Streblocerus spinulatus Smirnov 1992

Streblocerus spinulatus Smirnov, 1992 Fig. 2 Idris & Fernando 1981a: 237–238, Figs. 8–10 (pygmaeus); Idris 1983: 42–43, Fig. 20 (pygmaeus); Smirnov 1992: 126, Figs. 528–530. Material examined. Several parthenogenetic females from a forest waterbody near Muadzam Shah, Pahang, (3.12474° N, 102.9969° E), 18.10.2013; 11 parthenogenetic females from Chini Lake, Pahang state (3.43257° N, 02.9186° E), 19.03.2013; several parthenogenetic females from various locations in Bera Lake, Pahang, on 1.02.2018. Body shape of the studied specimens (Fig. 2A–C) is typical of the genus, with a head length of about half the length of the valves. Valves and head are covered by a peculiar scale-like sculpture. The morphology of antennule, antenna and labrum is typical of the genus (Fig. 2D–E). Streblocerus spinulatus clearly differs from the Eurasian S. serricaudatus s. lato (see Hudec 2010 and Tiang-nga et al. 2020), Venezuelan S. superserricaudatus Smirnov, Alvarez & Castillo, 1995 (see Smirnov et al. 1995) and West African S. inexpectatus Dumont, 1981 (see Dumont 1981) in absence of denticles on preanal margin of the postabdomen (see Fig. 2F). Streblocerus spinulatus differs from its sibling species, S. pigmaeus Sars, 1901, in having much longer setulae on preanal margin of the postabdomen (see Fig. 2F). Streblocerus spinulatus was described by Idris & Fernando (1981a) from Peninsular Malaysia as S. pygmaeus Sars, 1901, although the latter is described from Brazil and is known from the Central and South America. Smirnov (1992) has proposed that this population belongs to a distinct species. Streblocerus spinulatus is known from a few localities in Peninsular Malaysia: Chini Lake, Pahang (our data), Subang Lake, Selangor, Batang Bertunjai pond, Selangor and Mengkarak rice field and Pahang (Idris & Fernando 1981a). Also, the species was observed in one locality in Sabah, East Malaysia (Sinev & Yusoff 2018) and in North-East Thailand (Tiang-nga et al. 2020). Records of Streblocerus from China in Chiang & Du (1979) might also belong to S. spinulatus and should be revised.