Stigmaeus palustris, 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 : 651-653

Stigmaeus palustris n. sp.

( Figures 11-15 )

Description

Female ( Figures 11-15 ) — Length of idiosoma 505 (535), width 280 (330) (Two females measured).

Idiosomal dorsum ( Figures 11A , 15B, C ) — Idiosoma fusiform, soft, mostly striated. Eyes absent. Propodosomal plate with setae vi and ve, weakly defined by more narrow striae than outside ones; with distinct median propodosomal apodeme and tiny dimples ( Figure 15B ). Area anteriorly and anterolaterally to propodosomal plate with numerous microtubercles. All dorsal setae smooth; setae ve and c 2 long, pointed; other dorsal setae short, bluntended. Setae c 2 situated laterally. Ratio ve/sci = 4. Suranal plate divided, with two pairs of setae. Setae e 2 and f 1 situated on platelets, remaining surface of hysterosoma without plates. Lengths of dorsal setae: vi 29 (32), ve 105 (100), sci 26 (36), sce 33 (32), c 1 24 (21), c 2 110 (120), d 1 22 (22), d 2 22 (22), e 1 23 (21), e 2 23 (24), f 1 34 (31), h 1 33 (33), h 2 36 (33).

Idiosomal venter ( Figure 11B ) — Ventral setae smooth and pointed, four pairs of aggenital setae; ag 1 situated on soft cuticle; ag 2 – ag 4 on weakly defined platelet. Two pairs of genital setae. Cuticle posteriad to gnathosomal base and posterolaterad to coxae IV with microtubercles. Endopodal plates weakly developed. Coxal fields with small dimples. Lengths of ventral setae: 1 a 40 (42), 1 b 30 (29), 1 c 87 (92), 2 b 150 (160), 2 c 42 (44), 3 a 44 (43), 3 b 36 (37), 3 c 24 (26), 4 a 100 (105), 4 b 28 (30), 4 c 24 (23), ag 1 26 (27), ag 2 22 (22), ag 3 26 (27), ag 4 39 (38), g 1 26 (28), g 2 50 (50), ps 1 49 (45), ps 2 42 (41), ps 3 28 (26).

Gnathosoma ( Figures 12 , 15A, D ) — Tibial claw large. Setae l’ of palpal tibia thin, seta-like. All palpal setae pointed; setae of femur and genu weakly barbed. 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) small, thick, with distinctly rounded tip. Chelicerae dorsally with numerous dimples ( Figure 15A ). Rostrum of subcapitulum long. Subcapitular setae pointed and smooth. Basal part of subcapitulum without reticulation ( Figure 15D ). Lengths of subcapitular setae: m 34 (35), n 37 (38), or 1 19 (20), or 2 16 (16).

Legs ( Figures 13 , 14 ) — Empodial raylets distinctly capitate. Leg segments without reticulation. Leg I ( Figure 13A ). Coxae I posterodorsally with small, thick, with distinctly rounded tip leg supracoxal setae (el). Leg setation: Tr 1 (v’), Fe 4 (d, l’, l", bv"), Ge 5 (d, l’, l", v’, k), Ti 5(1) (d, l’, l", v’, v", φp), Ta 13(1) (p’, p", tc’, tc", ft ’, ft", u’, u", a’, a", pl’, pl", vs, ω). Setae d of tibia, (p) and (tc) of tarsus are eupathidia. Seta k 8 (9) needle-like. Solenidion ω short 11 (10), finger-shaped; solenidion φp 23 (18) attenuate. solenidion φ absent. Setae (ft), (pl), (a) and vs of tarsus weakly barbed; (u) smooth. Leg II ( Figure 13B ). Leg setation: Tr 1 (v’), Fe 4 (d, l’, l", bv"), Ge 1 (l’), Ti 5(1) (d, l’, l", v’, v", φp), Ta 8(1) (tc’, tc", u’, u", a’, a", vs, pl’, ω). Seta p’ of tarsus absent. Solenidion ω 9 (9) finger-shaped; solenidion φp 16 (15) attenuate. Seta pl’ weakly barbed, other tarsal setae smooth. Setae d of tibia and (tc) of tarsus very long and smooth. Leg III ( Figure 14A ). Leg setation: Tr 1 (v’), Fe 2 (d, 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 6 (6) baculiform; solenidion φp 17 (18) attenuate. Setae d of tibia and (tc) of tarsus very long and smooth. Seta v’ of trochanter weakly barbed, other leg setae smooth. Leg IV ( Figure 14B ). Leg setation: Tr 1 (v’), Fe 2 (d, ev’), Ge 0, Ti 5(1) (d, l’, l", v’, v", φp), Ta 7 (tc’, tc", u’, u", a’, a", vs). Solenidion ω absent; solenidion φp 17 (16) attenuate. Setae d of tibia and (tc) of tarsus very long and smooth. Setae v" of tibia and v’ of trochanter weakly barbed, other leg setae smooth.

Male and immatures unknown.

Type material — Female holotype, slide N° VS171114, Chile, Patagonia, vicinity of Punta Arenas, 53°38’028"S, 70°57’017"W, 17 November 2014, Sphagnum magellanicum in swamp, coll. V. A. Stolbov. Paratypes: 1 female, same data .

Etymology — The name of the new species is derived from Latin word palustris meaning swamp and refers to a habitat of the new species.

Differential diagnosis — The new species is most similar to S. arboricola Wood, 1981 , described from New Zealand ( Fan and Zhang 2005), by soft and finely striated body, divided suranal plate and similar leg setation. However, it differs from the latter by the absence of seta h 3 (vs. present in S. arboricola ), absence of seta l’ of femur III (vs. present in S. arboricola ), absence of solenidion ω of tarsus IV (vs. present in S. arboricola ).

Figures

FIGURE 11: Stigmaeus palustris n. sp., female: A – idiosomal dorsum, B – idiosomal venter.

FIGURE 12: Stigmaeus palustris n. sp., female: A – gnathosoma dorsally, B – subcapitulum.

FIGURE 13: Stigmaeus palustris n. sp., female: A – leg I, B – leg II.

FIGURE 14: Stigmaeus palustris n. sp., female: A – leg III, B – leg IV.

FIGURE 15: DIC micrographs of Stigmaeus palustris n. sp., female: A – gnathosoma dorsally, B – prodorsum, C – opisthosoma dorsally, D – gnathosoma ventrally.