Christovizetes Krivolutsky (Acari: Oribatida: Microzetidae), a newly recorded genus from caves in China, with description of a new species

A new species of oribatid mites of the genus Christovizetes (Acari: Oribatida: Microzetidae), Christovizetes longisaetosus sp. nov. is described based on adult specimens collected from caves in Yunnan Province, Southwestern China. This genus is reported from China for the first time. The new species could be distinguished from other three known species of the genus by the following combination of characteristics: (1) distinctly longer notogastral setae lm, lp, h1-3, (2) notogastral setae lp located anterior to lyrifissure im, (3) each lamellar cusp with four teeth, among which two inner teeth much longer and thinner than two outers, (4) aggenital setae smooth. A key to the four species of this genus is given.


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).
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.
Anogenital region (Fig. 1B) -Six pairs of genital setae simple, g 1 (13) slightly barbed, distinctly longer than other minute smooth setae (g 2 -g 6 , 3), g 4 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, ad 3 inserted posterior level of an 1 . Adanal lyrifissure (iad) parallel and close to anal plate, located between ad 2 and ad 3 .

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 g 1 , as twice long as ag, distinctly longer than other minute genital setae (g 2 -g 6 ), as half long as ag (versus g 1 slightly longer than other genital setae which are not minute).