Aturus caucasicus, Tuzovskij, 2022

Tuzovskij, Petr V., 2022, A new water mite species of the genus Aturus Kramer, 1875 (Acari, Hydrachnidia, Aturidae) from North Caucasus, Zootaxa 5104 (3), pp. 445-450 : 445-448

Aturus caucasicus sp. n.

Figs 1–10

Type series. Holotype: male, slide 1836, Europe, Russia, Krasnodar Kray, Seversk District, Ubin stream near settlement Ubinskaya , 44.718693 N, 38.532789 E, depth 0.2-0.5 m, substrates: stones, gravel, 6 June 1976, leg. P. V. Tuzovskij . Paratypes (11males and 14 females) collected in the same locality : 1 female 16 May 1976, 6 females 17 May 1976, 2 males and 2 females 17 May 1976, 1 male 27 May 1976, 1 female 29 May 1976, 1 male 31 May 1976, 3 males and 1 female 3 June 1976, 1 male and 2 females 9 June 1976, 3 males and 1 female 16 June 1976.

Male. Color red. Idiosoma ( Figs 9–10 ) nearly circular (L/ W 1.00 –1.13), with two pairs of unequal, posteromedial ballon-like inflated setae flanking gonopore. Setae Fch long and thick, trichobothria thin and short. Dorsal shield very large, covering almost all dorsum, slightly narrowed anterior to middle, expanded posteriorly, fused with ventral shield caudally and bearing postocularia and 5 pairs of glandularia, one pair of slit organs (i5) and excretory pore; setae Hi thick bifurcated or trifurcated, other setae simple, seta and glandularium Sci distinctly separated on each side, setae Sci, Li and Pi longer and thicker than setae Si. Setae Oe, He, Sce and Le situated in the dorsal furrow, close together or Oe a little distanced from the remaining setae; Oe and He thick bifurcated, Oe longer than He, Sce and Le short, thin. Setae Pi situated laterally to Si, their bases form nearly a transverse row. First pair of slit organs (i1) fused with sclerites bearing glandularia and setae Vi, i2 fused with sclerites bearing glandularia and setae Oe, i3 fused with sclerites bearing glandularia and setae Le, i4 located in posterior portion of dorsal furrow. Posterior part of dorsal shield with two groups numerous unequal, hair-like setae. Posterolateral and posterior idiosoma with numerous rather long densely-arranged setae.

Ventral shield ( Fig. 2 ) large and occupied all ventral surface, bearing setae and glandularia Hv, Se, Ci and Pe, with deep median cleft caudally, 6–8 genital setae and 8–11 acetabula along posterior margin on each side, two of these (occasionally one or three) shifted to a posteroventral position flanking gonopore. Setae Ci, Se and Pe situated near posterolateral margin of ventral shield close to genital plate on each side. Gnathosoma with short anchoral process.

Ejaculatory complex ( Fig. 3 ) proximal chamber moderately developed with pointed tip, anterior arms rather long, thick curved, posterior arms long, thin and almost straight.

Pedipalp compact ( Fig. 4 ): P-1 short, with single dorsodistal seta; P-2 large, with straight or slightly convex ventral margin, bearing five dorsal setae and pointed mediodistal projection; P-3 with two dorsodistal setae; P-4 long, with convex ventral margin, two unequal ventral setae (thick and thin) distally to middle of segment, short distal peg-like seta and two fine distal setae.

III-Leg-4/5 a little thickened distally ( Fig. 5 ), III-Leg-4 with four subequal thick and two fine distal setae; III-Leg-5 with three short and two long, thick proximal setae, two long whip-like dorsodistal setae and 13–17 rather long ventral setae. IV-Leg-4 thickened distally, with two ventrodistal pointed unequal sword-like setae (one distinctly more enlarged than the other), one long, thick curved ventral seta with blunt tip, seven comparatively short, thick pointed unequal distal setae and several thin, short dorsal ones ( Fig. 6 ). IV-Leg-5 slightly curved, proximally with five thick setae, four of these with various dentation and five comparatively thin ventral setae; distal margin bearing one irregularly-curved long flattened seta and seven unequal simple setae.

I–III-Leg claws with three clawlets ( Fig. 7 ): central clawlet longest, external clawlet thinner and shorter than internal one. Claws of fourth leg asymmetrical ( Fig. 8 ): shape of one claw typical, other claw with long internal clawlet, short, thick central clawlet and short, thin external one.

Measurements (n=10). Idiosoma L 310–350, W 300–315; dorsal plates L 305–320, W 250–260; capitulum L 75–78, W 60–65; pedipalp segments (P-1-5) L: 15–18, 42–48, 36–42, 67–75, 27–30; leg segments L: I-Leg-1–6: 35–38, 48–60, 45–52, 65–72, 78–85, 85–95; II-Leg-1-6: 35-42, 42-55, 54-58, 72-78, 90-100, 90-110; III-Leg-1-6: 35–48, 54–60, 55–65, 85–95, 130–150, 125–135; IV-Leg-1–6: 70–85, 78–82, 65–72, 95–102, 125–140, 125–140.

Female. Idiosoma flat. Dorsal and ventral shields present. Idiosoma ( Figs 9–10 ) broad (L/ W 1.05 –1.13), with convex lateral margins, frontal margin with small median incision. All idiosomal setae simple. Dorsal shield very large, covering nearly all dorsum, posterior margin concave, bearing postocularia and 3 pairs of glandularia. Setae Fch, Oe, Hi, He longer and thicker than others idiosomal setae. First pair of slit organs (i1) fused with sclerites bearing glandularia and setae Vi, i2 fused with Oe, i3 fused with Sce, i4 fused with Le, i5 located on soft membrane ventrocaudally. Excretory pore and setae Si located posterior to zone of primary sclerotization.

Coxal shield ( Fig. 10 ) large covering about 4/5 ventral side, with small posteromedian indentation. Setae Ci, Pe and Se situated between posterior margin of coxal shield and genital plates; Se located in laterocaudal position between coxal shield and acetabular plate on each side. Genital plates close to posterior margin of coxal shield, with 10–12 pairs of acetabula of various size, lateral acetabula usually smaller than medial and located in two rows. Each genital plate with three setae (two medial and one lateral). Fifth pairs of slit organs and setae Pi located caudally on soft interscutal membrane.

Measurements (n=10). Idiosoma L 360–375, W 330–345; dorsal plates L 300–315, W 245–255; capitulum L 70–75, W 60–65; pedipalp segments (P-1-5) L: 12–18, 48–60, 33–36, 60–65, 28–31; leg segments L: I-Leg-1–6: 35–42, 48–51, 40–45, 50–60, 65–72, 72–78; II-Leg-1–6: 35–42, 42–51, 45–48, 60–65, 70–73, 78–85; III-Leg-1-6: 35–42, 42–55, 48–55, 68–72, 92–96, 95–105; IV-Leg-1–6: 60–65, 54–60, 60–66, 78–85, 100–110, 100–110.

Differential diagnosis. The present species is similar to Aturus intermedius Protz, 1900 in the structure of the idiosoma. Differences between the A. caucasicus sp.n. and A. intermedius in the following characters (character states of A. intermedius are given in parentheses, data from Gerecke 2014 and Gerecke et al. 2016): Male: idiosoma relatively small and nearly circular, L/W 315–350/300–315 μm (rather large, L/W 380–400/280–300μm, Fig. 11 ); genital field with 8 - 11pairs of acetabula (with 12–15 pairs of acetabula); III-Leg-4 with four distal setae subequal in size, Fig. 5 (one long seta and three short setae, Fig. 12 ), III-Leg-5 with three short, thick and two long, thick proximal setae (with three subequal thick proximal setae, but without two long, thick proximal setae); IV-Leg-4 with one long, thick curved distoventral seta with blunt tip, Fig. 6 (without such seta, Fig. 13 ). Female: idiosoma small and nearly circular, L/W 360–375/330–345μm (rather large, L/W 400–450/300–350μm), genital field with 10–12 pairs of acetabula (with 15–20 pairs of acetabula).

Larva. Unknown.

Deutonymph. Unknown.

Etymology. The species epithet “ caucasicus ” is derived from the name of the region where it was collected (Caucasus).

Habitat. Running waters.

Distribution. Europe, Russia: North Caucasus.

Figures

FIGURES 1–2. Aturus caucasicus sp.n., male: 1, dorsal view; 2, ventral view. Scale bar: 1-2 = 100 μm.

FIGURES 3–8. Aturus caucasicus sp.n., male: 3, ejaculatory complex; 4, pedipalp, lateral view; 5, III-Leg-4-6; 6, IV-Leg-4-6; 7, claw of leg III; 8, claws of leg IV. Scale bars: 3-4, 7-8, 5-6 = 50 μm.

FIGURES 9–10. Aturus caucasicus sp.n., female: 9, dorsal view; 10, ventral view. Scale bar: 9-10 = 100 μm.

FIGURES 11–14. Aturus intermedius Protz, 1900, male: 11, dorsal view; 12, III-Leg-4-6; 13, IV-Leg-4-5; 11-12 after Gerecke 2014; 13, after Gerecke et al. 2016.