Aturus similis, 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 : 4-7

Aturus similis sp. n.

( Figs. 6–13 )

Type series. Holotype: male (4919- IBIW), Russia, Primory Territory, “Ussuri National Nature Reserve”, Komarovka River; depth 20–30 cm; substrate: pebbles, sand. 29.05.1984, leg. T.S. Vshivkova. Paratypes: 1 male (9505- IBIW), with same locality as holotype, 1.06.1984, leg. T.S. Vshivkova; 2 males (66-67-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 18–30 cm; substrate: boulders, cobbles, pebbles. 25.11.1993, leg. T.M. Tiunova; 2 males (446-kas– IBSS, 459-kas– IBSS), Russia, Primory Territory, Artemovsky Urban District, Steklyanukha River, N 43°21.027’; E 132°27.723’; depth 30 cm below the sediment surface; substrate: cobbles, pebbles, coarse- and medium-grained sand, 12.06.2010, leg. K.A. Semenchenko, D.A. Sidorov.

Description. Male. Idiosoma flattened dorsoventrally. Dorsal and ventral shields present, both with porous surfaces. Frontal margin convex, with small median incision and small median tubercle ( Fig. 6 ). Eyes located dorsally. Setae Fp, Oi and Pi without glandularia, other idiosomal setae associated with glandularia. Setae Fch slightly thicker than proterosomal setae Fp, Vi, Ve and Oi. Setae Vi and first pair of lyriform organs (i1) situated on small platelets. Dorsal shield very large, covering nearly all dorsum, fused with ventral shield caudally; with 2 pieces of muscle attachment scars between and laterally to setae Hi and Se, with 6 pairs of setae: Oi, Hi, Si, Se, Ci and Pi; setae Hi long, thick, other setae short and hair-like. Setae Oe, He and Sci situated on soft interscutal membrane. Setae Oe and He long and approximately subequal in length. All dorsal setae simple not bifurcate. Second pair of lyriform organs (i2) situated on sclerites bearing setae Oe, i3 on sclerites bearing setae Sci, i4 on soft membrane posterior to Li, i5 on dorsal shield laterally setae Pi. Excretory pore opens on dorsal shield caudally between setae Ci. Posterolateral surface of dorsum with numerous short, thin setae, forming 1 transverse row. In addition, dorsum with a few moderately long terminal setae and very long unequal posterolateral ones, anterolateral of them considerably shorter than posterior setae.

Ventral shield ( Fig. 7 ) with deep median cleft and 6–10 genital acetabula along posterior margin on each side. Setae Sce shifted to ventral side and located in front of genital field, Pe and Le situated near posterolateral margins of venter. Median cleft with 3–5 thin setae on each side.

Capitulum slightly elongated with short anchoral process. Trochanter of pedipalp ( Fig. 8 ) short, thin with 1 dorsodistal seta. Ventral margin of femur slightly convex in distal half. Femur with 3 unequal relatively short dorsoproximal setae and 2 rather long dorsodistal ones. Genu with one dorsoproximal and 2 dorsodistal approximately subequal setae, its ventral margin slightly concave. Tibia longer than femur, expanded distally with 2 ventrodistal setae (one thick and one thin), 2 thin dorsodistal ones and short distolateral spine.

Leg III unmodifed. Trochanter of leg IV ( Fig. 9 ) with single short proximal setae and 2 dorsodistal ones; basifemur IV long curved and considerably longer than telofemur; genu IV expanded distally, with 2 long pointed sword-like setae which slightly longer than tibia, with 7–10 rather long unequal distal setae, 1–2 dorsoproximal thin ones and 1 short ventrolateral spine. Tibia IV ( Fig. 10 ) with 2 relatively long distolateral sword-shaped setae, 2 dorsodistal setae and a few unequal ones. Tarsus considerably shorter than tibia, narrowed proximally and expanded distally with slightly convex dorsal margin. Claws ( Fig. 11 ) asymmetrical with 3 unequal denticles: external denticle shorter and thinner than other ones, central denticle relatively wider, longer or shorter than internal ones.

Measurements (n=4). Length of idiosoma 355–403, width 277–290; length of dorsal shield 323–335, width 244–270; length of capitulum 70–90, width 53–67; length of basal segment of chelicera 60–67, length of cheliceral stylet 24–27; length of capitular bay 80–95; length of pedipalpal segments (P-1–5): 18–22, 50–56, 35–39, 65–67, 21–24; length of leg segments: I-L- 1–6—39 –48, 53–65, 48–51, 60–70, 71–84, 82–92; II-L- 1–6—36 –43, 47–62, 45–51, 63–70, 78–86, 84–92; III-L- 1–6—42 –48, 48–67, 54–65, 85–92, 100–113, 100–103; IV-L- 1–6—59 –81, 144–162, 86–97, 125–140, 108–117, 78–86.

Female. Idiosoma flat. Dorsal shield covering nearly all dorsal surface. Frontal margin convex, with small median incision ( Fig. 12 ). Setae Fp, Oi and Pi without glandularia; other idiosomal setae associated with glandularia. Setae Fch and Oe longer and thicker than proterosomal setae Fp, Vi, Ve and Oi. Setae Vi and first pair of lyriform organs (i1) situated on small platelets. Dorsal shield porous, bearing 4 pairs of setae: Oi, Hi, Si, Se, with small indentation in caudal part. Setae Oe, He, Sci, Li and Ci situated on smooth interscutal membrane. Second pair of lyriform organs (i2) situated posterior to sclerites bearing setae Oe, i3 posterior to sclerites bearing setae Sci, i4 posterior to Li, i5 on ventral surface laterally to setae Pi.

Excretory pore opens posterior to dorsal shield on sclerite between setae Ci. Coxal shield ( Fig. 13 ) occupying about 4/5 of ventral surface. Setae Sce and Pe situated on posterior margin of coxal shield. Anterior genital sclerite well developed. Genital field with 9–10 pairs of acetabula, forming 1 row on plate along posterior margin of each side, each genital plate bearing 2 median thin setae. Pedipalps similar to those of male.

Measurements (n=1). Length of idiosoma 416, width 304; length of dorsal shield 343, width 264; length of capitulum 92, width 54; length of basal segment of chelicera 72, length of cheliceral stylet 24; length of capitular bay 78; length of pedipalpal segments (P-1–5): 22, 54, 38, 70, 24; length of leg segments: I-L- 1–6—46, 48, 46, 65, 78, 78; II-L- 1–6—43, 56, 46, 62, 84, 86; III-L- 1–6—46, 62, 54, 78, 97, 92; IV-L- 1–6—62, 105, 81, 110, 112, 94.

Differential diagnosis. The new species is similar to the Aturus amatsuensis Imamura & Nagatsuka, 1983 . The male of Aturus similis sp. n. possesses 1 row of short setae along the posterolateral margin of idiosoma, the posterolateral idiosoma margin with long unequal setae, the pedipalpal femur with convex ventrodistal margin, a tongue-shaped appendage absent on the genital cleft, the genu of leg IV only with 2 long sword-like setae. In contrast, the male of A. amatsuensis possesses 2 rows of short setae along the posterolateral margin of idiosoma, long subequal setae on posterolateral idiosoma margin, the pedipalpal femur with straight ventral margin, a tongueshaped appendage present on the genital cleft, the genu of leg IV with 2 long and 1 relatively short sword-like setae ( Imamura & Nagatsuka 1983). Aturus similis sp. n. has also some features in common with A. triangularis sp. n. (see above in differential diagnosis of A. triangularis sp. n.).

Etymology. The species name similis is Latin for "resembling", as the new species has many features in common with A. amatsuensis from Japan.

Habitat. Superficial and interstitial waters.

Distribution. Russia: Far East, Primory Territory.

Figures

FIGURES 6 – 7. Aturus similis sp. n., male: 6, idiosoma, dorsal view; 7, idiosoma, ventral view. Scale bar = 100 µm.

FIGURES 8 – 11. Aturus similis sp. n., male: 8, pedipalp, lateral view; 9, trochanter, basifemur, telofemur and genu of leg IV; 10, tibia and tarsus of leg IV; 11, claws of leg IV. Scale bars = 50 µm for Figs. 9 – 10; 25 µm for Fig. 8; 20 µm for Fig. 11.

FIGURES 12 – 13. Aturus similis sp. n., female: 12, idiosoma, dorsal view; 13, idiosoma, ventral view. Scale bar = 50 µm.