Sperchon (Sperchon) uralensis, Kolesnikov & Stolbov, 2025

Kolesnikov, Vasiliy B. & Stolbov, Vitaly A., 2025, Review of the genus Sperchon Kramer, 1877 (Acari, Hydrachnidia: Sperchontidae) from Russia, Zootaxa 5666 (1), pp. 53-73 : 60-65

Sperchon (Sperchon) uralensis sp. nov.

( Figs 5–7 , 11C,D )

Material examined. Holotype: male, Russia, Nether-polar Urals, Khanty-Mansi Autonomous Okrug, Beryozovsky district, Kobyla-Yu River , 64°30'24.1"N 59°33'22.8"E, 571 m a.s.l., 23.07.2023, leg. V. Stolbov ( Fig. 1B ).

Diagnosis. Integument dorsally with numerous long folds, between which are located few rounded or elongated papillae, ventrally with undulating fine folds. Glandularia platelets of dorsum not enlarged, with small muscle attachment platelets (Dc-2-4 and Dl-1-4), Dl-1 consosting of two small platelets, Dl-2 consisting of three small platelets. Cx-I+II not fused, Cx-III with a small medial glandular opening. Ventral with muscle attachment platelets present. Acetabula 1 and 2 elongated, distance between these acetabula is one times greater than their length. Excretory pore surrounded bу а sclerotized ring, located distinctly closer to Vgl-3 than to Vgl-1. P-2 not shortened or widened, with a pointed distoventral projection with three distal short setae and one short spiniform basal seta. P-3 without ventral setae. Ventral peg-like seta on P-4 very small, far apart. P-5 more than twice as long as wide. Few dorsal setae of IV-L-3-5 not plumose.

Description

Male. Integument dorsally with numerous long folds, between which are located rare rounded or elongated papillae; ventrally with undulating fine folds. Dorsoglandularia and lateroglandularia are located on small (diameter 55-70) chitinous platelets with irregular shaped edges. Seta Dgl-1 slightly spiniform, very short, smooth. Preocularia are located on small chitinous platelets (diameter 30), postocularia—larger (diameter 82-90, approximately the same diameter as the ocular plate). Frontale pore (Fr) present. Dorsocentralia and dorsolateralia muscle attachment plates (Dc-2-4 and Dl-1-4) present, Dc-3 larger (110-125/60-70) than others (20-50), elongated with a constriction in the middle, Dl-1 consisting of two small platelts, Dl-2 consisting of three small platelets. Five pairs lyriform organs (i 1-5) present. Cx-I+II medially close to each other and in close contact, but not fused. Cx-III with a small medial glandular opening (Cxgl-4). Coxoglandularia platelets 2 (Cxgl-2), lateroglandularia 3 (Lgl-3) and ventroglandularia 2 and 3 (Vgl-2-3) platelets small (40-50), ventroglandularia 1 (Vgl-1) a little smaller (30). Ventralia muscle attachment plates (V-1-3) present, small (20-30). Excretory pore surrounded bу а sclerotized ring (60), located distinctly closer to Vgl-3 than to Vgl-1. Genital plates not enlarged (251) with 14 medial and 5 lateral setae. Acetabula 1 and 2 (Ac- 1-2) slightly elongated, small (55-65/30), distance between Ac-1 and Ac-2 is one times greater than their length. Acetabulum 3 round, larger (50). Postgenital platelet present (50). Pregenetal platelets small (25).

Gnathosoma with rostrum shorter than gnathosomal base. Palp: P-1 with one small spiniform dorsal setae; P-2 not shortened or widened, with 12 spiniform dorsal setae, a pointed distoventral projection with three distal short setae and one short (not longer than distoventral projection) spiniform basal seta; P-3 with three spiniform and two short filiform dorsal setae, ventral margin without setae and denticulation; P-4 longer than P-3, narrow (length/ height 6.3), with two slightly developed ventral tubercles, bearing minute peg-like setae, proximal tubercle slightly larger than distal one, proximal peg-like seta is located slightly distal to middle of P-4, distal one is closer to the distal margin of P-4 (length of P-5 noticeably longer than distance from distal ventral peg-like seta on P-4 to distal edge of P-4), the distance between peg-like setae is twice as long as the height of P-4, between peg-like setae two minute filiform setae, distal spine seta rounded at top; P-5 more than twice as long as wide, with large distal spines, two ventral spines of approximately the same size, one small dorsal spines before solenidion, one bifurcated seta (branches are equivalent) and four filiform setae (distance between bases of distal and ventral filiform setae slightly larger than length of ventral setae).

Leg segments slender, IV-L-3-5 with few thin dorsal setae, not plumose, other setae spiniform or short filiform. Ambulacrum with claw blade well protruding bearing a long dorsal and a shorter ventral clawlet.

Female unknown.

Measurements. Idiosoma L 1270, W 1010; distance between anterior end of Cx-I and posterior end of Cx-IV, 590; Cx-III W, 832. Palp dL/H ratio: P-1 40/64, 0.62; P-2 153/117, 1.3; P-3 189/99, 1.9; P-4 313/50, 6.3; P-5 77/26, 2.9. Gnathosoma L 276; chelicera L 290. Leg segments dL: I-L-2–6: 128, 191, 325, 351, 299; IV-L: 160, 177, 208, 390, 385, 320.

Etymology. The species is named after the Ural Mountains where it was found.

Remarks. The new species is most similar to Sperchon questor in the following characters: integument with papillae and undulating fine folds; acetabula Ac-1 and Ac-2 slightly elongated; ventral setae P-3 absent; ventral spiniform seta P-2 present; length of P-5 is noticeably less than distance from distal ventral peg-like seta on P- 4 to distal edge of P-4; distance between bases of distal and ventral filiform setae longer than length of ventral setae. However, the new species is noticeably different from S. questor by the following characters: P-4 not longer than P-2+3 (vs. P-4 longer than P-2+ 3 in S. questor ); ventrodistal process on P-2 with 3 setae, not bifurcated (vs. ventrodistal process on P-2 with two setae, clearly bifurcated in S. questor ); dorsal integument with few papillae (vs. papillae numerous in S. questor ).

Figures

FIGURES 1. Type locality of the new species: A—Sperchon (Sperchon) zhavoronkovae sp. nov.; B—Sperchon (Sperchon) uralensis sp. nov.

FIGURES 5. Sperchon (Sperchon) uralensis sp. nov., male: A—idiosoma, dorsal view; B—idiosoma, ventral view. Scale bar 500 µm.

FIGURES 6. Sperchon (Sperchon) uralensis sp. nov., male: A—palp; B—P-5 and distal part of P-4; C—gnathosoma; D— chelicera; E—genital plates. Scale bar 100 µm, except B—10 µm.

FIGURES 7. Sperchon (Sperchon) uralensis sp. nov., male: A—leg I; B—leg II; C—leg III; D—leg IV. Scale bar 100 µm.

FIGURES 11. Integument dorsally (A, C, E) and ventrally (B, D, F), DIC images: A, B—Sperchon (Sperchon) zhavoronkovae sp. nov.; C, D—Sperchon (Sperchon) uralensis sp. nov.; E, F—Sperchon (Hispidosperchon) setiger.