Redescription of Papillacarus hirsutus with remarks on taxonomic status of Papillacarus arboriseta (Acari: Oribatida: Lohmanniidae)

The adult instar of an oribatid mite, Papillacarus hirsutus (Aoki, 1961) is redescribed, including the first detailed descriptions of the gnathosoma and legs. Some morphological characters of P. hirsutus from different regions (Japan, Vietnam, China, Tahiti, Philippines) are analyzed, and P. arboriseta Jeleva and Vu, 1987 is recognized as a junior synonym of the former species.


INTRODUCTION
The oribatid mite family Lohmanniidae comprises 21 genera and 192 species that are collectively distributed in the pantropical and subtropical regions of the world (Subías 2004(Subías , online version 2010. Papillacarus is a lohmanniid genus that was proposed by Kunst (1959) with Lohmannia murcioides aciculata Berlese, 1904 as type species. It is one of the largest genera in the family, comprising more than 25 species, the majority of which have restricted geographical distribution.
Papillacarus hirsutus (Aoki, 1961) was described as Cryptacarus hirsutus from Japan. Subsequent collections showed it to be distributed more widely in tropical regions and the oriental part of Palearctics (Subías 2004(Subías , online version 2010. The original description (Aoki 1961) of this species was incomplete (lacking, for example, important information about the gnathosoma and legs), even after some subsequent redescriptions (Hammer 1972;Corpuz-Raros 1979;Wen et al. 1984). Our main objective is to provide a more complete redescription of this species. We also discuss the taxonomic status of P. arboriseta, which was briefly described by Jeleva and Vu (1987), based on specimens from northern Vietnam. These authors compared P. arboriseta only with P. ramosus Balogh, 1961, but they did not notice the great similarity of their species with P. hirsutus. As the differences between these two species were unclear, Balogh and Balogh (2002) considered P. arboriseta as a species inquirenda. Below, we compare topotypes of these two species and conclude that they are conspecific.

MATERIALS AND METHODS
Four adults (topotype materials) of P. hirsutus were obtained from Japan, 33°28' N, 139°35' E, Yokohama city, Kanagawa prefecture, 42 m above sea level, collected in dark loamy soil and litter in a Castanopsis forest (Castanopsis sieboldii): 08 August, by S. Shimano. Specimens are mounted whole on two slides, with Hoyer's medium.
Also, 20 adults of P. hirsutus were obtained from southern Vietnam, 11°25' N, 107°25' E, Cat Tien National Park, 149 m above sea level, from dark loamy soil of a Lagerstroemia forest, February-March 2009, collected by A.E. Anichkin. Specimens are stored in 70% alcohol in tubes. Vietnamese specimens were mounted in lactic acid on temporary cavity slides for measurement and illustration. All body measurements are presented in micrometers. Body length was measured in lateral view, from the tip of the rostrum to the posterior edge of the ventral plate, to avoid discrepancies caused by different degrees of notogastral distortion. Notogastral width refers to the maximum width in dorsal aspect. Lengths of body setae were measured in lateral aspect. Some specimens were dissected for detailed study.
Formulae for leg setation are given in parentheses according to the sequence trochanter-femurgenu-tibia-tarsus (famulus included). Formulae for leg solenidia are given in square brackets according to the sequence genu-tibia-tarsus.
Terminology used in this paper follows that of Grandjean (1950).
2. absence of neotrichial setae is obviously a misinterpretation. Some such setae are well visible in Figures 1a, 1b of Jeleva and Vu (1987, p. 11). Unfortunately, the figures of P. arboriseta provided by above authors are small-sized, so it is difficult to determine the exact number of neotrichial setae. All compared four topotype materials of P. arboriseta from central Vietnam show strongly developed neotrichial setae.

Character
Our data Literature data from: