Acta Arachnologica, 50(1); 15-20, September 28, 2001 A new damaeid mite of the genus Dyobelba (Acari: Oribatida: Damaeidae) from Korea Badamdorj Bayartogtokh', Seong-Sik Choi2& Jun-ichi Aoki3 Abstract - A new species of oribatid mite belonging to the genus Dyobelba is described from Korea. Dyobelba paucituberculata sp. nov. can be distinguished from the other species of Dyobelba by the complete absence of prodorsal enantiophyses B, D, epimeral and dorsosejugal enantiophyses E2, V and discidium, the presence of microtubercles at the bases of epimeral setae of 1, 2, 3-series and 4b, and the presence of two setae on trochanter IV. Some information on generic diagnosis and distribution of hitherto known species of Dyobelba are given. Key words - Oribatida, Damaeidae, Dyobelba, new species, Korea Introduction The oribatid mite genus Dyobelba was established by Norton (1978) with Oribata carolinensis Banks 1947 as the type species. Members of this genus are known primarily from litter of various types of forests, mosses, decaying wood and organic horizon of soils. At the present moment five species (D, armata Norton, D. biclavata Wang & Norton, D. carolinensis (Banks), D. reevesi Norton & Ryabinin and D. tectopediosa (Jacot)) are known and they are distributed in the United States (Jacot 1938; Banks 1947; Norton 1978; Marshall et al. 1987; Norton & Ryabinin 1994), Chile (Norton 1979), China (Wang & Norton 1993) and Mongolia (Bayartogtokh 2000). In the present work a new species, Dyobelba paucituberculata sp. nov. is described from Korea, and it is the second representative of Dyobelba recorded from Palaearctic Region. The morphological terminology used in this paper is based on that (with a few modifications) developed by Grandjean (1960) as applied by Norton (1978). Body length is 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 distension. Notogastral length is measured in lateral aspect, from the anterior to the posterior edge. Notogastral width refers to the maximum width in dorsal aspect. Hysterosomal dorso-ventral thickness is measured in lateral aspect, from the edge of the ventral plate to the dorsal edge of the notogaster in postgenital transect. Notogastral thickness is measured in lateral aspect, from the dorsal to the ventral edge of the notogaster. Length of leg segments is measured in lateral aspect, and includes the portion inserted into the next segment. Genus Dyobelba Norton 1978 Tibiae II and III each with associated seta d coupled with solenidion cp(in a single species D. reevesi Norton & Ryabinin, seta d lacking on tibia II); trochanter IV with one or two setae; femora III and IV mostly with 4 setae on each (five setae in D. biclavata); prodorsal enantiophyses B and D usually present, but completely absent in D. paucituberculata sp. nov.; spinae adnatae mostly present (absent only in D. armata); propodolateral apophyses P mostly absent, but rarely present; ventral enantiophyses S present; discidium present, but absent in D. paucituberculata sp. nov.; epimeral setal formula 3-1-3-4 or 3-3-3-4. In a recent classification of the oribatid mite genera, Balogh & Balogh (1992) considered that spinae adnatae are absent in Dyobelba. However, most of the known species of this genus (other than D. armata) have 16 B. Bayartogtokh conspicuously developed spinae adnatae, which are directed anteromediad or anterolaterad. et al. acters of Dyobelba. tubercles absent; Dyobelba paucituberculata sp. nov. (Figs. -3) Diagnosis. Medium sized species with general char- Fig. 1. all prodorsal finely barbed lamellar smooth, flagellate smooth, lighter size, Propodolateral of prodorsal directed Dyobelba paucituberculata sp. nov., holotype. A: Dorsal Acta Arachnologica, 50(1), September setae on color; sensillus notogastral spinae anteroventrad; 2001 B: Lateral P absent; B and D completely smooth, seta; distally; view; apophysis enantiophyses except only very very long, thin, setae short, thin, adnatae tectum of moderate podocephalic view. OArachnological Society of Japan in A new Dyobelba fossa not projected; ventral enantiophyses E2 and V completely absent; enatiophysis S well developed; epimeral regions II and III with three setae on each and IV with four setae; epimeral setae of 1, 2, 3 -series and 4b situated on distinctly developed microtubercles; discidium absent; setae d on genua I-III slightly longer and thicker than their coupled solenidia a; solenidia cpof tibiae II and III slightly shorter than their associated setae d ; trochanter IV with two setae. Measurements. Body length 476-512 ,um; length of from Korea 17 notogaster 324-348 ,um; width of notogaster 292-328 ,1m; dorsoventral thickness of hysterosoma 264-272 ,im. Integument. Body color yellowish brown. Surface of body and leg segments with very thick granular cerotegument. Conspicuous microtubercles present on prodorsum and around leg acetabula. Adherent debris or exuvial scalps absent. Prodorsum. Rostrum rounded in dorsal view, but conspicuously projected in lateral view. Rostral seta (ro) medium long, relatively thick, smooth. Lamellar Fig. 2. Dyobelba paucituberculata sp. nov., holotype. A: Ventral view; B: Leg I (right, antiaxial aspect); C: Leg II (right, antiaxial aspect); D: Leg III (right, antiaxial aspect); E: Leg IV (right, antiaxial aspect) Acta Arachnologica, 50(1), September 2001 OArachnological Society of Japan 18 B. Bayartogtokh seta (le) slightly longer and thicker than ro, with very fine barbs on its lateral margin. Interlamellar seta (in) relatively short, smooth, directed posterolaterally. Exobothridial seta (ex) thin, nearly as long as in. Sensillus (ss) thin, smooth, very long, finely attenuate and strongly flagellate distally. Bothridium (bo) irregular funnel-shaped, directed posterolaterad. Tubercles of prodorsal enantiophyses B and D completely absent. Propodolateral apophysis P absent (Figs. 1A, 3A & B). Notogaster. Almost circular viewed perpendicular to circumgastric scissure, nearly as long as wide. Thickness et al. of notogaster 160-176 ,i m; dorsal contour evenly rounded. Spinae adnatae (sa) moderate in size, in dorsal aspect directed anteromediad, but in lateral aspect strongly curved anteroventrad; distance between their bases nearly as long as that of notogastral setae la-la. Notogastral setae short, thin and smooth, not darkly pigmented, but lighter in color. Notogastral lyrifissures ia, im, ih, ip, ips and opisthosomal gland opening (gla) well visible in lateral view (Figs. lA, B, 3A, C & D). Gnathosoma. Infracapitular mentum slightly wider than long, with a few microtubercles. Hypostomal setae Fig. 3. Dyobelba paucituberculata sp. nov. A: Dorsal view; B: Lateral view; C: Dorsosejugal region, spina adnata and interlamellar seta are indicated by arrow; D: Posterior view of notogaster (cerotegument partly removed), seta h3 is indicated by arrow. Acta Arachnologica, 50(1), September 2001 OArachnological Society of Japan A new Dyobelba h, m and a medium long, all of them thin, smooth (Fig. 2A). Chelicera normal, fixed and movable digits with a few blunt teeth. Tragardh's organ narrow; setae cha and chb conspicuously barbed. Palp normal, palpal setation: 0-2-1-3-9 including solenidion w on tarsus. Epimeral region. Tectum of podocephalic fossa not projected, but slightly rounded under trochanter I. Epimeral enantiophysis E2 and ventrosejugal enantiophysis V completely absent. Parastigmatic enantiophysis S well developed, tubercles Sa and Sp subtriangular; distal projection of anterior tubercle Sa very slightly longer than that of Sp. Discidium (di) completely absent. Epimeral setae medium long; setae la, 1b, 1c, 2a, 2b, 2c, 3a, 3b, 3c and 4b situated on distinctly developed microtubercles. Epimeral region II with three setae; epimeral setal formula: 3-3-3-4 (Fig. 2A). Ano-genital region. Structure normal for genus; anogenital setae medium long, smooth. Adanal lyrifissure (iad) situated obliquely, at level slightly anterior to anal setae ant. Genital plates with a few microtubercles (Fig. 2A). Legs. Length measurements of leg segments are shown in Table 1. Distal tectum of trochantera III and IV very poorly projected. Setae d on genua I-III slightly longer and thicker than their coupled solenidia a; solenidia cPof tibiae II and III slightly shorter than their associated setae d. Formula of leg setation (including famulus): I (1-7-4-4-20); II (1-6-4-5-17) III (2-4-3-417); IV (2-4-3-3-14); formula of solenidia: I (1-2-2); II (1-1-2); III (1-1-0); IV (0-1-0). Structure and setation of legs I-IV as shown in Figs. 2B-2E. Material examined. Holotype: Cheonwang-bong (1915 m above sea level; the top of Mt. Jurisan), Sancheong-gun, Kyungsang Nam-do, southern Korea, 04 October, 1997. Forty-seven paratypes: same data as holotype. Thirty-four paratypes: Baikrockdam (1950 m above sea level, the top of Mt. Hallasan), Cheju-do (southernmost island of Korea), 16 October, 1997, Leg. S. S. Choi. The holotype and 76 paratypes (alcohol preserved) are deposited in the collection of the Laboratory of Plant Protection, College of Agriculture, Wonkwang Table 1. Length of leg segments vaucituberculata sp. nov. (mm) of Dyobelba from Korea 19 University, Korea. Three paratypes (alcohol preserved) are deposited in the acarology collection of the National Science Museum, Tokyo, Japan and one paratype is deposited in the collection of the Department of Zoology, National University of Mongolia, Ulaanbaatar, Mongolia. Remarks. Dyobelba paucituberculata sp. nov. is easily distinguishable from any other species of Dyobelba by the complete absence of the prodorsal enantiophyses B, D, epimeral and dorsosejugal enantiophyses E2, V and discidium, the presence of microtubercles at the bases of epimeral setae of 1, 2, 3-series and 4b, and the presence of two setae on trochanter IV. The other members of this genus have at least one pair of tubercles on the prodorsum and epimeral region, well-developed discidium and only one seta on trochanter IV. In spite of these principal diagnostic features, the new species is somewhat resemble D. biclavata, described by Wang and Norton (1993) from China in two characters. In the original description of D. biclavata, one pair of epimeral tubercles E2a is indicated as Ta (Wang & Norton 1993). Such tubercles, however, are not found in the Mongolian specimens (Bayartogtokh, 2000). Another similar character is the presence of neotrichous setae (3 pairs) on epimeral region II of both the species. However, the new species can be clearly differentiated from D. biclavata in the 1) very long and distally flagellate sensilli as opposed to relatively short and straight sensilli in D, biclavata; 2) anteromedially directed spinae adnatae as opposed to anterolaterally curved spinae adnatae in D. biclavata, 3) laterally situated notogastral setae c,, h, and h2 as opposed to medially situated setae in D. biclavata; 4) centrally situated aggenital setae as opposed to laterally removed setae ag in D, biclavata, 5) presence of two and four setae on trochanter IV and femora III, IV, respectively as opposed to one and five setae in the respective segments of D, biclavata, and 6) much smaller body size. Etymology. The specific name combining "pau-ci" and "tuberculum" is taken from the Latin meaning `few or little' and `tubercle', respectively, and refers to the complete absence of tubercles of the prodorsal and ventral enantiophyses B, D, E2 and V and presence of only xparastigmatic tubercles Sa and Sp. Acknowledgments We Norton, obtaining Acta Arachnologica, 50(1), September 2001 OArachnological Society would State us of Japan like to University copy of express our of New Jacot's thanks York, paper to Prof. Syracuse, and for the R. A. USA for loan of 20 B. Bayartogtokh specimens of D. This study was partly tectopediosa Promotion of Science. Jacot supported for comparative by the Japan Society study. for the References Balogh, J. & P. Balogh, 1992. The Oribatid Mites Genera of the World. Vol. 1. 263 pp. Hungarian National Museum Press, Budapest. Banks, N., 1947. On some Acarina from North Carolina. Psyche, 54: 110-141. Bayartogtokh, B., 2000. Two species of damaeid mites (Acari: Oribatida: Damaeidae) from Mongolia, with notes on distribution of the genera Epidamaeus and Dyobelba. Biogeography, 2: 67-79. Grandj ean, F., 1960. Damaeus arvernensis n. sp. (Oribate). Acarologia, 2 (2): 250-275. Jacot, A. P., 1938. Some new Western North Carolina moss-mites. Proc. Ent. Soc Wash., 40 (1): 10-14. et al. Marshall, V. G., R. M. Reeves & R. A. Norton, 1987. Catalogue of the Oribatida (Acari) of Continental United States and Canada. Mem. Ent. Soc. Canada, 139: 1-418. Norton, R. A., 1978. Generic concepts in the Damaeidae (Acari: Oribatei). I. Three new taxa based on species of Nathan Banks. Acarologia, 20 (4): 603-622. Norton, R. A., 1979. Damaeidae (Acari: Oribatei) collected by the Hungarian Soil Zoological Expeditions to South America. Folia. Ent. Hung., 32 (1): 55-64. Norton, R. A. & N. A. Ryabinin, 1994. New alpine damaeid mite (Acari: Oribatida) from New Hampshire, USA. 35 (4): 373-380. Wang, H. & R. A. Norton, 1993. A new species of the genus Dyobelba from China (Acari: Oribatida: Damaeidae). Acta Zootaxon. Sin., 18 (1): 66-69. (In Chinese with English summary) Acceped Janunary 31, 2001 /Accepted March 2, 2001