Unionicola samaraensis sp.n.

(Figs 28A–E, 29A–D)

Holotype: 1 female (free-swimming), slide 7453- IBIW, Russia: Samara Province, Krasnoyar District, Kondurcha River (right inflow of the Sok River), depth 0.5–1.0 m, 0 7.08.1997, leg. P.V. Tuzovskij.

Diagnosis. Female. Dorsum with a pair of platelets; coxal plates III+IV elongated with straight medial margin; P-3 with long lateroproximal seta and short dorsodistal seta, P-4 with large distolateral tubercle, P-5 moderately long with slightly concave ventral margin; anterior genital plates without subcutaneous accretion; swimming setae on IV-Leg-5 shorter than IV-Leg-6; claws of legs I thick, hook-like, claws of legs II–IV thin sickle-shaped.

Description. Female. Dorsum witha pair of anterior platelets (Fig. 28A), posterior platelets not developed. Anterior and posterior coxal groups (Fig. 28B) divided by relatively narrow interspace, sclerites, bearing setae and glandularia Le, larger than sclerites bearing other idiosomal setae. Apodemes of first coxal group rather long and extending beyond to anterior margin of third coxae. Coxal plates III+IV elongated (L/W ratio 1.25) with straight medial margin. Surface of all coxal plates with reticulations. Genital acetabula relatively small and occupy less than half of area of each plate. Anterior genital plates wide and narrow, posteromedial spine thicker than anteromedial one on each side (Fig. 28C). Posterior plates more or less triangular, with 5–6 short, thin setae each, acetabula less than half of area of each plate.

Pedipalps (Fig. 28D) short and stocky: P-2 with straight ventral margin and four short dorsal setae, P-3 with one long lateroproximal seta and one relatively short dorsodistal seta; P-4 weakly curved, of subequal thickness along entire length, with large distolateral tubercle and two very small tubercles, one small tubercle located near middle of segment, both other tubercles located distally, small proximal tubercle and large lateral tubercle bearing thin seta each and small distal tubercle bearing short peg-like seta; P-5 moderately long with two long dorsodistal spines and two relatively short ventrodistal ones (Fig. 28E). P-5 ventral margin slightly concave.

Figure 29A shows the proportion and chaetotaxy of the first leg. Legs II–IV long, slender; all segments, except trochanter, cylindrical and with swimming setae. The number of distal swimming setae on legs IV is as follows (Fig. 29B): three on genu and on tibia. Swimming setae on leg II shorter than swimming setae on legs III–IV; swimming setae on IV-Leg-5 shorter than IV-Leg-6. Claws of legs I (Fig. 29C) thick hook-like with two unequal clawlets; claws of legs II–IV thin slightly curved with short dorsal clawlet and long ventral (Fig. 29D).

Measurements (n=1). Idiosoma L 810; coxae III+IV L 285, W 225; anterior dorsal platelets L 55, W 25; anterior genital plates L 65, W 108; posterior genital plates L 90, W 90; pedipalpal segments (P-1–5) L: 30, 130, 65, 125, 48; leg segments L: I-Leg- 1–6—60, 135, 160, 225, 175, 150; II-Leg- 1–6—60, 160, 180, 285, 310, 310; III-Leg- 1–6—75, 160, 175, 250, 325, 300; IV-Leg-1–6—125, 170, 210, 275, 485, 260.

Differential diagnosis. The present species is similar to the Unionicola aculeata . The female of Unionicola samaraensis sp.n. differs from U. aculeata in the following characters (character states of U. aculeata are indicated in parenthesis): in the female of U. samaraensis sp.n. posterior dorsal platelets not developed (dorsum with two pairs of small unequal platelets); the anterior genital plates without anterior subcutaneous accretions, Fig. 28C (with anterior subcutaneous accretions, Fig. 18C), the small proximal tubercle on P-4 located near middle of segment, Fig. 28D (distally to middle of segment, Fig. 19A), P-5 with slightly concave ventral margin (with strongly concave ventral margin), swimming setae on IV-Leg-5 shorter than IV-Leg-6, Fig. 29B (swimming setae on IV-Leg-5 longer than IV-Leg-6, Fig. 19B).

Etymology. The species epithet “ samaraensis ” is derived from the name of the Province where it was collected (Samara).

Male. Unknown.

Deutonymph. Unknown.

Larva. Unknown.

Habitat. Running waters.

Hosts. Unknown.

Distribution. Europe (Russia: Samara Province).