Athyreacarus angustus, Khaustov & Frolov, 2019

Khaustov, Alexander A. & Frolov, Andrey V., 2019, Revision of the genus Athyreacarus (Acari: Athyreacaridae), Zootaxa 4647 (1), pp. 168-225 : 208-211

Athyreacarus angustus sp. nov.

( Figs 43–48 )

Description. Female ( Figs 43–48 ). Body fusiform. Length of idiosoma 305 (270–345), width 160 (145–175).

Gnathosoma ( Figs 48 A–C). Gnathosomal capsule, excluding palps, almost triangular in outline, length 49 (42– 50), width 46 (40–46). Two pairs of barbed, blunt-ended cheliceral setae cha 28 (27–30) and chb 22 (20–22) ( Fig. 48A ). Postpalpal setae (pp) 5 (5–7) needle-like, with few weak lateral projections ( Fig. 48B ). Setae m 16 (13–17) and n 49 (40–50) pointed; setae m smooth, n weakly barbed. Setae dFe 13 (13–16) and dGe 25 (22–29) barbed; dFe blunt-ended, dGe pointed. Tibial claw with split tip ( Fig. 48C ).

Idiosomal dorsum ( Figs 43A , 46A , 47A, B ). All dorsal shields with numerous small sparsely distributed dimples ( Figs 47A, B ). Hysterosomal shields D and EF narrow, not covering lateral surfaces of hysterosoma. Prodorsal shield with distinct lateral projections. Setae sc 1 well developed. Setae sc 2, c 1, c 2, and d smooth or with 1–2 barbs, other dorsal setae barbed. Setae v 2, sc 1, e and h 2 blunt-ended, other dorsal setae pointed. Cupules and pore-like structures on hysterosomal tergites C, D and EF not evident. Cupules ih present, round, located anterolaterally to bases of setae h 1. Pseudanal segment much shorter than tergite H. Lengths of dorsal setae: v 1 52 (48–53), v 2 21 (17–23), sc 1 6 (6–7), sc 2 130 (115–135), c 1 90 (77–91), c 2 120 (105–140), d 115 (110–130), e 28 (22–35), f 120 (110–130), h 1 82 (73–90), h 2 43 (31–44). Distances between setae: v 1 – v 1 20 (19–21), v 2 –v 2 50 (44–53), sc 1 –sc 1 60 (57–66), sc 2 –sc 2 43 (37–46), c 1 – c 1 53 (44–58), c 1 – c 2 29 (27–40), d–d 57 (48–58), e–e 53 (47–56), f–f 54 (44–63), h 1 – h 1 34 (27–39), h 1 – h 2 16 (13–17).

Idiosomal venter ( Figs 43B , 46B , 47C, D ). All ventral plates with numerous small dimples ( Fig. 47C, D ). All ventral setae weakly barbed. Setae 1 b, 1 c, 2 b, 2 c, 3 a, 3 c, 4 c, ag 1, ps 2 and ps 3 blunt-ended, other ventral setae pointed. Ap1 thin, almost as wide as ap2, ap5 long, reaching beyond bases of setae 4 a. Aggenital plate with three pairs of aggenital setae. Anal opening terminal. Length of mid-sternal plate 47 (46–56), width 28 (27–34); ratio length/width 1.5–1.7. Lengths of ventral setae: 1 a 31 (28–33), 1 b 15 (11–16), 1 c 12 (11–13), 2 a 41 (35–42), 2 b 12/16 (13–16), 2 c 13 (11–14), 3 a 17 (13–18), 3 b 35 (26–41), 3 c 15 (14–17), 4 a 22/28 (17–29), 4 b 31 (26–38), 4 c 20 (15–20), ag 1 24 (21–34), ag 2 52 (33–53), ag 3 48 (35–51), ps 1 51 (43–52), ps 2 56 (44–57), ps 3 34 (31–37).

Legs ( Figs 44 , 45 , 48D ). Length of legs: I 110 (95–115), II 93 (81–110), III 110 (97–125), IV 135 (115–155). Leg I ( Fig. 44A ) narrow, almost as thick as leg II; setae v’ of trochanter, v’ of femur, k of tibia, pl’, s, and pv” of tarsus smooth, other leg setae (except eupathidia) weakly barbed; setae v’ of trochanter, v’ of femur, and k of tibia blunt-ended, other leg setae pointed; lengths of solenidia ω 1 13 (12–14), ω 2 12 (11–14), φ 1 13 (12–13), φ 2 10 (8–10); ω 1 digitiform, ω 2, φ 1 and φ 2 baculiform. Leg II ( Fig. 44B ): solenidion ω 14 (13–15) digitiform, solenidion φ 12 (11–13) baculiform; all leg setae barbed; setae v’ of trochanter and l’ of femur blunt-ended, other leg setae pointed. Leg III ( Fig. 45A ) similar in shape and length to leg II; solenidion φ 12 (11–12) baculiform; all leg setae barbed; setae v’ of trochanter and v’ of femur blunt-ended, other leg setae pointed. Leg IV ( Figs 45B , 48D ): solenidion φ 12 (11–12) baculiform; all leg setae barbed; setae v’ of trochanter, v’ of femur, and p’ of tarsus blunt-ended, other leg setae pointed; solenidia on tibiae II–IV unusually long and thin ( Fig. 48D ).

Type material. Female holotype, slide No. ZISP T-Ath-003, UNITED STATES OF AMERICA, Kaweah , California, 15.IV, on a beetle Bolbelasmus horni (Rivers) . Paratype: 8 females, same data .

Type deposition. The holotype and two paratypes are deposited in the collection of the Zoological Institute of RAS, Saint Petersburg, Russia; two paratypes are deposited in the collection of the University of Michigan Museum of Zoology, Ann Arbor, USA ; other paratypes are deposited in the collection of the Tyumen State University Museum of Zoology , Tyumen, Russia .

Differential diagnosis. The new species is most similar to A. ovalis by the presence of two pairs of cheliceral setae, absence of cupules and pore-like structures on hysterosomal tergites C, D, and EF, presence of three pairs of aggenital setae and the characteristic shape of the palpal tibial claw. The new species differs from A. ovalis by having setae sc 1 distinct, at least 6 in length (vs only alveolar remnant of setae sc 1 present in A. ovalis ), apodemes 1 narrow, almost as wide as apodemes 2 (vs apodemes 1 wide, much wider than apodemes 2 in A. ovalis ), and presence of cupules ih (vs not evident in A. ovalis ).

Etymology. The name of the new species derives from the Latin word “ angustus ” meaning “ narrow ” and refers to the very narrow hysterosomal tergites of the new species.

Figures

FIGURE 43. Athyreacarus angustus sp. nov., female: A—dorsum of body, B—venter of body.

FIGURE 44. Athyreacarus angustus sp. nov., female: A—left leg I in dorsal view, B—left leg II in dorsal view.

FIGURE 45. Athyreacarus angustus sp. nov., female: A—left leg III in dorsal view, B—left leg III in dorsal view.

FIGURE 46. Phase-contrast micrographs of Athyreacarus angustus sp. nov., female: A—general aspect dorsally, B—general aspect ventrally.

FIGURE 47. Phase-contrast micrographs of Athyreacarus angustus sp. nov., female: A—prodorsal shield, B—hysterosoma in dorsal view, C—anterior sternal plate, D— aggenital and midsternal plates and part of coxal fields IV.

FIGURE 48. SEM micrographs of Athyreacarus angustus sp. nov., female:A—gnathosoma in dorsal view, B— left postpalpal seta, C—distal part of gnathosoma in ventral view, D—leg IV in dorsal view.