Utaxatax (Utaxatax) stolbovi, Tuzovskij, 2020

Tuzovskij, Petr V., 2020, Description of a new water mite of the genus Utaxatax (Acari, Hydrachnidia: Anisitsiellidae) from Kazakhstan, Zootaxa 4860 (3), pp. 445-450 : 445-450

Utaxatax (Utaxatax) stolbovi sp. n.

( Figs 1 –13)

Type series. Holotype: female, slide 9915, Asia , Kazakhstan, Turkestan Province , Tyulkubaskiy District , Aksu-Zhabagly Nature Reserve, stream Taldybulak, 42°25’01.9”N 70°28’22.3”E, 1230 m, depth 30–40 cm, ground: stones, mosses, 10.08.2019, leg. V. Stolbov . Paratypes: 3 males, same locality and data as holotype .

Diagnosis. Dorsal plate large, with five pair of setae; eye-lenses on frontal platelets; excretory pore fused with ventral shield; setae Ci and Se located in the soft interscutal membrane; insertion of IV-Legs situated postero-laterally to insertions of III-Legs; P-3 ventral seta longer than ventral seta(e) on P-2 and P-4; IV-leg-6 with long terminal seta.

Description. Both sexes. Contour of idiosoma egg-shaped ( Fig. 1 ). Dorsal shield large and elongate (L/W ratio 1.52–1.66), with rounded anterior and posterior margins, bearing trichobothria Oi and four pairs of setae (Vi, Oe, Hi, Sci). In the frontal membranous space a pair of transverse platelets ( Fig. 3 ) bearing the seta Fch, trichobothrium Fp and lenses of lateral eyes each; Fch long and thick, Fp comparatively short, thin and three-furcated. Glandularia Vi, Oe, Hi and Sci located closely to lateral margins of the shield, trichobothria Oi located medially to Oe. Dorsal furrow wide, containing five pairs of setae (Ve, He, Sce, Li, Si) and four pairs of slit organs (i2–i5), first pair (i1) free or associated with frontal platelets ( Fig. 3 ). Dorsal surface of the shield with a fine porosity.

Anterior coxal groups separated medially and from the third coxal plates, but articular membrane very narrow, a curved suture line extending across third coxal plates immediately lateral to a pair of glandularia (Pe); posterior coxal groups fused medially and with ventral shield ( Fig. 2 ). Glandularia Hv located between coxal plates II and III laterally. Posterior part of the ventral shield bearing setae Pi and Le. Excretory pore fused with posterior margin of the ventral shield, flanking setae (Ci) and Se located in the soft interscutal membrane. Insertion of IV-Legs situated postero-lateral to insertions of III-Legs. All coxal plates and posterior part of ventral shield with a fine porosity; in addition, surface of coxal plates IV with a few short strips. Genital field bearing three pairs of subequal acetabula flanking the gonopore and covered by paired of genital flaps when flaps are closed.

Capitulum ( Fig. 4 ) with short rostrum, ventral margin slightly convex. Basal segment of chelicera ( Fig. 5 ) with a well-developed dorsomedial processus, chela short and sickle-shaped.

Pedipalp ( Fig. 6 ): P-1 short, with a single dorsodistal seta; P-2 large, with straight or slightly convex ventral margin, bearing five to six short, thick dorsal setae and one long, thick ventral seta; P-3 relatively short, with three to four thick dorsal setae various in length, and one long ventral seta which is longer than ventral seta(e) on P-2 and P-4; P-4 ventral margin with a slightly pointed projection, maximum height a little distally from segment centre.

Shape and arrangement of setae on leg segments as shown in Figs 8–11 . III/IV-Leg-1 subequal in size and larger than I/II-Leg-1. IV-Leg-6 with a rather long, thick distal seta (L45–50). Claws of legs I–II equal in shape, with long, pointed internal clawlet and short external clawlet, claw lamella slightly developed, with a ventral spur (Fig.13). Claws of legs III without sexual dimorphism, with long pointed internal clawlet and short external clawlet, claw lamella without ventral spur ( Fig. 14 ). Leg III claws larger than other leg claws.

Female. Genital field large, genital flaps elongate (L/W ratio 3.0), with parallel medial and lateral margins and bearing several fine setae each ( Fig. 2 ). The fourth coxal plates a little extend posterior to the genital field.

Measurements (n=1). Idiosoma L 490, W 365; dorsal shield L 480, W 290; capitulum L 108; seta Fch 45; coxal plates I ml 48; coxal plates III ml 63, W 125; coxal plates IV ml 185; distance between posterior margins: genital field to coxae IV 30; genital flaps L 150, W 50, genital acetabula (ac-1–3) L: 36, 36, 36; capitulum L 108; chelicera: basal segment105–110, chela 35–37; pedipalp segments (P–1–5) L: 24, 60, 42, 75, 21; leg segments L: I-Leg-1–6: 40, 40, 54, 50, 54, 63; II-Leg-1–6: 45, 54, 48, 60, 60, 66; III-Leg-1–6: 65, 45, 60, 90, 102, 85; IV-Leg-1–6: 54, 42, 60, 60, 54, 65.

M ale. Dorsal surface and ventral surface, except size and proportion of genital field, similar to female. Coxal plates IV very large, their posterior margins extending far posterior to the genital field ( Fig.7 ). Measurements (n=3). Idiosoma L 470–480, W 390–395; dorsal shield L 420–450, W 270–280; seta Fch 48–55; coxal plates I ml 48; coxal plates III ml 54–60, W 108–114; coxal plates IV ml 185–190; distance between posterior margins: genital field to coxae IV 65–72; genital flaps L: 90–102, W 33–36, genital acetabula (ac-1–3) L:28–30, 24–30, 24–30; capitulum L 95–102; chelicera: basal segment 105–110, chela 35–37; pedipalp segments (P–1–5) L: 21–24, 51–54, 30–35, 60–66, 18–19; leg segments L: I-Leg-1–6: 36, 54, 48, 48, 54, 65; II-Leg-1–6: 39, 60, 48, 54, 54–60, 60–66; III-Leg-1–6: 54–60, 48–54, 54–60, 80–85, 95–100, 72–78; IV-Leg-1–6: 54–60, 50–54, 54–60, 65–70, 65–85, 75–85.

Remarks. The present species is similar to the Himalayan Utaxatax brahmeri Panesar, 2004 in the contour of an idiosoma and structure of the fourth pair of coxal plates. Differences between the two species are found in the following characters (character states of U. brahmeri given in parentheses, data from Panesar 2004): female fourth coxal plates extending a little posterior to genital field, Fig. 2 (well extending posterior to genital field, Fig. 14 ); setae and glandularia Ci and Se located in the soft interscutal membrane (fused with posterior margin of ventral shield);P-3 ventral seta longer than ventral seta(e) on P-2 and P-4,(not longer than ventral seta(e) on P-2 and P-3, Fig. 15 ); IV-leg-6 terminal seta long, Fig. 11 (comparatively short, Fig. 16 ).

Etymology. The species is named after the collector, Dr. Vitaly Stolbov.

Habitat. Running waters.

Distribution. Asia, Kazakhstan: Turkestan Province.

Figures

FIGURES 1–2.Utaxatax (Utaxatax) stolbovi sp.n., female: 1, dorsal view; 2, ventral view. Scale bar: 100 μm.

FIGURES 3–7. Utaxatax (Utaxatax) stolbovi sp.n, adult: 3,anterior frontal platelet; 4, capitulum, lateral view; 5, chelicera; 6, pedipalp; 7, male; 3–6, female; 7, male.Scale bars: 3–6 = 50 μm, 7 = 100 μm.

FIGURES 8–11. Utaxatax (Utaxatax) stolbovi sp.n., male: 8, leg I; 9, leg II; 10, leg. III; 11, leg IV; 12, claw of leg I; 13, claw of leg III. Scale bars: 8–11, 12–13 = 50 μm.

FIGURES 14–16.Utaxatax (Utaxatax) brahmeri., female: 14, dorsal view; 15, pedipalp; 16, IV-Leg-1-6 (after Panesar 2004). Scale bars: 100 μm.