Coronatella (Coronatella) rectangula (Sars, 1862)

22. Coronatella (Coronatella) rectangula (Sars, 1862) View in CoL

Localities and specimens found: 16 – 1♀; 25 – 1♀ em; 97 – 1♀.

Distribution and ecology. Coronatella rectangula (formerly most often recognized as Alona rectangula Sars, 1862 ) is a very confusing taxon with a complicated taxonomic history and many synonyms ( Van Damme & Dumont 2008; Van Damme et al. 2010, 2013; Sinev 2017; Korovchinsky et al. 2021b; WoRMS Editorial Board 2024). Until recently, it was supposed that it has an almost global distribution ( Kotov et al. 2013a). According to modern concepts, the distribution of the typical form of this chydorid seems to be limited to the Palearctic and Oriental regions (Sinev 2017; Korovchinsky et al. 2021b), although the Southeast Asian populations have some differences and require additional research ( Sinev & Yusoff 2015; Sinev et al. 2015; Sinev 2016, 2017). The findings of C. rectangula -like specimens are rather common in the Oriental and adjacent areas ( Chiang & Du 1979; Rajapaksa & Fernando 1982a; Idris 1983; Michael & Sharma 1998; Sanoamuang 1998; Tanaka & Ohtaka 2010; Maiphae et al. 2005, 2008; Rane 2011; Chatterjee et al. 2013; Korovchinsky 2013; Kotov et al. 2013b; Ji et al. 2015; Sinev & Yusoff 2015; Sinev et al. 2015; Sinev 2016; Sharma & Sharma 2017; Gogoi et al. 2018; Tiang-nga et al. 2020; Choedchim & Maiphae 2023). In Vietnam, this crustacean is well known as well ( Shirota 1966; Dang et al. 1980, 2002; Dang & Ho 2001; Duong et al. 2008; Gusakov et al. 2014; Zhdanova 2014).

Coronatella rectangula is considered one of the most eurybiont representatives of the Aloninae . It occurs in almost all types of water bodies of any trophic level, in a wide range of environments. The species is found both in plankton and benthos. In big water bodies, it prefers littoral habitats, usually with aquatic vegetation (Van Damme et al. 2010; Sinev 2016; Korovchinsky et al. 2021b). In our samples, the species was rare and in low concentrations.