Nicsmirnovius eximius

35. Nicsmirnovius eximius (Kiser, 1948) Localities and specimens found: 77 – 4♀, 6♀ ov, 4♀ em, 8j; 79 – 1♀, 1♀ ov, 3j. Distribution and ecology. According to the present views, N. eximius (formerly known as Alona eximia Kiser, 1948) is distributed generally in Southeast Asia and China (Idris 1983; Sanoamuang 1998; Kotov & Sanoamuang 2004a; Van Damme et al. 2003, 2013; Maiphae et al. 2005, 2008; Tanaka & Ohtaka 2010; Korovchinsky 2013; Kotov et al. 2013b; Ji et al. 2015; Sinev 2016; Tiang-nga et al. 2020; Dadykin et al. 2023). At the same time, it is known that the species penetrates north, up to the Trans-Baikal and Primorsky territories of Russian Asia (Korovchinsky et al. 2021b). In Vietnam, this crustacean is common and widespread (Dang & Ho 2001; Dang et al. 2002; Sinev 2011, 2012; Sinev & Korovchinsky 2013; Gusakov et al. 2014; Phan et al. 2015; Sinev et al. 2017). Nicsmirnovius eximius is considered a bottom-dwelling rheophilic species, preferring the littoral of lotic water bodies (streams, rivers, waterfalls, dams, channels) in zones with moderate current (Van Damme et al. 2003; Sinev 2016; Korovchinsky et al. 2021b). Sometimes it occurs in stagnant basins too: ponds, lakes, reservoirs, rice fields, floodplains, swamps (Idris 1983; Dang & Ho 2001; Kotov & Sanoamuang 2004a; Tanaka & Ohtaka 2010; Tiang-nga et al. 2020; Dadykin et al. 2023). According to Sinev et al. (2017), in rivers and streams the species can be most abundant in thickets of macrophytes and among well-washed rocks, but it is rare in the layer of bottom sediments. We found a population of N. eximius in Vietnam only in one of the forest streams (see Appendix 1).