Thyopsis gereckei, Tuzovskij, 2021

Tuzovskij, Petr V., 2021, Description of a new water mite species of the genus Thyopsis (Protz, 1899) (Acari Hydrachnidia: Hydryphantidae) from Kazakhstan, Zootaxa 4985 (1), pp. 145-150 : 145-150

Thyopsis gereckei sp. n.

( Figs 1–11 )

Type series. Holotype: male, slide 9941, Asia , Kazakhstan, Turkestan Province , Tyulkubaskiy District , Aksu-Zhabagly Nature Reserve, Karalma stream, 42°27’53.2”N 70°34’53.0”E, 1316 m, depth 20 cm, substrates: stones, mosses, 12.09.2019, leg. V. Stolbov . Paratype: 1 male, same locality and data as holotype . Additional material: 1 male, AksuZhabagly Nature Reserve , Taldybulak stream, 42°24‘04.4“N 70°28‘13.7“E, 1450 m, depth 20 cm, substrates: stones, mosses, 12.09.2019, leg. V. Stolbov .

Diagnosis. Dorsocentral plates fused into a reticulated dorsal shield in which individual plates are distinct, and surrounded by a secondary reticulation, dorsocentral plates (dc. 5) completely fused to each other, capitulum with very short rostrum; pedipalp stout, P-4 proximal distoventral seta short and thick, distal seta comparatively long and thin; posterior genital acetabula larger than ac-1 and ac-2 on each side, genital field with 38–50 pairs of setae; tarsi of all legs shorter than I-IV-Leg-5 and without lateral setae.

Description. Male. All dorsalia greatly expanded and fused into a reticulated dorsal shield in which individual plates are distinct, with only small, more or less triangular areas surrounded the glandularia ( Fig. 1 ). Praefrontale oval and a little wider than long; postfrontale subrectangular and longer than wide; dorsocentral plates (dc.1 and dc. 3) slightly separated, dc.2 contiguous but not fused to each other, dc. 4 well separated and narrowed medially, dc.5 completely fused to each other and much longer than wide. Dorsal shield surrounded by a secondary reticulation and bearing trichobothria Oi, setae Oe, Hi, Sci, Li and Si. Setae Fch, Fp and Vi located in the zone of secondary reticulation, and Ve, He, Sce and Le situated on the interscutal membrane on each side. Median eye small and unpigmented, lateral eyes in capsules, eye lenses separated and surrounded by extensions of dorsal shield.

Coxal plates in four groups (Fig. 2). Anterior coxal groups without apodemes. Coxal plate III with a nose-shaped medial projection extending beyond medial margin of coxal plate IV. Number of coxal setae variable: Cx-I with 25–30, Cx-II with 17-21, Cx-III with 18–22, Cx-IV with 8–13 rather long, thin setae. Integument with pointed papillae (Fig. 3). Genital field with three pairs of acetabula, ac. 3 large than both other acetabula on each side, ac. 2 and ac. 3 lying nearly in a transverse line. Genital flap elongate (L/W ratio 2.5–2.7) and bearing 38–50 of setae on each side, their anterior margin straight or oblique, gonopore nearly as long as flaps ( Fig. 4 ). Ejaculatory complex proximal chamber relative large, proximal arms massive, strongly curved, broadest basally, tapering gradually to apex, distal arms slightly developed ( Fig. 5 ). Excretory pore surrounded by a sclerotized ring and located between setae Pi. Genital field and excretory pore well separated. Pregenital sclerite not developed, postgenital sclerite very small. Pedipalp stout ( Fig.6 ): P-1 relatively short with five to eight short subequal setae, P-2 ventral margin straight, with 9-10 short subequal setae; P-3 a little shorter than P-2, with two short unequal dorsoproximal setae and one comparatively long dorsodistal seta; P-4 ventral margin with two unequal distal setae: proximal from them short, thick, distal seta comparatively long and thin, dorsodistal peg-like seta shorter and thicker than proximal one.

Ventral margin of capitulum slightly convex, rostrum very short ( Fig. 7 ). Chelicera ( Fig. 8 ) rather slender, basal segment large with dorsal hump near middle of segment; chela short, length basal segment/chela ratio 2.8–3.2.

Legs very stout, densely covered with strong setae. Shape and arrangement of setae on legs I and IV as shown in Figs 9–10 , respectively. I-IV-Leg-6 shorter than I-IV-Leg-5 and without lateral setae; IV-Leg-4 much longer than IV-Leg-5. Leg claws simple, hook-like ( Fig. 11 ).

Measurements (n=3). Dorsal shield L 1250–1560, W 900–1035; genital flap L 285–315, W 110–135; capitulum L 285–310, rostrum L 20–25; cheliceral segments: base L 275–285, chela L 85–100; acetabula (ac. 1–3) D: 35–55, 35–50, 60–65; ejaculatory complex L 150; pedipalp segments (P-1-5) L: 50–55, 130–150, 75–88, 135–155, 35–38; leg segments L: I-Leg-1-6: 120–125, 175–200, 85–100, 125–135, 150–165, 120–125; II-Leg-1–6: 125–135, 185–210, 100–125, 150– 185, 185–200, 125–150; III-Leg-1–6: 135–175, 150–175, 100–115, 160–175, 175–190, 125–140; IV-Leg-1–6: 175–235, 185–200, 125–150, 310–325, 175–200, 125–140.

Female. Unknown.

Remarks. The present species is similar to Th. maderensis and Th. rothae in the structure of the dorsal shield in which individual plates are distinct. Differences between the Th. gereckei sp. n. and Th. maderensis are found in the following characters (character states of Th. maderensis are given in parentheses, data from Lundblad 1942 and Bader 1983): dorsal shield with secondary reticulation, Fig.1 (without secondary reticulation, but having three to four rows of distinctly developed meshes, Fig. 12 ), glandularia and setae Si located in the zone of primary reticulation (posterior to the zone of primary reticulation). Thyopsis rothae differs in the dorsal shield without secondary reticulation, dc. 5 not narrowed medially, dc. 5 and dl. 4 subequal in length ( Fig. 13 ), capitulum with rather long rostrum ( Bader 1983).

Etymology. The species is named after Prof. Dr Reinhard Gerecke ( Germany).

Habitat. Running waters.

Distribution. Asia, Kazakhstan: Turkestan Province.

Figures

FIGURES 1. Thyopsis gereckei sp. n., male: 1, dorsal view. Scale bar: 200μm.

FIGURES 4–6. Thyopsis gereckei sp.n.,male: 2, ventral view; 3, fragment of integument; 4, left half of genital field; 5, ejaculatory complex; 6, pedipalp. Scale bars: 2 = 200μm, 3, 5 = 50 μm; 4, 6 = 100 μm.

FIGURES 7–11. Thyopsis gereckei sp.n., male: 7, capitulum; 8, chelicera; 9, leg I; 10, leg IV; 11, claws of leg IV. Scale bars: 7–8, 9–10 = 100 μm, 11 = 50 μm.

FIGURES 12–13. Thyopsis (from Bader, 1983, modified): 12, Th. maderensis Lundblad, 1941, male, dorsal view; 13, Th. rothae Oezkan, 1982, male, dorsal view.