Eustigmaeus extremiorientalis, 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 : 322-329

Eustigmaeus extremiorientalis n. sp.

( Figures 1-6 )

Description Female ( Figures 1-6 ) — Idiosoma almost round in outline. Length of idiosoma 340 (320 – 340), width 270 (270 – 280).

Idiosomal dorsum ( Figures 1A , 5A, B , 6A, B ) — Idiosoma completely covered by 2 large and well sclerotized plates. Plates with large round dimples ( Figures 1A , 5A , 6B ) and weak subcuticular reticulation. Dorsal setae situated on short protuberances, subequal, widened distally and strongly barbed ( Figures 5A, B ). Setae e 2 absent. Setae h 1 and h 2 situated ventrally. Setae h 2 only slightly thickened, not widened distally and weakly barbed. Lengths of dorsal setae: vi 42 (40 – 43), ve 50 (48 – 51), sci 38 (37 – 40), sce 31 (30 – 33), c 1 40 (39 – 41), c 2 28 (27 – 29), d 1 41 (40 – 43), d 2 35 (34 – 36), e 1 43 (42 – 44), f 1 46 (43 – 46), h 1 33 (31 – 34), h 2 19 (17 – 20).

Idiosomal venter ( Figures 1B , 5C , 6C, D ) — With 2 pairs of callosities between idiosomal plate and humeral plate. Anterior callosity slightly larger than posterior one ( Figure 5C ). Suranal plate situated ventrally, with distinct large dimples. Endopodal plates separated medially distinctly reticulated. Humeral plate subtriangular, with distinct large dimples. Most of ventral setae weakly barbed; with 2 pairs of simple subequal aggenital, and 3 pairs of simple pseudanal setae; setae ps 2 clearly shorter than subequal ps 1 and ps 3. Lengths of ventral setae: 1 a 23 (21 – 24), 1 b 22 (20 – 23), 1 c 16 (15 – 19), 2 b 16 (15 – 18), 2 c 17 (14 – 17), 3 a 20 (18 – 22), 3 b 16 (13 – 17), 3 c 16 (13 – 17), 4 a 19 (17 – 20), 4 b 17 (16 – 18), 4 c 15 (13 – 16), ag 1 16 (15 – 17), ag 2 18 (16 – 19), ps 1 14 (14 – 16), ps 2 11 (10 – 11), ps 3 16 (15 – 17).

Gnathosoma ( Figures 2 , 5B, D , 6E, F ) — Tibial claw well-developed. Setae l’ on palpal tibia very short, spine-like ( Figure 2B ). Setae d and l’ of palpal femur widened distally and strongly barbed; other palpal setae of femur, genu and tibia (except l’Ti) pointed and barbed; seta va of palp-tarsus weakly barbed; other setae of palp-tarsus 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) needlelike. Rostrum of subcapitulum ( Figure 2C ) short and wide. Subcapitular setae or 1 smooth, distinctly thickened, curved and blunt-ended; other subcapitular setae simple, pointed. Basal part of subcapitulum with numerous small dimples and weak subcuticular reticulation ( Figure 5D ). Length of subcapitular setae: m 19 (18 – 22), n 18 (17 – 21), or 1 12 (11 – 12), or 2 12 (11 – 12). Chelicerae dorsally with numerous small dimples ( Figure 5B ).

Legs ( Figures 3 , 4 ) — Empodial raylets capitate. Leg I ( Figure 3A ). Coxae I posterodorsally with needle-like leg supracoxal setae (el). 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), T a 13(1) (p’, p", tc’, tc", ft’, ft", u’, u", a’, a", pl’, pl", vs, ω). Setae (p) and (tc) of tarsus are eupathidia. Setae d, l’, l" of tibia, l’, l", d of genu, l" and d of femur distinctly thickened distally and strongly barbed, situated on protuberances. Seta k 8 (8 – 9). Solenidion ω short 15 (13 – 15), finger-shaped; solenidia Φ 8 (8 – 9) and Φp 11 (10 – 11) baculiform. Setae (ft), (pl) and vs of tarsus weakly barbed; (a), (u) smooth. Leg II ( Figure 3B ). Leg setation: 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 p’ and tc’ of tarsus represented by eupathidia. Setae d, l’ and l" of tibia, d, l’ and l" of genu, d and l" of femur distinctly thickened distally and strongly barbed, situated on protuberances. Solenidion ω 9 (9 – 10) finger-shaped; solenidion Φp 7 (7 – 8) baculiform. Seta k 6 (5 – 6). Setae tc" and vs of tarsus weakly barbed; (a), (u) and pl’ of tarsus smooth. Leg III ( Figure 4A ). 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 5 (4 – 5) baculiform; solenidion Φp 6 (5 – 6) baculiform. Setae d, l’ of tibia, d of genu, d and l’ of femur distinctly thickened distally and strongly barbed, situated on protuberances. Setae (u) of tarsus smooth, other tarsal setae weakly barbed. Leg IV ( Figure 4B ). 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 – 5) baculiform; solenidion Φp 6 (5 – 6) baculiform. Setae d, l’, l" of tibia, d of genu and femur distinctly thickened distally and strongly barbed, situated on protuberances. Setae (u) of tarsus smooth, other tarsal setae weakly barbed.

Male and immatures: unknown.

Type material — Female holotype, slide No ST181215, Russia: Primorskiy kray, Vladivostok , Botanical Garden-Institute , Far Eastern Branch of the Russian Academy of Sciences , 43°13’26.3"N, 131°59’34.6"E, from mosses on log, 18 December 2015, coll. S. Tupitsyn. Paratypes: 17 females, same data as holotype .

Etymology — The new species name refers to its distribution in the Far East of Russia.

Differential diagnosis — The new species is most similar to E. absens Do ˘gan, 2005, described from Turkey (Do ˘gan 2005), by the absence of setae e 2, presence of two callosities, only one seta on trochanter III and two pairs of aggenital setae. The new species differs from E. absens by distinctly thickened distally and strongly barbed dorsal idiosomal setae (vs. baculiform and weakly barbed in E. absens ) and by setae sci longer than sce (vs. sci about two times shorter than sce in E. absens ).

Figures

FIGURE 1: Eustigmaeus extremiorientalis n. sp., female: A – idiosomal dorsum, B – idiosomal venter.

FIGURE 2: Eustigmaeus extremiorientalis n. sp., female: A – gnathosoma dorsally, B – distal part of tibia and tarsus of palp, C – subcapitulum.

FIGURE 3: Eustigmaeus extremiorientalis n. sp., female: A – leg I, B – leg II.

FIGURE 4: Eustigmaeus extremiorientalis n. sp., female., female: A – leg III, B – leg IV.

FIGURE 5: Phase-contrast micrographs of Eustigmaeus extremiorientalis n. sp., female: A – central part of prodorsum, B – anterior part of prodorsum and chelicerae, C – humeral plate and callosities, D – subcapitulum.

FIGURE 6: SEM photos of Eustigmaeus extremiorientalis n. sp., female: A – dorsal view of body, B – prodorsum, C – ventral view of body, D – ano-genital area, E – gnathosoma ventrally, F – palp laterally.