Sperchon (Sperchon) zhavoronkovae, 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 : 58-60

Sperchon (Sperchon) zhavoronkovae sp. nov.

( Figs 2–4 , 11A,B )

Material examined. Holotype: female, Russia, Nether-polar Urals, Khanty-Mansi Autonomous Okrug, Beryozovsky district, Shaitanka River , 64°34'05.9"N 59°40'50.6"E, 407 m a.s.l., among moss on stones, 25.07.2023, leg. V. Stolbov ( Fig. 1A ).

Diagnosis. Integument dorsally with flat papillae separated by short folds, ventrally with undulating folds. Glandularia platelets of dorsum not enlarged, without muscle attachment platelets (except Dl-2). Cx-I+II not fused, Cx-III with a small medial glandular opening. Venter without muscle attachment platelets.Acetabula 1 and 2 rounded, the small, distance between these acetabula is 1 – 2 times greater than their length. Excretory pore surrounded bу а sclerotized ring, located distinctly closer to Vgl-3. P-2 not shortened or widened, with a pointed distoventral projection and two distal short setae and one long spiniform basal seta. P-3 without ventral setae. Ventral peg-like seta on P-4 small, far distanced rom each other. P-5 twice as long as it is wide. IV-L-3 – 5 with few slightly serrated dorsal setae.

Description

Female. Integument dorsally with flat, papillae separated by short folds, which are located predominantly in the transverse direction of the idiosoma; ventrally with undulating fine folds, which are located predominantly in the transverse direction of the idiosoma. Dorsoglandularia and lateroglandularia are located on medium-sized (diameter 80 – 100) chitinous platelets with irregular shaped edges. Seta Dgl-1 slightly spiniform, short, smooth. Preocularia setae are located on small chitinous platelets (diameter 35), postocularia—larger (diameter 90, approximately the same diameter as the ocular plate). Frontale pore (Fr) present. Dorsocentralia muscle attachment plates (Dc) absent, only one pair small (25) dorsolateralia plates Dl-2 present. Five pairs of 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). Coxoglandulare plates 2 (Cxgl-2) and lateroglandularia 3 (Lgl-3) medium-sized (70), ventroglandularia 1 (Vgl- 1) small (35), other ventroglandularia platelets (Vgl-2-4) larger (80-90). Excretory pore surrounded bу а sclerotized ring (103), located distinctly closer to Vgl-3 than to Vgl-1. Genital plates not enlarged (225) with 17 – 18 medial and 6 – 7 lateral setae. Acetabula 1 and 2 (Ac-1-2) rounded, small (35 – 40), distance between Ac-1 and Ac-2 is 1 – 2 times greater than their length. Acetabulum 3 round, larger (47). Postgenital and ventral sclerites (Vc) absent.

Gnathosoma with rostrum shorter than gnathosomal base. Palp: P-1 with one small spiniform dorsal setae; P-2 not shortened or widened, with nine spiniform dorsal setae, a pointed distoventral projection with two distal short setae and one long (longer than distoventral projection) spiniform basal seta; P-3 with five spiniform and two short filiform dorsal setae, ventral margin without setae and denticulation; P-4 longer than P-3, narrow (length/height 6.2), with two slightly developed ventral tubercles, bearing peg-like setae (proximal seta slightly larger that distal), proximal tubercle larger than distal one, proximal peg-like seta is located almost in the middle of P-4, the distal one is closer to the distal margin of P-4 (length of P-5 approximately equal to distance from distal ventral peg-like seta on P-4 to distal edge of P-4), the distance between peg-like setae is more than twice as long as the height of P-4, between peg-like setae two short filiform setae, distal spine seta pointed, slightly widened towards the top; P-5 twice as long as wide, with large distal spines, two approximately the same size as ventral spines, 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 very short than length of ventral setae).

Leg segments slender, IV-L-3-5 with few slightly serrated dorsal setae, other setae spiniform or short filiform. Ambulacrum with claw blade well protruding bearing a long dorsal and a shorter ventral clawlet.

Male unknown.

Measurements. Idiosoma L 1430, W 1100; distance between anterior end of Cx-I and posterior end of Cx-IV, 627; Cx-III W, 790. Palp dL/H ratio: P-1 52/58, 0.89; P-2 153/111, 1.37; P-3 176/100, 1.76; P-4 270/44, 6.1; P-5 44/22, 2.0. Gnathosoma L 298; chelicera L 285. Leg segments dL: I-L-2–6: 136, 175, 267, 283, 231; IV-L: 154, 201, 191, 405, 382, 317.

Etymology. The species is named after of the late Dr. Olga D. Zhavoronkova for her contributions to the study of water mites.

Remarks. The new species is most similar to Sperchon fluviatilis in the following characters: integument with undulating fine ridges; ventral setae P-3 absent; ventral spiniform seta P-2 present; distance between bases of distal and ventral filiform setae very short than length of ventral setae. However, the new species is noticeably different from S. fluviatilis by the following characters: length of P-5 approximately equal to distance from distal ventral peg-like seta on P-4 to distal edge of P-4 (vs. length of P-5 shorter than distance from distal ventral peg-like seta on P-4 to distal edge of P- 4 in S. fluviatilis ); acetabula not large, distance between Ac-1 and Ac-2 is 1-2 times greater than their length (vs. acetabula large, distance between Ac-1 and Ac-2 is 1/2 times less than their length in S. fluviatilis ); folds of skin covers on back and behind genital opening are arranged in transverse rows (vs. arranged in irregular rows in S. fluviatilis ); anus with sclerotized plate (vs. without sclerotized plate in S. fluviatilis ).

Figures

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

FIGURES 2. Sperchon (Sperchon) zhavoronkovae sp. nov., female: A—idiosoma, dorsal view; B—idiosoma, ventral view. Scale bar 500 µm.

FIGURES 3. Sperchon (Sperchon) zhavoronkovae sp. nov., female: 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 4. Sperchon (Sperchon) zhavoronkovae sp. nov., female: 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.