Latonopsis australis Sars 1888

1. Latonopsis cf. australis Sars, 1888 Localities and specimens found: 30 − 8♀, 1♀ ov, 9j; 31 − 1♀, 1j; 41 − 5♀, 1♀ ov, 8j; 42 − 1♀, 1j; 46 − 1♀; 50 − 1♀, 60j; 51 −41j. Distribution and ecology. Latonopsis australis s. lat. is a cosmopolitan species group distributed mainly in the tropics and subtropics around the world but also found in temperate areas of Europe, Asia and North America. To date, these crustaceans are known from all continents and biogeographic regions apart from Antarctica (Korovchinsky 2004, 2018; Kotov et al. 2013a; Korovchinsky et al. 2021b). This is one of the most frequently recorded (as L. australis, L. cf. australis or L. australis -group of species) cladocerans in Southeast Asia and the Oriental region generally (Fernando 1974, 1980; Chiang & Du 1979; Idris & Fernando 1981; Idris 1983; Sharma & Michael 1987; Michael & Sharma 1988; Sanoamuang 1998; Rane 2002, 2005, 2011; Maiphae et al. 2005, 2008; Tanaka & Ohtaka 2010; Chatterjee et al. 2013; Korovchinsky 2013; Kotov et al. 2013b; Van Damme et al. 2013; Pascual et al. 2014; Sinev et al. 2015; Xiang et al. 2015; Lopez et al. 2017; Sharma & Sharma 2017; Gogoi et al. 2018; Sinev & Yusoff 2018; Tiang-nga et al. 2020; Choedchim & Maiphae 2023), including Vietnam (Dang et al. 1980, 2002; Dang & Ho 2001; Sinev & Korovchinsky 2013; Gusakov et al. 2014). Latonopsis australis inhabits a wide range of biotopes, from littoral zones of large lakes and reservoirs (mainly with good vegetation) to various shallow and small, permanent and temporary water bodies: oxbow and floodplain lakes, little rivers, ponds, swamps, peat swamps, rice fields, etc. (Idris 1983; Dang & Ho 2001; Korovchinsky 2004, 2018; Lopez et al. 2017; Sinev & Yusoff 2018). This crustacean belongs to the few benthic representatives of the family Sididae, preferring bottom sediments for their habitat, although it also occurs in thickets of aquatic vegetation and in open pelagic parts of water bodies too (Korovchinsky 2004, 2018; Pascual et al. 2014). When disturbed, it is able to move unevenly for a short time (Korovchinsky 2018). According to Rane (2002), L. australis can be rather common among partially submerged floating plants. In our material, it was also found in the rhizosphere of a water hyacinth (Eichhornia crassipes (Martius)) and a floating moss (Salvinia sp.). Moreover, in these samples (Nos. 50, 51; here and beyond, see section “Localities and specimens found” and Appendix 1 for more detailed information on the number of specimens and locality characteristics of the taxon under discussion), it was the most abundant. Remarks. Latonopsis australis s. str. was originally described from Australia (Sars 1888). Korovchinsky (2004, 2018) defines this taxon as a L. australis group of species that, in addition to the typical form, includes several close, poorly described congeners. The global population of this group (and the Oriental region is no exception) still needs a thorough review (Korovchinsky 2004, 2018; Tanaka & Ohtaka 2010; Chatterjee et al. 2013; Kotov et al. 2013b; Lopez et al. 2017; Sinev & Yusoff 2018).