Petalomium brevicaudus, Khaustov, Alexander A., 2016

Khaustov, Alexander A., 2016, New species and a record of myrmecophilous mites of the families Neopygmephoridae and Microdispidae (Acari: Heterostigmatina: Pygmephoroidea) associated with Lasius umbratus (Hymenoptera: Formicidae) from Western Siberia, Russia, Zootaxa 4137 (3), pp. 375-390 : 376-380

Petalomium brevicaudus sp. n.

( Figs. 1–4 )

Description. FEMALE (holotype, Figs. 1–4 ). Body weakly sclerotized. Length of idiosoma 365 (300–340), width 200 (190–230). Gnathosoma ( Fig. 2 ). Gnathosomal capsule semioval, with subequal length and width, dorsally with 2 pairs of smooth, pointed cheliceral setae (cha, chb). Setae chb 21 (19–22) distinctly longer than cha 11 (11– 13). Dorsal median apodeme weakly developed. Pair of spine-like postpalpal setae (pp) situated anteriorly to setae cha. Ventral gnathosoma with 1 pair of smooth, pointed subcapitular setae m 17 (17–20) and 1 pair of round pits situated posteromedially to bases of m. Palps freely articulated to gnathosomal capsule, with smooth, pointed setae dFe and dGe dorsolaterally. Setae dGe distinctly longer than dFe. Palps ventrally with large accessory setigenous structure (ass) and well-developed solenidion. Palps terminated with small claw. Pharyngeal pumps grouped together. Pharyngeal pump I small; about 2 times shorter than pump III; pharyngeal pump II large, about 5 times longer than pharyngeal pump III. Idiosomal dorsum ( Fig. 1 A). Only posterior part of prodorsum covered by anterior margin of tergite C, with 2 pairs of setae (v 2, sc 2), 1 pair of clavate and weakly barbed trichobothria (sc 1) with pointed apex and 1 pair of round stigmata with transverse slit-like openings. All dorsal plates smooth. Setae v 2 smooth, other dorsal setae distinctly barbed; Setae c 2 and h 2 pointed; other dorsal setae blunt-ended. Posterior margin of tergite C weakly concave; posterior margin of tergite H undulate. Cupules ia on tergite D and ih on tergite H small, round. Lengths of dorsal setae: v 2 10 (10–12), sc 2 48 (46–49), c 1 81 (79–90), c 2 91 (88–100), d 69 (67–78), e 36 (35–45), f 105 (100–110), h 1 66 (65–73), h 2 56 (55–62). Distances between setae: v 2 –v 2 47 (45–49), sc 2 –sc 2 53 (52–55), c 1– c 1 77 (75–86), c 1– c 2 48 (46–56), d–d 86 (84–93), e–f 19 (18–22), f–f 83 (80–90), h 1– h 1 36 (34–40), h 1– h 2 18 (17–19). Idiosomal venter ( Fig. 1 B). All ventral plates smooth. Pseudanal setae smooth, other ventral setae barbed. Setae 1 b not bifurcate. Apodemes 1 (ap1) well developed and joined with prosternal apodeme (appr); apodemes 2 (ap2) well-developed, thin, joined with appr, prosternal and sejugal (apsej) apodemes welldeveloped; apodemes 3 (ap3) well-developed, straight, joined with poststernal apodeme (appo). Apodemes 4 (ap4) well sclerotized, long and joined with appo; apodemes 5 absent. Posterior margin of posterior sternal plate convex in middle part. Posterior margin of aggenital plate almost straight. Anterior genital sclerite (ags) small, bell-like, posterior genital sclerite (pgs) large, triangular, median genital sclerite (mgs), small and rounded. Lengths of ventral setae: 1 a 41 (39–46), 1 b 35 (34–40), 2 a 42 (40–48), 2 b 24 (23–26), 3 a 34 (33–38), 3 b 39 (37–41), 3 c 37 (35–42), 4 a 45 (44–59), 4 b 54 (52–70), 4 c 47 (45–58), ps 1 17 (16–18), ps 2 12 (12–13), ps 3 10 (10–12). Legs ( Figs. 3 , 4 ). Leg I ( Fig. 3 A) only slightly shorter than leg II. Setal formula: 1–3–4–16 (4). Tibiotarsus not thickened, with terminal claw situated on distinct pretarsus, tip of the claw thin. Lengths of solenidia ω 1 10 (10–11) <ω 2 11 (11–13)> φ 1 9 (9–10) = φ 2 10 (9–10); ω 2 baculiform, φ 1 and φ 2 weakly clavate, ω 1 finger-shaped. Eupathidium tc” situated on very short pinnaculum. Seta d of femur broadened, slightly curved at the tip. Setae d of tibiotarsus, l’ and v’ of genu blunt-ended, barbed; seta l’ of femur blunt-ended, smooth, other leg setae (except eupathidia) pointed and sparsely barbed. Leg II ( Fig. 3 B). Setal formula: 1–3–3–4(1)–6(1). Tarsus with sickle-like padded claws and large flipper-like empodium. Solenidion ω 9 (9–10), finger-shaped, solenidion φ 6 (6–7) weakly clavate. All leg setae barbed; setae v’ of genu and l’ of tibia blunt-ended, other leg setae pointed. Leg III ( Fig. 4 A) similar in shape and length to leg II. Setal formula: 1–2–2–4(1)–6. Claws and empodium of same shape as on tarsus II. Solenidion φ 6 (6–7) weakly clavate. All leg setae barbed. Seta d of femur blunt-ended, other leg setae pointed. Leg IV ( Fig. 4 B). Setal formula: 1–2–1–4(1)–6. Tarsus long and thin, pretarsus short, with 2 small simple claws and small empodium. Solenidion φ 6 (6–8) weakly clavate. All leg setae barbed; setae d of femur, v’ of genu and tibia and v” of tibia blunt-ended, other leg setae pointed.

MALE and LARVA unknown.

Type material. Female holotype, slide No. AK 130915, RUSSIA: Kurgan Province, Zverinogolovskiy district, vicinity of settlement Ukrainets, 54°24ʹ11.6ʺN, 64°49ʹ08.6ʺE, on ants Lasius umbratus , 13 September 2015, coll. A.A. Khaustov; paratypes: 5 females, same data.

Etymology. The specific epithet is combined of two Latin words: brevis (= short) and caudus (= tail) and refers to short pseudanal (caudal) setae.

Differential diagnosis. The new species is most similar to P. foliiger ( Mahunka and Mahunka-Papp, 1980) by the short and smooth pseudanal setae and similar relative lengths of the hysterosomal setae. It differs from P. foliiger by the simple pseudanal setae (vs. foliate in P. foliiger ) and not swollen base of solenidion ω 1 of tibiotarsus I (vs. base of solenidion ω 1 of tibiotarsus I distinctly swollen in P. foliiger ). Additionally setae f are distinctly longer than h 1 (vs. f and h 1 subequal in P. foliiger ).

Figures

FIGURE 1. Petalomium brevicaudus sp. nov., female: A—idiosomal dorsum, B—idiosomal venter.

FIGURE 2. Petalomium brevicaudus sp. nov., female: A—gnathosoma in dorsal view, B—gnathosoma and pharyngeal pumps in ventral view.

FIGURE 3. Petalomium brevicaudus sp. nov., female: A—right leg I in dorsal view, B—right leg II in dorsal view.

FIGURE 4. Petalomium brevicaudus sp. nov., female: A—right leg III in dorsal view, – B—right leg IV in dorsal view.