﻿Two new species and new records of Otocepheidae (Acari, Oribatida) from Yunnan, Southwest China

﻿Abstract This work includes taxonomic data on four species of oribatid mites of the family Otocepheidae from Yunnan, China. Two new species of the genera Basiceramerus and Eurostocepheus are described, respectively. Basiceramerusovatussp. nov. differs from B.bangladeshensis Corpuz-Raros & Gruèzo, 2008 by the wavy marginalis passing the base of the adanal setae, prodorsal condyles well separated from median ones, a ventral ridge present, and the anal plate foveolate; it differs from B.igorotus Corpuz-Raros & Gruèzo, 2011 from Vietnam by the wavy marginalis passing the base of the adanal setae, a connected tutorium and lamelliform expansion, a ventral ridge present, a smooth genital plate, and seta an2 located close to the median margin of the anal opening; it differs from B.igorotus from the Philippines by the lamellar setae inserted behind the tip of the lamella, separated prodorsal condyles, lyrifissure im posterior to gla, genital plate smooth, anal plate foveolate, and the wavy marginalis passing the base of the adanal setae. Eurostocepheus (Eurostocepheus) sinutussp. nov. differs from other known species of this genus by having a ventral groove between the genital aperture and the ventral ridge, eight pairs of notogastral setae, and distinctly shorter and thinner notogastral setae p1, p2, p3, h3. Eurostocepheus (Eurostocepheus) aquilinus Aoki, 1965 and E. (E.) mahunkai Mondal & Kundu, 1999 are reported for the first time from China.


Introduction
During identification of the oribatid mite material collected from Yunnan, Southwest China, we found four otocepheid species; among them two species are new to science belonging to the genera Basiceramerus and Eurostocepheus, and the others, Eurostocepheus (Eurostocepheus) aquilinus Aoki, 1965 and E. (E.) mahunkai Mondal & Kundu, 1999, are new records for China.
Basiceramerus was proposed by Corpuz-Raros with Basiceramerus upelbensis Corpuz-Raros, 1979 as the type species. Currently, the genus comprises six species, which are distributed in the subtropics of Asia: the Philippines, Bangladesh and Vietnam (Subías 2004(Subías , online version 2021. Before the present study, this genus had not been reported from China. The species herein described follows the generic characters (based on data from Corpuz-Raros 1979;Corpuz-Raros and Gruèzo 2008): fused median notogastral condyles present, apodemata II and apodemata sj long, 4 pairs genital, 1 pair aggenital, 2 pairs anal, 3 pairs adanal setae present, and leg setae u setiform (L-type) on tarsi I, thorn-like (S-type) on tarsi II-IV.
Eurostocepheus Aoki, 1965, which is distinguished from other genera of Otocepheidae mainly by its disproportionately dilated pedotectum II and conspicuously developed costula, comprises two subgenera: Eurostocepheus (Eurostocepheus) Aoki, 1965 and Eurostocepheus (Cerostocepheus) Mahunka, 1973. The main subgeneric difference lies in the number of genital setae, either 4 or 5 pairs respectively. Nine species of this genus, all from the Oriental region, were hitherto reported (Subías 2004(Subías , online version updated in 2021; among them only one species, Eurostocepheus (E.) heterotrichus Wen, 1999, has been recorded in China (Wen 1999;Chen, Liu and Wang 2010). A revised generic diagnosis and an identification key to known subgenera and species of this genus were given by Ermilov and Starý (2017).
In the following study, the two new species Basiceramerus ovatus sp. nov., Eurostocepheus (Eurostocepheus) sinutus sp. nov., are described and illustrated based on adults, and expanded descriptions and illustrations of E. (E.) aquilinus and E. (E.) mahunkai based in part on new information are provided.

Materials and methods
Specimens were mounted in lactic acid on temporary cavity slides for measurement and illustration. The body length was measured in lateral view, from the tip of the rostrum to the posterior edge of the ventral plate. Notogastral width refers to the maximum width in dorsal aspect. Lengths of body setae were measured in lateral aspect. All body measurements are presented in micrometers. Formulae for leg setation are given in parentheses according to the sequence trochanter-femur-genu-tibia-tarsus (famulus included). Formulae for leg solenidia are given in square brackets according to the sequence genu-tibia-tarsus.
Notogaster. L/W of notogaster about 1.3. Lateral notogastral condyles triangular, with a tiny convex at bottom. One median notogastral condyle present, rounded. Ten pairs of notogastral setae, glabrous, setiform, nearly equal in length. Setae lm and lyrifissures im located nearly same level. All lyrifissures (im, ip, ih, ips, except ia) well visible in dorsal view, ip located between p 2 and p 3 , ips between h 3 and p 3 . Opisthonotal gland openings located anterior and very close to im. Vitta marginalis distinct.
Anogenital region. Genital plates smooth. Four pairs of genital setae (mutual distances g 1 -g 1 ≈g 2 -g 2 ≈g 4 -g 4 <g 3 -g 3 ). Aggenital lyrifissures located close and anterolateral to genital aperture. One pair of aggenital, two pairs of anal (mutual distances an 1 - an 1 <an 2 -an 2 , seta an 1 located close to median margin of anal opening) and three pairs of adanal setae similar in length. Setae ad 3 -ad 3 well below level of anterior margin of anal opening. Anal plate foveolate. Lyrifissures iad located in diagonal position and close to anal aperture, below level of anterior margin of anal opening. A wavy marginalis, like vitta marginalis, passing the base of adanal setae, ending beyond level of anterior margin of anal opening.
Type deposition. All type specimens are deposited in the collection of the Institute of Zoology, Chinese Academy of Sciences, Beijing (IZAS).
Etymology. The specific name "ovatus" is from Latin for "egg" refers to the oval notogaster in dorsal view.
Remarks. The new species is morphologically similar to B. bangladeshensis Corpuz-Raros & Gruèzo, 2008 from Bangladesh and B. igorotus Corpuz-Raros & Gruèzo, 2011 from the Philippines and Vietnam (Ermilov and Anichkin 2013) in having two median prodorsal condyles. However, the new species differs from B. bangladeshensis by the wavy marginalis, like vitta marginalis, passing the base of adanal setae (vs. none), prodorsal condyles well separated from the median ones (vs. all prodorsal condyles touching at base), ventral ridge present (vs. none), anal plate foveolate (vs. granulate, without foveolae). The species B. igorotus was reported from the Philippines and Vietnam by Corpuz-Raros and Gruèzo (2011) and Ermilov and Anichkin (2013) respectively. The latter recorded instances of intraspecific or geographical variability based on their specimens from Vietnam: body size larger and more elongate, interlamellar setae shorter, lamellar setae longer, lateral notogastral condyles narrower, medial notogastral condyles touching base of lateral notogastral condyles, genital plate smooth in the Vietnamese specimens. The new species differs from B. igorotus from Vietnam by the wavy marginalis passing the base of adanal setae (vs. none), tutorium and lamelliform expansion nearly touching (vs. well separated), ventral ridge present (vs. none), genital plate smooth (vs. finely striate), seta an 1 located close to the median margin of the anal opening (vs. an 1 well removed from median margin of anal opening); it differs from B. igorotus from the Philippines by the lamellar setae inserted behind the tip of the lamella (vs. lamellar setae arising outside the base of cuspis), separated prodorsal condyles (vs. prodorsal condyles all touching at base), im posterior to gla (vs. im anterior to gla), genital plate smooth (vs. finely striate), anal plate foveolate (vs. granulate), wavy marginalis, like vitta marginalis, passing the base of adanal setae (vs. none). Table 1. Leg setation and solenidia of adult Basiceramerus ovatus sp. nov. Roman letters refer to normal setae, Greek letters to solenidia (except ɛ=famulus). Single prime (') marks setae on the anterior and double prime (") setae on the posterior side of a given leg segment. Parentheses refer to a pair of setae. Tr -trochanter, Fe -femur, Ge -genu, Ti -Tibia, Ta -tarsus.

Leg
Tr Integument. Body color dark brownish. Body surface relatively smooth. Prodorsum. Rostrum broadly rounded. Rostral setae curved inward, densely barbed outside. Lamellar setae inserted behind tip of costula, curved inward, roughened externally. Interlamellar setae slightly barbed. Bothridial setae with a long fusiform head and a curved peduncle in dorsal view. Exobothridial setae short, hardly visible in dorsal view. Costula strong, weakly "S" shaped, largest width of mutual distance anteriorly, curved inward around setae le. Bothridium opening laterally, dorsal bothridial plate nearly straight, ventral bothridial plate invisible in dorsal view. Tutorium developed weakly. Lamelliform expansion curved and pointing to base of seta ro in lateral view. Two pairs of prodorsal condyles present, lateral prodorsal condyles broadly flattened and wide, median prodorsal condyles drop-shaped.
Notogaster. L/W of notogaster about 1.1. Surface of notogaster relatively smooth in dorsal view, without visible foveola or granules. Anterior margin of notogaster distinctly moved forward. Lateral notogastral condyles trapezoid, with triangular tip outside, which markedly anterior to medial prodorsal condyles. Median notogastral condyles absent. Eight pairs of notogastral setae, c, la, lm, lp longer than others distinctly, setiform and slightly barbed distally, p 1 , p 2 , p 3 , h 3 short and ciliform. All lyrifissures well visible, ip located between p 1 and p 2 on left side while it between p 2 and p 3 on right side, ips between h 3 and p 3 . Opisthonotal gland openings located close to lyrifissure im. Vitta marginalis distinct. Lyrifissures im and setae lm almost located at same level.
Legs. Monodactylous. Claw of each leg strong and smooth. Formulae of leg setation and solenidia (Table 3) Type deposition. Type specimen is deposited in the collection of the IZAS. Etymology. The specific name "sinutus" is from Latin for "sinus" refers to the ventral groove between genital aperture and ventral ridge.
Remarks. As possessing the conspicuously developed costula and the distinctly dilated posterior pedotecta II, which are diagnostic characters of the genus, this new species should be placed into the genus Eurostocepheus. The new species can be easily distinguished from other known species of this genus by its huge body size, eight pairs of notogastral setae and its ventral groove between the genital aperture and the ventral ridge.

Diagnosis
Notogaster. L/W of notogaster about 1.3. Lateral notogastral condyles triangular. Median notogastral condyles absent. Ten pairs of notogastral setae nearly equal in length. All lyrifissures well visible, ip located between p 2 and p 3 , ips between h 3 and p 3 . Opisthonotal gland openings located close to lyrifissure im. Vitta marginalis distinct. Lyrifissures im and setae lm located nearly same level.
Anogenital region. Genital plates sculptured irregularly with several strong furrows. Four pairs of genital setae (largest mutual distance is g 3 -g 3 ). Aggenital lyrifissures located close and anterolateral to genital aperture. One pair of aggenital, two pairs of anal (mutual distances an 1 -an 1 <an 2 -an 2 ) and three pairs of adanal setae similar in length. Setae ad 3 -ad 3 below level of anterior margin of anal opening. Adanal lyrifissures located longitudinally and close to anal aperture, below level of anterior margin of anal opening.
Legs. Monodactylous. Claw of each leg strong and smooth. Formulae of leg setation and solenidia (Table 2)
Integument. Body color light brownish. Body surface densely foveolate (not well visible on notogaster).
Prodorsum. Rostrum broadly rounded. Rostral setae moderately curved inward, densely barbed outside. Lamellar setae inserted behind tip of costula, curved inward, roughened externally. Interlamellar setae slightly barbed. Bothridial setae with a long fusiform head and a strongly curved peduncle. Exobothridial setae short. Mutual distance of costula gradually narrow from base to tip. Bothridium opening laterally, dorsal bothridial plate nearly straight, ventral bothridial plate triangular in dorsal view. Tutorium fainted. Two pairs of prodorsal condyles present, lateral prodorsal condyles broadly rounded, with bottom straight, median prodorsal condyles rounded, not conspicuous, well separated from each other. Mutual distance between   absent. Ten pairs of notogastral setae slightly barbed, setiform. A pair of notchs present in external margin of anterior notogaster, beside lyrifissure ia. All lyrifissures well visible, ip located between p 2 and p 3 , ips between h 3 and p 3 . Opisthonotal gland openings located posterior and close to lyrifissure im. Vitta marginalis distinct. Lyrifissures im and setae lm located nearly same line.
Anogenital region. Genital plates covered with longitudinal furrows. Four pairs of genital setae (mutual distances g 1 -g 1 ≈g 2 -g 2 ≈g 4 -g 4 <g 3 -g 3 ). Aggenital lyrifissures located close and anterolateral to genital aperture. One pair of aggenital, two pairs of anal (mutual distances an 1 -an 1 ≈an 2 -an 2 ) and three pairs of adanal setae similar in length. Setae ad 3 -ad 3 below level of anterior margin of anal opening. Adanal lyrifissures located in diagonal position and close to anal aperture, below level of anterior margin of anal opening.