Coronatella (Coronatella) trachystriata

23. * Coronatella (Coronatella) trachystriata (Chen, Zhang et Liu, 1994) Localities and specimens found: 3 – 1♀ em; 25 – 1♀, 1♀ em, 1j. Distribution and ecology. This is a rare East Asian member of the genus, originally classified as a subspecies of Alona (now Coronatella) rectangula: A. rectangula trachystriata Chen, Zhang et Liu, 1994 (Chen et al. 1994; Van Damme et al. 2010; Sinev et al. 2024). Until now, the species has only been recorded in the Far East of Russia (Amur River basin), South Korea and China, including Hainan Island (Kotov et al. 2011, 2017; Ji et al. 2015; Sinev et al. 2015; Sinev 2016, 2017; Korovchinsky et al. 2021b; Sinev et al. 2024). The present work is the first report of C. trachystriata specimens in Vietnam and the southernmost record of them. The species lifestyle and ecology are still weakly understood. Until now, it was found in lakes, ponds, reservoirs and river mouths (Chen et al. 1994; Kotov et al. 2011; Sinev et al. 2015, 2024; Korovchinsky et al. 2021b). According to recent observations in one of the lakes in China (Sinev et al. 2024), C. trachystriata is obviously a bottom-dwelling species which prefers soft sediments at some distance from the shallowest coastal zone. It can also occur sporadically in plankton due to the agitation of bottom sediments by waves. During our research, several exemplars of this species were found on the open shoreline of two reservoirs on sandy and sandy-silty deposits (see Appendix 1).