Fu, Liu ¹ ; Zhang, Feng ² and Chen, Jun ³

¹College of Life Science, Hebei University, Baoding, 071002, China & Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
²College of Life Science, Hebei University, Baoding, 071002, China.
³Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China & College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.

2023 - Volume: 63 Issue: 1 pages: 180-187

ZooBank LSID: 08142788-DD29-4924-8565-2978F98E557B

Original research

Keywords

Abstract

Introduction

The genus Christovizetes of the family Microzetidae was established by Krivolutsky (1975) with Christovizetes ovatus Krivolutsky, 1975 found in Tajikistan as the type species. Then, Mahunka (1995) reported the second species of the genus, C. prasadi, from Thailand, and Akrami and Behmanesh (2011) described the third congener, C. iranensis, from Iran. According to above three references, the main generic characters of this genus are as follows: tutorium wide and long, projecting from under the lamellae and with dense small setae; lamellae with numerous teeth on their external edge, located marginally and connected by a narrow translamella, with long lamellar setae.

During the study of oribatid specimens collected from caves in Southwestern China, the authors found a new species of Christovizetes, which is also a newly recorded genus from China.

In 1932, Willmann described Belba lengersdorfi from the stalactite cave, which is the first record of cave oribatid mites (Willmann 1932). Since then, more and more oribatid mites have been found in caves in Europe, Asia, and North America (Alexander 1995, Wauthy and Ducarme 2006, Nakamura et al. 2010). By 2021, 272 species in 89 genera representing 33 families of Oribatida have been reported from caves all over the world.

Up to now, there is only one reference about oribatid mites inhabiting caves in China, in which the authors (Yang et al. 2021) listed 20 families of Oribatida collected from four caves in Guizhou Province, southwestern China, without detailed information of collection and description for the taxa.

In present paper, the new species was described and a key to the all known species of Christovizetes was provided.

Material and methods

Soil samples with bat guano, humus, rat droppings, decaying wood, separately were collected from caves. The distance between the sampling site and the entrance of the cave was measured with laser range finder. The mites were extracted with Berlese-Tullgren funnels and kept into 80% ethyl alcohol. Observations, figures, measurements and descriptions were based on adult specimens mounted in temporary cavity slides. Drawings were made with a camera lucida connected with a Leica transmission light microscope ''Leica DM 2500″, and digitally inked in Photoshop (Adobe Photoshop CC 2018). The body length was measured in lateral view, from the tip of the rostrum to the posterior edge of the ventral plate. Notogastral and body width refers to the maximum width in dorsal view. Lengths of body setae were measured in lateral view. All body measurements are presented in micrometers. Formulas for leg setation are given in parentheses according to the sequence trochanter-femur-genu-tibia-tarsus (famulus included). Formulas for leg solenidia are given in square brackets according to the sequence genu-tibia-tarsus.

Morphological terminology used in this paper follows that of F. Grandjean: see Travé and Vachon (1975) for references, Norton (1977) for leg setal nomenclature, and Norton and Behan-Pelletier (2009) for overview.

All specimens are kept in alcohol and deposited in IZAS — the National Animal Collection Resource Center of China, Institute of Zoology, Chinese Academy of Sciences, Beijing (Zhang 2018).

The following abbreviations are used: lam = lamella; tu = tutorium; ro, le, in, bs, ex = rostral, lamellar, interlamellar, bothridial and exobothridial setae, respectively; c, la, lm, lp, h, p = notogastral setae; ia, im, ip, ih, ips = notogastral lyrifissures; gla = opisthonotal gland opening; h, m, a = subcapitular setae; v, l, d, cm, acm, ul, sul, vt, lt = palp setae; ω = palp and leg solenidion; cha, chb = cheliceral setae; Tg = Trägårdh's organ; Pd I, Pd II = pedotecta I, II, respectively; 1a, 1b, 1c, 2a, 3a, 3b, 3c, 4a, 4b, 4c = epimeral setae; dis = discidium; cp = circumpedal carina; g, ag, an, ad = genital, aggenital, anal and adanal setae, respectively; iad = adanal lyrifissure; Tr, Fe, Ge, Ti, Ta = leg trochanter, femur, genu, tibia, tarsus, respectively; p.a. = leg porose area; ω, σ, φ = leg solenidia; ɛ = leg famulus; v, ev, bv, l, d, ft, tc, it, p, u, a, s, pv, pl = leg setae.

Family Microzetidae

Genus Christovizetes Krivolutsky, 1975

Christovizetes longisaetosus sp. nov.

ZOOBANK: 6FEBBD2B-2C9E-4C2D-BE38-E05C99BF8FDC

(Figs. 1–3)

Material examined

Holotype: Male (in alcohol, IZAS-FL-21-412), China, Yunnan Province, Maguan County, Xinfa Zhai Village, Xinfa Zhai Cave, 23°10′33.51″N, 104°15′35.7″E, 1361m a.s.l., bat guano, 452m from the cave entrance, 14.X.2021, coll. Liu Fu.

Paratypes: (four males and one female in alcohol, IZAS-FL-21-412), with same data as the holotype.

Etymology

The specific name ''longisaetosus'' is a combination derived from the Latin words ''longus'' meaning long and ''saeta'' meaning seta, which refers the long notogastral setae of the new species. The name is given as Latin adjective.

Diagnosis

The new species is characterized by the combination of following characteristics: body size 263–300 × 175–187; each lamellar cusp bifurcated as four long and strong teeth, two inner teeth longer and thinner distinctly than two outers; interlamellar setae inserted in interlamellar region, adjacent to lamellae; notogastral setae lm, lp, h_1-3 long (23–25), smooth, lp located anterior to lyrifissure im; anterodistal and lateral margin of pteromorph dentate; aggenital setae smooth.

Description

Measurements — Body length: 263–300 (holotype: 300; five paratypes: 263–280); body width: 175–187 (holotype: 187; five paratypes: 175–180).

Integument — Body color light brownish. General body surface smooth.

Prodorsum — (Figs. 1A, C) — Rostrum conical, rostral setae (85–88) thin, long, and simple, flagellate distally. Lamellae very wide, connected by translamella and not covering prodorsum basally and medially, each lamellar cusp with four long and strong teeth, two outer teeth distinctly shorter and thicker than the two inner ones, first third of outer lamellar margin (anterior to le insertion) dentate, with five to eight small tooth-like projections, lamellar surface covered by longitudinal rugae, lamellar setae (110–113) thick, long and simple, flagellate distally, inserted on lamellar surface in median concavity of cusps. Interlamellar setae (25–27) slightly thick, spine-like, inserted in interlamellar region adjacent to lamellae. Bothridial setae (127–130) setiform, densely ciliate. Exobothridial setae (35–37) thick and barbed. Tutoria large, wide, projecting from under lamellae, anteriorly and laterally covered with dense bristle-like setae.

Notogaster — (Figs. 1A, C) — Notogaster wider than long (175–187 × 135–145), somewhat semicircular. Dorsosejugal suture well defined, slightly convex medially. Pteromorph some triangular-shaped, with fine wrinkles, anterodistal and lateral margins dentated. Nine pairs of notogastral setae thin, smooth; p₁ and p₂ (6) shorter than other setae obviously, lm, lp, h_1-3 (23–25) the longest. Setae la (12–15) located posterior-lateral to c (12–15), and lp anterior to lyrifissure im. Only lyrifissures im distinct, ia, ip, ih and ips not visible. Opisthonotal gland openings (gla) located posteriorly to im.

Gnathosoma — (Fig. 2) — Subcapitulum slightly longer than wide (68–70 × 60–63). Subcapitular setae (h, 13; m, 11; a, 8) setiform, h barbed, m and a smooth. Pedipalp (49–53) with setation 0-2-1-3-9 (+ω). Chelicera (57–60) with two setae, cha (13) and chb (12) thin, setiform.

Epimeral and lateral podosomal regions (Fig. 1B) — Epimeral setal formula: 3-1-3-3. All setae simple, barbed, 3b, 4c, and 1b (15) slightly longer than others (11). Pedotecta I and II with rugae. Discidium triangular. Circumpedal carinae thick, long, almost reaching anterior margin of PdI.

Anogenital region (Fig. 1B) — Six pairs of genital setae simple, g₁ (13) slightly barbed, distinctly longer than other minute smooth setae (g₂ –g₆ , 3), g₄ in a parallel line in respect to the others. One pair of aggenital setae (7–9) smooth. Two pairs of anal (4) and three pairs of adanal (4) setae thin, smooth, ad₃ inserted posterior level of an₁ . Adanal lyrifissure (iad) parallel and close to anal plate, located between ad₂ and ad₃ .

Legs — (Fig. 3) — All legs monodactylous. Claw of each leg smooth. Formulas of leg setation and solenidia: I (1-5-2-4-18) [1-2-2], II (1-5-2-4-15) [1-1-2], III (2-3-1-3-15) [1-1-0], IV (1-2-2-3-12) [0-1-0]; homology of setae and solenidia indicated in Table 1.

Remarks

On the basis of the diagnosis with tutoria large, wide, projecting from under the lamellae and covering with dense setae, lateral margin of lamella bearing small teeth, each lamella bifurcated at distal part, and lamellar setae long, the new species clearly belongs to the genus Christovizetes. However, there are some distinct morphological differences between the new species and the known species.

Christovizetes longisaetosus sp. nov. is morphologically most similar to C. prasadi Mahunka, 1995 from Thailand in having long rostral setae, well-developed translamella, slightly convex dorsosejugal suture, and the genital setae disposition, but differs from the latter by: the two inner teeth of lamellar cusp longer and thinner distinctly than the two outers (versus the two outers almost same shape as the two inners); interlamellar setae located in interlamellar region (versus on lamellar surface); notogastral setae lm, lp, h_1-3 similar in length as the interlamellar setae (versus those setae about 1/2 length of the interlamellar setae); setae lp anterior to lyrifissure im (versus posterior to im); aggenital setae smooth (versus barbed obviously); genital setae g₁ , as twice long as ag, distinctly longer than other minute genital setae (g₂-g₆ ), as half long as ag (versus g₁ slightly longer than other genital setae which are not minute).

Christovizetes longisaetosus sp. nov. differs from C. iranensis Akrami & Behmanesh, 2011 from Iran by: the inner two teeth of lamellar cusp longer than the outer two (versus the inner two slightly shorter than the outer two); setae lp anterior to lyrifissure im (versus posterior to im); genital setae g_1, as twice long as ag, distinctly longer than other minute genital setae (g₂-g₆ ), as half long as ag (versus setae g₁ slightly longer than other genital setae); genital setae g₄ in a parallel line in respect to the others (versus g_1-3 parallel, g_4-6 parallel); aggenital setae smooth (versus strongly barbed); translamella well-developed (versus weakly-developed); dorsosejugal suture slightly convex (versus distinctly convex); small pteromorphae (versus large).Christovizetes longisaetosus sp. nov. differs from C. ovatus Krivolutsky, 1975 from Tajikistan by: lamellar cusp divided into two branches, each branch bifurcated with two long teeth, and length of inner two teeth about 1/2 length of inner branch (versus lamellar cusp divided into two branches, but the outside branch without bifurcation, the inner one bifurcated with two small teeth, and length of teeth about 1/5 length of inner branch); notogastral setae c and la inserted on the base of the pteromorphae (versus on the median part of the notogaster); rostal setae long (versus short); pteromorphae dentate anterodistally and laterally (versus smooth).

Key to known species of Christovizetes

1. Outside branch of lamellar cusp without bifurcation, rostral setae distinctly short, almost same length as interlamellar setae, margin of pteromorphae smooth
...... C. ovatus Krivolutsky, 1975

— Outside branch of lamellar cusp divided distally into two teeth; rostral setae distinctly longer than interlamellar setae, margin of ptermorphae dentate
...... 2

2. Notogastral setae lp located anterior to lyrifissure im; genital setae g₁ much longer than other minute genital setae; aggenital setae smooth
...... C. longisaetosus sp. nov.

— Notogastral setae lp posterior to lyrifissure im; genital setae g₁ slightly longer than other genital setae; aggenital setae barbed
...... 3

3. Two inner teeth of lamellar cusp almost same shape as the two outers, interlamellar setae on the lamellar surface, notogastral setae lp located anterior to opisthonotal gland opening gla
...... C. prasadi Mahunka, 1995

— Two inner teeth of lamellar cusp obviously shorter and thicker than the two outers, interlamellar setae located in interlamellar region adjacent to lamellae, notogastral setae lp located posterior to opisthonotal gland opening gla
...... C. iranensis Akrami & Behmanesh, 2011

Acknowledgement

The authors thanks Shu-Jing Xu and Cheng-Lin Liu for their help in article preparing, Ze-Gang Feng for his help in specimen collecting. This work was supported by the National Natural Science Foundation of China (no. 32070421), the National Science & Technology Fundamental Resources Investigation Program of China (Grant No. 2019FY101800), and the Second Tibetan Plateau Scientific Expedition and Research (STEP) Program (grant no. 2019QZKK05010600).

References

1. Akrami M.A., Behmanesh M. 2011. A new species of Christovizetes Krivolutsky (Acari: Oribatida: Microzetidae) from Iran. Syst. Appl. Acarol., 16: 247-251. https://doi.org/10.11158/saa.16.3.9
2. Alexander B. 1995. Cave-dwelling oribatid mites (Acarina, Cryptostigmata) from east Austria. Verh. Zool-Bot. Ges. Österreich., 132: 81-107.
3. Krivolutsky D.A. 1975. In: Ghilyarov, M.S. (ed.) Opredelitel Obitayushcich v Pochve Kleschej- Sarcoptiformes. Nauka, Moskva. 491pp.
4. Mahunka S. 1995. Christovizetes prasadi sp. n., a new microzetid species from Thailand (Acari: Oribatida). Int. J. Acarol., 21: 239-242. https://doi.org/10.1080/01647959508684066
5. Nakamura Y.N., Fukumori S., Fujikawa T. 2010. Oribatid fauna (Acari, Oribatida) from the Kumaya cave of Iheya village in central Ryukyu arc, south Japan, with a description of several new species. Acarologia, 50(4): 439-477. https://doi.org/10.1051/acarologia/20101988
6. Norton R.A. 1977. A review of F. Grandjean's system of leg chaetotaxy in the Oribatei (Acari) and its application to the family Damaeidae. In: Dindal, D.L. (Ed.), Biology of Oribatid Mites. SUNY College of Environmental Science and Forestry, Syracuse, pp. 33-61.
7. Norton R.A., Behan-Pelletier V.M. 2009. Chapter 15. Suborder Oribatida. In: Krantz, G.W. & Walter, D.E. (Eds.), A Manual of Acarology. Texas Tech University Press, Lubbock, pp. 430-564.
8. Travé J., Vachon M. 1975. François Grandjean. 1882-1975 (Notice biographique et bibliographique). Acarologia, 17 (1): 1-19.
9. Wauthy G., Ducarme X. 2006. Description of Hypogeoppia belgicae, a new species of cave mite (Acari, Oribatida), and comments on some characters. Belg. J. Zool., 136 (2): 203-218.
10. Willmann C. 1932. Milben aus Harzer Höhlen. Mitt. Höhlen- und Karstforsch., 1931-1932: 107-111.
11. Yang D.X., Li C., Wang C. 2021. Characteristics of soil meso-and microarthropods community inside and outside cave and the response to environmental factors. Chin. J. Ecol., 40 (10): 3184-3194.

instructions