Unionicola japonensis Viets, 1933

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 : 443-445

Unionicola japonensis Viets, 1933

( Figs 36A–D , 37A–E )

Material examined. 1 female (free-swimming): Russia, Primory Territory, Lesozavodsky District, Ussuri River basin, small lake near Gornye klyuchi, N 45°15.490’; E 133º30.195’, depth 1.2 m, substrate: silt, detritus; 14.07.2005, leg. K.A. Semenchenko, D.A. Sidorov.

Diagnosis. Adults. Dorsum with one pair of anterior elongated platelets; coxal plates III+IV elongated with straight medial margin; pedipalp short, stout, P-3 with long lateroproximal and relatively short mediodistal setae, P-4 all tubercles bearing thin, short seta, P-5 short, with slightly concave ventral margin and four unequal spines; females with 9–12 relatively small genital acetabula on each side; genital plates of male fused to each other by anterior ends only, with 14–20 acetabula on each plate; legs without swimming setae; claws of legs I and IV large bifid, claws II–III small sickle-shaped with subequal clawlets.

Description. Both sexes. Dorsum with one pair of elongated platelets ( Fig. 36A ). Anterior and posterior coxal groups ( Fig. 36B ) divided by narrow interspace; sclerites, bearing setae and glandularia Le, slightly larger than sclerites bearing other idiosomal setae. Apodemes of first coxal groups extending well beyond to anterior margin of third coxae. Coxal plates III+IV elongated (L/W ratio 1.5) with straight medial margin, posterior margin of coxal plate IV directed anterolaterally. Surface of all coxal plates punctated.

Pedipalps ( Fig. 37A ) short, stocky: P-2 with four (three proximal and single distal) short setae; P-3 with long lateroproximal and relatively short mediodistal setae; P-4 with two ventrolateral tubercles distally to middle of segment and one ventrodistal tubercle each bearing thin, short seta; P-5 short, with a large dorsodistal spine and three small unequal ventrodistal spines.

First legs thick and shorter than legs II–IV. Legs II–IV long, slender; all segments, except trochanter, cylindrical and without swimming setae ( Fig. 37B ). Claws of legs I and IV relatively large bifid, with unequal clawlets ( Fig. 37C, 37E ); claws of legs II–III smaller, sickle-shaped with subequal short clawlets ( Fig. 37D ).

Female. Genital acetabula 9–12 pairs, lying on four genital plates, relatively small and occupy less than half of area of each plate ( Fig. 36C ). Anterior genital plates with four to five unequal acetabula, two rather large unequal inner spines and four thin setae each. Posterior genital plates with six to seven acetabula and four short, thin setae each.

Measurements (n=1). Idiosoma L 1020; coxae III+IV L 462, W 310; dorsal platelets L 150, W 48; anterior genital plates L 86, W 156; posterior genital plates L 102, W 100; pedipalpal segments (P-1–5) L: 26, 178, 100, 162, 62; leg segments L: I-Leg-1–6—125, 191, 198, 270, 244, 231; II-Leg- 1–6—86, 205, 211, 297, 284, 253; III- Leg- 1–6—92, 178, 185, 251, 218, 220; IV-Leg-1–6—152, 205, 207, 310, 350, 317.

Male. Genital field ( Fig. 36D ) with 2 elongated plates, fused to each other by anterior ends only, of nearly equal width, its internal edge slightly concave; external edge slightly convex; each genital plate with 14–20 acetabula and some setae ( Sokolow 1940, Imamura 1953a).

Larva. Unknown.

Deutonymph. See Imamura (1953a).

Habitat. Lakes, ponds.

Hosts. Viviparidae : Cipangopaludina chinensis malleata (Reeve) and C. japonica (Martens) ( Imamura 1953a, 1953b; Viets 1933; Sokolow 1940).

Distribution. Asia: Japan ( Viets 1933; Imamura 1953a, 1953b) and Russia (Primory Territory) ( Sokolow 1940). Wen and Zhu (1999) described a closely related species from China, U. chelata Wen et Zhu, 1999 .

Figures

FIGURES 36 A – D. Unionicola japonensis, adults: A, anterior dorsal plates; B, coxal plates; C – D, genital field; A – C, female; D, male (after Imamura, 1953 a). Scale bars = 100 Μm.

FIGURES 37 A – E. Unionicola japonensis, female: A, pedipalp, lateral view; B, IV-Leg- 1 – 6; C, claw of leg I; D, claw of leg II; E, claw of leg IV. Scale bars: A – B = 100 Μm, C – E = 25 Μm.