The oribatid mite genus Papillocepheus (Acari, Oribatida, Tetracondylidae), with description of a new species from southern Vietnam

Abstract The genus Papillocepheus is recorded in the Oriental region for the first time. A new species, Papillocepheus primus sp. n., is described from southern Vietnam; the description is based on specimens collected from semidecayed leaves and litter of Dong Nai Biosphere Reserve and Bu Gia Map National Park. The new generic diagnosis of Papillocepheus and an identification key to the known species of this genus are given.

In the course of taxonomic identification of Vietnamese oribatid mites collected in October and November 2013 we found one new species, belonging to the genus Papillocepheus. Hence, the genus is recorded in Vietnam and the Oriental region for the first time. The main purpose of our paper is to describe and illustrate this species.
Also, the new generic diagnosis of Papillocepheus and an identification key to the known species of this genus are provided.
All specimens were studied in lactic acid, mounted in temporary cavity slides for the duration of the study, and then stored in 70% ethanol in vials. Body measurements are presented in micrometers. 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. Formulae for leg setation are given in parentheses according to the sequence of trochanter-femur-genu-tibia-tarsus (famulus included). Formulae for leg solenidia are given in square brackets according to the sequence of genu-tibia-tarsus. Terminology used in this paper mostly follows that of Norton and Behan-Pelletier (2009 Balogh & Mahunka, 1966 New generic diagnosis (based partially on data from: Balogh and Mahunka 1966;Hammer 1966).
Tetracondylidae with the following combination of characters: costulae dorsal or dorso-lateral, reach the insertions of lamellar setae; transcostula present or absent; rostral, lamellar and interlamellar setae well developed, setiform or weakly dilated distally or medio-distally; sensilli with short stalk and clavate head; exobothridial setae absent; notogaster with 8-10 pairs of setae, all medium size or short; majority of notogastral setae clearly dilated in distal or medial part, phylliform or willow leaf shaped; medial prodorsal and notogastral condyles usually absent, when present, separated; epimeral formula 3-1-3-3, sometimes some setae absent or represented by alveoli; genital plates with three setae; aggenital setae present or absent; anal plates with two pairs of setae; three pairs of adanal setae present; adanal setae ad 3 located in lateral or preanal position; localization of adanal lyrifissures different among types; setae u of all leg tarsi setiform.
Integument. Body color yellow-brownish. Body surface and legs covered by granular cerotegument; granules conical (length up to 4). Body surface (including genital and anal plates) densely microfoveolate (diameter of foveolae up to 1). Lateral parts of prodorsum, notogaster and anogenital region additionally with larger foveolae (diameter of foveolae up to 6). Lateral region of body near to pedotecta II and anterior margin of notogaster partially tuberculate (diameter of tubercles up to 8).
Comparison. Papillocepheus primus sp. n. can be distinguished from all known species of the genus Papillocepheus by the key, which is presented below.  (Mahunka, 1978)