One new species of the subgenus Cosmogalumna (Acari: Oribatida: Galumnidae: Galumna) from Japan with supplementary description of Galumna (Cosmogalumna) ornata Aoki, 1988

The present work deals with two members of the oribatid mite subgenus Galumna (Cosmogalumna) Aoki, 1988 from Japan. A new species, G. (C.) centroclathrata n. sp. is morphologically most similar to G. (C.) praeoccupata Subías, 2004 from China; however it differs from it by conspicuous granular ornamentation on the surface of the pteromorph, the shape of the polygonal sculpture on the notogaster, and a conspicuous linear sculpture on the middle part of the genital plates. Galumna (Cosmogalumna) ornata Aoki, 1988, the type species of the subgenus, is additionally described based on the specimens from the type locality. The position of lamellar setae slightly anteriad to L lines and the presence of 10 pairs of minute notogastral setae should be considered in any future identification of G. (C.) ornata.


INTRODUCTION
The family Galumnidae Jacot, 1925 includes 33 genera, 11 subgenera, 522 species and 33 subspecies (Subías 2004(Subías updated in 2016. Among the genera, Galumna Heyden, 1826 is the largest: it includes seven subgenera and 192 species (including nine subspecies). Of these, the nominotypical subgenus Galumna contains the majority (172 species and nine subspecies). Aoki (1988) proposed Cosmogalumna as a new genus based on the presence of notogastral polygonal sculpture. Currently, Galumna (Cosmogalumna) contains 11 species, which are distributed in Oriental, Neotropic and Palearctic Regions (Sub-ías 2004updated in 2016, Ermilov and Friedrich 2016. Modified subgeneric diagnosis and an identificaiton key to known species were proposed by Ermilov and Corpuz-Raros (2015). However, based on our observation on notogastral microsetae by SEM and modified subgeneric diagnosis provided by Ermilov and Corpuz-Raros (2015), the subgeneric diagnosis of Galumna (Cosmogalumna) can be further modified as follows: with characters of the genus Galumna (Ermilov et al. 2013); lamellar setae inserted usually between lamellar and sublamellar lines, rarely between lamellar lines; notogaster with 10 pairs of microsetae or setal alveoli; surface of notogaster covered by reticulate pattern.
During taxonomic survey of oribatid mites from Japan, we found two Cosmogalumna species; first one is the type species of the subgenus, Cosmogalumna ornata Aoki, 1988, and the other species is new. The main goal of this paper is to describe the new species and provide an additional description of Cosmogalumna ornata.
Oribatid mites were mounted in lactic acid on temporary cavity slides for measurement and illustration, with gam chloral liquied for permanent slides. For scanning electron microscopy (SEM), mites were fixed in 99.5% ethanol. Dehydration was conducted with graded ethanol series aceton and pentane. The specimens were placed on aluminum stubs with a double-stick carbon tape and coated with palladium-gold, then studied using Hitachi S3400-N scanning electron microscope. The morphological terminology used below is mostly that developed over many years by Grandjean (see Travé and Vachon, 1975 for references). All measurements are given as a range, with the mean in parentheses. Body length was measured in dorsal or ventral view, from the tip of the rostrum to the posterior edge of the ventral plate. Setal formulas are given as numbers per segment for appendages (from trochanter to tarsus, famuls included) as number per podosomal segment (I-IV). Diagnosis -Body length and width: 339 -356 × 252 -299 µm. Sexual dimorphism not observed. Sensillus with long stalk and short, rounded distally head with minute spicules. Lamellar setae inserted slightly anteriorly from line L. Dorsosejugal suture well developed. Middle part of notogaster and ventral plate ornamented with polygonal sculpture, remaining part minutely foveolated throughout. Notogastral porose areas with densely spotted surface. Medial pore (mp) on notogaster present. Surface of pteromorph ornamented with conspicuous granules centrally. Genital plates with conspicuous linear sculpture centrally. slightly barbed. Lamellar setae (le) (approx. 18 µm) thin, slightly barbed, inserted just anterior to line L. Interlamellar setae (in) minute (approx. 3 µm), thin, smooth, hard to see. Sensillus (ss) with long stalk and short, rounded distally head, covered by minute spicules. Exobothridial setae not observed. Dorsosejugal porose areas (Ad) oval; posterior to seta in. Dorsophragmata (hy) near anterior notogastral margin.
Type deposition -Holotype (NSMT-Ac 14208, female) on slide: mosses growth on the rocks by the stream in a Cryptomeria forest, Misatocho, Tsu city, Mie Prefecture, 34°45'49.8"N, 136°21'11.1"E, Roman letters refer to normal setae (e to famulus), Greek letters to solenidia. Single prime (') marks setae on anterior and double prime (") setae on posterior side of the given leg segment. Parentheses refer to a pair of setae.

Leg
Trochanter Femur Genu Tibia Tarsus  Aoki and Hu, 1993) from Yunnan Province, China in 1) long sensillus having rounded distally head with minute spicules, 2) polygonal sculpture on the middle part of notogaster and middle part of ventral plate, and 3) presence of medial pore on the notogaster. However, Galumna (Cosmogalumna) centroclathrata n. sp. differs from G. (C.) praeoccupata in having 1) conspicuous granular ornamentation on the whole surface of pteromorph, 2) polygonal sculpture on the dorsal side of notogaster has a form of a pair of weak arches connected in the middle part of notogaster (bended at both lyrifissure im and at the middle point of setae lp) spreaded transversely up to the mid-distance between notogastral setae la and gla at both side of notogaster, while in G. (C.) praeoccupata Subías, 2004, it has a form of straight band terminating on each side with a large cloud-like expansion, spreaded longitudinally between notogastral setae lm and nearby gla, spreaded transversely beyond the mid-distance between notogastral setae la and gla. 3) conspicuous linear sculpture on the genital plates. Integument (Figs. 6, 7A-C, E-H, 8A-F) -Body color brown to dark brown. Body surface fully foveolated minutely. Prodorsum with dense granules and striations; especially central part with larger granules, faint longitudinal striations along its lateral margins. Surface of pteromorph fully ornamented with conspicuous granules, with fine granules in anterior part. Notogaster fully ornamented with polygonal network. Surface of all porose areas ornamented with multiple conspicuous granules (approx. 3 µm) (see Aoki (1988), fig. 3). Anterior margin of ventral plate granulated, posterior to genital aperture ornamented with polygonal network except smooth posterior edge. Mentum plate with irregular granules. Each genital plate ornamented with granules, fine wrinkles in its distal edge, and longitudinal striation running nearly parallel with the median border. Surface of anal plate ornamented with irregularly shaped granules.

DISCUSSION
Two of Cosmogalumna species seem to be endemic to one of the southwestern islands of Japan: G. (C.) hiroyoshii from Ishigakijima Island and G. (C.) yonaguniensis from Yonagunijima Island. In contrast, G. (C.) ornata is recorded commonly, from various localities in southwestern archiperago in Japan, e.g. Nakanoshima Island as type locality, Takarajima Island, Tokashikijima Island, Miyakojima Island, Ishigakijima Island, Yonagunijima Island, and Okinawajima Island (Aoki, 2009). Therefore, this new species of Galumna (Cosmogalumna) found in Mie prefecture is the first record of the subgenus from Honshu Island in Japan, and the northernmost record of this subgenus in the world. Ermilov and Corpuz-Raros (2015) mentioned "notogaster with 10 pairs of setal alveoli" in their modified subgeneric diagnosis based on Aoki (1988). However, our SEM observation on the specimens of G. (C.) ornata Aoki, 1988 from its type localitiy showed the presence of ten pairs of very short (approx. 3 µm) notogastral setae (Fig. 8D). Aoki (1988) described lamellar setae as inserted between carinae L and S, however, our observation exhibits that the lamellar setae were inserted slightly anterior to the L lines. Aoki (1988) overlooked the location of setae. Ermilov and Corpuz-Raros (2015) mentioned "lamellar setae inserted usually between lamellar and sublamellar lines, rarely between lamellar lines" and our observation supports their modified subgeneric diagnosis. These corrections should be considered in any future identification of the species.