Eustigmaeus tjumeniensis Khaustov and Tolstikov

Khaustov, Alexander A. & Tolstikov, Andrei V., 2014, A new species and new records of the genus Eustigmaeus (Acari: Prostigmata: Stigmaeidae) from Western Siberia, Zootaxa 3861 (6), pp. 531-553 : 532-539

Eustigmaeus tjumeniensis Khaustov and Tolstikov sp. nov.

( Figs. 1–15 , 28–31)

Description. FEMALE (holotype, Figs. 1–8 , 28–31). Idiosoma almost round in outline. Length of idiosoma 430 (425–435), width 385 (360–385). Idiosomal dorsum ( Figs. 1 , 28, 29). Idiosoma completely covered by 2 large and well sclerotized plates. Plates with dimples of 2 types: very large in lateral, and small in medial parts of plates. Central part of prodorsal plate with distinct depression (Fig. 28). Diameter of eyes 13 (13–17). Dorsal setae situated on protuberances, subequal, lanceolate, smooth or with very small barbs (Figs. 30–31). Sometimes setae sce, d 2, e 1, e 2, and f 1 with 1 large subapical barb. Length of dorsal setae: vi 52 (44–52), ve 57 (57–59), sci 43 (39–44), sce 38 (36–38), c 1 44 (42–44), c 2 16 (15–17), d 1 47 (46–47), d 2 39 (36–39), e 1 56 (54–56), e 2 46 (46–52), f 1 63 (63–65), h 1 48 (48–52), h 2 30 (30–35). Distances between setae: vi– vi 19 (15–19), ve–ve 151 (145–152), sci–sci 295 (280–300), sce–sce 360 (340–360), c 1– c 1 115 (97–120), d 1– d 1 255 (245–260), d 2– d 2 375 (350–375), e 1– e 1 190 (185–195), e 2– e 2 285 (285–290), f 1– f 1 110 (105–110). Idiosomal venter ( Fig. 2 ). With 2 pairs of callosities between idiosomal plate and humeral plate. Suranal plate situated ventrally, with distinct large dimples. Endopodal plates separated medially, distinctly reticulated. Humeral plate triangular, reticulated. With 3 pairs of simple subequal aggenital, and 3 pairs of simple subegual pseudanal setae. Length of ventral setae: 1 a 21 (19–27), 1 b 19 (19–22), 1 c 15 (14–18), 2 b 17 (15–18), 2 c 14 (14–16), 3 a 21 (18–24), 3 b 13 (13–18), 3 c 13 (13–17), 4 a 22 (20–22), 4 b 18 (18–20), 4 c 15 (15–22), ag 1 15 (15–17), ag 2 16 (16–18), ag 3 18 (18–20), ps 1 17 (14–18), ps 2 16 (16–17), ps 3 16 (15–20). Gnathosoma ( Figs. 3–4 ). Tibial claw well-developed. Setae l’ on palpal tibia spine–like ( Fig. 3 ). Setae on palpal femur and genu barbed, other palpal setae smooth. Number of setae on palpal segments: Tr 0, Fe 3 (d, l’, v”), Ge 2 (d, l”), Ti 3 (d, l’, l”), Ta 8(1) (fused eupathidia ul’, ul”, sul, eupathidion acm, ba, bp, lp, 1 solenidion ω). Palpal supracoxal setae (elcp) peg-like. Rostrum of subcapitulum ( Fig. 4 ) relatively short and wide. Subcapitular setae or 1 smooth, distinctly thickened, curved and blunt–ended; other subcapitular setae simple, pointed. Basal part of subcapitulum without distinct reticulation. Length of subcapitular setae: m 20 (20–24), n 24 (20–24), or 1 13 (13–14), or 2 15 (14–16). Legs ( Figs. 5–8 ). Empodial raylets pointed. Leg I ( Fig. 5 ). Coxae I posterodorsally with peg-like leg supracoxal setae (elcl). Leg chaetotaxy: Tr 1 (v’), Fe 6 (d, l’, l”, v’, v”, bv”), Ge 4 (d, l’, l ”, k), Ti 5(2) (d, l’, l”, v’, v”, φ, φp), Ta 13(1) (p’, p”, tc’, tc”, ft’, ft”, u’, u”, a’, a”, pl’, pl”, vs, ω). Setae d on tibia and (p), (tc), (ft) on tarsus are eupathidia. Setae d, l’, l” on tibia, l’, l”, d on genu, l” and d on femur distinctly thickened, lanceolate, situated on protuberances; setae d on femur, l’ on genu and tibia with several large barbs in distal half. Seta k 10 (10–11). Solenidion ω long 30 (30–36), finger-shaped; solenidion φ 8 (8–9) baculiform, φp attenuate 20 (20–22). Leg II ( Fig. 6 ). Leg chaetotaxy: Tr 1 (v’), Fe 5 (d, l’, l”, v’, bv”), Ge 4 (d, l’, l”, k), Ti 5(1) (d, l’, l”, v’, v”, φ), Ta 9(1) (p’, tc’, tc”, u’, u”, a’, a”, pl’, vs, ω). Setae d on tibia, p’ and tc’ on tarsus represented by eupathidia. Setae l’ and l” on tibia, d, l’ and l” on genu, d and l” on femur distinctly thickened, lanceolate, usually with several large barbs, situated on protuberances. Solenidion ω 15 (15–16) finger-shaped; solenidion φ 18 (18–19) attenuate. Seta k 6 (5–6). Leg III ( Fig. 7 ). Leg setation: Tr 1 (v’), Fe 3 (d, l’, ev’), Ge 1 (d), Ti 5(1) (d, l’, l”, v’, v”, φ), Ta 7 (1) (tc’, tc”, u’, u”, a’, a”, vs, ω). Solenidion ω 4 (4–5) baculiform; solenidion φ 11 (9–12) attenuate. Setae d, l’ on tibia, d on genu, d and l’ on femur distinctly thickened, lanceolate, sometimes with several barbs. Leg IV ( Fig. 8 ). Leg setation: Tr 1 (v’), Fe 2 (d, ev’), Ge 1 (d), Ti 5(1) (d, l’, l”, v’, v”, φ), Ta 7(1) (tc’, tc”, u’, u”, a’, a”, vs, ω). Solenidion ω 4(4) baculiform; solenidion φ 13 (11–13) attenuate. Setae d, l’, l” on tibia, d on genu, and d on femur distinctly thickened, lanceolate, sometimes with several barbs.

MALE ( Figs. 9–14 ). Idiosoma oval, much smaller than female. Length of idiosoma 290–295, width 220–225. Idiosomal dorsum ( Fig. 9 ). Dorsal idiosomal plates with dimples of 2 types: very large in lateral, and small in medial parts of plates. Dorsal setae lanceolate, with very small barbs. Some setae with 1 large subapical barb or without it. Setae f 1 situated on distinct protuberances. Suranal plate dorsal. Diameter of eyes 13–14. Length of dorsal setae: vi 31–33, ve 35–36, sci 22–24, sce 26–30, c 1 17–18, c 2 19, d 1 22–23, d 2 26–27, e 1 20 –21, e 2 32 –34, f 1 47–48, h 1 11–12, h 2 30–32. Distances between setae: vi– vi 13–19, ve–ve 96–97, sci–sci 163–169, sce–sce 209–212, c 1– c 1 79–80, d 1– d 1 149–152, d 2– d 2 199–200, e 1– e 1 88 –95, e 2– e 2 137–141, f 1– f 1 61–68. Idiosomal venter ( Fig. 10 ).

Podosoma similar with that of female. With 2 pairs of simple subequal aggenital setae. Pseudanal setae small, smooth; ps 2 situated on protuberances. Length of ventral setae: 1 a 21–22, 1 b 16–17, 1 c 16–17, 2 b 12–16, 2 c 13–15, 3 a 17–25, 3 b 16–17, 3 c 16–17, 4 a 18–20, 4 b 18–20, 4 c 17–19, ag 1 15–16, ag 2 14–15, ps 1 5, ps 2 3–4, ps 3 12–13. Gnathosoma ( Fig.11 ). Chelicerae, palps and shape of subcapitular setae as in female. Anterolateral parts of subcapitulum with one pair of large flanges ( Fig. 11 ). Length of subcapitular setae: m 18–23, n 17–19, or 1 12–13, or 2 11–14. Legs ( Figs. 12–15 ). Similar with that of female but tarsi I–IV with additional large finger-shaped male solenidion (ω ♂). Length of solenidia and setae k on legs I–IV: I— ω 25–29, ω ♂ 33–34, φ 5–6, φp 19–20, k 8–9; II— ω 15–16, ω ♂ 29–30, φ 16–17, k 5; III— ω 4, ω ♂29–30, φ 7–8; IV— ω 4, ω ♂ 23–28, φ 7–13.

Type material. Female holotype, slide № A 310514, RUSSIA: Tyumen Province, vicinities of lake Kuchak, 57 0 21’18” N, 66 0 03’01” E, from mosses Plagiomnium cuspidatum (Hedw.) T. Kop. (Mniaceae) and Brachythecium salebrosum (Web. et Mohr) B.S.G. ( Brachytheciaceae ), near water, 31 May 2014, coll. A.V. Tolstikov. Paratypes: 10 females, same data as holotype; 8 females, 2 males at same place, 14 June 2014, coll. A.A. Khaustov.

Etymology. The new species name refers to Tyumen, the city and the large region of Western Siberia where the mites were collected.

Differential diagnosis. The new species is most similar to E. frigida ( Habeeb, 1958) based on redescriptions provided by Gerson (1972b) and Fan & Zhang (2004) by the shape of the body, subequal dorsal setae situated on the protuberances, presence of two callosities, ventral position of the suranal plate. It differs from E. frigida by the lanceolate dorsal body setae without apical barbs (in E. frigida the dorsal body setae are truncate distally, with several distinct apical barbs), by the presence of two types (large and small) of dimples on the dorsal plate (dimples on the dorsal plates of E. frigida are large and uniform). It also differs by the presence of one seta on trochanter III (two in E. frigida ).

Figures

FIGURE 11. Eustigmaeus tjumeniensis Khaustov and Tolstikov sp. nov., male: — subcapitulum.

FIGURES 1 – 2. Eustigmaeus tjumeniensis Khaustov and Tolstikov sp. nov., female: 1 — idiosomal dorsum, 2 — idiosomal venter.

FIGURES 3 – 4. Eustigmaeus tjumeniensis Khaustov and Tolstikov sp. nov., female: 3 — gnathosoma dorsally, 4 — subcapitulum.

FIGURES 5 – 6. Eustigmaeus tjumeniensis Khaustov and Tolstikov sp. nov., female: 5 — leg I, 6 — leg II.

FIGURES 7 – 8. Eustigmaeus tjumeniensis Khaustov and Tolstikov sp. nov., female: 7 — leg III, – 8 — leg IV.

FIGURES 9 – 10. Eustigmaeus tjumeniensis Khaustov and Tolstikov sp. nov., male: 9 — idiosomal dorsum, 10 — idiosomal venter.

FIGURES 12 – 13. Eustigmaeus tjumeniensis Khaustov and Tolstikov sp. nov., male: 12 — leg I, 13 — leg II.

FIGURES 14 – 15. Eustigmaeus tjumeniensis Khaustov and Tolstikov sp. nov., male: 14 – leg III, 15 — leg IV.