0; 6 ) Population structure and abundance. At sites 23, 24, and 36—a few (2 to 5) juvenile specimens and females including one with eggs (estimated total abundance 1–2 x10 3 /m2), at 31—numerous (about 100) juveniles, females and gravid females in equal proportion (36 x10 3 individuals/m2). Ecology and distribution. Amphibiont. Dwells in water, wet soil and mosses. Cosmopolitan. Recorded from all continents except Antarctica ( Andrássy 2007 ). Frequently observed in Vietnam ( Nguyen & Nguyen 2005 ; Nguyen 2007 ; Gagarin & Nguyen 2008a ). 3. * Ironus paludicola Schneider, 1937 — {8} (5, 0, 0, 0; 1 ) Population structure and abundance. Some juvenile specimens (5), females (6) and gravid females (2) (5 x10 3 /m2). Ecology and distribution. Hydrobiont. Found in various waterbodies in Indonesia ( Sumatra ), North ( Mexico ), Central (Costa-Rica) and South (Surinam) America and Africa ( Mauritania, Tanzania, Ethiopia ) ( Tsalolikhin 1996 ; Andrássy 2011 ). First record from Vietnam . Remarks. Males are unknown ( Andrássy 2011 ).