Unionicola bonzi (Claparède, 1869), Claparede, 1869

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 : 427-429

Unionicola bonzi (Claparède, 1869)

( Figs 22A–D , 23A–D )

Material examined. 1 male, 3 females (free-swimming): Ukraine, Odessa Province, Danube River near settlement Vilkovo, 0 3.07.2011, leg. L.N. Yanovich, T.V. Shevchuk.

Diagnosis. Adults. Dorsum with single pair of platelets; coxal plates III+IV nearly as long as wide with convex medial margin; P-3 with 2 almost subequal proximal setae; P-4 tapering distally with 3 very small ventral tubercles, P-5 moderately long with strongly concave ventral margin; anterior genital plates of female without anterior subcutaneous projection; genital plates of male relatively narrow, fused to each other by posterior ends only; swimming setae on IV-Leg-5 shorter than IV-Leg-6; claws of all legs subequal, sickle-shaped with short dorsal clawlet and long ventral one.

Description. Both sexes. Dorsum with distinct developed anterior platelets ( Fig. 22A ), posterior platelets not developed. Anterior and posterior coxal groups ( Fig. 22B ) divided by rather wide interspace; sclerites, bearing setae and glandularia Le, larger than sclerites bearing other idiosomal setae. Apodemes of first coxal group not reaching to anterior margin of third coxae. Coxal plates III+IV subquadrate (L/W ratio 1.0–1.2) with convex 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. 23A ) short and stocky, first 3 segments and proximal portion of tibia expanded dorsoventrally.

P-2 with 5 unequal setae, P-3 with two almost subequal proximal setae; P-4 tapering distally, with two very small ventral tubercles distally to middle of segment and each bearing thin short seta and one small ventrodistal tubercle bearing short peg-like seta; P-5 relatively short (P-4/P-5 L 1.8–2.1) with strongly concave ventral margin, both dorsal spines longer than both ventral ones.

Tarsi of all legs slightly thickened distally ( Figs 23B–C ). 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. 23C ): one on telofemur, two on genu and 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 all legs subequal, sickle-shaped with short dorsal clawlet and long ventral one ( Fig. 23D ).

Female. Anterior genital plates wide without anterior subcutaneous projections, each with two short nearly subequal inner spines and two thin lateral setae ( Fig. 22C ). Posterior plates more or less triangular, each with short, thin inner seta and 3–5 thin lateral setae.

Measurements (n=2). Idiosoma L 600–650; coxae III+IV L 190–200, W 160–175; anterior dorsal platelets L 35–40, W 15–20; anterior genital plates L 72–85, W 130–145; posterior genital plates L 80–85, W 78–95; pedipalpal segments (P-1–5) L: 18–24, 100–110, 50–60, 100–105, 50–54; leg segments L: I-Leg– 1–6—48 –55, 75–80, 100–105, 135–145, 115–125, 108–120; II-Leg– 1–6—48 –55, 85–90, 105–115, 155–165, 165–175, 140–150; III-Leg– 1–6—48 –55, 70–85, 90–95, 110–120, 130–140, 120–130; IV-Leg– 1–6—85 –90, 90–95, 115–120, 140–150, 180–195, 180–185.

Male. Genital plates ( Fig. 22D ) fused to each other by posterior ends only, with 8–10 thin setae on each side.

Measurements (n=1). Idiosoma L 650; coxae III+IV L 160–180, W 150–165; anterior dorsal platelets L 30–35, W 8–10; genital field L 220–230, W of one genital plate 40–45; pedipalpal segments (P-1–5) L: 18, 90, 42, 85, 42; leg segments L: I-Leg- 1–6—42, 65, 90,120, 100, 110; II-Leg- 1–6—42, 85, 95, 130, 145, 140; III-Leg- 1–6—48, 65, 78, 105, 120, 120; IV-Leg- 1–6—65, 72, 95, 125, 155, 150.

Deutonymph. See Imamura (1953b), Hevers (1979).

Larva. See Hevers (1980).

Habitat. Lakes, ponds, running waters.

Hosts. Unionidae : Unio pictorum Linnaeus , U. crassus Philipsson , U. tumidus Philipsson and Anodonta cygnea Linnaeus ( Viets & Plate 1954; Hevers 1980).

Distribution. Widely distributed in Europe including the European part of Russia ( Viets 1936, 1956; Sokolow 1940; Lundblad 1968; Viets 1978). Hevers (1984) described U. imamurai (sibling species of U. bonzi ) in Japan based upon some relatively small differences; Wen and his colleagues report Hevers’ species in China ( Wen & Zhu, 1999).

Figures

FIGURES 22 A – D. Unionicola bonzi, adults: A, dorsal plates; B, coxal plates; C – D, genital field; A – C, female; D, male. Scale bars: A – B = 100 Μm; C – D = 50 Μm.

FIGURES 23 A – D. Unionicola bonzi, adults: A, pedipalp, lateral view; B, I- Leg- 1 – 6; C, IV-Leg- 1 – 6; D, claw of leg IV. Scale bars: A, D = 50 Μm, B – C = 100 Μm.