Atractides (Atractides) aksuensis sp. n.

(Figs 11–17)

Type series. Holotype: male, slide 9955, Asia, Kazakhstan, Turkestan Province, Tyulkubaskiy District, Aksu-Zhabagly Nature Reserve, Aksu stream, 42°19′36.4″N 70°22′17.8″E, 1350 m, depth about 1 m, substrates large stones, mosses, white sand, 15.08.2019, leg. V. Stolbov . Paratype: 1 male, same locality and data as holotype . Additional material: 1 male, Aksu-Zhabagly Nature Reserve, Ulken-Kaindy stream inflow of Aksu river, 42°23’48.4”N 70°37’27.5”E, 1890 m, depth 0.5 m, substrates: stones mosses, 14.08.2019, leg. V. Stolbov .

Diagnosis. Male. Coxal plates I+II close to coxal plates III+IV but not forming a coxal shield; genital plate wider than long, anterior margin straight, with 18-21 setae on each side; capitular bay V-shaped. P-2 with moderately large ventrodistal protrusion, P-3 with six thick setae ventral margin slightly convex distally, I-Leg-5 S-1 and S-2 subequal in width, S-1-2 separation 12–15.

Description. Male. Colour in life unknown. The idiosoma oval, integument smooth, muscle insertions unsclerotized. Coxal plates I+II close to coxal plates III+IV at their touching edges, but not forming a coxal shield (Fig. 11). Posteromedial margin of coxal plates I+II rather broad and slightly convex, apodemes of anterior coxal groups short directed laterally. Median suture line between coxal plates I indistinct, central sub-dermal projection small and not reaching to posterior margin. Capitular bay V-shaped. Seta and glandularium Hv situated in posterolateral part of coxal plate II. Medial margin of coxal plates III+IV straight or forming an obtuse angle, glandularium and seta Pe situated near middle of anterior margin of coxal plate IV, posterior margin of coxal plate IV straight or slightly convex. Genital plate (Fig. 12) wider than long (L/W ratio 0.79–0.94), anterior margin straight, posterior margin moderately indented, bearing 19–22 fine setae on each side, acetabula rather large in an obtuse triangle. The setae Pi and Ci separated, excretory pore unsclerotized (Fig. 13).

Pedipalp (Fig. 14) stout: P-1 short, thin with a single short dorsodistal seta; P-2 ventral margin convex distally, bearing five unequal dorsal setae; one or both distal setae longer than proximal ones; P-3 with six thick setae (four dorsal and two distventral) and two to four thin ones, ventral margin slightly convex distally; P-4 slightly protruding near proximoventral seta, sword seta short pointed and located between ventral setae, bases of ventral setae divide tibia into three unequal sectors (3:2:2), dorsolateral setae numerous located in central and distal parts of segment.

All legs without swimming setae. I-Leg-5 seta S-1and S-2 distally narrowed (Fig. 15), bluntly pointed, S-1 longish, S-2 thicker than S-1, proximally enlarged, distance between S-1 and S-2 short; I-L-6 ventral margin strong curved, basally thickened, in the centre narrowed, distally with almost parallel dorsal and ventral margins, much shorter than I-Leg-5 (I- Leg-5/6 ratio 1.47–1.68). Posterior legs, in particular IV legs, very slender, with a few setae on each segment (Fig. 16). Leg claws with two pointed denticles, ventral clawlet a little shorter than external one; lamella of with concave ventral margin (Fig. 17).

Measurements (n=3). Idiosoma L 680–810, W 440–525; coxal plates I+II L 215–230, W 210, mL 115–120; coxal plates III+IV L 195–240, W 170–180; genital plate L 105–125, W 120–145; genital acetabula (ac. 1–3) L/W: 42–48/34– 42, 42–54/24–30, 42–48/30–42; glandularia D: 15–18; pedipalp total L 260–295, L/H, L/H ratio: P-1, 24–30/28–30, 0.9–1.0; P-2, 60–65/53–55, 1.1–1.2; P-3, 68–72/34–36, 1.9–2.0; P-4, 78–102/40–42, 1.85–2.4; P-5, 23–25/11.5–12, 2.0; leg segments, L, L/H ratio: I–Leg-1, 48–55, 1.14–1.28; I–Leg-2, 75–90, 1.85–1.90; I–Leg-3, 84–90, 2.0–2.14; I–Leg-4, 125–150, 3.06–3.12; I–Leg-5, 150–162, 3.37–3.57; I–Leg-6, 95–102, 3.4–3.55; II–Leg-1–6, L: 54–60, 50–80, 75–100, 100–110, 105–115, 115–120; III–Leg–1–6, L: 50–60, 55–70, 75–85, 120–125, 135–145, 120–132; IV–Leg–1–6, L: 95– 115, 90–95, 120–140, 180–190, 205–220, 160–180; I-Leg-6: HA = 29–32, HB = 16–19, HC =19–22; I-Leg-6, distance between S-1 and S-2 12 –15; S-1 L/W, L/W ratio 70–90/11–12, 6.36–7.5; S-2 L/W, L/W ratio 62–70/12–13.8, 5.07–5.16.

Female. Unknown.

Differential diagnosis. The present species is closely related to Atractides filimonovae sp. n .. The new species differs from A. filimonovae sp. n. in the following characters (character states of male A. filimonova e sp. n. are indicated in parenthesis): the genital plate with straight anterior margin, bearing 18–21 fine setae on each side, Fig. 12 (with slightly convex posterior margin and bearing 27–28 setae, Fig. 2); capitular bay U-shaped, Fig. 1 (V-shaped, Fig. 11); I-Leg-5 S-1 and S-2 subequal in width, Fig. 15 (S-1 distinctly thinner than S-2, Fig. 5).

Etymology. The species is named after the river (Aksu) where it was collected.

Habitat. Running waters.

Distribution. Asia: Kazakhstan: Turkestan Province.