Leydigia (Neoleydigia) ciliata (Gauthier, 1939)

32. Leydigia (Neoleydigia) ciliata (Gauthier, 1939) View in CoL

Localities and specimens found: 49 – 1♀; 100 –2j.

Distribution and ecology. This representative of the genus is more widespread than the previous one. It is well known in tropical and subtropical areas of Africa and Asia and is also found, but less frequently, in Australia ( Smirnov & Timms 1983; Kotov 2009; Sinev, 2017; Korovchinsky et al. 2021b). In Africa and Australia, the southern limit of its distribution reaches areas with a moderate climate ( Smirnov & Timms 1983; Kotov 2009). In turn, in East Asia, the species penetrates as far north as South Korea ( Jeong et al. 2014). Leydigia ciliata is common in the countries of the Oriental realm ( Chiang & Du 1979; Swar & Fernando 1979; Michael & Sharma 1988; Rane 2002; Maiphae et al. 2008; Tanaka & Ohtaka 2010; Sinev & Sanoamuang 2011; Kotov et al. 2013b; Chatterjee et al. 2013; Ji et al. 2015; Padhye & Dumont 2015; Sinev & Yusoff 2015, 2018; Sinev et al. 2015, 2020; Sinev 2016; Sharma & Sharma 2017; Choedchim & Maiphae 2023; Dadykin et al. 2023; Padhye et al. 2023). In Vietnam, L. ciliata is not very widespread but perhaps it was noted here earlier under other name (see details in Remarks) ( Sinev & Korovchinsky 2013; Sinev & Semenyuk 2021).

Leydigia ciliata is a benthic species, apparently preferring silty and silty-clay deposits (Sinev 2016; Korovchinsky et al. 2021b). The species is most common in lakes and ponds but is also found in rice fields, peat swamps, channels, rivers, streams and other water bodies ( Kotov et al. 2003; Kotov 2009; Sinev & Korovchinsky 2013; Sinev & Yusoff 2015; Sinev et al. 2015; Sinev 2016; Choedchim & Maiphae 2023; Dadykin et al. 2023). In our samples, this crustacean was rare and few. It was detected in a floodplain lake and in the riparian zone of a branch of the Mekong Delta (see Appendix 1).

Remarks. It should be noted that reports of finds in Vietnam of L. acanthocercoides (Fischer, 1854) (e.g., by Shirota (1966), Dang et al. (1980, 2002), Dang & Ho (2001), Phan et al. (2015)), a northern member of the genus ( Kotov 2009; Korovchinsky et al. 2021b), are very likely erroneous and should also be attributed to L. ciliata ( Sinev & Korovchinsky 2013) . The same is obviously true of the records of L. acanthocercoides in China and India ( Chatterjee et al. 2013; Dadykin et al. 2023). The Indian records of L. australis and L. hardingi Kurz, 1875 most likely refer to L. ciliata too ( Chatterjee et al. 2013). Kotov et al. (2012, 2013b) pointed out that the Oriental populations of L. ciliata need additional verification, as Sinev & Sanoamuang (2011) found some differences between the males from Asia and those from Africa (the region of the original description of the species). In Korovchinsky’s (2013) review, L. ciliata is presented as a complex of species.