Water mites of the genus Unionicola Haldeman, 1842 (Acari, Hydrachnidia, Unionicolidae) in Russia Author Tuzovskij, Petr V. Author Semenchenko, Ksenia A. text Zootaxa 2015 3919 3 401 456 journal article 10.11646/zootaxa.3919.3.1 dec3bc79-023d-454e-9ed8-4dfb8c3f0b6a 1175-5326 241378 FF49DAFE-EA8E-473B-9F3D-CEB670B4882B Unionicola aculeata (Koenike, 1890) ( Figs 18A–D , 19A–D ) Material examined. 8 males , 7 females : Russia , Samara Province, Stavropol District, National natural Park “Samarskaya Luka”, Gusinoe Lake, July–September 1992 . 7 males , 9 females : Yaroslavl Province, Nekouz District, Rybinsk reservoir near settlement Borok, September–October 2003 , 2013, leg. P.V. Tuzovskij. All males and females are collected free-swimming. Diagnosis. Adults. Dorsum with two pairs of small unequal platelets; coxal plates III+IV elongated with straight medial margin; P-3 with long lateroproximal seta and relatively short dorsodistal seta; P-4 tapering distally, ventrolateral tubercles located distally to middle of segment, P-5 moderately long with strongly concave ventral margin; anterior genital plates of female each with long subcutaneous accretion; genital plates of male relatively narrow and fused to each other by posterior ends only; swimming setae on IV-Leg-5 slightly longer than IV-Leg-6; claws of legs I thick, hook-like, claws of legs II–IV thin sickle-shaped. Description. Both sexes . Dorsum with two pairs of small unequal platelets ( Fig. 18A ), anterior platelets relatively large, elongate; posterior platelets oval or circular and considerably smaller than anterior ones. Anterior and posterior coxal groups ( Fig.18B ) 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 well extending beyond to anterior margin of third coxae. Coxal plates III+IV elongated (L/W ratio 1.2–1.3) 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. Pedipalps ( Fig. 19A ) short and stocky, first three segments and proximal portion of tibia expanded dorsoventrally, P-2 with four (three proximal and single dorsodistal) short setae, P-3 with one long lateroproximal seta and one relatively short dorsodistal seta; P-4 tapering distally, with two unequal ventrolateral tubercles distally to middle of segment and each bearing thin short seta and one ventrodistal tubercle bearing short peg-like seta, and with one thin dorsoproximal seta; P-5 relatively short (P-4/P-5 L 1.8–2.0) with strongly concave ventral margin. FIGURES 18A–D . Unionicola aculeata , adults: A, dorsal plates; B, coxal plates; C–D, genital field; A–C, female; D, male. Scale bars= 100 Μm. 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. 19B ): two on telofemur, 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 little longer than IV-Leg- 6, the last with three long, thick subequal ventral setae. Claws of legs I ( Fig. 19C ) thick, hook-like with two unequal clawlets; claws of legs II–IV sickle-shaped with short dorsal clawlet and long ventral one ( Fig. 19D ). Female. Anterior genital plates wide each with long anterior subcutaneous accretion, posterior inner spine thicker than anterior inner on each side ( Fig. 18C ). Posterior plates more or less triangular, each with short, thin inner seta and 7–9 short, thin lateral setae. Measurements (n=9). Idiosoma L 900–1140; coxae III+IV L 325–365, W 250–270; anterior dorsal platelets L 75–90, W 25–30; posterior dorsal platelets L 18–25, W 12–18; anterior genital plates L 75–90, W 125–150; posterior genital plates L 100–115, W 110–140; pedipalpal segments (P–1–5) L: 24–33, 180–190, 90–100, 160–165, 80–90; leg segments L: I-Leg- 1–6—90 –105, 225–260, 240–260, 350–370, 220–245, 225–240; II-Leg- 1–6—80 –100, 250–260, 265–285, 355–390, 365–385, 285–325; III-Leg- 1–6—90 –100, 200–215, 210–220, 210–220, 260–270, 265–285, 255–265; IV-Leg-1–6—145–170, 200–230, 265–280, 315–330, 390–410, 350–360. Male . Genital plates ( Fig. 18D ) relatively narrow, fused to each other by posterior ends only, with 10–13 thin setae on each side. Measurements (n=5). Idiosoma L 815–940; coxae III+IV L 305–325, W 200–225; anterior dorsal platelets L 65–75, W 25–30; genital field L 220–230, genital plate W 54–60; pedipalpal segments (P-1–5) L: 16–24, 135–145, 55–82, 130–150, 70–82; leg segments L: I-Leg- 1–6—80 –100, 225–240, 240–250, 325–345, 220–230, 210–230; II- Leg- 1–6—80 –90, 220–250, 270–285, 375–385, 350–370, 290–305; III-Leg- 1–6—80 –90, 175–205, 200–270, 250–260, 250–270, 240–260; IV-Leg-1–6—130–140, 185–230, 250–260, 300–320, 355–375, 305–335. FIGURES 19A–D . Unionicola aculeata , female: A, pedipalp, lateral view; B, IV-Leg4–6; C, claw of leg I; D, claw of leg IV. Scale bars: A = 100 Μm, B = 200 Μm, C–D = 50 Μm. Deutonymph . See Hevers (1979) . Larva . See Hevers (1980) , Wainstein (1980) . Habitat. Lakes, reservoirs, ponds, running waters. Hosts. Unionidae and Viviparidae . Very numerous hosts on different continents ( Viets & Plate 1954 ; Hevers 1980 ; Böttger 1972 ; Wen & Zhu 1999 ; Edwards & Vidrine 2013 ). Distribution. Europe, Asia, North America ( Viets 1936 , 1956 ; Sokolow 1940 ; Lundblad 1968 ; Viets 1978 ; Edwards & Vidrine 2013 ).