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Oribatid Mites of the Superfamilies Gymnodamaeoidea and Plateremaeoidea (Acari: Oribatida) from Steppe of Russia

Badamdorj Bayartogtokh1 and Ilya Smelyansky2
1-Department of Zoology, Faculty of Biology, National University of Mongolia, Ulaanbaatar 210646, Mongolia, e-mail: bayartogtokh@num.edu.mn
2-Siberian Environmental Centre, P.O. Box 547, Novosibirsk 630090, Russia, e-mail: ilya@ecoclub.nsu.ru

Abstract

Oribatid mites belonging to the superfamilies Gymnodamaeoidea and Plateremaeoidea collected from steppe soils of Russia are studied. Two new species, Pedrocortesella minuta sp. nov. and Pleodamaeus tuberculatus sp. nov. are described. In addition, three known species, Licnodamaeus pulcherrimus (Paoli, 1908) and Plesiodamaeus glaber Mihelèiè, 1957 are redescribed, with notes on their distributions.

Keyword: Acari,Oribatida,Gymnodamaeoidea,Plateremaeoidea,new species,Russia

Introduction

The oribatid mite superfamilies Gymnodamaeoidea and Plateremaeoidea are known to be rather diverse mostly in the Northern Hemisphere and
most species are inhabitants of litter of forests, mosses, decaying woods and organic and mineral soil layers. However, many species of
Plateremaeoidea are xerophilous, and they distributed in the soils of arid habitats such as steppe and semideserts. The present work is part of the series of studies on systematics and ecology of oribatid mites of grassland habitats of Russia, Kazakhstan and Mongolia. The description of two new species belonging to the genera Pedrocortesella and Pleodamaeus and the supplementary description of two known species of the genera Licnodamaeus and Plesiodamaeus are presented here. Ruiz et al. (1990) included the species Plesiodamaeus glaber Mihelèiè, 1957 in the genus
Jacotella Banks, while Woas (1992) listed this species under the genus Gymnodamaeus Kulczynski. However, the articulation of leg segments in species of Jacotella is in sockets, while that in Plesiodamaeis-species is not in sockets. Members of another genus, Gymnodamaeus have
contiguous anal and genital apertures as opposed to the well separated openings in species of Plesiodamaeus. Moreover, all species of
Plesiodamaeus have distinctly developed prominent folds on the posterior end of the notogaster, but not developed in the species of Gymnodamaeus. Therefore, we consider Plesiodamaeus as a valid genus, although the current supraspecific classification of Gymnodamaeoidea and Plateremaeoidea is artificial and too restrictive.

Material and Methods

The species were collected between 1991 and 1999 from soils in grassland habitats of the southwestern part of Russia. Descriptions or
redescriptions of the species are based on adults. The type locality and habitat characteristics for each species are given in the respective “Material
examined” sections. The taxonomic terminology used in this paper is based on that (with a few modifications) developed by Grandjean (1931, 1933, 1964), as summarized and applied by Covarrubias (1968), Fernandez (1987) and Paschoal (1982). Body length is measured in lateral view, from the tip of the rostrum to the posterior edge of the notogaster. Notogastral length is measured in lateral aspect, from the anterior to the posterior edge. Notogastral width refers to the maximum width in dorsal aspect. Measurements are given in micrometers and the average values are given in parentheses after the ranges.