Aturus triangularis, Semenchenko, Ksenia A. & Tuzovskij, Petr V., 2011

Semenchenko, Ksenia A. & Tuzovskij, Petr V., 2011, New water mites species of the genus Aturus Kramer (Acariformes, Aturidae) from the Far East of Russia, Zootaxa 2933, pp. 1-26 : 2-3

Aturus triangularis sp. n.

( Figs. 1–5 )

Type series. Holotype: male (62-kas– IBSS), Russia, Primory Territory, Khasansky District, “Kedrovaya Pad National Nature Biosphere Reserve”, Sea of Japan basin, Kedrovaya River, N 43°06.056’; E 131°33.310’; depth 12–50 cm; substrate: boulders, cobbles, pebbles. 8.11.1993, leg. T.M. Tiunova. Paratypes: 5 males (57, 60-61, 63- 64-kas– IBSS), same data as holotype.

Description. Male. Idiosoma elongate with triangular anterior portion, frontal margin with small median incision ( Fig. 1 ). Dorsal shield with net structure, ventral shield porous. Setae Fp, Oi and Pi without glandularia, other idiosomal setae associated with glandularia. Setae Fch, Fp, Vi and Oe longer than proterosomal setae Ve and Oi. First pair of lyriform organs (i1) situated in front of platelets with setae Vi. Dorsal shield separated from ventral shield, with 6 pairs of simple setae: Oi, Hi, Si, Se, Ci and Pi. Setae Oe and He situated on soft interscutal membrane. Seta Li and its glandularium separated from each other—seta located on dorsal side, glandularium on ventral side. Second pair of lyriform organs (i2) situated posterior to sclerites bearing setae Oe, i3 posterior to Sci, i4 on soft interscutal membrane posterior to Li, i5 on dorsal shield above setae Pi. Excretory pore opens caudally on the dorsal shield. Posterolateral surface of dorsum with numerous thin setae, forming 1 row.

Ventral shield ( Fig. 2 ) with deep median cleft and 7–11 genital acetabula on each side. Setae Sce shifted to ventral side and located in front of genital acetabula. Setae Pe and Le situated near posterolateral margins of venter. Median cleft with 4–5 thin setae on each side.

Capitulum slightly elongated with short anchoral process. Trochanter of pedipalp ( Fig. 3 ) short, thin with 1 dorsodistal seta. Ventral margin of femur straight. Femur with 3 dorsoproximal setae and 2 dorsodistal ones. Genu with 2 dorsodistal setae, its ventral margin concave. Tibia with straight ventral margin, its height subequal along segment, with 2 ventrodistal setae (one thick and one thin) and short distolateral spine.

Leg III unmodifed. Trochanter of leg IV ( Fig. 4 ) with single short proximal setae and 2 dorsodistal ones; basifemur IV curved; genu IV expanded distally, with 2 ventrodistal sword-like setae exceeding length of tibia, 2 long curved setae, 5 distal stout setae and some dorsal setae of different length; tibia with 3 proximal feathered setae, 6 ventral long setae and few distal setae of different length (dorsodistal seta feathered); tarsus shorter than tibia, expanded distally with straight dorsal margin. Claws ( Fig. 5 ) asymmetrical: one claw with long central denticle and short external and internal denticles (internal denticle rounded, other denticles with acute tips), other claw with very short acute external and longer rounded central and acute internal denticles.

Measurements (n=3). Length of idiosoma 442–449, width 310–336; length of dorsal shield 369–383, width 266–290; length of capitulum 92–94, width 65–67; length of basal segment of chelicera 73–86, length of cheliceral stylet 25–27; length of capitular bay 92–94; length of pedipalpal segments (P-1–5): 23–24, 46–48, 30–32, 59–62, 18–21; length of leg segments: I-L- 1–6—46 –48, 57–59, 53–54, 70–73, 73–87, 84–86; II-L- 1–6 –35 –43, 60–62, 53–56, 73–78, 84–86, 86–88; III-L- 1–6—46 –48, 67–70, 65–67, 94–97, 105–108, 96–98; IV-L- 1–6—86 –89, 137– 140, 111–113, 146–148, 127–130, 113–116.

Differential diagnosis. The new species is more closely related to Aturus similis sp. n. (see below). It differs from the latter species in the following characters (character states of A. similis sp. n. are given in parentheses): anterior portion of the idiosoma triangular (convex), posterolateral setae on dorsum short, forming 1 row (2 rows present on posterolateral margin from short and long setae), ventral margin of pedipalpal femur without developed ventrodistal projection (with ventrodistal projection), genu of leg IV bearing 2 long curved setae (no curved setae present on this segment).

Etymology. The species is named for the triangular anterior portion of the idiosoma.

Habitat. Running waters.

Distribution. Russia: Far East, Primory Territory.

Figures

FIGURES 1 – 5. Aturus triangularis sp. n., male: 1, idiosoma, dorsal view; 2, idiosoma, ventral view; 3, pedipalp, lateral view; 4, leg IV; 5, claws of leg IV. Scale bars = 50 µm for Figs. 1 – 2, 4; 25 µm for Figs. 3, 5.