Unionicola minor (Soar, 1900)

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 : 417-419

Unionicola minor (Soar, 1900)

( Figs 14A–D , 15A–D )

Material examined. 7 males, 2 females: Russia, Yaroslavl Province, Nekouz District, pond in settlement Borok, Juny 1975; 2 males, 4 females: Samara Province, Stavropol District, National natural Park “Samarskaya Luka”, small like near village Koltsovo, July–September 1992, leg. P.V. Tuzovskij. All males and females are collected free-swimming.

Diagnosis. Adults. Dorsum usually with two pairs of small unequal platelets; coxal plates III+IV elongated with straight medial margin; P-3 with long unequal setae (longer than segment), base of lateral seta located distally to middle of segment, P-4 with long unequal tubercles, P-5 with slightly concave ventral margin; medial setae on all genital plates in female long and subequal; genital plates of male relatively narrow, separated or fused to each other by posterior ends only; swimming setae on IV-Leg-5 shorter than IV-Leg-6; claws of legs I thick, hook-like, claws of legs II–IV thin, sickle-shaped.

Description. Both sexes. Dorsum usually with two pairs of small unequal platelets, anterior platelets relatively large, elongate ( Fig. 14A ); posterior platelets very small or not developed. Anterior and posterior coxal groups ( Fig. 14B ) divided by rather wide interspace; sclerites, bearing setae and glandularia Le, much larger than sclerites bearing other idiosomal setae. Apodemes of first coxal group reaching or slightly extending beyond to anterior margin of third coxae. Coxal plates III+IV elongated (L/W ratio 1.25–1.42) with straight medial margin.

Pedipalps ( Fig. 15A ) moderately in size: P-2 with nearly straight ventral margin, with three to four proximal setae and single dorsodistal seta; P-3 with two long unequal setae (much longer than segment), lateral seta longer than dorsodistal one and situated distally to middle of segment, P-4 with long tubercles, lateral tubercle slightly longer than proximoventral tubercle, bases of these tubercles situated near middle of segment; P-5 shorter than P-4 (P-4/P-5 L 1.30–1.45) with slightly concave ventral margin, all simple thin setae and spines short and located distally.

Legs II–IV long, slender. The number of distal swimming setae on legs IV is as follows ( Fig. 15B ): three on genu and on tibia. Leg claws I ( Fig. 15C ) thick, hook-like with two unequal clawlets, claws of legs II–IV ( Fig. 15D ) sickle-shaped with very short dorsal clawlet and long ventral one.

Female. Anterior and posterior genital plates nearly subequal in shape and size ( Fig. 14C ), anterior plates without front subcutaneous projections, both medial setae long and subequal; posterior plates with long anteromedial seta and 4–6 short, thin setae. All acetabula moderately in size and occupy less than one half of area of each plate.

Measurements (n=6). Idiosoma L 610–815; coxae III+IV L 225–255, W 180–200; anterior genital plates L 55–65, W 55–75; pedipalpal segments (P–1–5) L: 20–35, 115–125, 65–75, 105–125, 80–85; leg segments L: I- Leg- 1–6—70 –85, 185–200, 210–230, 290–345, 200–245, 185–230; II-Leg- 1–6—70 –85, 195–215, 225–285, 290–350, 315–400, 270–305; III-Leg- 1–6—70 –80, 160–180, 180–195, 210–240, 250–305, 220–270; IV-Leg- 1–6—105–125, 180–205, 220–230, 240–270, 340–390, 270–345.

Male. Genital plates relatively narrow, separated or fused to each other by posterior ends only ( Fig. 14D ), 8–9 thin unequal setae on each side. All acetabula subequal and occupy less than half of area of each plate.

Measurements (n=9). Idiosoma L 610–815; coxae III+IV L 190–220, W 55–70; genital field L 190–220, genital plate W 55–70; pedipalpal segments (P–1–5) L: 20–35, 90–100, 50–65, 90–115, 65–80; leg segments L: I- Leg- 1–6—55 –80, 165–205, 180–225, 260–305, 180–220, 180–220; II-Leg- 1–6—60 –80, 185–220, 220–285, 260–360, 315–400, 260–335; III-Leg- 1–6—55 –60, 155–190, 170–195, 200–245, 240–285, 205–245; IV-Leg- 1–6—105–140, 155–205, 195–245, 235–295, 315–385, 260–335.

Deutonymph. See Imamura (1953b), Hevers (1979), Tuzovskij (1990).

Larva. See Hevers (1980).

Habitat. Lakes, ponds, running waters.

Hosts. Spongillidae ( Hevers 1980) .

Distribution. Europe ( Viets 1956, Viets 1978); Asia ( Japan, South Korea) ( Imamura 1953b; Chung & Kim 1995).

Figures

FIGURES 14 A – D. Unionicola minor, adults: A, anterior dorsal plates; B, coxal plates; C – D, genital field; A – C, female; D, male. Scale bars: A – B = 100 Μm, C = 100 Μm, D = 50 Μm.

FIGURES 15 A – D. Unionicola minor, female: A, pedipalp, lateral view; B, IV-Leg- 4 – 6; C, claw of leg I; D, claw of leg IV. Scale bars: A = 50 Μm, B = 200 Μm, C – D = 100 Μm.