Pediculaster rarus, 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 : 332-334

Pediculaster rarus sp. nov.

Zoobank: B3B6E53C-F601-46F5-A384-38011767AB4F

( Figs 13–15 )

Description

Phoretic female ( Figs 13–15 ) — Length of idiosoma 280, width 130.

Gnathosoma ( Fig. 13 ) – Length of gnathosomal capsule 25, width 29. Dorsal median apodeme well developed. All gnathosomal setae smooth; setae cha 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 distinctly outside gnathosomal capsule; php 2 and php 3 oval, situated close to each other on long oesophagus and far separated from php 1. Lengths of gnathosomal setae: cha 7, chb 11, dFe 8, dGe 15, m 17.

Idiosomal dorsum ( Fig. 13A ) – All dorsal shields with numerous small round dimples. Stigmata small, oval, one-chambered and associated with long tracheal trunks. All dorsal setae blunt-ended; setae h 2 smooth, other dorsal setae barbed; trichobothria sc 1 short, spherical. Cupules ia on tergite D and ih on tergite H very small, round. Tergites C, D, and EF with porous areas as illustrated. Lengths of dorsal setae: v 1 25, v 2 24, sc 2 46, c 1 32, c 2 39, d 35, e 22, f 38, h 1 36, h 2 6. Distances between setae: v 1 – v 1 11, v 2 – v 2 26, sc 2 – sc 2 35, c 1 – c 1 36, c 1 – c 2 25, d–d 50, e–f 14, f –f 43, h 1 – h 1 37, h 1 – h 2 13.

Idiosomal venter ( Fig. 13B ) – Ventral plates with numerous small round dimples. Setae 1 b, 1 c, 2 b, 3 c, 4 b, and 4 c pointed, other ventral setae blunt-ended; setae ps 2 barbed, other ventral setae smooth; setae 2 b much longer than other ventral setae; setae ps 2 situated distinctly anteriad ps 1. 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 evenly rounded, without median lobe. Anterior and posterior genital sclerites long and narrow; median genital sclerite indistinct. Lengths of ventral setae: 1 a 10, 1 b 14, 1 c 12, 2 a 12, 2 b 73, 2 c 13, 3 a 16, 3 b 13, 3 c 20, 4 a 12, 4 b 21, 4 c 19, ps 1 7, ps 2 7, ps 3 27.

Legs ( Figs 14 , 15 ) – Leg I ( Fig. 14A ). 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, slightly wider than genu. Lengths of solenidia ω 1 21, ω 2 11, φ 1 7, φ 2 6; solenidion φ 1 clavate, other solenidia finger-shaped. Setae p (), (tc) and (ft) eupathid-like; eupathidium p” very short ( Fig. 14A ´); seta d of femur smooth, spatulate distally; setae v’ of trochanter and pl’ of tibiotarsus smooth and pointed; seta k of tibiotarsus smooth and weakly blunt-ended; 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(1) (d, l’, v’, v”, φ), Ta 6(1) (pl”, tc’, tc”, pv’, pv”, u’, ω). Solenidion ω 10 finger-shaped, solenidion φ 3 weakly clavate, situated in depression. Tarsal claws with thickened basal half; empodium long and narrow, with widened tip. Setae v’ of trochanter and tc” of tarsus smooth and pointed; setae u’ of tarsus blunt-ended and barbed, other leg setae pointed and barbed. Leg III ( Fig. 15A ). Leg setation: v’ Tr), 1 Fe(2 (d, v’), Ge 2 (l’, v’), Ti 4(1) (d, l’, v’, v”, φ), Ta 6 (pl”, tc’, tc”, pv’, pv”, u’). Claws and empodium as on tarsus II. Solenidion φ 3 weakly clavate, situated in depression. Seta tc” of tarsus smooth and pointed; setae v’ of femur and u’ of tarsus blunt-ended and barbed, other leg setae pointed and barbed. Leg IV ( Fig. 15B ). Leg setation: Tr v’ 1), (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 pointed and barbed.

Non-phoretic female, male and larva unknown.

Type material — Phoretic female holotype slide ZISP T-Pygm-006: Russia, Tyumen Province, Tyumen district, vicinity of lake Kuchak, 57°21’N, 66°03’E, in rotting stamp, 26 September 2018, A.A. Khaustov leg.

Type deposition — The holotype is deposited in the collection of the Zoological Institute of RAS, Saint Petersburg, Russia.

Etymology — The name of the new species is derived from Latin rarus meaning rare and refers to its rareness.

Remark — The new species is described based on single specimen. However, it is in good condition and very well differs from closely related species. All attempts to collect additional specimens were unsuccessful.

Differential diagnosis — The new species is most similar to P. chistyakovi Khaustov and Ermilov, 2008 by the presence of three pairs of setae on coxal fields I and II, setae ps 3 distinctly longer than ps 2, setae v 1 and v 2 subequal, and setae 2 b much longer than a 2. The new species can be distinguished from the latter in having setae sc 2, c 2, f, and h 1 blunt-ended (setae sc 2, c 2, f, and h 1 pointed in P. chistyakovi ), by setae ps 2 situated distinctly anteriad ps 1 (setae ps 2 and ps 1 situated on the same level in P. chistyakovi ), by much shorter setae d on femur and tibia IV which not exceed beyond tip of tarsus (setae d on femur and tibia IV very long and exceed beyond tip of tarsus in P. chistyakovi ), and by the presence of ap5 (ap5 absent in P. chistyakovi ).

Figures

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

Figure 13 Pediculaster rarussp. nov., phoretic female: A – dorsum of the body, B – venter of the body. Legs omitted.

Figure 14 Pediculaster rarus sp. nov., phoretic female: A – left leg I, dorsal aspect, B – left leg II, dorsal aspect.

Figure 15 Pediculaster rarus sp. nov., phoretic female: A – left leg III, dorsal aspect, B – left leg IV, dorsal aspect.