Athyreacarus pusillus, Khaustov & Frolov, 2019

Khaustov, Alexander A. & Frolov, Andrey V., 2019, Revision of the genus Athyreacarus (Acari: Athyreacaridae), Zootaxa 4647 (1), pp. 168-225 : 199-202

Athyreacarus pusillus sp. nov.

( Figs 33–37 )

Description. Female ( Figs 33–37 ). Body fusiform. Length of idiosoma 230 (240, 270), width 125 (130, 155).

Gnathosoma . Gnathosomal capsule, excluding palps, almost oval, length 44 (42, 45), width 46 (45, 53). One pair of barbed, blunt-ended cheliceral setae cha 20 (20, 21). Postpalpal setae (pp) 5 (4, 5) needle-like. Subcapitular setae m 11 (10, 12) and n 22 (24, 25) pointed and weakly barbed. Setae dFe 12 (13) and dGe 22 (20, 21) barbed and blunt-ended. Tibiotarsus dorsomedially with well developed rodlike eupathid. Tibial claw small, slightly hooked.

Idiosomal dorsum ( Figs 33A , 36A , 37A, B ). All dorsal shields with numerous small sparsely distributed dimples ( Figs 37A, B ). Hysterosomal shields almost completely covering hysterosoma and only lateral margins with soft cuticle. Prodorsal shield without lateral projections, only alveoli of setae sc 1 present. All dorsal setae blunt-ended and barbed. Cupules ia on tergite D, im on tergite EF, and ih on tergite H small, round. Pore-like structures on tergites C, D, and EF not evident. Cupules ip on tergite EF not evident. Cupules ih located dorsally, anterolaterally to bases of setae h 1. Pseudanal segment much shorter than tergite H. Lengths of dorsal setae: v 1 45 (45, 47), v 2 24 (23, 24), sc 2 72 (80, 81), c 1 26 (26, 29), c 2 69 (73, 87), d 80 (81, 94), e 21 (12, 17), f 96 (100, 105), h 1 61 (66, 72), h 2 21 (20–21). Distances between setae: v 1 –v 1 13 (15, 17), v 2 –v 2 37 (39, 42), sc 1 –sc 1 42 (45, 47), sc 2 –sc 2 38 (37, 42), c 1 – c 1 42 (42, 47), c 1 – c 2 27 (26, 32), d–d 46 (46, 54), e–e 44 (41, 47), f–f 46 (47, 49), h 1 – h 1 32 (34, 35), h 1 – h 2 11 (11).

Idiosomal venter ( Figs 33B , 36B , 37C, D ). All ventral plates with numerous small dimples ( Figs 37C, D ), dimples on aggenital and midsternal plates arranged slightly more densely than on other plates. All ventral and caudal setae weakly barbed and blunt-ended, except pointed ps 3. Ap1 slightly thickened, ap5 long, reaching beyond bases of setae 4 a. Aggenital plate with two pairs of aggenital setae. Anal opening subterminal. Length of mid-sternal plate 46 (44, 46), width 46 (43, 44); ratio length/width 1.0–1.1. Lengths of ventral setae: 1 a 17 (15, 18), 1 b 10 (11), 1 c 16 (14), 2 a 20 (20, 21), 2 b 15 (16), 2 c 10 (10, 11), 3 a 14 (14, 15), 3 b 16 (16, 17), 3 c 16 (15, 16), 4 a 16 (15, 17), 4 b 18/22 (19, 20), 4 c 15 (13, 16), ag 1 15 (12, 16), ag 2 16 (14, 16), ps 1 40 (45, 46), ps 2 35 (33, 42), ps 3 21 (21, 22).

Legs ( Figs 34 , 35 ). Length of legs: I 90 (85, 90), II 72 (75, 77), III 90 (86, 90), IV 105 (105, 110). Leg I ( Fig. 34A ): setae v’ of trochanter, v’ of femur, k of tibia, and pv” of tarsus smooth, other leg setae (except eupathidia) weakly barbed; setae l’, v” of genu, d, l’, v” of tibia, (pl), s and pv’ of tarsus pointed, other leg setae blunt-ended; lengths of solenidia ω 1 12 (9, 12), ω 2 7 (8, 9), φ 1 9 (8, 11), φ 2 7 (6, 7); ω 1 and φ 1 digitiform, ω 2 and φ 2 clavate. Leg II ( Fig. 34B ): solenidion ω 11 (12, 13) digitiform, solenidion φ 5 (4, 5) clavate; all leg setae barbed; setae v’ of trochanter, d, v’, l’ of femur, v’, l’, l” of genu, l’ of tibia, (tc) and pl” of tarsus blunt-ended, other leg setae pointed. Leg III ( Fig. 35A ) similar in shape and length to leg II; solenidion φ 5 (4) clavate; all leg setae barbed; setae d, v ’, v ” of tibia pointed, other leg setae blunt-ended. Leg IV ( Fig. 35B ): solenidion φ 3 (4) clavate: all leg setae barbed; seta v” of tibia pointed, other leg setae blunt-ended.

Type material. Female holotype, slide No. 1738.1, BRASIL, Distrito Federal, Brasilia, III.2001, N. Degallier leg., on a beetle A. brasilicus . Paratypes: 2 females, same data.

Type deposition. The holotype is deposited in the collection of UNESP—Universidade Estadual Paulista, Department of Zoology and Botany, 15054—000 São José do Rio Preto—SP, Brazil ; two paratypes are deposited in the collection of the Tyumen State University Museum of Zoology , Tyumen, Russia .

Differential diagnosis. See differential diagnosis for A. vazdemelloi .

Etymology. The name of the new species derives from the Latin word “ pusillus ” meaning “ tiny ” and refers to the very small body size of females of this species.

Figures

FIGURE 33. Athyreacarus pusillus sp. nov., female: A—dorsum of body, B—venter of body.

FIGURE 34. Athyreacarus pusillus sp. nov., female: A—left leg I in dorsal view, B—left leg II in dorsal view.

FIGURE 35. Athyreacarus pusillus sp. nov., female: A—left leg III in dorsal view, B—left leg III in dorsal view.

FIGURE 36. Phase-contrast micrographs of Athyreacarus pusillus sp. nov., female: A—general aspect dorsally, B—general aspect ventrally.

FIGURE 37. Phase-contrast micrographs of Athyreacarus pusillus sp. nov., female: A—prodorsal shield, B—hysterosoma in dorsal view, C—anterior sternal plate, and coxal fields III, D—hysterosoma in ventral view.