Coronatella (Coronatella) rectangula (Sars, 1862)

(Fig. 6H–M)

Diagnosis. Parthenogenetic female. Body length 0.32–0.38 mm, body ovoid in lateral view (Fig. 6H). Carapace ornamented with obscure longitudinal lines. Postabdomen short, slightly narrowing towards its distal end, preanal angle acute (Fig. 6J). Postanal margin with 4–5 large solitary spines and 2–3 groups of spinulae (Fig. 6J, K); 6–7 groups of long lateral setulae on lateral surface of the postanal portion (Fig. 6J). Inner distal lobe of thoracic limb I with two setae (2 and 3); seta 2 bears two large spines; seta 3 with a single spine (Fig. 6I).

Male. Body length 0.36 m, body more elongate than that of female (Fig. 6L). Postabdomen short, strongly narrowing towards its distal end, with prominent preanal angle (Fig. 6M). Postanal angle rounded. Gonopores located at distal end of the postabdomen. Armature of postanal portion conforms to that of female, except of marginal spines with are replaced by groups of setulae (Fig. 6M). Postabdominal claw short; basal spine thick, length of basal spine is about 0.32 length of the claw. Distal portion of the claw with a row of spines on its inner side (Fig. 6M).

Remarks. The species is common in Tajikistan, occurring in different types of water bodies in South Tajikistan and Tajik Pamir (locs. 4, 8, 10, 17, 18, 22, 24, 30, 31). Coronatella rectangula was previously reported for Tajikistan as Alona rectangula Sars, 1862 (Werestschagin 1923; Ozhegova & Sinelnikova 1963; Ozhegova et al. 1963; Gurvich 1974; Khaitov 1978; Mukhamediev 1986; Khaitov 2011, 2013). C. rectangula is one of the most common species of Aloninae in temperate regions of Eurasia, but southern borders of its distribution remain unclear (Korovchinsky & Kotov 2021; Sinev et al. 2022). The species can be easily confused with its recently described congeners (Sinev 2022; Sinev et al. 2022), while populations of C. cf. rectangula from Central Asia have never been studied properly. Morphology of studied males and parthenogenetic females well conforms to the diagnosis of European C. rectangula (Van Damme & Dumont 2008; Sinev 2022).