Eulimnadia behningi Smirnov, 1949

Dadykin, Ivan A., Karimov, Gafur N., Sinev, Artem Y., Volkova, Polina A. & Kotov, Alexey A., 2024, Branchiopoda (Crustacea: Anostraca and Diplostraca) diversity in Tajik Pamir and plain West and South Tajikistan, Zootaxa 5497 (1), pp. 1-32 : 19-21

Eulimnadia behningi Smirnov, 1949

( Fig. 5)

Description. Hermaphrodite. Body length 1.5–10.2 mm, with a maximum height of 0.8–3.2 mm slightly anteriorly displaced in adults ( Fig. 5A). Carapace ovoid in lateral view, laterally flattened. Valves transparent, lacking growth lines. Dorsal margin slightly convex, dorso-anterior and dorso-posterior angles distinct.

Head with a relatively weak prominence anteriorly to dorsal organ; dorsal organ pedunculate ( Fig. 5B). Anteroventral angle of the head with a small notch; ventral margin slightly concave. Rostrum short. Ocellus triangular. Antennule unisegmented, elongate, with 6–7 projections on its anterior margin ( Fig. 5B). Antennae biramous, both rami 7-segmented, with uniform armature of 2–5 anterior spines and 2–5 posterior feathered setae ( Fig. 5A). Trunk 18-segmented, bearing 15 pairs of thoracic appendages. The last 10 segments of the trunk bearing 2–3 short spinulae. Thoracic appendages of similar structure, having epipodite, exopodite, endopodite and five endites. Epipodites large, leaf-like, with smooth margins. Exopodite and endopodite with a uniform armature of long feathered setae ( Figs. 5D, F); appendages of IX and X pairs with exopodite extending dorsally, forming an egg filament ( Fig. 5F). Endites 2–5 conical to spatulate, have a uniform armature: inner margin with a posterior row of 10–30 long bisegmented feathered setae and with an anterior row of 8–15 relatively short unisegmented feathered setae ( Figs. 5D, F). Endite 1 with a row of 15–25 long bisegmented feathered setae on its posterior surface; two convex serrate claws apically; a row of 3–4 large bisegmented feathered setae on the anterior surface ( Fig. 5E). Telson short, with almost parallel dorsal and ventral margins; anal opening situated at distal end of the telson ( Fig. 5C). Ventral margin forming a short finger-like projection ventrally to claw base. Dorsal edge with 13 teeth; the distalmost one is the largest, as long as the width of the cercopod basally; teeth 2, 7 and 11 relatively large, the latter teeth small. Cercopods long, thick, slightly convex in its distal third ( Fig. 5C); distal third bearing 10–14 small spines; a large spine at 2/3 of the length from the cercopod base; a row of 8–10 feathered setae proximally.

Cyst morphology unknown.

Male. Body length 6.0–8.0 mm, body height 2.5–2.8 mm. General morphology conforms to that of the hermaphrodite. Thoracic limbs I and II armed with clasping organs. Endopodite of limb I 3-segmented ( Figs. 5G, H): the proximal endopodal segment with a spherical outgrowth bearing a row of short setae and a field of blunt spines on its occlusal margin ( Fig. 5G); posterior surface of the outgrowth with a group of 7–8 feathered setae; two distal endopodal segments elongate, cylindrical, forming a palp ( Fig. 5H). A row of four apical setae on the posterior side of proximal palp segment. A field of short setae on the tip of the palp. Endite 5 hook-like, bearing a sucker apically and a field of tubercles subapically; a row of four setae on outer edge of endite 5 ( Figs. 5G, H). Clasping organ of limb II has a similar structure, except of 3-segmented endopodal palp.

Remarks. Eulimnadia behningi was observed in a single puddle in the vicinity of Bokhtar, Khatlon Region ( Fig. 1, loc. 14; see also Table 1). Only slight differences from the diagnosis in its first description were observed, including absence of growth lines and a number of setae on dorsal margin of truncal segments; also, observed individuals were somewhat larger than the type population. The species was described from the rice fields near Samarkand, Uzbekistan ( Smirnov 1949). Later, it was found in the analogous locality in the vicinity of Isfara, Tajik Fergana Valley ( Mukhamediev 1986, reported as Eulimnidia behningi ). Eulimnadia behningi is a rare species observed only in temporary water bodies of Uzbekistan and Tajikistan to date ( Smirnov 1949; Mukhamediev 1986).