Piona anadyrensis, Tuzovskij, Petr V., 2013

Tuzovskij, Petr V., 2013, New water mite species of the genus Piona Koch, 1842 (Acari, Hydrachnidia: Pionidae) from Northeastern Russia, Zootaxa 3664 (3), pp. 321-334 : 327-331

Piona anadyrensis sp. n.

( Figs 24–43 )

Type series. Holotype: male, slide 2857, Russia, Chukotka, Anadyr District, small thermocarstic lake on right bank of Anadyr River in 12 km down stream from the settlement Markovo, depth 0.3–0.8 m, 3 September 1979, leg. P.V. Tuzovskij. Paratypes: two males, three females and one deutonymph from the same locality as holotype: one female collection date as holotype; two males, one female and one deutonymph 30 July 1981, and one female 9 September 1981; leg. P.V. Tuzovskij.

Description. Male. Idiosoma oval, integument soft and striated. Dorsum with two small curved platelets, ratio L/ W 1.7 –2.0 ( Fig. 24 ). The number and position of idiosomal setae typical for the genus Piona . All dorsal setae thin and approximately equal in length, but setae Fch ( Fig. 25 ) thicker than other idiosomal setae associated with glandularia and trichobothria. First coxae with rather long medial margins which are close together but not fused, with relatively long posterior apodemes ( Fig. 26 ). Sclerites bearing setae Hv lying free and located between anterior and posterior coxal groups. Posterior coxal groups fused medially along entire length, suture line between third and fourth coxal plates incomplete obliterated medially. Posterior corners of fourth coxal plates projecting. Genital field lightly fused with the fourth coxal plates and only reaching laterally to posterior projections of fourth coxal plates; gonopore oval, a large, deep genital pit present posterior to the gonopore; 15–21 genital acetabula on each side, two pairs larger than others. Excretory pore surrounded by narrow sclerotized ring.

Ejaculatory complex with long proximal arms and relatively short distal arms, proximal chamber large with a curving, narrow proximal projection forming four coils ( Fig. 29 ).

Chelicera ( Fig. 27 ) with large basal segment and short crescent stylet.

Pedipalp ( Fig. 28 ) moderately slender: P–1 with single short dorsodistal seta, P–2 with six to seven unequal setae; P–3 with three subequal setae, lateral seta located near middle of segment; P–4 slightly longer than P–2, both ventral setae located on tubercles, distal tubercle large than proximal tubercle; ventrodistal spine short located on small tubercle; P–5 with proximal solenidion, five thin setae and four very short, thick distal spines.

I–Leg-5–6 and II–Leg-5–6 along entire length an identical thickness ( Fig. 30 ); III–Leg-5 long, straight, III– Leg-6 short and club–shaped ( Fig. 31 ); IV–Leg-4 thick, with a deep concavity bearing numerous unequal spine– like setae ( Fig. 32 ), IV–Leg-5 straight considerable longer than IV-Leg- 4. I –Leg-4 with two to three, I–Leg-5 with six to seven, II-Leg-4 with eight to nine, II-Leg-5 with nine to ten, III-Leg-5 with ten to thirteen short swimming setae. Legs IV with long swimming setae with the following numbers: five to six on IV–Leg-4, eleven to twelve on IV–Leg-5. Claws of tarsi I–II and IV with relatively long clawlets ( Fig. 33 ). Claws of legs III asymmetric ( Fig. 34 ); large claw with thick, long, straight dorsal clawlet and a relatively thin slightly curved ventral clawlet; small claw with a thick, short pointed dorsal clawlet and a thin and relatively long ventral clawlet with widely rounded tip.

Measurements (n=3). L of idiosoma 1050–1200; L dorsal platelets 100–110, W 55–60; L of seta Fch 50–60; W of genital field 435–500; L of cheliceral segments: base 270–295, stylet 95–115; dorsal L of pedipalpal segments (P–1–5): 73–82, 250–285, 120–140, 285–320, 170–180; L of leg segments: I–Leg-1–6: 115–130, 235–260, 235–265, 355–390, 425–475, 355–375; II–Leg-1–6: 130–140, 245–285, 240–285, 380–425, 440–490, 355–375; III–Leg-1–6: 130–140, 220–260, 185–205, 330–350, 490–515, 200–220; IV–Leg-1–6: 235–245, 220–245, 175–190, 350–370, 445–490, 380–410.

Female. Idiosoma oval, integument soft and striated. Dorsum similar as in of the male. All coxal groups separated and covering about half of the ventral surface ( Fig. 35 ). Anterior coxal plates with short apodemes. Sclerites bearing setae setae Hv lying free and located between anterior and posterior coxal groups. Medial margin of coxal plate IV 2.5 times longer than medial margin of coxal plate III. Posterior margins of coxal plates IV forming obtuse angles, apodemes slightly developed. Genital opening and acetabular plates approximately equal in length. Acetabular plates nearly as long as wide, slightly concave medially and rounded laterally; 21–28 genital acetabula on each side, two pairs larger than others. Anterior large acetabulum located in anteromedial corner of acetabular plate, second large acetabulum located a little posterior to middle of the plate. All acetabula and two pairs of genital setae located on the acetabular plates, one seta located anteromedially and one seta located posteromedially on each side; in additional, five to six pairs of genital setae located in integument between acetabular plates and pregenital sclerite.

Pedipalp slender ( Fig. 36 ): P–1 with a single, short dorsodistal seta; P–2 relatively large, with straight ventral margin and bearing seven or eight dorsal setae; P–3 with concave ventral margin, with three short subequal setae, base of lateral seta located near middle of segment; P–4 a little longer than P–2, proximoventral seta located on small tubercle, distoventral seta on relatively large tubercle, distoventral spine short, located on tubercle; P–5 with proximal solenidion, five thin setae and four thick, short distal spines.

Legs thin and slender. I–Leg-4 with one or two, I–Leg-5 with four to six short swimming setae ( Fig. 37 ). Legs II–IV with long swimming setae with the following numbers: five to eight on II–Leg-4, eight to eleven on II–Leg- 5, III–Leg-4 and IV-leg-4, eleven to fourteen on III–Leg-5 and IV–Leg-5. All leg claws with long external clawlet and relatively short internal clawlet, lamella with convex ventral margin ( Fig. 38 ).

Measurements (n=3). L of idiosoma 1140–1650; L dorsal platelets 100–110, W 50–60; L of seta Fch 50–60; L of acetabular plates 200–210, W of acetabular plates 200–215; L of cheliceral segments: base 325–385, claw 130– 140; dorsal L of pedipalp segments (P–1–5): 80–105, 290–335, 135–180, 350–390, 180–205; L of leg segments: I– Leg-1–6: 120–155, 245–325, 275–325, 425–475, 490–545, 405–440; II–Leg-1–6: 145–165, 285–325, 270–360, 480– 540, 545–605, 405–480; III–Leg-1–6: 160–190, 285–325, 300–350, 480–545, 570–630, 440–490; IV–Leg-1–6: 260–285, 325–375, 360–410, 545–610, 585–655, 430–455.

Deutonymph. Dorsum with two platelets ( Fig. 39 ). Setae Fch short ( Fig. 40 ). Coxal plates like those the female, but with smaller number of setae ( Fig. 41 ).

Acetabular plates fused to each other medially, oblique, directed anteromedially, with two acetabula and three setae each. Lateral acetabulum a little larger than median acetabula, distance between lateral and median acetabula longer than diameter of posterior acetabulum. Genital sclerite much larger than pregenital sclerite.

Pedipalp stout ( Fig. 42 ): P–1 short, without seta; P–2 large, with straight ventral margin and bearing three subequal dorsal setae (one proximal and two distal); P–3 with two short unequal setae, base of lateral seta located near middle of segment; P–4 a little longer than P–2, proximoventral seta located on small tubercle, distoventral seta on relatively large tubercle; distoventral spine short, located on tubercle; P–5 with proximal solenidion, three thin setae and four thick distal unequal spines.

Legs thin and slender. I–Leg-4 and I–Leg-5 with one short swimming seta ( Fig. 43 ). Legs II–IV with long swimming setae, with the following numbers: two setae on II–Leg-4, III–Leg-4 and IV–Leg-4, three setae on II– Leg-5, three or four setae on II–Leg-5 and III–Leg-5, four or five setae on IV–Leg-5.

Measurements (n=1). L of idiosoma 410; L dorsal platelets 48–50, W 20–25; L of seta Fch 30; L of acetabular plate 120, W of acetabular plate 55–60; diameter of genital acetabula (ac.1–2): 25–28, 30–35; L of cheliceral segments: base 165, stylet 63; dorsal L of pedipalpal segments (P–1–5): 39, 145, 78, 162, 108; L of leg segments: I–Leg-1–6: 65, 110, 120, 165, 210, 190; II–Leg-1–6: 65, 115, 125, 185, 235, 210; III–Leg-1–6: 78, 115, 125, 185, 245, 220; IV–Leg-1–6: 110, 125, 150, 220, 280, 220.

Differential diagnosis. The present species is similar to the North American species Piona brunsoni Cook, 1960 (Cook 1960, Smith 1976) but differs in the following characters (character states of P. brunsoni are indicated in parenthesis after Cook 1960): In the adults of P. anadyrensis sp. n. P–3 with three setae (two setae), male: the genital opening elongate, oval (broad, transverse); setae Pe not fused with coxal plates IV (fused with posteromedial margin of coxal plates IV); III–Leg-6 club-shaped and curved (long, not club-shaped, straight), small claw of III–Leg-6 with an unequal dorsal and ventral clawlets (with subequal dorsal and ventral clawlets); female: genital plate with one posteromedial seta (with three posteromedial setae), anterior large acetabulum located in anteromedial corner of acetabular plate (located near middle of medial margin of the plate); I–Leg-5 with swimming setae and several heavy setae, Fig. 43 (I–Leg-5 with numerous heavy setae and without swimming setae).

Etymology. The species epithet anadyrensis is derived from the name of the district where it was collected (Anadyr).

Habitat. Standing waters.

Distribution. Asia ( Russia, Magadan Province).

Figures

FIGURES 24 – 28. Piona anadyrensis sp. n., male: 24, dorsal platelets; 25, seta Fch; 26, coxal plates and genital field; 27, chelicera; 28, pedipalp. Scale bars: 24, 26, 28 = 200 μm, 25, 27 = 50 μm.

FIGURES 29 – 34. Piona anadyrensis sp. n., male: 29, ejaculatory complex; 30, tibia and tarsus of leg I; 31, tibia and tarsus of leg III; 32, genu and tibia of leg IV; 33, claw of leg I; 34, claws of leg III. Scale bars: 29, 33 – 34 = 50 μm, 30 – 32 = 200 μm.

FIGURES 35 – 38. Piona anadyrensis sp. n., female: 35, coxal plates and genital field; 36, pedipalp, lateral view; 37, tibia and tarsus of leg I; 38, claw of leg I; Scale bars: 35, 37 = 200 μm, 36 = 100 μm, 38 = 50 μm.

FIGURES 39 – 43. Piona anadyrensis sp. n., deutonymph: 39, dorsal platelets; 40, seta Fch; 41, idiosoma, ventral view; 42, pedipalp, lateral view; 43, genu, tibia and tarsus of leg IV. Scale bars: 39, 41 = 100 μm, 40, 42 – 43 = 50 μm.