Unionicola setipella sp.n.

(Figs 30A–E, 31A–D)

Holotype: 1 male (free-swimming), slide 3750- IBIW, Russia: Yaroslavl Province, Nekouz District, Rybinsk reservoir near village Pogorelka, 20.10.1969, leg. P.V. Tuzovskij.

Diagnosis. Male. Dorsum with two pairs of small unequal platelets; coxal plates III+IV elongated with straight medial margin; P-3 with long lateroproximal seta and relatively short dorsodistal seta, P-4 tapering distally, ventrolateral tubercles very long, situated distally to middle of segment, P-5 moderately long, four unequal distal spine and strongly concave ventral margin, both dorsodistal spines larger than both ventrodistal; genital plates separated, narrowed proximally, widely rounded distally; swimming setae on IV-Leg-5 shorter than IV-Leg-6; leg claws I hook-like slightly thicker than claws of legs II–IV.

Description. Male. Dorsum with two pairs of small unequal platelets (Fig. 30A), anterior platelets relatively large, elongated; posterior platelets oval and considerably smaller than anterior ones. Anterior and posterior coxal groups (Fig. 30B) divided by relatively wide interspace, sclerites, bearing setae and glandularia Le, larger than sclerites bearing other idiosomal setae. Apodemes of first coxal group moderately developed. Coxal plates III+IV elongated (L/W ratio 1.3) with straight medial margin. Surface of all coxal plates with reticulations.

Pedipalps (Fig. 30C) moderately long: P-2 with straight ventral margin with four (three proximal and single dorsodistal) short setae; P-3 with long lateral seta and one relatively short dorsodistal seta, base of lateral seta located anteriorly to middle of segment; P-4 slightly tapering distally, with long distolateral tubercle bearing short, thin seta and two small ventral tubercles in distal half of segment, anterior from them bearing short, thin setae and posterior tubercle bearing short peg-like seta; P-5 (Fig. 30D) moderately long with four unequal distal spines strongly concave ventral margin, both dorsal spines longer than both ventral ones.

Genital plates (Fig. 30E) separated, narrowed proximally, widely rounded distally, each with five unequal acetabula and 11 short, thin setae; additional, one pair of genital setae situated on soft integument flanking to genital field.

Figure 31A shows the proportion and chaetotaxy of the first leg. Legs II–IV long, slender; all segments, except trochanter, cylindrical. The number of distal swimming setae on legs IV is as follows (Fig. 31B): two on IV-L-3, five (three long and two relatively short) on IV-L-4 and three on IV-L-5. Swimming setae on leg II shorter than swimming setae on legs III–IV. All legs, except trochanter and basifemur, with very numerous thin, short setae. Leg I claws (Fig. 31C) hook-like slightly thicker than claws of legs II–IV (Fig. 31D).

Measurements (n=1). Idiosoma L 1190; coxae III+IV L 320, W 240; anterior dorsal platelets L 65, W 18; genital plates L 210, W 70; pedipalpal segments (P–1–5) L: 35, 160, 65, 150, 78; leg segments L: I-Leg- 1–6—95, 190, 235, 320, 230, 245; II-Leg- 1–6—95, 190, 240, 325, 385, 330; III-Leg- 1–6—90, 170, 215, 270, 290, 275; IV- Leg-1–6—155, 190, 260, 325, 410, 380.

Female. Unknown.

Deutonymph. Unknown.

Larva. Unknown.

Differential diagnosis. The present species is similar to the Unionicola setipes . The male of Unionicola setipella sp.n. differs from the male of U. setipes in the following characters (character states of U. setipes follow Sokolow 1931, 1940 and are indicated in parenthesis). Male—the anterior dorsal platelets more elongated and larger than posterior ones, Fig. 30A (oval and smaller than posterior ones, Fig. 32A), P-4 with long lateral tubercle, Fig. 30C (short lateral tubercle, Fig. 32C).

Etymology. The species epithet “ setipella ” is derived from the name of the similar species, Unionicola setipes .

Habitat. Reservoirs.

Hosts. Unknown.

Distribution. Europe (Russia, Yaroslavl Province).