Athyreacarus primitivus sp. nov.

(Figures 1–6)

Description. Female (Figures 1–6). Body well sclerotized. Length of idiosoma 320 (315–330), width 200 (185– 205). Gnathosoma (Figures 1, 5 C, D). Gnathosomal capsule, excluding palps, almost oval, its length 53 (50–55), width 57 (52–57). Dorsally with two pairs of barbed, blunt-ended cheliceral setae (cha, chb). Setae cha 29 (26–29) longer than chb 22 (19–22). Dorsal median apodeme well developed. Postpalpal setae (pp) needle-like, situated laterally to setae cha. Gnathosomal venter with two pairs of smooth, pointed subcapitular setae m 15 (13–16) and n 48 (42–49) (Figure 5 C). Palps freely articulated to gnathosomal capsule, with weakly barbed setae dFe and dGe dorsolaterally, setae dGe pointed, more than twice longer than blunt-ended dFe. Tibiotarsus dorsomedially with tiny rodlike eupathidion. Palps ventrally with small accessory setigenous structure (ass) medially and fusiform solenidion laterally. Palps terminated with well-developed tibial claw. Cheliceral stylets strong, curved (Figure 5 D). Pharynx divided into four subequal transversely striated pharyngeal pumps situated close to each other (php) inside gnathosomal capsule (Figure 5 D).

Idiosomal dorsum (Figures 1 A, 4A, C, F, 5A). All dorsal shields with numerous dimples (Figures 4 F, 5A). Prodorsal shield with three pairs of setae (v 1, v 2, sc 2), one pair of round pits (sc 1) and one pair of round stigmata (Figure 4 F). Stigmata associated with long tracheal trunks. Posterior part of prodorsal shield covers anterior part of tergite C. Setae v 2 smooth, needle-like; setae v 1 and sc 2 pointed, barbed. Tergite C divided into three parts; median with well-developed setae c 1 and lateral parts with setae c 2. Cupules ia on tergite D, im, ip on tergite EF and ih on tergite H small, round (Figure 5 A). All dorsal hysterosomal setae barbed. Setae c 1, e and h 2 blunt-ended, other dorsal hysterosomal setae pointed. Lengths of dorsal setae: v 1 42 (42–49), v 2 12 (10–13), sc 2 85 (84–65), c 1 28 (27– 31), c 2 94 (94–110), d 93 (92–94), e 17 (17–19), f 95 (95–99), h 1 97 (92–98), h 2 27 (27–30). Distances between setae: v 1 –v 1 36 (33–36), v 2 –v 2 62 (60–62), sc 1 –sc 1 73 (71–74), sc 2 –sc 2 72 (67–72), c 1– c 1 60 (56–66), c 1– c 2 46 (45– 46), d–d 71 (68–72), e–e 75 (72–76), f–f 77 (73–78), h 1– h 1 44 (39–46), h 1– h 2 14 (13–14).

Idiosomal venter (Figures 1 B, 4B, D, E, 5B). All ventral plates with numerous dimples. Setae 1 b, 1 c, 2 b, 2 c, 3 c, 4 c and ag 1 needle-like; setae 3 a blunt-ended; other ventral setae pointed. Setae 4 a, 4 b and ag 1-3 smooth, other ventral setae weakly barbed. Apodemes 1 (ap1) very thick and joined with prosternal apodeme (appr); apodemes 2 (ap2) well developed and joined with appr, sejugal (apsej) apodeme well developed only in lateral parts; apodemes 3 (ap3), apodemes 4 (ap4) and apodemes 5 well developed. Setae 4 b situated on midsternal plate. Aggenital plate with three pairs of aggenital setae. Pseudanal segment with three pairs of setae; setae ps 3 situated on dorsal side of segment, ps 1, 2 on ventral. Lengths of ventral setae: 1 a 32 (28–33), 1 b 10 (10–11), 1 c 15 (13–15), 2 a 42 (37–43), 2 b 20 (17–20), 2 c 11 (8–11), 3 a 12 (12–13), 3 b 36 (33–37), 3 c 13 (13–14), 4 a 14 (14–16), 4 b 34 (26–34), 4 c 13 (13– 14), ag 1 19 (19–20), ag 2 33 (32–39), ag 3 49 (43–50), ps 1 39 (28–39), ps 2 83 (69–83), ps 3 78 (65–78).

Legs (Figures 2, 3, 5 E, F, 6). Tarsi II-IV with longitudinal subcuticular canal ventrally clearly visible in compound microscope (Figure 5 F), but invisible in SEM (Figure 6 A). Leg I (Figure 2 A, 5E, 6B) slightly longer and thicker than leg II. Setal formula: 1–5–5–6(2) –13(2). Tarsus with massive claw (Figure 6 B). Setae u’ and u” separated and modified; spine-like (Figure 5 E). Setae v’ of femur, d, v’, l” of genu, v’ and k of tibia blunt-ended; other leg setae (except eupathidia) pointed. Setae v’ of trochanter, v’, l’, l” of femur, d, k of tibia smooth; other leg setae (except eupathidia) weakly barbed. Lengths of solenidia ω 1 12 (11–12)> ω 2 8 (7–8) <φ 1 12 (12)> φ 2 8 (7–8); ω 1 and φ 1 finger-shaped, ω 2 and φ 2 baculiform. Leg II (Figures 2 B, 6A). Setal formula: 1–3–3–4(1)–7(1). Tarsal claws thick, with massive basal protuberance (Figure 6 A); empodium very large. Solenidion ω 12 (10–12), fingershaped, solenidion φ 9 (8–9) baculiform. All leg setae weakly barbed; seta l’ of femur blunt-ended; other leg setae pointed. Leg III (Figure 3 A, 5F) similar in shape and length to leg II. Setal formula: 1–2–3–4(1)–7. Claws and empodium of same shape as on tarsus II. Solenidion φ 9 (8–9) baculiform. All leg setae weakly barbed; setae v’ of femur and l” of genu blunt-ended; other leg setae pointed. Femur divided into basi- and telofemur. Leg IV (Figure 3 B) longer than leg III. Setal formula: 1–2–2–4(1)–7. Tarsal claws without large basal protuberance. Solenidion φ 9 (8–9) baculiform. All leg setae weakly barbed; setae v’ of femur, l” of genu and p’ of tarsus blunt-ended; other leg setae pointed. Femur divided into basi- and telofemur.

Male and immatures unknown.

Type material. Female holotype, slide No. 10720, Brazil, Mato Grosso, Cuiabá municipality, October 2016, A. Frolov leg., on a beetle Bolbapium howdeni Martínez. The mites were attached to the membrane connecting hind coxae and abdomen; paratypes: 12 females, same data.

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

Differential diagnosis. The new species differs considerably from A. pleiotretus Lindquist, Kaliszewski and Rack, 1990, described from Honduras (Lindquist, Kaliszewski & Rack 1990) by the presence of two pairs of cheliceral setae (vs. one in A. pleiotretus), presence of well-developed setae v 2 and c 1 (vs. vestigial and absent, respectively, in A. pleiotretus), presence of three pairs of aggenital setae (vs. two in A. pleiotretus), and unmodified tectal setae on tarsi II and III (vs. spatulate in A. pleiotretus).

Etymology. The name of the new species is referring to the presence of many primitive morphological characters.