Pediculaster bisetus, Khaustov, 2020

Khaustov, Alexander A., 2020, Three new species and new records of Pediculaster (Acari: Pygmephoridae) from Western Siberia, Russia, Acarologia 60 (2), pp. 317-337 : 328-331

Pediculaster bisetus sp. nov.

Zoobank: 4AAFFE22-DC6F-40FD-B423-D666234F4DD3

( Figs 9 B–12)

Description

Phoretic female ( Figs 9 B–12) — Length of idiosoma 210 (210–240), width 96 (105–115).

Gnathosoma ( Figs 9B , 10 ) – Length of gnathosomal capsule 20 (20–21), width 21 (22– 24). Dorsal median apodeme weakly developed. All gnathosomal setae smooth; setae cha and chb blunt-ended, other gnathosomal setae pointed. Palp tibiotarsus with well-developed blunt-tipped claw and tiny eupathid-like seta; palps ventrally with well-developed solenidion and mushroom-shaped accessory setigenous structure. Php 1 small, bow-shaped, located inside gnathosomal capsule; php 2 oval, php 3 with lateral “wings” ( Fig. 9B ), both pumps situated close to each other on long oesophagus and far separated from php 1. Lengths of gnathosomal setae: cha 6 (6), chb 8 (7–8), dFe 6 (6–8), dGe 7 (7–10), m 12 (12–13).

Idiosomal dorsum ( Fig. 10A ) – All dorsal shields with numerous small round dimples. Stigmata small, oval, one-chambered and associated with long tracheal trunks. Setae e and h 2 smooth, other dorsal setae barbed; setae h 2 pointed, other dorsal setae blunt-ended; trichobothria sc 1 short, spherical. Cupules ia on tergite D and ih on tergite H very small, round. Lengths of dorsal setae: v 1 22 (21–23), v 2 21 (18–21), sc 2 36 (36–40), c 1 24 (24–29), c 2 31 (31–39), d 29 (29–36), e 8 (8–13), f 31 (31–38), h 1 29 (29–34), h 2 5 (5–7). Distances between setae: v 1 – v 1 8 (7–9), v 2 – v 2 22 (21–22), sc 2 – sc 2 31 (31–34), c 1 – c 1 33 (33–39), c 1 – c 2 20 (20–23), d–d 49 (49–61), e–f 6 (5–7), f –f 49 (49–59), h 1 – h 1 44 (44–53), h 1 – h 2 5 (5–8).

Idiosomal venter ( Fig. 10B ) – Ventral plates with numerous small round dimples. Setae 1 b pointed, other ventral setae blunt-ended; setae ps 2 barbed, over ventral setae smooth. Setae 2 b on coxal fields II absent. Ap1, ap2 and apsej well developed and joined with appr; ap3 and ap4 well developed and joined with appo; ap5 weaker sclerotized than other apodemes and joined with appo. Posterior margin of poststernal plate with weak median lobe. Anterior and posterior genital sclerites long and narrow; median genital sclerite small, oval. Lengths of ventral setae: 1 a 10 (9–11), 1 b 13 (13–14), 1 c 9 (9), 2 a 10 (10–12), 2 c 7 (6–8), 3 a 10 (10–12), 3 b 10 (10–11), 3 c 12 (12), 4 a 9 (9–10), 4 b 12 (11–14), 4 c 10 (10–12), ps 1 4 (4–5), ps 2 16 (14–16), ps 3 3 (3).

Legs ( Figs 11 , 12 ) – Leg I ( Fig. 11A ). Leg setation: Tr v’) 1, (Fe 4 (d, l’, l”, v”), Ge 4 (l’, l”, v’, v”), TiTa 17(4) (d, l’, l”, v’, v”, k, pl’, pl”, p’, p”, tc’, tc”, ft’, ft”, s, pv’, pv”, ω 1, ω 2, φ 1, φ 2). Tibiotarsus cylindrical, as wide as genu. Lengths of solenidia ω 1 8 (8–9), ω 2 4 (4), φ 1 7 (7), φ 2 4 (4–5); all solenidia clavate. Setae (p), (tc) and (ft) eupathid-like; seta d of femur smooth, spatulate distally; seta pl’ of tibiotarsus smooth and pointed; setae v’ of trochanter and k of tibiotarsus smooth or with one barb and blunt-ended; setae l’ of femur and (l) of genu blunt-ended and barbed; other leg setae (except eupathidia) pointed and barbed. Leg II ( Fig. 11B ). Leg setation: Tr 1 (v’), Fe 3 (d, l’, v”), Ge 3 (l’, l”, v’), Ti 4 (d, l’, v’, v”), Ta 6(1) (pl”, tc’, tc”, pv’, pv”, u’, ω). Solenidion ω 5 (5) clavate, solenidion φ absent, but pore-like structure situated on its typical insertion point. Tarsal claws with thickened basal half; empodium long and narrow, with widened tip. Setae v’ of trochanter and l’ of femur smooth and blunt-ended; setae d of femur and u’ of tarsus blunt-ended and barbed, other leg setae pointed. Leg III ( Fig. 12A). Leg setation: Tr 1 (v’), F2 3 (d, v’), Ge 2 (l’, v’), Ti 4 (d, l’, v’, v”), Ta 6 (pl”, tc’, tc”, pv’, pv”, u’). Claws and empodium as on tarsus II. Solenidion φ absent, but pore-like structure situated on its typical insertion point. All leg setae barbed; setae v’ of trochanter, d, v’ of femur and u’ of tarsus blunt-ended, other leg setae pointed. Leg IV ( Fig. 12B ). Leg setation: Tr 0, Fe 2 (d, v’), Ge 1 (v’), Ti 4 (d, l’, v’, v”), Ta 6 (pl”, tc’, tc”, pv’, pv”, u’). Claws simple, hooked, empodium as on tarsi II and III. Solenidion φ absent, but pore-like structure situated on its typical insertion point. All leg setae barbed; setae d and v’ of femur blunt-ended, other leg setae pointed.

Non-phoretic female, male and larva unknown.

Type material — Phoretic female holotype slide ZISP T-Pygm-005: Russia, Tyumen Province, Tyumen, “ Zatyumenskiy park”, 57°09’ N, 65°26’ E, in the rotting log of birch, 29 September 2019, A.A. Khaustov leg. Paratypes: 11 phoretic females, same data as holotype.

Type deposition — The holotype and 2 phoretic female paratypes are deposited in the collection of the Zoological Institute of RAS, Saint Petersburg, Russia ; other paratypes are deposited in the mite collection of the Tyumen State University Museum of Zoology, Tyumen, Russia.

Etymology — The name of the new species is a combination of two Latin words bi meaning two and seta meaning bristle and refers to presence of two pairs of setae on coxal fields II.

Differential diagnosis — The new species is most similar to P. athiasae ( Wicht, 1970) by the presence of three pairs of setae on coxal fields I, two pairs of setae on coxal fields II, subequal setae v 1 and v 2 and well-developed ap5. The new species can be distinguished from the latter in having one-chambered stigmata (two-chambered P. in athiasae ), by smooth setae e (setae e barbed in P. athiasae ), by the absence of seta on trochanter IV (trochanter IV with seta in P. athiasae ), and distinctly shorter dorsal body setae (dorsal body setae distinctly longer in P. athiasae ).

Figures

Figure 9 DIC micrographs of pharyngeal pumps II and III of phoretic females: A – Pediculaster tjumeniensis sp. nov.„ B – Pediculaster bisetus sp. nov.

Figure 10 Pediculaster bisetussp. nov., phoretic female: A – dorsum of the body, B – venter of the body. Legs omitted.

Figure 11 Pediculaster bisetussp. nov., phoretic female: A – right leg I, dorsal aspect, B – right leg II, dorsal aspect.

Figure 12 Pediculaster bisetus sp. nov., phoretic female: A – right leg III, dorsal aspect, B – right leg IV, dorsal aspect.