Stigmaeus flexisetus, Khaustov, 2016

Khaustov, A. A., 2016, New species and records of mites of the family Stigmaeidae (Acari: Prostigmata) collected from mosses in Southern Chile, Acarologia 56 (4), pp. 639-679 : 657-664

Stigmaeus flexisetus n. sp.

( Figures 16-22 )

Description

Female ( Figures 16-19 , 22 ) — Length of idiosoma 405 (335), width 260 (285) (two females measured).

Idiosomal dorsum ( Figures 16A , 22A, B, D ) — Idiosoma oval, soft, mostly covered by smooth dorsal plates. Eyes present. Propodosomal plate with setae vi, ve and sci; setae sce situated on separate platelets. Postocular bodies large, weakly defined. Striae anteriorly to propodosomal plate without microtubercles. All dorsal setae pointed; setae f 1, h 1 and h 2 weakly barbed in basal half, other dorsal setae smooth. Setae ve, sce, c 2, d 1, d 2, e 1, e 2, f 1, h 1 and h 2 very long and flexible. Ratio ve/sci = 6,2. Setae e 1 situated on platelets separated from central hysterosomal plate ( Figures 22A, B, D ); in female holotype right seta e 1 situated on platelet, which partly fused to central hysterosomal plate ( Figure 22D ). Suranal plate not divided, with two pairs of setae. Setae d 2, e 2, and f 1 situated on separate plates. Lengths of dorsal setae: vi 67 (100), ve 180 (190), sci 29 (27), sce 150 (160), c 1 76 (90), c 2 130 (140), d 1 120 (140), d 2 145 (165), e 1 115 (135), e 2 160 (175), f 1 100 (160), h 1 100 (125), h 2 90 (110).

Idiosomal venter ( Figure 16B ) — Ventral setae smooth or weakly barbed, pointed. Three pairs of aggenital setae situated on single plate. One pair of genital setae. Endopodal plates without subcuticular reticulation. Lengths of ventral setae: 1 a 35 (47), 1 b 36 (35), 1 c 57 (60), 2 b 57 (56), 2 c 38 (34), 3 a 42 (43), 3 b 33 (31), 3 c 33 (31), 4 a 49 (45), 4 b 33 (36), 4 c 32 (31), ag 1 37 (43), ag 2 35 (41), ag 3 42 (43), g 36 (34), ps 1 70 (80), ps 2 39 (45), ps 3 36 (41).

Gnathosoma ( Figure 17 ) — Tibial claw large. Setae l’ of palpal tibia thin, seta-like. All palpal setae pointed; setae of femur and genu weakly barbed; seta va of palptarsus weakly barbed; other setae of palptarsus 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 (ep) with thickened basal part and thin distal one. Chelicerae dorsally smooth. Rostrum of subcapitulum long. Subcapitular setae pointed, smooth. Basal part of subcapitulum without reticulation ( Figure 22C ). Lengths of subcapitular setae: m 46 (53), n 32 (29), or 1 27 (24), or 2 30 (33).

Legs ( Figures 18 – 19 ) — Empodial raylets weakly capitate. Leg segments without reticulation. Leg I ( Figure 18A ). Coxae I posterodorsally with supracoxal setae (el) thickened basally and thin in distal half. Leg setation: 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 of tibia, (p), (tc) and (ft) of tarsus are eupathidia. Seta k 6 (10) needle-like. Solenidion ω 16 (21), finger-shaped; solenidion φp 30 (33) attenuate. solenidion φ 11 (13) baculiform. All setae of tarsus (except eupathidia) weakly barbed. Leg II ( Figure 18B ). Leg setation: Tr 1 (v’), Fe 5 (d, l’, l", v’, bv"), Ge 3 (l’, l", k), Ti 5(1) (d, l’, l", v’, v", φp), Ta 9(1) (p’, tc’, tc", u’, u", a’, a", pl’, vs, ω). Setae p’ and tc’ of tarsus are eupathidia. Solenidion ω 12 (16) fingershaped; solenidion φp 27 (31) attenuate. Setae d of tibia and femur long and smooth. All setae of tarsus (except eupathidia) weakly barbed. Leg III ( Figure 19A ). Leg setation: Tr 2 (l’, v’), Fe 3 (d, l’, ev’), Ge 0, Ti 5(1) (d, l’, l", v’, v", φp), Ta 7(1) (tc’, tc", u’, u", a’, a", vs, ω). Solenidion ω 7 (9) baculiform; solenidion φp 23 (24) attenuate. Setae d of tibia long and smooth. Seta (a) and vs of tarsus weakly barbed, other tarsal setae smooth. Leg IV ( Figure 19B ). Leg setation: Tr 1 (v’), Fe 2 (d, ev’), Ge 1 (d), Ti 5(1) (d, l’, l", v’, v", φp), Ta 7(1) (tc’, tc", u’, u", a’, a", vs, ω). Sometimes seta d of genu IV absent. Solenidion ω 8 (8) baculiform; solenidion φp 22 (23) attenuate. Setae d of tibia long and smooth. Setae (tc) of tarsus smooth, other tarsal setae weakly barbed.

Male ( Figures 20 , 21 ) — Similar with female, but smaller. Length of idiosoma 345, width 235.

Idiosomal dorsum ( Figure 20A ) — Central hysterosomal plate with three pairs of setae. Lengths of dorsal setae: vi 62, ve 165, sci 25, sce 125, c 1 62, c 2 120, d 1 76, d 2 130, e 1 76, e 2 125, f 1 135, h 1 51, h 2 97. Setae ps 1-3 situated dorsally; ps 1-2 short, spine-like.

Idiosomal venter ( Figure 20B ) — Aggenital setae situated on single plate. Only one right seta ag 1 present in a single available specimen. Lengths of ventral setae: 1 a 35, 1 b 36, 1 c 55, 2 b 45, 2 c 36, 3 a 35, 3 b 29, 3 c 24, 4 a 43, 4 b 28, 4 c 27, ag 1 34, ag 2 32, ag 3 39, ps 1 6, ps 2 8, ps 3 25. Aedeagus weakly sclerotized, difficult to discern.

Legs ( Figure 21 ) — Leg setation as in female, except presence of large male solenidia ω ♂ on tarsi I – IV.

Immatures unknown.

Type material — Female holotype, slide N° AK231015, Chile, Patagonia, vicinity of Punta Arenas, 53°38’028"S, 70°57’017"W, 23 October 2015, in Sphagnum magellanicum on swamp, coll. A.A. Khaustov. Paratypes: 1 female, same data ; 1 male, same place, 13. November 2014, coll. V. A. Stolbov .

Etymology — The name of the new species is derived from Latin words flexus meaning to bend and seta and refers to thin and flexible dorsal setae.

Differential diagnosis — The new species is most similar to S. ayyildizi Dönel and Do ˘gan, 2011, described from Turkey (Dönel and Do ˘gan 2011), by smooth dorsal plates, three pairs of aggenital setae situated on single plate, presence of eyes. However, it differs from the latter by much longer dorsal body setae, absence of seta d on genu III (vs. present in S. ayyildizi ), presence of five setae on femur II (vs. four in S. ayyildizi ), absence of seta d on genu II (vs. present in S. ayyildizi ).

Figures

FIGURE 16: Stigmaeus flexisetus n. sp., female: A – idiosomal dorsum, B – idiosomal venter.

FIGURE 17: Stigmaeus flexisetus n. sp., female: A – gnathosoma dorsally, B – subcapitulum.

FIGURE 18: Stigmaeus flexisetus n. sp., female: A – leg I, B – leg II.

FIGURE 19: Stigmaeus flexisetus n. sp., female: A – leg III, B – leg IV.

FIGURE 20: Stigmaeus flexisetus n. sp., male: A – opisthosomal dorsum, B – opisthosomal venter.

FIGURE 21: Stigmaeus flexisetus n. sp., male: A-D – solenidia on tarsi I-IV, respectively.

FIGURE 22: Phase-contrast micrographs of Stigmaeus flexisetus n. sp., female: A – hysterosomal dorsum of holotype, B – hysterosomal dorsum of paratype, C – subcapitulum, D – setae e1 of holotype.