Atractides (Atractides) komarovkaensis, Tuzovskij, Petr V., 2011

Tuzovskij, Petr V., 2011, Four new water mite species of the genus Atractides Koch (Acari: Hydrachnidia: Hygrobatidae) from Russia, Zootaxa 2738, pp. 41-59 : 53-56

Atractides (Atractides) komarovkaensis sp. n.

( Figs 40–51 )

Material examined. Holotype female, Russia, Far East, Primory Territory, Dalnegorsk District, Ussuri National Park, the Komarovka River, 10. 07I. 1984, coll. T. Vshivkova, slide 4951. The holotype is deposited in the collection of Institute for Biology of Inland Waters (Borok, Russia).

Diagnosis. Setae Fch thick, stick–shaped; setae Oe, Hi and He slightly longer but considerably thinner than Fch; rostrum long well outstanding to anterior margin of capitulum; apodemes of anterior coxal plates in right angle, posteromedial margin of coxae I wide and convex; gonopore considerably longer than genital plates; pedipalpal femur short with convex ventral margin but without ventrodistal expansion; sword seta on P–4 rather long pointed, inserted near ventrodistal seta; tibia of leg I slightly thickened in distal half, with short ventral spine near S1, seta S1 longer than S2 and separated by rather greater interspace, both these setae pointed and approximately equal in width.

Description. Female. Color yellow in preservative liquid. Body flat oval, integument soft with very fine strips. Number and position of idiosomal setae typical for representatives of the genus Atractides . Setae Fch ( Fig. 40 ) relatively short, thick; setae Oe, Hi and He ( Fig. 41 ) slightly longer but considerably thinner than Fch; trichobothria Fp and Oi without glandularia ( Fig. 42 ), other idiosomal dorsal setae associated with glandularia short and hair-like ( Fig. 43 ). Coxae of legs ( Fig. 44 ) covering about half of ventral surface. Median suture between coxae I clearly developed; central sub–dermal projection and apodemes of anterior coxae short, apodemes in right angle. Posteromedial margin of coxae I wide and convex. Setae Hv located in lateral portion of coxae II. Coxae III+IV trapezoidal, their medial margin rather wide and rounded. Glandularia and seta Pe situated near middle of`anterior margins of coxae IV. Setae Pi without glandularia, their bases fused or separated from setae Ci, excretory pore unsclerotized ( Fig. 45 ). Genital plates ( Fig. 46 ) elongate (ratio length/width = 3.0) with 3 acetabula and 13 thin setae each. Genital acetabula arranged in an arc, all acetabula approximately subequal in length, but posterior pair of acetabula slightly wider than anterior and median acetabula. Gonopore considerably longer than genital plates, anterior and posterior genital sclerites nearly equal in width. Capitulum ( Fig. 44 ) wide, ratio length/width 1.15. Rostrum well developed, outstanding to anterior margin of capitulum; ventral hypostomal setae shorter than dorsal setae. Basal segment of chelicera large, cheliceral stylet well developed, crescent with a few small teeth on concave side ( Fig. 47 ).

Pedipalp ( Fig. 48 ) slender; trochanter short with single dorsodistal seta; femur with slightly convex ventral margin, five dorsal unequal setae; genu considerably longer than femur with straight ventral margin, two short proximal and two long stout dorsodistal setae and several subequal thin setae. Pedipalpal tibia straight, slightly longer than genu, with a few dorsal setae; bases of ventral setae divide tibia into three unequal sectors (1–2–2), sword seta rather large, placed near ventrodistal seta.

Legs without swimming setae. Genu of leg I ( Fig. 49 ) not thickened distally with two ventroproximal and two ventrodistal short spine-like setae. Tibia of leg I slightly thickened in distal half, with short ventral spine near S1 and a few thin dorsal and ventral setae; seta S1 longer than S2 and separated by rather greater interspace, both these setae pointed and approximately equal in width; curved seta moderately developed. Tarsus of leg I slender, thin slightly curved dorsoventrally, its anterior, median and terminal portions approximately subequal in thickness. Posterior legs, especially legs IV ( Fig. 50 ) slender, genu and tibia with a few thin and thick short setae, tibia with fine setae only. Claws of leg I lesser than claws of legs II–IV. All leg claws with two denticles, external denticle slightly longer than internal denticle, lamella rather long with concave ventral margin ( Fig. 51 ).

Measurements, n=1. Length of body 975; length of setae Fch 55–60, length of setae Oe, Hi and He 65–75; length of coxae I+II 290, width 295; length of medial portion of coxae I 100; length of coxae III+IV 230, width 170; lengths of genital plate 110, width 35; length/width of genital acetabula (ac. 1–3): 33–36/24, 30–33/27–30, 30–33/33–35; length of capitulum 125, length of basal segment of chelicera 155, length of cheliceral stylet 65; lengths of pedipalpal segments (P1–5): 32, 66, 80, 90, 30; length/width of sword seta on P 4 25/6; lengths of leg segments: I–Leg. 1–6—55, 90, 120, 190, 185, 145; II–Leg. 1–6—55, 65, 100, 130, 130, 120; III–Leg.1–6: 50, 60, 95, 155, 170, 140; IV–Leg. 1–6—95, 85, 150, 215, 230, 180; tibia of leg I: length of seta S 1 100, width 13; length of seta S2 70, width 15, distance between setae S1 and S2 30.

Differential diagnosis. The present species is similar to Atractides inflatipalpis (K.Viets, 1950) , A. inflatipes (Lundblad, 1956) and A. fluviatilis (Szalay, 1929) . The new species differs from Atractides inflatipalpis in the following characters (character states of female A. inflatipalpis are indicated in parenthesis from Gerecke 2003): integument striated (lineated), pedipalpal femur convex without ventrodistal expansion (straight with ventrodistal expansion), length of sword seta on P–4 nearly equal distance between ventral setae (considerably shorter), tibia and tarsus of leg I relatively short, respectively 185 and 145 µm (rather long, respectively 234 and 194 µm), pedipalp relatively short, total length 296 µm (rather long, total length 363 µm). The gonopore and genital plates of female A. inflatipes approximately subequal in length, the anterior genital sclerite considerable wider than posterior sclerite, setae S1 and S2 on tibia of leg I heteromorphic with obtuse tips ( Gerecke 2003); in contrast, in female A. komarovkaensis the gonopore longer than genital plates, the anterior and posterior genital sclerites approximately subequal in width, setae S1 and S2 on tibia of leg I pointed and nearly subequal in shape. The genital plates of female A. fluviatilis wide and longer than gonopore, acetabula in obtuse triangular; P-2 with ventrodistal protruding, ventral margin P-4 slightly protruding near proximoventral seta ( Gerecke 2003); in contrast, in female A. komarovkaensis sp. n. the genital plates relatively narrow and shorter than gonopore, acetabula in an arc line; P-2 without ventrodistal seta protruding, ventral margin P-4 not protruding near proximoventral seta.

Etymology. The species is named after the river where it was collected (Komarovka).

Habitat. Running waters.

Distribution. Asia ( Russia, Far East, Primory Territory).

Figures

FIGURES 40 – 47. Atractides komarovkaensis sp. n., female: 40, seta Fch; 41, seta He; 42, trichobothria Oi; 43, seta with glandularia; 44, capitulum and coxal plates, ventral view; 45, excretory pore, setae Ci and Pi; 47, chelicera (part). Scale bars: 41 – 46 = 100 µm, 47 = 50 µm.

FIGURES 48 – 51. Atractides komarovkaensis sp. n., female: 48, pedipalp, lateral view; 49, genu, tibia and tarsus of leg I; 50, genu, tibia and tarsus of leg IV; 51, claw of leg III. Scale bars: 48, 51 = 50 µm, 49 – 50 = 100 µm.