To the knowledge of the genus Sadocepheus (Acari, Oribatida, Compactozetidae)

The oribatid mite genus Sadocepheus Aoki, 1965 is recorded for the first time from the Philippines; one new species is described from the leaf litter of secondary forest in Mindanao Island. Sadocepheus donvictorianoensis Ermilov & Corpuz-Raros sp. nov. differs from the most similar species, S. elevatus Mahunka, 1987 by the larger body size, long medial and short lateral teeth of the lamellae and shorter adanal setae. Revised generic diagnosis and the data on distribution and ecology of Sadocepheus species are presented. close to each other dorsally. Trägårdh’s organ tapered. Epimeral setal formula 3–1–3–3. Pedotecta I represented by large laminae, pedotecta II quadrangular in ventral view. Discidia strong, elongate triangular. Six to nine pairs of genital, one pair of aggenital, two pairs of anal and three pairs of adanal setae setiform. Adanal lyrifissures located close to anal aperture, in paraanal or inverse apoanal positions. Legs monodactylous.

During taxonomic study of the Philippine mite material, we found a new species of Sadocepheus. This genus is recorded for the first time from this country. The main goal of the paper is to describe and illustrate a new species, revise generic diagnosis and give information on distribution and ecology of Sadocepheus species in the world.
This work is part of our study on the oribatid fauna of the Philippines (e.g. Ermilov & Corpuz-Raros 2015, 2016, 2017.
Specimens were mounted in lactic acid on temporary cavity slides for measurement and illustration. 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 of notogaster in dorsal view. Lengths of body setae were measured in lateral aspect. 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-tibiatarsus. Drawings were made with a camera lucida using a Leica transmission light microscope "Leica DM 2500". Morphological terminology used in this paper follows that of F. Grandjean: see Travé & Vachon (1975) for references, Norton (1977) for leg setal nomenclature, and Norton & Behan-Pelletier (2009), for overview.
The following collection is used: TSUMZ -Tyumen State University Museum of Zoology, Tyumen, Russia.
Juvenile instars. Not known.

Leg
Tr Fe Ge Ti Ta

(tc), (p), (u), (a), s, (pv)
Roman letters refer to normal setae, Greek letters refer to solenidia (except ɛfamulus). One apostrophe (') marks setae on anterior and double apostrophe (") setae on posterior side of the given leg segment. Parentheses refer to a pair of setae Type deposition. The holotype (female) and two paratypes (female and male) are deposited (ethanol with drop of glycerol) in TSUMZ.
Etymology. The specific name "donvictorianoensis" refers to Don Victoriano, the Philippine municipality (in Misamis Occidental Province, Mindanao Island), where holotype and one paratype of the new species were discovered.
Remarks. Sadocepheus donvictorianoensis Ermilov & Corpuz-Raros sp. nov. is morphologically most similar to Sadocepheus elevatus Mahunka, 1987 from Borneo in having bifurcate lamellae and long adanal setae. However, the new species differs from the latter by the larger body size (747-780 × 630 versus 542-591 × 486-518), long medial and short lateral teeth of the lamellae (versus teeth similar in length) and setiform adanal setae shorter than length of anal plates (versus adanal setae flagellate, longer than length of anal plates.
The species S. breviseta (Balogh, 1986) was described from Bogota, Columbia without information on sample type (Balogh 1986); S. dubius Hammer, 1979 was collected from ferns, liverworts, Selaginella, mosses on branches and roots, different small plants and dead leaves on mountain slope with scattered, tall trees and shrubs in the Selecta Park, Java (Hammer 1979); S. elevatus Mahunka, 1987 was found in dry and decaying leaf litter in forests of Sepilok, Borneo (Mahunka 1987); S. foveolatus Luxton, 1988 was recorded from wet moss beneath beech in Canaan Road, Takaka Hill, Nelson, New Zealand (Luxton 1988); S. franzi (Balogh, 1986) was described from soil in Cuesta la Starria, Chile (Balogh 1986); S. granulatus (Balogh & Mahunka, 1969) was collected from decaying leaves interwoven with hyphae in forest about 20 km from Manaus, Brazil (Balogh & Mahunka 1969), also known from Paraguay without information on sample type (Balogh & Mahunka 1981) and different Brazilian localities (see summarized data from Oliveira et al. 2017); S. longisetus (Balogh, 1986) was reported from litter or rain forest in eastern Cordilles at Monterredondo, Colombia (Balogh 1986); S. makarchevae Sitnikova, 1975 was found from litter and dust of stub of forest in Primorsky Kray, Russia (Sitnikova 1975a); S. subniger (Ewing, 1917) was collected from ground under old pieces of forest in Iowa, U.S.A. (Ewing 1917); S. tohokuensis Fujikawa, 2003 was described from lichens and misses on the trunks of living beech trees in Nippon, Japan (Fujikawa 2003); S. undulatus undulatus Aoki, 1965 was reported from Sado Island, Japan without information on sample type (Aoki 1965), some localities in Japan (e.g. Aoki et al. 2004;Harada et al. 2008) and China (see summarized data from Chen et al. 2010); S. undulatus setiger Fujita & Fujikawa, 1986 was collected from shady place, covered with bamboo-grass, and fern in mixed forest of Naroyo, Japan (Fujita & Fujikawa 1986); S. yakuensis Aoki, 2006 was described from Shiratani Unsui Valley, Yaki Island, the Okinawa Islands, Japan without information on sample type (Aoki 2006).