Unionicola figuralis Koch 1836

Unionicola figuralis (Koch, 1836)

(Figs 8A–C, 9A–D)

Material examined. 5 males, 5 females: Russia, Magadan Province, Anadyr District, small lakes near settlement Markovo, July–September 1981; 2 females: Samara Province, Stavropol District, National natural Park “Samarskaya Luka”, Gusinoe Lake, July 1992; 3 males, 3 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. Dorsal platelets not developed; medial margin of coxal plates III+IV straight and nearly as long as wide; P-3 with two unequal distal setae, lateral seta longer than dorsal one, P-4 tapering distally, with two long and one short ventral tubercles, P-5 long with slightly concave ventral margin, all dorsodistal spines very short; anterior genital plates of female without anterior subcutaneous projections, each with two rather thick, long setae, posterior plates more or less triangular, each with one long, thick anteromedial seta and 4–6 thin setae; genital plates of male wide, fused to each other by anterior and posterior ends; swimming setae on IV-Leg-5 much shorter than IV-Leg-6, the latter with 3 thickened setae; claws of legs I thick, hook-like, claws of legs II–IV thin, sickle-shaped.

Description. Both sexes. Dorsal platelets not developed. Anterior and posterior coxal groups (Fig. 8A) divided by rather wide interspace; sclerites, bearing setae and glandularia Le, small. Apodemes of first coxal group reaching or extending to anterior margin of third coxae. Coxal plates III+IV subquadrate (L/W ratio 0.95–1.2) with straight medial margin. Surface of all coxal plates with reticulations.

Pedipalps (Fig. 9A) short and stocky, P-2 with four subequal setae, P-3 with two unequal distal setae, lateral seta longer than dorsal one; P-4 tapering distally, with two long and one short ventral tubercles, long proximal tubercle and short tubercle each bearing thin short seta and one long ventrodistal tubercle bearing short peg-like seta; P-5 long with slightly concave ventral margin, all dorsodistal spines very short.

Legs II–IV long, slender; all segments, except trochanter, cylindrical and with swimming setae. The number of distal swimming setae on legs IV is follows (Fig. 9B): one on telofemur, three on genu and tibia. Swimming setae on leg II shorter than swimming setae on legs III–IV; swimming setae on IV-Leg-5 much shorter than IV-Leg-6. Claws of legs I (Fig. 9C) thick, hook-like with two unequal clawlets; claws of legs II–IV sickle-shaped with short dorsal clawlet and long ventral one (Fig. 9D).

Female. Anterior genital plates wide without anterior subcutaneous accretion each, with two long, thick subequal setae and two rather thick, long setae each; posterior plates more or less triangular, with 1 long, thick anteromedial seta, each with 4–6 thin setae; acetabula small and occupy less than one half of each plate (Fig. 8B).

Measurements (n=10). Idiosoma L 810–1150; coxae III+IV L 350–390, W 310–400; anterior genital plates L 60–75, W 85–100; posterior genital plates L 85–100, W 85–100; pedipalpal segments (P-1–5) L: 24–33, 120–145. 65–82, 114–150, 114–147; leg segments L: I-Leg- 1–6—95 –125, 260–310, 275–350, 400–490, 315–385, 325–385; II-Leg- 1–6—95 –125, 315–350, 415–450, 550–620, 595–695, 575–645; III-Leg- 1–6—90 –115, 265–285, 315–360, 364–425, 415–490, 365–415; IV-Leg-1–6—170–190, 260–295, 380–435, 495–590, 570–670, 530–645.

Male. Genital plates (Fig. 8C) wide, fused to each other by anterior and posterior ends, with 8–10 thin setae on each side; in additional, one pair of genital setae located on soft integument flanking genital field. All acetabula approximately equal in size.

Measurements (n=8). Idiosoma L 850–900; coxae III+IV L 275–325, W 260–315; genital field L 185–200, W 200–225; pedipalpal segments (P-1–5) L: 24–32, 105–125, 55–65, 95–105, 95–105; leg segments L: I-Leg- 1–6—90 –105, 235–295, 265–305, 390–450, 305–345, 305–350; II-Leg- 1–6—90 –105, 285–345, 430–485, 510–590, 550–620, 445–500; III-Leg- 1–6—90 –105, 240–260, 285–325, 355–385, 405–465, 340–370; IV-Leg- 1–6—135–165, 240–270, 350–400, 480–540, 570–655, 505–570.

Deutonymph. See Hevers (1979).

Larva. See Tuzovskij (2012).

Habitat. Lakes, ponds, running waters.

Hosts. Unknown.

Distribution. Europe, Asia, Africa, North and South America (Viets 1956; Sokolow 1940; Lundblad 1968; Viets 1978).