A new species of the genus Hoplocheylus Atyeo and Baker (Acariformes: Heterostigmata: Tarsocheylidae), H. lindquisti Xu & Zhang sp. nov., is described based on larva, deutonymph, adult male and female specimens collected from the bark of dead Pinus massoniana Lamb. infested with Monochamus alternatus (Coleoptera: Cerambycidae) in Fuzhou city, China. This is the first report of the genus Hoplocheylus and the family Tarsocheylidae in China.
Introduction
Tarsocheylidae (Acariformes: Heterostigmata), the earliest-derivative lineage of Heterostigmata and the only family reported so far for the superfamily Tarsocheyloidea, was erected by Atyeo and Baker (1964) with two genera, Tarsocheylus Berlese, 1904 and Hoplocheylus Atyeo and Baker, 1964. Tarsocheylids are slender mites found in soil, sand, humus, forest, rodent nest litter, rotting wood, trunk cavities of deciduous trees or under elytra of passalid beetles (Lindquist 1976; Walter et al. 2009). So far, 14 species of the genus Hoplocheylus have been described (Cooreman 1951; Atyeo & Baker 1964; Lindquist 1976, 1987; Amin et al. 2014; Khaustov 2015; Fuangarworn & Butcher 2016; Arjomandi et al. 2018; Khaustov & Ermilov 2018): H. atomarius (Berlese 1913); H. aethiopicus (Cooreman, 1951); H. jonnstoni Atyeo and Baker, 1964; H. longispinus Atyeo & Baker, 1964; H. pickardi Smiley & Moser, 1968 ; H. americanus Delfinado & Baker, 1974; H. arnoldii Livshitz & Mitrofanov, 1973; H. sogdianicus Barilo & Sharipov, 1987; H. fereshtae Amin et al., 2014; H. magnificus Khaustov, 2015; H. nudus Fuangarworn & Butcher, 2016; H. longisetosus Fuangarworn & Butcher, 2016; H. evansi Arjomandi & Hajiqanbar, 2018; H. zanzibariensis Khaustov & Ermilov, 2018.
Hoplocheylus is a widespread genus, previously reported from North America, Central Africa, Southern Europe and Asia (Lindquist 1976; Walter et al. 2009; Khaustov 2015; Fuangarworn & Butcher 2016; Arjomandi et al. 2018; Khaustov & Ermilov 2018). In this paper, we describe a new species H. lindquisti Xu & Zhang sp. nov. collected from pine bark in Fuzhou city, China, which represents a new record of the Tarsocheylidae to China.
Material and methods
The dead trees of Pinus massoniana Lamb. infested by Monochamus alternatus were collected in Minhou county, Fuzhou city, Fujian province, China. The specimens were extracted from the bark using a Berlese funnel and separated under a stereomicroscope. All mites were removed and cleared in lactic acid, and mounted in Hoyer's medium. Specimens were examined at 400x and 1000x magnification by using differential interference contrast of a Leica DM5000B compound microscope.
In the descriptions, nomenclature for idiosomal and leg setae follows that of Lindquist (1986, 1987), and nomenclature for subcapitular, palp and cheliceral setae follows Khaustov (2015) and Khaustov & Ermilov (2018). All measurements are given in micrometers (μm). The measurements of the holotype are presented, followed by the paratype as a range in parentheses. For leg setae the number of solenidia is given in parentheses. Legs were measured from the base of trochanter to the tip of tarsus excluding claws.
Systematics
Family Tarsocheylidae Atyeo and Baker, 1964
Genus
Hoplocheylus
Atyeo and Baker, 1964
Type species: Tarsocheylus atomarius Berlese, 1913, by original designation
Hoplocheylus lindquisti Xu & Zhang sp. nov. (Figs 1–7)
Description
FEMALE (Figs 1, 2, 3A). Body weakly sclerotized. Length of idiosoma 425 (375-440), length of body including gnathosoma 475 (420-485), width 100 (75-100).
Gnathosoma (Fig. 3A). In dorsal view, stylophore subtrapezoidal, 50 (45-50) length, 45 (42-47) width, movable digits blade-like. Palps 3-segmented, trochanter inconspicuous, without setae; femurogenu with two setae, femoral seta longer than genual seta; tibiotarsus with large tibial claw; setae ba and l’ basally fused and modified into paired dome-like spines; eupathidia ul’ and ul” represented by duplex of setae. Solenidion ω weakly clavate. Postpalpal setae (pp) peg-like. Length of gnathosomal setae: cha 15 (14-16), chb 5 (4-6), m 15 (10-17), n 38 (30-45), or 5 (4-5). Subcapitular setae m less than half of n. Hypostome with a pair of short spine-like hypostomal papillae. Pharynx thin-walled, without lateral projections.
Idiosomal dorsum (Fig. 1A). Prodorsum with large, weakly sclerotized, smooth prodorsal shield, with numerous small round dimples in posterior half. Stigmata oval, not prominent, associated with long tracheal trunks. Setae v2 blunt-ended; v1 and sc2 pointed; and bothridia sc1 with capitate sensilla. Opisthosomal tergite normally developed. Setae c1, d, e and h2 blunt-ended, other dorsal setae pointed. Cupules normal, ia inserted on membranous integument on both sides of tergite D, im located posteriorly to e, ip posterior to f, ih posterior to h2. Lengths of dorsal setae: v1 43 (40-47), v2 15 (11-17), sc1 20 (18-21), sc2 58 (50-58), c1 18 (16-22), c2 53 (47-55), d 18 (18-20), e 20 (17-20), f 46 (42-53), h1 46 (42-53), h2 18 (15-18). Anal opening terminal, flanked by a pair of plates bearing three pairs of setae, ps1 42 (42-45), ps2 32 (32-38), ps3 8 (6-8). Idiosomal venter (Fig. 1B). Large rectangular midsternal plate situated in the space between coxal fields II and III. Weakly sclerotized apodemes 4 (ap4) and 5 (ap5) present between coxal fields II and IV and near the posterior margin of coxal fields IV, respectively. Setae 4a and ag1 located on narrow longitudinal smooth plates. Aggenital plate with deep incision on posterior margin, with two pairs of aggenital setae ag2 and ag3. Genital opening elongated with four pairs of genital setae (g1, g2, g3 and g4). Coxal setation 4-3-3-3, all coxal setae blunt-ended except 1c and 2b pointed. Lengths of ventral setae: 1a 11 (8-11), 1b 9 (7-9), 1c 21 (15-22), 1d 7 (6-8), 2a 17 (15-17), 2b 45 (38-47), 2c 17 (15-19), 3a 12 (12-15), 3b 15 (12-15), 3c 12 (12-13), 4a 9 (9-11), 4b 8 (8-10), 4c 8 (6-10), ag1 13 (10-13), ag2 14 (12-14), ag3 15 (12-15), g1 10 (9-11), g2 6 (4-6), g3 6 (4-6), g4 6 (4-6).
Legs (Fig. 2). Lengths of legs: I 105 (93-120), II 60 (60-70), III 83 (68-85), IV 110 (90-110). Leg I (Fig. 2A). Leg setation: Tr 1 (v’), Fe 5 (d, l’, l”, v’, bv”), Ge 5 (d, l’, l”, v’, v”), Ti 6 (2) (d, l’, l”, v’, v”, k, ϕ1, ϕ2), Ta 14 (2) (p’, p”, tc’, tc”, ft’, ft”, pl’, pl”, u’, u”, pv’, pv”, s, bl’, ω1, ω2). Tarsus with a pair of simple hooked claws, empodium absent. Lengths of solenidia: ω1 5 (5-7), ω2 3 (3-5), ϕ1 7 (7-8), ϕ2 4 (3-5). Solenidion ω1 finger-shaped, approximately reaching tip of tarsus. Solenidion ω2 clavate, situated near the base of seta pl”. Seta ft’, ft”, p’, p”, tc’, tc”, bl’and pv” thick and slightly blunt-ended. Seta p’ approximately as long as setae p”; setae ft’ and ft” subequal. Tibia I solinidion ϕ1 clavate distally, ϕ2 about half of ϕ1 and clavate. Seta k thickened. Setae v’, bv” and l’ of femur, and v’ and l’ of tibia blunt-ended, other leg setae pointed. Leg II (Fig. 2B). Leg setation: Tr 1 (v’), Fe 3 (d, l’, v”), Ge 4 (l’, l”, v’, v”), Ti 5 (1) (d, l’, l”, v’, v”, ϕ), Ta 8 (1) (tc’, tc”, p’, u’, u”, pv’, pv”, pl”, ω). Tarsus with a pair of hooked claws. Empodium flipper-like, with weakly undulate distal margin. Lengths of solenidia: ω 4 (4-5), ϕ 3. Solenidion ω finger-shaped. Seta p’ imperceptibly bifurcated at tip. Tibia II with solenidion ϕ clavate. Seta d longer than l’, v’, l” and v”. Leg III (Fig. 2C). Leg setation: Tr 2 (l’, v’), Fe 2 (d, v’), Ge 4 (l’, l”, v’, v”), Ti 5 (1) (d, l’, l”, v’, v”, ϕ), Ta 8 (tc’, tc”, p’, u’, u”, pv’, pv”, pl”). Solenidion ϕ 3 weakly clavate. Claws and empodium as on tarsus II. Seta p’ of tarsus and l’ of trochanter weakly blunt-ended, other leg setae pointed. Leg IV (Fig. 2D). Leg setation: Tr 1 (v’), Fe 2 (d, v’), Ge 5 (d, l’, l”, v’, v”), Ti 5 (d, l’, l”, v’, v”), Ta 7 (tc’, tc”, p’, u’, u”, pv’, pv”). Claws and empodium as on tarsus II. Seta p’ of tarsus and d of genu weakly blunt-ended, other setae pointed.
MALE (Figs 3C–E, 4–5). Body weakly sclerotized. Length of idiosoma 320-360, length of body including gnathosoma 360-400, width 80-90. In dorsal view, stylophore subtrapezoidal, 40-45 length, 34-38 width, movable digit blade-like. Length of gnathosomal setae: cha 12, chb 4-5, m 12, n 26-30, or 3-4. Idiosomal dorsum and venter (Fig. 4) as in female except aggenital plate and genital area fused. Lengths of dorsal setae: v1 30-36, v2 10 -12, sc116-18, sc2 44-47, c1 13-18, c2 42-48, d 15-18, e 15-17, f 37-38, h1 34-37, h2 12-15, ps1 30-33, ps2 18-26, ps3 7. Lengths of ventral setae: 1a 8-10, 1b 6-7, 1c 12-13, 1d 4-5, 2a 12-15, 2b 22-30, 2c 11-15, 3a 10-12, 3b 11-13, 3c 10-11, 4a 8-10, 4b 6-8, 4c 6-8, ag1 9-11, ag2 11, ag3 11-12, g1 5-6, g2 5-6, g3 5-6, g4 5-6. Legs (Fig. 5). Lengths of legs: I 92-100, II 52-55, III 62-68, IV 82-85. Leg setation as in female. Lengths of solenidia: I ω1 6, ω2 3, ϕ1 7, ϕ2 3-4, II ω 3-4, ϕ 3, III ϕ 3.
DEUTONYMPH (Figs 3B, 6). Body weakly sclerotized. Length of idiosoma 320-330, length of body including gnathosoma 360-370, width 78-80. Length of gnathosomal setae: cha 12-13, chb 3-4, m 12-13, n 26-30, or 3-4. Idiosomal dorsum as in female, except sc1 blunt-ended. Lengths of dorsal setae: v1 22-36, v2 6-10, sc1 9-12, sc2 35-48, c1 15-18, c2 42-45, d 15-17, e 13-16, f 38-43, h1 37-38, h2 15, ps1 29-31, ps2 27-28, ps3 5-6. Lengths of ventral setae: 1a 7-8, 1b 6, 1c 12-13, 1d 5, 2a 13-15, 2b 21-24, 2c 13, 3a 12-13, 3b 11-13, 3c 10, 4a 8-10, 4b 5-7, ag1 10-11, ag2 10-11, ag3 8-10, g1 5, g2 5. Legs (Fig. 6). Lengths of legs: I 92-93, II 58-62, III 70-72, IV 85-90. Leg setation as in female except trochanter IV without seta v’. Leg setation: I 1-5-5-6+2ϕ-14+2ω, II 1-3-4-5+ϕ-8+ω, III 2-2-4-5+ω-8, IV 0-2-5-5-7. Lengths of solenidia: I ω1 5-6, ω2 2-3, ϕ1 7, ϕ2 3-4, II ω 4, ϕ 3, III ϕ 2-3.
PROTONYMPH unknown.
LARVA (Fig. 7). Body weakly sclerotized. Length of idiosoma 215, length of body including gnathosoma 250, width 90. Length of gnathosomal setae: cha 11, chb 3, m 10, n 27. Idiosomal dorsum as in female. Lengths of dorsal setae: v1 29, v2 69, sc1 8, sc2 40, c1 15, c2 44, d 16, e 15, f 36, h1 32, h2 31, ps1 8, ps2 14, ps3 5. Lengths of ventral setae: 1a 12, 1b 6, 2a 13, 2b 14, 3a 14, 3b 10. Legs (Fig. 7). Lengths of legs: I 80, II 52, III 64. Leg setation: I 0-5-5-6+ϕ-14+ω, II 0-3-4-5+ϕ-8+ω, III 0-2-4-5+ω-8. Lengths of solenidia: I ω1 5-6, ω2 2-3, ϕ1 7, ϕ2 3-4, II ω 4, ϕ 3, III ϕ 2-3.
Type material
Holotype female, Guangming village, Minhou county, Fuzhou city, Fujian province, China, 17 Apr., 2019, by Yu-Zhen Zhu, Jie-Qin Wu and Yun Xu, ex. the barks of Pinus massoniana Lamb infested by Monochamus alternatus (Coleoptera: Cerambycidae). Paratypes: 15 females, 7 males, 3 deutonymphs and 1 larva, same data as holotype; 6 females, Lianguang village, Minhou county, 13 Mar., 2019, by Yu-Zhen Zhu, Jie-Qin Wu and Yun Xu. The holotype and 9 paratypes (4 females, 3 males, 1 deutonymph and 1 larva) will be deposited in the National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences, Beijing (NZMC); 23 paratypes (17 females, 4 males and 2 deutonymphs) are deposited in the Department of Plant Protection, Fujian Agriculture and Forestry University, China (FAFU).
Etymology
The new species is named in honour of the distinguished acarologist Evert E. Lindquist, who made great contributions to the systematic study of mites.
Differential diagnosis
The new species is similar to Hoplocheylus pickardi Smiley and Moser 1968 and H. magnificus Khaustov, 2015 by the absence of solenidion on tibia IV, setae 4a and ag1 situated on the plates, solenidion ω1 distinctly longer than ω2, setae p’ on tarsi II-IV distally bifurcated; but mainly differs in the following characters: solenidion ω1 on tarsus I not reaching beyond tip of claws (solenidion ω1 distinctly reaching beyond tip of claws in H. magnificus), tarsi I with 14 setae excluding solenidion (tarsi I with 13 setae in H. pickardi); chb minute about one-third of cha (chb and cha subequal in length in H. pickardi (according to Fig. 1 in Smiley and Moser, 1968) and H. magnificus); genital setae g2, g3 and g4 subequal in length, g1 about twice as long as g2 (4 pairs of genital setae subequal in length in H. pickardi (according to Fig. 2 in Smiley and Moser, 1968) and H. magnificus); anal setae ps3 about one-fourth of ps2 (pseudanal setae ps3 about half of ps2 in H. pickardi (according to Fig. 2 in Smiley and Moser, 1968) and H. magnificus).
FIGURE 1.
Hoplocheylus lindquisti Xu & Zhang sp. nov. (adult female). A. dorsal view of body; B. ventral view of body. Legs omitted.
FIGURE 2.
Hoplocheylus lindquisti Xu & Zhang sp. nov. (adult female, right side legs in dorsal view). A. leg I; B. leg II; C. leg III; D. leg IV.
FIGURE 3.
Hoplocheylus lindquisti Xu & Zhang sp. nov. A. ventral view of gnathosoma (adult female); B. ventral view of posterior hysterosoma (deutonymph); C–E (adult male). C. ventral view of palp; D. ventral view of gnathosoma; E. ventral view of posterior hysterosoma.
FIGURE 4.
Hoplocheylus lindquisti Xu & Zhang sp. nov. (adult male). A. dorsal view of body; B. ventral view of body. Legs omitted.
FIGURE 5.
Hoplocheylus lindquisti Xu & Zhang sp. nov. (adult male, right side legs in dorsal view). A. leg I; B. leg II; C. leg III; D. leg IV.
Acknowledgements
We are very grateful to Dr. Qing-Hai Fan (Plant Health & Environment Laboratory, Ministry for Primary Industries, Auckland, New Zealand) for review the manuscript, to Associate Prof. Mei-Xiang Wu (Fujian Agriculture and Forestry University, China) for her continued support in providing lab space to Yun Xu. This project was supported by The National Key Research and Development Program (2017YFD0600105), the National Natural Science Foundation of China (31702044) and China Postdoctoral Science Foundation (2017M612113).
