Stigmaeus mollibus, Khaustov, 2016

Khaustov, A. A., 2016, Two new species and a new record of mites of the family Stigmaeidae (Acari: Prostigmata) collected from mosses in Russia, Acarologia 56 (3), pp. 321-339 : 329-337

publication ID	https://doi.org/ 10.1051/acarologia/20162249
persistent identifier	https://treatment.plazi.org/id/474687CD-FFCA-FF90-7454-FA262BA1EA96
treatment provided by	Marcus
scientific name	Stigmaeus mollibus
status	sp. nov.

Treatment

Stigmaeus mollibus n. sp.

( Figures 7-15 View FIGURE View FIGURE )

Description Female (Figsures 7-10, 15) — Length of idiosoma 350 (350 – 390), width 175 (175 – 230).

Idiosomal dorsum ( Figures 7A View FIGURE , 15A, C, D View FIGURE ) — 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. Area anteriorly and anterolaterally to propodosomal plate with numerous microtubercles. Setae ve, c 2, and h 3 pointed, sparsely barbed. Other dorsal setae distinctly blunt-ended and barbed. Setae c 2 situated ventrally. Ratio ve/sci = 3.3. Suranal plate divided, with three pairs of setae. Setae e 1 and f 1 situated on platelets ( Figure 15D View FIGURE ), remaining surface of hysterosoma without plates. Lengths of dorsal setae: vi 11 (11 – 14), ve 43 (43 – 45), sci 13 (13 – 15), sce 16 (15 – 16), c 1 12 (12 – 15), c 2 45 (45 – 53), d 1 11 (11 – 12), d 2 10 (10 – 11), e 1 12 (11 – 13), e 2 10 (10 – 12), f 1 16 (16 – 17), h 1 16 (16 – 18), h 2 31 (27 – 31), h 3 18 (18 – 23).

Idiosomal venter ( Figures 7B View FIGURE , 15B View FIGURE ) — Ventral setae weakly barbed and pointed, except for ps 1 - ps 3 which are barbed and blunt-ended. Four pairs of aggenital setae; ag 1 situated on separate small platelets; 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. Lengths of ventral setae: 1 a 22 (22 – 24), 1 b 20 (20 – 22), 1 c 29 (26 – 30), 2 b 50 (47 – 54), 2 c 27 (27 – 34), 3 a 25 (25 – 29), 3 b 20 (17 – 20), 3 c 17 (17 – 19), 4 a 20 (20 – 24), 4 b 14 (14 – 15), 4 c 12 (12 – 14), ag 1 18 (18 – 20), ag 2 18 (18 – 19), ag 3 20 (20 – 23), ag 4 22 (22 – 24), g 1 19 (19 – 20), g 2 22 (22 – 24), ps 1 20 (19 – 21), ps 2 23 (19 – 23), ps 3 15 (15 – 17).

Gnathosoma ( Figure 8 View FIGURE ) — Tibial claw large. Setae l’ of palpal tibia thin, seta-like ( Figure 8A View FIGURE ). 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 1 (d), 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. Rostrum of subcapitulum ( Fig. 8B View FIGURE ) relatively long, with lateral lobes. Subcapitular setae pointed; n weakly barbed in basal part, other setae smooth. Basal part of subcapitulum without reticulation. Lengths of subcapitular setae: m 20 (20 – 22), n 63 (60 – 65), or 1 10 (10 – 11), or 2 11 (11 – 12).

Legs ( Figures 9-10) — Empodial raylets capitate. Leg segments without reticulation. Leg I ( Figure 9A). 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 6 (d, l’, l", v’, 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 and (p), (tc) and ft’ of tarsus are eupathidia. Seta k 6 (6 – 7). Solenidion ω short 12 (11 – 12), fingershaped; solenidion Φp 15 (14 – 15) uniformly thin. solenidion Φ absent. Setae ft", (pl) and vs of tarsus weakly barbed; (u) and (a) smooth. Leg II ( Figure 9B). Leg setation: Tr 1 (v’), Fe 4 (d, l’, l", bv"), Ge 2 (l’, l"), Ti 5(1) (d, l’, l", v’, v", Φp), Ta 8(1) (tc’, tc", u’, u", a’, a", pl’, vs, ω). Setae p’ of tarsus absent. Solenidion ω 9 (8 – 9) finger-shaped; solenidion Φp 10 (10 – 11) uniformly thin. All tarsal setae smooth. Setae d of tibia and tc’ of tarsus very long and smooth. Leg III ( Figure 10A View FIGURE ). Leg setation: Tr 2 (v’, l’), 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 5 (5 – 6) baculiform; solenidion Φp 9 (9 – 10) uniformly thin. Setae d of tibia and (tc) of tarsus very long and smooth. Leg IV ( Figure 10B View FIGURE ). 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). Solenidion ω 5 (4 – 5) baculiform; solenidion Φp 9 (9 – 11) uniformly thin. Setae d of tibia and (ts) of tarsus extra-long and smooth.

Male ( Figure 11 View FIGURE ) — Similar with female, but smaller and with more narrow posterior end of the body. Length of idiosoma 290, width 155. Idiosomal dorsum ( Figure 11A View FIGURE ) — As in female, except absence of setae h 3. Lengths of dorsal setae: vi 9, ve 38, sci 10, sce 13, c 1 11, c 2 37, d 1 10, d 2 10, e 1 11, e 2 10, f 1 16, h 1 17, h 2 23.

Idiosomal venter ( Figure 11B View FIGURE ) — Podosoma as in female. Opisthosomal venter with three pairs of aggenital setae situated on longitudinal platelets. Pseudanal setae ps 1-2 spine-like, smooth, ps 3 bluntended and weakly barbed. Penis short, thin, weakly sclerotized. Legs ( Figures 12-13 View FIGURE View FIGURE ) — Leg setation as in female, except presence of large male solenidia ω ♂ on tarsi I-IV.

Deutonymph ( Figure 14 View FIGURE ) — In general similar with female, but little smaller. Length of idiosoma 335, width 175.

Idiosomal dorsum ( Figure 14A View FIGURE ) — As in female, except absence of setae h 3 and undivided suranal plate. Lengths of dorsal setae: vi 12, ve 45, sci 11, sce 18, c 1 15, c 2 45, d 1 9, d 2 11, e 1 10, e 2 9, f 1 17, h 1 18, h 2 24.

Idiosomal venter ( Figure 14B View FIGURE ) — Podosoma as in female. Opisthosomal venter with three pairs of aggenital setae; setae ag 3 situated on small platelets.

Legs ( Figure 12-13 View FIGURE View FIGURE ) — Leg setation as in female, except absence of setae on trochanter and genu IV.

Type material — Female holotype, slide No AK040415, Russia, Tyumen Province, Tyumen Province, vicinities of lake Kuchak , 57°20’05.3"N 66°03’08.9"E, 4 April 2015, moss on soil, coll. A.A. Khaustov. Paratypes: 9 females, 1 male, 1 deutonymph, same data GoogleMaps .

Etymology — The name of the new species is derived from Latin word mollibus meaning soft and refers to soft and weakly sclerotized body.

Differential diagnosis — The new species is most similar to S. shendabadiensis Haddad, Akbari and Lotfollahi, 2010 , described from Iran ( Haddad et al. 2010), by soft and finely striated body, divided suranal plate with three pairs of setae and similar leg setation. However, it differs from the latter by absence of seta l" of palpgenu (vs. present in S. shendabadiensis ), absence of solenidion Φ of tibia I (vs. present in S. shendabadiensis ), setae d 2 and e 2 situated on striated cuticle (vs. d 2 and e 2 situated on platelets in S. shendabadiensis ).

Stigmaeus mimus Summers, 1962 Stigmaeus mimus, Summers 1962, p. 511 , figs. 19-20.

Material examined — Seven females, Russia, Leningrad Province, vicinity of Sestroretsk station, Sestroretsk swamp, in wet moss Sphagnum magellanicum Brid. (Bryophyta: Sphagnaceae ), 28 June 2015, 60°07’22,8"N, 30°02’36,9"E, coll. D.A. Filippov.

Remarks — This species was described in the U.S.A. (Arizona) from litter under Juglans rupestris ( Summers 1962) . It was also recorded from litter in Latvia ( Kuznetsov and Petrov 1984). This is a new record for the fauna of Russia.