51. Dunhevedia crassa King, 1853

Localities and specimens found: 30 – 1♀.

Distribution and ecology. It is assumed that D. crassa is distributed throughout the world in warm latitudes, up to the south of temperate regions, but its worldwide populations still need to be revised (Smirnov 1996; Kotov et al. 2013 a, 2013b; Błędzki & Rybak 2016; Korovchinsky et al. 2021b). The species is widely known in the Oriental region (Fernando 1974, 1980; Idris & Fernando 1981; Idris 1983; Michael & Sharma 1988; Sanoamuang 1998; Rane 2002, 2005, 2011; Maiphae et al. 2005, 2008; Chatterjee et al. 2013; Korovchinsky 2013; Van Damme et al. 2013; Ji et al. 2015; Sinev & Yusoff 2015, 2018; Choedchim et al. 2017; Lopez et al. 2017; Sharma & Sharma 2017; Tiang-nga et al. 2020; Choedchim & Maiphae 2023; Dadykin et al. 2023). In Vietnam, it is registered throughout the country (Dang et al. 1980, 2002; Dang & Ho 2001; Sinev & Korovchinsky 2013; Gusakov et al. 2014).

Dunhevedia crassa is a littoral species which occurs, as a rule, in the sites with well developed vegetation in a variety of water bodies (mostly lentic), both permanent and temporary. It can tolerate a fairly high level of salinity (up to 25.9‰) (Idris 1983; Smirnov 1996; Dang & Ho 2001; Sinev & Korovchinsky 2013; Błędzki & Rybak 2016; Korovchinsky et al. 2021b; Choedchim & Maiphae 2023). We found the only female of the species in a small lake located very close to the sea (see Appendix 1).

Remarks. This species was originally described from Australia. On other continents, D. crassa may represent a group of similar species that so far require careful comparative analysis (Smirnov 1996; Kotov et al. 2013b; Korovchinsky et al. 2021b).