The oribatid mite subgenus Galumna (Galumna) (Acari, Oribatida, Galumnidae) in the Philippines

Abstract Five species of the subgenus Galumna (Galumna) (Acari, Oribatida, Galumnidae) are registered in the Philippine oribatid mite fauna. A new species, Galumna (Galumna) makilingensis sp. n., is described; it is most similar morphologically to Galumna (Galumna) tokyoensis Aoki, 1966, but differs from the latter by the morphology of porose areas Aa and Ap, rostral setae, and length of interlamellar setae. Three species, Galumna (Galumna) crenata Deb & Raychaudhuri, 1975, Galumna (Galumna) cf. exigua Sellnick, 1925 and Galumna (Galumna) khoii Mahunka, 1989, are recorded in the Philippines for the first time. The species Galumna (Galumna) crenata is redescribed. An identification key to the Philippine species of Galumna (Galumna) is given.


Introduction
Galumna (Galumna) is the largest subgenus of Galumna Heyden, 1826, comprising 161 species, which have a cosmopolitan distribution (based on data by Subías 2004Subías , updated 2014. In the course of taxonomic identification of oribatid mites from the Philippines, we found five species of this subgenus: one species is represented as a new to science and other four are already known ones (see Checklist section below). At present, only G. (G.) flabellifera Hammer, 1958 was reported from the Philippines (see Corpuz-Raros 1979;Corpuz-Raros and Gruèzo 2011).
The primary goal of the present paper is to describe and illustrate a new species. The secondary goal is to make a supplementary description of G. (G.) crenata based on the Philippine material, which was originally described by Deb and Raychaudhuri (1975) from India. The first description of G. (G.) crenata was incomplete, and lacks information on the length of morphological structures, leg setation, solenidia, gnathosoma, and the illustrations were insufficient.
In addition, we present an identification key to the Philippine species of Galumna (Galumna) below.

Material and methods
The species of Galumna (Galumna) were found in 11 sites: 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. The 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. General terminology used in this paper follows that of Grandjean (summarized by Norton and Behan-Pelletier 2009). Drawings were made with the drawing tube using the Carl Zeiss transmission light microscope "Axioskop-2 Plus" at Tyumen State University, Russia.
Material examined. Holotype (female) and one paratype (female): L-45. Type deposition. The holotype is deposited in the collection of the Zoological Institute of the Russian Academy of Sciences, St. Petersburg, Russia; one paratype (dissected) is deposited in the collection of the Tyumen State University Museum of Zoology, Tyumen, Russia.
Etymology. The specific name "makilingensis" refers to the type locality, Mt. Makiling, the forest reservation of the University of the Philippines Los Baños.
Material examined. Four specimens (two females and two males): L-1. Remarks. Galumna (Galumna) crenata distinctly differs from other species of the sugenus by the presence of dentate anterior tectum of epimere I. The available Philippine specimens of this species are morphologically and in general appearance similar to the Indian specimens (Deb and Raychaudhuri, 1975). Three main differences are as follows: 1) Body longer (348-390 versus 319-325 in Indian specimens). We believe these differences represent intraspecific (perhaps geographical) variability.
2) Anterior notogastral margin is well visible (versus completely absent in Indian specimens); also, the text of other paper (Sarkar et al. 2007) on G. (G.) crenata assert that it is present.
3) Rostral, lamellar and interlamellar setae developed (versus absent in Indian specimens). We believe these differences can be erroneous. The reason is that Deb and Raychaudhuri (1975) inadequately described this species and, probably, they overlooked these setae, because the rostral setae are usually strongly pressed to the prodorsum surface and are often not visible in dorsal and ventral views, and the lamellar and interlamellar setae are minute, well visible only under high magnification.  Aoki 1964Aoki , 1965Aoki , 1982