Unionicola rezvoi Sokolow, 1931

Tuzovskij, Petr V. & Semenchenko, Ksenia A., 2015, Water mites of the genus Unionicola Haldeman, 1842 (Acari, Hydrachnidia, Unionicolidae) in Russia, Zootaxa 3919 (3), pp. 401-456 : 432-433

Unionicola rezvoi Sokolow, 1931

( Figs 26A–E , 27A–D )

Material examined. 14 females: Russia, PrimoryTerritory, Khankaysky District, Khanka Lake, Astrakhansky Bay, from mantle cavity of Sinanodonta sp., 16.07.2004, leg. E.I. Barabanschikov.

Diagnosis. Adults. Dorsum with three pairs of small elongated platelets; coxal plates III+IV longer than their width, with convex medial margin; P-3 with two long setae, P-4 slightly tapering distally, with three small tubercles two of which bearing setae, P-5 short, with slightly concave ventral margin; genital field with 5 pairs of genital acetabula, lying on two genital plates in males and four in females; genital plates of male converging posteriorly; 2–3 short thin setae on IV-L-4 and three setae on IV-L-5; claws of legs bifid with subequal clawlets.

Description. Both sexes. Dorsum with three pairs of small elongated platelets ( Fig. 26A ). Anterior and posterior coxal groups ( Fig. 26B ) divided by wide interspace, sclerites, bearing setae and glandularia Le, larger than sclerites bearing other idiosomal setae. Apodemes of anterior coxal groups not developed. Coxal plates III+IV elongated (L/W ratio 1.3) with rounded medial margin. Surface of all coxal plates with reticulations.

Pedipalps ( Fig. 26C ) short and stocky: P-2 with four short setae; P-3 with two long setae; P-4 slightly tapering distally, with three short tubercles two of which bearing seta, middle tubercle longer and more rounded; P-5 short, with slightly concave ventral margin.

First leg ( Fig. 27A ) shorter than legs II–IV, thick. Legs II–IV long, slender; all segments, except trochanter, cylindrical; with two to three short swimming setae on IV-L-4 and three on IV-L-5 ( Fig. 27B ). Claws of legs I–IV bifid with nearly equal clawlets ( Fig. 27C–D ).

Female. Anterior genital plates large, with two unequal acetabula, two short subequal medial spines and two thin, short setae on each side ( Fig. 26D ). Posterior plates more or less triangular, with a single long, thin inner seta and three more short thin setae.

Measurements (n=2). Idiosoma L 1615–1700; coxae III+IV L 448–462, W 343–370; first pair of dorsal platelets L 70–72, W 22–26; second pair of dorsal platelets L 64–66, W 35–38; third pair of dorsal platelets L 32–33, W 19–20; anterior genital plates L 151–152, W 105–106; posterior genital plates L 174–185, W 105–106; pedipalpal segments (P-1–5) L: 35–40, 132–158, 53–60, 130–132, 65–66; leg segments L: I-Leg-1–6—112–114, 145–191, 218–237, 264–350, 224–264, 210–220; II-Leg-1–6—105–112, 211–231, 343–356, 468–495, 409–442, 297–316; III-Leg-1–6—110–112, 172–191, 224–240, 266–284, 231–250, 211–231; IV-Leg-1–6—171–204, 200–204, 311–320, 356–363, 416–442, 297–310.

Male. Idiosoma L 750–800, short and wide. Genital field in posterior part of idiosoma, heart-shaped ( Fig. 26E ). Genital plates expanded anteriorly and narrowed distally. Genital acetabula 5 pairs, forming curved lines, middle acetabula usually larger than other ( Sokolow 1931, 1940).

Deutonymph. Unknown.

Larva. Unknown.

Habitat. Lakes, rivers.

Hosts. Unionidae : Cristaria plicata (Leach) ( Sokolow 1931, 1940) and Sinanodonta sp. (this study). Distribution. Russia (Primory Territory) ( Sokolow 1940).

Figures

FIGURES 26 A – E. Unionicola rezvoi, adults: A, dorsal plates; B, coxal plates; C, pedipalp; D – E, genital field; A – D, female; E, male (after Sokolow, 1931). Scale bars = 100 Μm.

FIGURES 27 A – D. Unionicola rezvoi, female: A, I-Leg- 1 – 6; B, IV-Leg- 1 – 6; C, claw of leg I; D, claw of leg IV. Scale bars: A – B = 50 Μm; C – D = 25 Μm.