Pediculaster tjumeniensis, 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 : 318-328

Pediculaster tjumeniensis sp. nov.

Zoobank: 9C126801-3491-4277-8757-9C9AE42FB5BD

( Figs 1–9A )

Description

Phoretic female ( Figs 1–3 , 9A ) — Length of idiosoma 265 (200–305), width 140 (105– 160).

Gnathosoma ( Figs 1 , 9A ) – Length of gnathosomal capsule 26 (23–27), width 29 (28–32). Dorsal median apodeme weakly developed. All gnathosomal setae pointed; setae cha, chb and dFe with few very small barbs, other gnathosomal setae smooth. Palp tibiotarsus with welldeveloped 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 and 3 oval ( Fig. 9A ), situated close to each other on long oesophagus and far separated from php 1. Lengths of gnathosomal setae: cha 10 (8–12), chb 14 (10–15), dFe 13 (9–13), dGe 18 (12–18), m 16 (11–16).

Idiosomal dorsum ( Fig. 1A ) – All dorsal shields with numerous small round dimples. Stigmata small, oval, one-chambered and associated with long tracheal trunks. All dorsal setae blunt-ended and barbed; trichobothria sc 1 short, spherical. Cupules ia on tergite D and ih on tergite H very small, round. Lengths of dorsal setae: v 1 29 (22–29), v 2 30 (25–32), sc 2 57 (43–58), c 1 40 (29–40), c 2 48 (35–52), d 43 (32–45), e 24 (17–24), f 45 (30–45), h 1 37 (27–38), h 2 14 (10–16). Distances between setae: v 1 – v 1 10 (10–12), v 2 – v 2 31 (26–32), sc 2 – sc 2 46 (41–53), c 1 – c 1 44 (33–49), c 1 – c 2 30 (21–34), d–d 73 (52–78), e–f 21 (15–23), f –f 45 (32–51), h 1 – h 1 51 (34–52), h 1 – h 2 18 (14–19).

Idiosomal venter ( Fig. 1B ) – Ventral plates with numerous small round dimples. Setae 1 b and 2 a pointed; other ventral setae blunt-ended; setae ps 1 and ps 3 smooth, over ventral setae weakly barbed; setae 2 a much longer than other ventral setae; in one specimen left seta 2 c abnormally long and pointed. 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 small, oval. Lengths of ventral setae: 1 a 19 (15–19), 1 b 26 (18–29), 1 c 17 (14–17), 2 a 43 (38–48), 2 b 18 (4–19), 2 c 16/20 (14–17), 3 a 18 (14–20), 3 b 16 (13–17), 3 c 19 (14–21), 4 a 16 (12–17), 4 b 19 (15–22), 4 c 18 (13–20), ps 1 8 (5–8), ps 2 26 (17–27), ps 3 7 (4–9).

Legs ( Figs 2 , 3 ) – Leg I ( Fig. 2A ). 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 slightly thickened, distinctly wider than genu. Lengths of solenidia ω 1 14 (11–14), ω 2 11 (9–11), φ 1 9 (7–9), φ 2 9 (8–10); solenidion φ 1 slightly clavate, other solenidia finger-shaped. Setae p (), (tc) and (ft) eupathid-like; seta d of femur smooth, spatulate distally; seta k of tibiotarsus smooth and weakly 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. 2B ). 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). Solenidia ω 9 (7–9) and φ 5 (4–5) finger-shaped. Tarsal claws with thickened basal half; empodium long and narrow, with widened tip. All leg setae barbed; setae d, l’ of femur and u’ of tarsus blunt-ended, other leg setae pointed. Leg III ( Fig. 3A ). Leg setation: Tr 1 (v’), F2 3 (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 4 (3–4) weakly clavate. All leg setae barbed; setae d, v’ of femur and l’ of genu blunt-ended, other leg setae pointed. Leg IV ( Fig. 3B ). Leg setation: Tr 1 (v’), Fe 2 (d, v’), Ge 1 (v’), Ti 4(1) (d, l’, v’, v”, φ), Ta 6 (pl”, tc’, tc”, pv’, pv”, u’). Claws simple, hooked, empodium narrower than on tarsi II and III. Solenidion φ 3 (2–3) rod-like. All leg setae barbed; seta v’ of femur blunt-ended, other leg setae pointed.

Non-phoretic female ( Figs 4–6 ) — Length of idiosoma 240–300, width 125–150.

Gnathosoma ( Fig. 4 ) – Length of gnathosomal capsule 27–31, width 33–38. Gnathosoma and pharyngeal pumps in general as in phoretic female, but cheliceral setae and seta dFe smooth. Lengths of gnathosomal setae: cha 9–11, chb 14–15, dFe 13–14, dGe 15–16, m 17–19.

Idiosomal dorsum ( Fig. 4A ) – as in phoretic female, but dorsal sclerites weaker sclerotized and dimples smaller, difficult to discern. Lengths of dorsal setae: v 1 19–23, v 2 19–24, sc 2 37–44, c 1 26–31, c 2 39–44, d 28–36, e 15–20, f 27–39, h 1 23–33, h 2 6–8. Distances between setae: v 1 – v 1 11–12, v 2 – v 2 28–32, sc 2 – sc 2 29–33, c 1 – c 1 40–45, c 1 – c 2 25–34, d–d 61–70, e–f 16–18, f –f 42–45, h 1 – h 1 45–49, h 1 – h 2 14–15.

Idiosomal venter ( Fig. 4B ) – similar to that of phoretic female, but plates weaker sclerotized and dimples smaller; setae 2 a normally not very long and blunt-ended, and only in one specimen left seta 2 a long and pointed and similar to that of phoretic female. Apsej indistinct; ap5 stronger sclerotized than in phoretic female. Lengths of ventral setae: 1 a 13–15, 1 b 13–18, 1 c 11–15, 2 a 14–33, 2 b 12–16, 2 c 10–13, 3 a 14–18, 3 b 13–17, 3 c 14–18, 4 a 12–15, 4 b 13–18, 4 c 14–15, ps 1 6, ps 2 17–22, ps 3 4–5.

Legs ( Figs 5 , 6 ) – Leg I ( Fig. 5A ). Tibia and tarsus separated. Tarsal claw simple, hooked. Leg setation: Tr 1 (v’), Fe 4 (d, l’, l”, v”), Ge 4 (l’, l”, v’, v”), Ti (6)(2) (d, l’, l”, v’, v”, k, φ 1, φ 2), Ta 13(2) (pl’, pl”, p’, p”, tc’, tc”, ft’, ft”, s, pv’, pv”, u’, u”, ω 1, ω 2). Lengths of solenidia ω 1 16–19, ω 2 13–15, φ 1 6–8, φ 2 10–11; solenidion φ 1 clavate, other solenidia finger-shaped. Setae (p), (tc) and (ft) eupathid-like; seta k of tibiotarsus smooth and weakly blunt-ended; other leg setae (except eupathidia) pointed and barbed. Leg II ( Fig. 5B ). Leg setation: v’ Tr), 1 (Fe 3 (d, l’, v”), Ge 3 (l’, l”, v’), Ti 4(1) (d, l’, v’, v”, φ), Ta 7(1) (pl”, tc’, tc”, pv’, pv”, u’, u”, ω). Solenidia ω 11–12 and φ 8–9 finger-shaped. Tarsal claws simple, hooked; empodium short and wide. All leg setae barbed; seta l’ of femur blunt-ended, other leg setae pointed. Leg III ( Fig. 6A ). Leg setation: Tr 1 (v’), Fe 2 (d, v’), Ge 2 (l’, v’), Ti 4(1) (d, l’, v’, v”, φ), Ta 7 (pl”, tc’, tc”, pv’, pv”, u’, u”). Claws and empodium as on tarsus II. Solenidion φ 6–7 finger-shaped. All leg setae barbed; seta v’ of femur blunt-ended, other leg setae pointed. Leg IV ( Fig. 6B ). Leg setation: Tr 1 (v’), Fe 2 (d, v’), Ge 1 (v’), Ti 4(1) (d, l’, v’, v”, φ), Ta 6 (pl”, tc’, tc”, pv’, pv”, u’). Claws and empodium as on tarsi II and III. Solenidion φ 3–4 rod-like. All leg setae barbed; seta v’ of femur blunt-ended, other leg setae pointed.

Larva ( Figs 7 , 8 ) — Length of idiosoma 195–215, width 105–115.

Gnathosoma ( Figs 7 , 8 ) – Length of gnathosomal capsule 27–30, width 31–34. Cheliceral setae cha short and thick, other gnathosomal setae smooth and pointed; setae chb absent.

Dorsal median apodeme absent. Accessory setigenous structure distinctly shorter than palpal solenidion. Subcapitulum with two pairs of setae (m, n). Lengths of gnathosomal setae: cha

3–4, dFe 9–10, dGe 12–14, m 14–15, n 10–11. Pharyngeal pumps 2 and 3 as in female, php 1 small, bow-shaped and situated on the short distance from php 2 inside propodosoma.

Idiosomal dorsum ( Fig. 7A ) – Prodorsum with one trapezium-shaped shield with four pairs of setae; tergite C divided into three plates, one median with one pair of setae c 1 and two laterals with setae c 2; tergites D, EF and H with same number of setae as in females. All dorsal setae strongly barbed; setae h 1 and h 2 pointed, other dorsal setae blunt-ended. Tergites D and H with small round cupules ia and ih, respectively. All dorsal shields with small round dimples. Lengths of dorsal setae: v 1 14–18, v 2 12–16, sc 1 21–29, sc 2 30–35, c 1 23–26, c 2 25–31, d 25–33, e 18–23, f 29–35, h 1 28–35, h 2 59–63. Distances between setae: v 1 – v 1 9–11, v 2 – v 2 41–45, sc 1 – sc 1 28–29, sc 2 – sc 2 49–53, c 1 – c 1 40–42, d–d 43, e–f 11–12, f –f 33–34, h 1 – h 1 12–14, h 1 – h 2 10–11.

Idiosomal venter ( Fig. 7B ) – Coxal fields I-III separated medially and with two pairs of setae each. Ap1, ap2 and ap3 well developed; other apodemes absent. All ventral setae barbed; setae ps 1-3 pointed, other ventral setae blunt-ended. Lengths of ventral setae: 1 a 11–13, 1 b 11–13, 2 a 12–13, 2 b 12–14, 3 a 15–20, 3 b 12–16, ps 1 14–16, ps 2 17–20, ps 3 18–20.

Legs ( Fig. 8 ) – Leg I ( Fig. 8A ). Tarsus with two simple hooked claws; empodium absent. Leg setation: Tr 0, Fe 4 (d, l’, l”, v”), Ge 4 (l’, l”, v’, v”), Ti (6)(1) (d, l’, l”, v’, v”, k, φ 1), Ta 11(1) (pl’, pl”, tc’, tc”, ft’, ft”, s, pv’, pv”, u’, u”, ω 1). Lengths of solenidia ω 1 10–14, φ 1 7–9; solenidion ω 1 finger-shaped; solenidion φ 1 clavate. Setae (tc) eupathid-like; seta k of tibiotarsus smooth and weakly blunt-ended; setae l’ of femur and v’ of genu blunt-ended and barbed, other leg setae (except eupathidia) pointed and barbed. Leg II ( Fig. 8B ). Leg setation: Tr 0, Fe 3 (d, l’, v”), Ge 3 (l’, l”, v’), Ti 4(1) (d, l’, v’, v”, φ), Ta 7(1) (pl”, tc’, tc”, pv’, pv”, u’, u”, ω). Solenidia ω 8–10 and φ 4–5 finger-shaped. Tarsal claws simple, hooked; empodium short and wide. Seta l’ of femur smooth and blunt-ended; seta v’ of genu barbed and blunt-ended, other leg setae pointed and barbed. Leg III ( Fig. 8C ). Leg setation: Tr 0), F d, 2 3 (v’), Ge 2 (l’, v’), Ti 4 (d, l’, v’, v”), Ta 7 (pl”, tc’, tc”, pv’, pv”, u’, u”). Claws and empodium as on tarsus II. Solenidion φ absent. Seta pl” of tarsus spine-shaped, smooth; setae d, v’ of femur and l’ of genu blunt-ended and barbed, other leg setae pointed and barbed. Femur not divided into basi- and telofemur.

Male unknown.

Type material — Phoretic female holotype slide ZISP T-Pygm-004: Russia, Tyumen Province, Tyumen, “Zatyumenskiy park”, 57°09’ N, 65°26’ E, in the rotting log of birch, 21 April 2019, A.A. Khaustov leg. Paratypes: 7 phoretic females, same data as holotype ; 4 phoretic and 4 non-phoretic females, same locality and collector, 10 July 2019 ; 2 phoretic females and 7 larvae, same locality and collector, 26 April 2019 .

Type deposition — The holotype and 4 phoretic females 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 refers to its distribution in Tyumen city, the capital of Tyumen Province, Russia.

Differential diagnosis — Phoretic female of the new species is most similar to P. sellnickianus ( Rack, 1964) and P. limosinae Samsinak, 1984 (not separable morphologically from P. sellnickianus ) by the presence of three pairs of setae on coxal fields I and II, setae ps 2 longer than ps 3, and setae 2 a much longer than b 2. The new species can be distinguished from P. sellnickianus by having setae c 2 clearly longer than c 1 (setae c 1 and c 2 subequal in P. sellnickianus ), by the presence of ap5 (ap5 absent in P. sellnickianus ), and setae e no more than twice longer than h 2 (setae e more than 3 times longer than h 2 in P. sellnickianus ). Non-phoretic female of the new species is most similar to P. permagnus ( Rack, 1971) but can be distinguished from it by longer distance between setae e and f, which less than 3 times shorter than distance f-f (e-f about 4 times shorter than f-f in P. permagnus ), by solenidion φ 2 distinctly longer than φ 1 (solenidia φ 2 and φ 1 subequal in P. permagnus ), and by much longer solenidion ω 2, which reaching far beyond the base of solenidion ω 1 (solenidion ω 2, much shorter and not reaching base of solenidion ω 1 in P. permagnus ). Larva of the new species can be distinguished from all described larvae of Pediculaster by the presence of setae n on subcapitulum (setae n absent in all described larvae of Pediculaster ).

Figures

Figure 1 Pediculaster tjumeniensissp. nov., phoretic female: A – dorsum of the body, B – venter of the body. Legs omitted.

Figure 2 Pediculaster tjumeniensissp. nov., phoretic female: A – left leg I, dorsal aspect, B – left leg II, dorsal aspect.

Figure 3 Pediculaster tjumeniensissp. nov., phoretic female: A – left leg III, dorsal aspect, B – left leg IV, dorsal aspect.

Figure 4 Pediculaster tjumeniensissp. nov., non-phoretic female: A – dorsum of the body, B – venter of the body. Legs omitted.

Figure 5 Pediculaster tjumeniensissp. nov., non-phoretic female: A – left leg I, dorsal aspect, B – left leg II, dorsal aspect.

Figure 6 Pediculaster tjumeniensissp. nov., non-phoretic female: A – left leg III, dorsal aspect, B – left leg IV, dorsal aspect.

Figure 7 Pediculaster tjumeniensissp. nov., larva: A – dorsum of the body, B – venter of the body. Legs omitted.

Figure 8 Pediculaster tjumeniensissp. nov., larva: A – left leg I, dorsal aspect, B – left leg II, dorsal aspect, C – left leg III, dorsal aspect.

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