Systematic & Applied Acarology 22(7): 915–924 (2017) http://doi.org/10.11158/saa.22.7.2 Article
ISSN 1362-1971 (print) ISSN 2056-6069 (online)
http://zoobank.org/urn:lsid:zoobank.org:pub:A5483492-E8C7-4F1D-BAFB-0A48E525FF6E
New species of the family Steganacaridae (Acari, Oribatida, Phthiracaroidea) from Northeast China with keys to known species of Austrophthiracarus and Hoplophthiracarus from the Palaearctic Region DONG LIU1, 2 & DONGHUI WU1, 3 1
Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, P. R. China; e-mail:
[email protected] 2 College of Earth Sciences, Jilin University, Changchun 130061, P. R. China 3 Corresponding author: e-mail:
[email protected]
Abstract In this study, two new species of steganacarid mites (Oribatida: Phthiracaroidea) from Northeast China, Austrophthiracarus setiformis Liu sp. nov. and Hoplophthiracarus acuminatus Liu sp. nov., are described and illustrated. Keys to known species of Austrophthiracarus and Hoplophthiracarus from the Palaearctic Region are provided to facilitate further studies of these groups. Key words: soil mites, ptyctimous mites, morphology, systematics
Introduction The superfamily Phthiracaroidea (Oribatida), which has nearly 900 described species in 10 genera, is the largest group of ptyctimous mites (Niedbała 1994, Subías 2004, updated in 2017). According to the analysis of the morphological characters, Phthiracaroidea is divided into Phthiracaridae and Steganacaridae (Niedbała 1986). The monotypic family Phthiracaridae is represented by the genus Phthiracarus, while the other genera are grouped to the family Steganacaridae. While sorting and identifying oribatid mite specimens, we identified two new species of the family Steganacaridae from Northeast China, one belonging to the genus Austrophthiracarus Balogh & Mahunka, 1978, and the other to the genus Hoplophthiracarus Jacot, 1933. Austrophthiracarus was erected by Balogh and Mahunka (1978) with A. radiatus as type species and was reviewed by Liu and Zhang (2016). A diagnosis of Austrophthiracarus is given in Liu and Zhang (2016). At present, Austrophthiracarus is represented by 125 species worldwide, and 20 species in the Palaearctic Region (Niedbała and Liu, in preparation). Hoplophthiracarus was proposed by Jacot (1933) with Hoploderma histricinum Berlese, 1908 as type species and was reviewed by Liu (2015). The diagnosis of Hoplophthiracarus mainly follows Niedbała (2011), except with a small revision: setae d on femora I remote or near distal end of segment. At present, Hoplophthiracarus is represented by 50 species in the world, and 14 species in the Palaearctic Region (Niedbała and Liu, in preparation). The purpose of this paper is to give detailed descriptions of the two new species. Keys to species of Austrophthiracarus and Hoplophthiracarus of the Palaearctic Region are proposed to facilitate identification, as we expect more new species of both genera to be discovered from this region.
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Material and methods All specimens were submerged in lactic acid and mounted on temporary cavity slides for measurement and description by using a light microscope equipped with a drawing attachment. Length of the body was measured in lateral view, from the tip of the rostrum to the posterior edge of the ventral plate. Width of body refers to the maximum width in dorsal view. Lengths of setae were measured in lateral aspect. Setal counts for leg segments is given according to the sequence trochanter–femur–genu–tibia–tarsus (famulus included). Formula for leg solenidia is given in parentheses. The unit of measurement is micrometre (μm). Terminology generally follows Niedbała (2000, 2011). The type material is deposited in the Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, China (NIGA).
Descriptions of new species Austrophthiracarus setiformis Liu sp. nov. (Figs 1A–F) Diagnosis: Surface of body densely punctate; median crista, posterior furrows and lateral carinae of prodorsum absent; dorsal sigillar field narrow; sensilli and lamellar setae long setiform; interlamellar and rostral setae short and fine; exobothridial setae vestigial; 16 pairs of long and thick notogastral setae, pointed distally, and two pairs of lyrifissures ia and im present; setae c2 further from anterior border than setae c1 and c3; one additional setae present in h series; vestigial setae f1 positioned posterior to setae h1; mentum h>h–h; formula of genital setae 7(4+3): 2; setae g6 situated between level of setae g4–g5; ano-adanal plates with five pairs of setae, setae an, ad1 and ad2 long and straight, setae ad3 short and fine; setae d on femora I situated remote from distal end of segment, at level of setae v’. Description. Measurements. Holotype: Prodorsum: length 255, width 180, height 95, setae: ss 95, ro 33, le 65, in 18; notogaster: length 550, width 370, height 362; setae: c1 122, d1 118, e1 105, h1 120, ps1 120, ps4 55; ventral region: ad1 55, ad2 70, ad3 20, an1 55, an2 52; genito-aggenital plate 150×110, ano-adanal plate 195×115. Paratypes: Prodorsum: length 240–270, width 170–185, height 90–95; notogaster: length 540–565, width 380–400, height 350–365. Integument. Colour yellowish. Surface of body densely punctate (only seen at high magnification). Prodorsum (Figs 1A–B). Median crista, posterior furrows and lateral carinae absent; sigillar fields distinct, dorsal region narrow, longer than lateral regions; sensilli (ss) long, thick, rough and setiform; interlamellar and rostral setae (in and ro) short, smooth and fine, rostral setae slightly thicker than interlamellar setae; lamellar setae (le) long, thick and rough, slightly thinner than sensilli; exobothridial setae (ex) vestigial; comparative lengths: ss>le>ro>in; in/le≈0.3, ro/le≈0.5; mutual distance of setae: in–in/ro–ro≈4.3. Notogaster (Fig. 1A). 16 pairs of long (c1/c1–d1≈0.9) setae present, nearly all long, thick, rough and pointed distally, except setae cp, h3 and ps4 thinner and shorter; setae c2 further from anterior border than setae c1 and c3; one additional setae present (h1’) with distribution as depicted in Fig. 1A; distance between setae ps2 and ps3 shorter than that between ps3 and ps4; vestigial setae f1 positioned posterior to setae h1, vestigial setae f2 present; two pairs of lyrifissures ia and im present. Ventral region (Figs 1A, C–D). Setae h of mentum longer than distance between them. Nine pairs of genital setae (g) arranged in two rows with formula: 7(4+3): 2; setae g6 situated between 916
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level of setae g4–g5; ano-adanal plates each with five setae; anal setae (an) thick and rough; adanal setae ad1 and ad2 long, thick, straight and rough; setae ad3 short and fine, similar in shape as genital setae; comparative length: ad2>ad1=an1>an2>ad3. Legs (Figs 1E–F). Chaetotaxy of legs complete; setal counts for leg segments: I: 1-4-2(2)-5(1)20(3); II: 1-3-2(1)-3(1)-13(2), III: 2-2-1(1)-2(1)-10, IV: 2-1-1-2(1)-10; setae d on femora I inserted at level of setae v’, remote from distal end of segment, setae l” situated nearly at same level of setae v”; setae a” on tarsi I, and setae ft” and a” on tarsi II curved distally; setae s and pv’ on tarsi IV present; setae s on tarsi I and II present. Material examined. Holotype: adult (NIGA, in alcohol, LD-11-39), China, Heilongjiang Province, Wudalianchi, from leaves in coniferous and broadleaved mixed forest, 30 Jun. 2011, leg. Dong Liu and Xin Sun. Paratypes: two adults (NIGA, in alcohol, LD-11-39), same data as holotype; one adult (NIGA, in alcohol, LD-11-38), same data as holotype; one adult (NIGA, in alcohol, LD11-36), from leaves in forest, other data same as holotype. Etymology. The new specific name refers to the shape of the sensillus. Remarks. This new species is close to Austrophthiracarus inusitatus (Niedbała, 1983a) from the eastern Palaearctic region, Austrophthiracarus jumbongiensis Niedbała, 2002 (see Kaczmarek & Niedbała 2002) from South Korea and Austrophthiracarus filiformis Liu & Chen, 2014 from China in having a similar shape of the sensilli, 16 pairs of long and thick notogastral setae, distance between ps3 and ps4 longer than the distance between ps2 and ps3, and ano-adanal plates without additional setae. The new species can be differentiated from A. jumbongiensis by the following features: (1) lamellar setae thick, exobothridial setae vestigial (versus le thin and flexible, ex not vestigial in A. jumbongiensis); (2) setae c2 further from anterior border than setae c1 and c3 (versus setae c2 and c3 further than c1); (3) two pairs of notogastral lyrifissures ia and im present (versus three pairs ia, im and ips present); (4) formula of genital setae 7(4+3): 2 (versus 6(4+2): 3); (5) setae ad3 short and fine (versus long and thick); (6) setae d on femora I inserted far from distal end of segment (versus close to distal end). This new species is also distinguished from A. filiformis by the following characters: (1) lateral carinae of prodorsum absent (versus present in A. filiformis); (2) lamellar setae thick, exobothridial setae vestigial (versus le short and fine, ex not vestigial); (3) two pairs of notogastral lyrifissures ia and im present (versus all four pairs ia, im, ih and ips present); (4) setae c2 further from anterior border than setae c1 and c3 (versus setae c1 and c2 further than c3); (5) formula of genital setae 7(4+3): 2 (versus 6(4+2): 3); (6) setae ad3 short and fine (versus long and thick); (7) setae h of mentum longer than distance between them (versus setae h minute, hro>in (versus in long, le thin, ex not vestigial, in>ro>ex>le); (3) setae c2 further from anterior border than setae c1 and c3 (versus setae c2 and c3 further than c1); (4) notogastral setae rough (versus covered with small spines); (5) formula of genital setae 7(4+3): 2 (versus 6(4+2): 3); (6) setae g9 similar in length to g6, g7 and g8 (versus g9 much longer); (7) setae ad3 short and fine (versus long and thick); (8) setae d on femora I inserted far from distal end of segment (versus near distal end).
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FIGURE 1. Austrophthiracarus setiformis Liu sp. nov.: A, lateral view of body (legs removed); B, prodorsum, dorsal view; C, left side of ventral plate; D, mentum of subcapitulum, palpi removed; E, femur I; F, tibia IV. Scale bars: A–C=100 μm; D–F=50 μm.
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Hoplophthiracarus acuminatus Liu sp. nov. (Figs 2A–F) Diagnosis: Surface of body punctate; median crista, posterior furrows and lateral carinae of prodorsum absent; dorsal sigillar field narrow; sensilli short and fusiform; prodorsal setae short and fine, except lamellar setae longer; 15 pairs of short and thin notogastral setae, and two pairs of lyrifissures ia and im present; setae c2 further from anterior border than setae c1 and c3; vestigial setae f1 positioned posterior to setae h1; mentum hss>ro>ex>in; in/le=0.3, ro/le=0.5; mutual distance of setae: in–in/ro– ro≈3.5. Notogaster (Fig. 2A). 15 pairs of setae (c1/c1–d1≈0.3) present, short, thin and tapering distally; setae c2 further from anterior border than setae c1 and c3, and setae c1 further than c3; vestigial setae f1 positioned posterior to setae h1, vestigial setae f2 present; two pairs of lyrifissures ia and im present. Ventral region (Figs 2A, C–D). Setae h of mentum shorter than distance between them. Nine pairs of genital setae arranged nearly in one row, except setae g6 positioned slightly further from inner margin, at level between setae g4–g5, genital formula: 7(4+3): 2; ano-adanal plates each with five setae, similar in shape and length as notogastral setae; comparative length: ad2>an1>ad1=an2>ad3. Legs (Figs 2E–F). Chaetotaxy of legs complete; setal counts for leg segments: I: 1-4-2(2)-5(1)19(3); II: 1-3-2(1)-3(1)-12(2), III: 2-2-1(1)-2(1)-10, IV: 2-1-1-2(1)-10; setae d on femora I inserted at level of between setae v” and v’, remote from distal end of segment; setae a” on tarsi I and setae ft” and a” on tarsi II curved distally; setae s and pv’ on tarsi IV present; setae s on tarsi I and II present. Material examined. Holotype: adult (NIGA, in alcohol, CB-12-001), China, Jilin Province, Dunhua, Dapuchaihe Town, Changbai Mt., from litter in forest, 450 m a.s.l., 28 May 2012, leg. Dong Liu, Xin Sun and Donghui Wu. Paratypes: three adults (NIGA, in alcohol, CB-12-001), same data as holotype. Etymology. The new specific name alludes to the shape of the notogastral setae. Remarks. The new species is similar to Hoplophthiracarus sangumburiensis Niedbała, 2002 (see Kaczmarek & Niedbała 2002) from South Korea and Hoplophthiracarus niahensis Niedbała, 2008a from Borneo in the presence of short sensilli, short and fine prodorsal, notogastral setae, especially interlamellar setae short, two pairs of notogastral lyrifissures ia and im, and setae d on femora I remote from distal end of segment. However, this new species can be distinguished from them by: (1) dorsal sigillar field narrow (versus large in H. sangumburiensis and H. niahensis); (2) lateral prodorsal carinae absent (versus present); (3) sensilli narrowly fusiform (versus widely rounded); (4) vestigial setae f1 positioned posterior to setae h1 (versus anterior); (5) notogastral setae 2017
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of h and ps series not situated in one line (versus in one line); (6) vestigial setae f2 present (versus absent in H. sangumburiensis); (7) genital setae nearly arranged in one row, except setae g6, genital formula 7(4+3): 2 (versus all in one row, and formula 6(4+2): 3); (8) genua IV with setae (versus without setae in H. sangumburiensis). Compared with Hoplophthiracarus tryssos Niedbała, 2004 from Brazil and Hoplophthiracarus paratryssos Niedbała & Starý, 2015 from Madagascar, they have short sensilli, and similar shape of notogastral setae, but differ by the following characters: lateral prodorsal carinae absent (versus present in H. tryssos and H. paratryssos); interlamellar setae short (versus much longer); vestigial setae f1 positioned posterior to setae h1 (versus anterior); vestigial setae f2 positioned posteriorly above h3 (versus anteriorly above); notogastral setae of h and ps series situated not in one line (versus in one line); genital formula 7(4+3): 2 (versus 4: 5 in H. tryssos, 6(4+2): 3 in H. paratryssos); femora I with four setae (versus three setae in H. paratryssos); genua IV with setae (versus without setae in H. tryssos). Key to species of Austrophthiracarus known from the Palaearctic Region (type locality indicated) 1 Notogaster with 15 pairs of setae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 – 2 – 3 – 4 – 5 – 6 – 7 – 8 – 9 – 10 – 11 – 12 – 13
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Notogaster with more than 15 pairs of setae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Notogastral setae not all similar in shape, setae c2, c3, cp, h3 and ps4 smooth, filiform, others stronger, curved and barbed in distal half . . . . . . . . . . . . . . . . . . . . . A. duplex (Mahunka & Mahunka-Papp, 2010) (Greece) All notogastral setae similar in shape. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Notogastral setae longer, c1>c1–d1; genital setae g7 situated anterior to g5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. papillosus (Parry, 1979) (Austria) Notogastral setae shorter, c1h–h.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. heterotrichus (Mahunka, 1979) (Crete) SYSTEMATIC & APPLIED ACAROLOGY
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Dorsal prodorsal sigillar field longer than laterals; mentum h1/2h–h. . . . . . . . . . . . . . . . . . . . . . .A. pavidus (Berlese, 1913) (Italy) Head of sensilli rounded; mentum hc1–d1; vestigial setae f1 situated anterior to h1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. rabacalensis Niedbała, 2013 (see Niedbała & Dabert 2013) (Madeira) Notogastral setae shorter, c1
