Zootaxa 4088 (1): 112–128 ISSN 1175-5326 (print edition) http://www.mapress.com/j/zt/ Article ZOOTAXA Copyright © 2016 Magnolia Press ISSN 1175-5334 (online edition) http://doi.org/10.11646/zootaxa.4088.1.5 http://zoobank.org/urn:lsid:zoobank.org:pub:C1EA3A19-D65F-4E39-97D3-0311A85A4816 (Collembola) of Buryat Republic. III. The genera and Agrenia, with a note on 'Claw index'

MIKHAIL POTAPOV1 , AYUNA GULGENOVA2 & MARINA BABYKINA3 1Moscow Pedagogical State University, Moscow 129164, Kibalchicha St. 6 b. 5, Russia. E-mail: [email protected] 2Buryat State University, Ulan-Ude 670000, Smolina St. 24a, Russia. E-mail: [email protected] 3Khingansky State Nature Reserve, Arkhara 676740, Dorozhnyi St. 6, Russia. E-mail: [email protected]

Abstract

Two genera are revised based on material from Buryatia (Russia, East Siberia). Vertagopus ceratus sp. nov. and V. asiat- icus sp. nov. are described of which the former species is strictly alpine and is defined by pale colouration, the presence of chaetae on the anterior side of the ventral tube, and abundant sensillar chaetotaxy. V. asiaticus sp. nov. is widely dis- tributed in Asia and is unusual due to only 9 chaetae in apical whorl on tibiotarsi. A key to species of Vertagopus Börner, recorded in the republic is given, and notes on morphology, distribution, and ecology are provided. In the genus Agrenia Börner, a form similar with A. bidenticulata was recorded in mountainous areas. Buryatian populations considerably differ from the diagnosis of the typical arctic A.bidenticulata (Tullberg) by a much longer claw. A conception of A. bidenticulata sensu lato complex is temporarily proposed basing on available materials from Palearctic, including High Arctic, sub-Arc- tic and South Siberian mountains. The complex consists of several local forms which are different in Claw index and as- sociated Tibiotarsus/Claw ratio, while the dependence of the two indexes on the latitude is shown.

Key words: distribution area of species, Baikal, Buryatia, new species,

Introduction

This paper is our fourth special contribution to taxonomy of Isotomidae of Buryatia (Potapov & Chimitova 2009, Chimitova & Potapov 2011, Potapov & Gulgenova 2013). During the progress of our sampling of Siberian Collembola we paid considerable attention to such microhabitats as decaying wood, looser bark of dead trees, and aquatic sites that made it possible to collect the representative collection of two genera of subfamily : Vertagopus Börner and Agrenia Börner. In this work we make the revision of these two genera of the Buryat Republic. An annotated list of seven species of the genera, including new, is given. Many new records from the areas adjacent to Buryatia are also cited for the new species.

Material and methods

The types are deposited in the collection of the Department of Zoology & Ecology of MSPU (Moscow, Russia) and Department of Zoology of BSU (Ulan-Ude, Russia). Abbreviations: alt.—altitude; A1, A2, A7—chaetae of apical whorl in tibiotarsi; Abd.I–VI—abdominal segments I–VI; accp—accessory p-row s-chaeta; Ant.I–IV—antennal segments I–IV; as—anterosubmedial s- chaeta; bms—basal micro s-chaeta on antennal segments; BSU—Buryat State University; ca.—approximately; di, de—dorso-internal and dorso-external chaetae of dens; e7—guard of labial papilla E; Leg I,II,III—first, second and third pairs of legs; M—macrochaeta; microsens in the text or ms in the text and figures—micro s-chaeta(e) (=microsensillum(a) auct.); macrosens or sens in the text or s in the text and figures—macro s-chaeta or s-chaetae (=macrosensillum(a) or sensillum(a) auct.); MSPU—Moscow State Pedagogical University; PAO—postantennal organ; T1–T4—additional chaetae of apical whorl in tibiotarsi; Th.II–III—thoracic segments II and III; tun— tunica.

112 Accepted by W.M. Weiner: 18 Dec. 2015; published: 8 Mar. 2016 Collectors: A.G.—Ayuna Gulgenova, A.B.—Anatoly Babenko, L.V.—Lilya Vanyavina, M.P.—Mikhail Potapov, N.K.—Natalia Kuznetsova, V.B.—Valery Bulavintsev.

Results

List of Buryatian Vertagopus and Agrenia species

Genus Vertagopus V. ceratus sp. nov. V. asiaticus sp. nov. V. laricis Martynova, 1975 V. pseudocinereus Fjellberg, 1975 V. westerlundi (Reuter, 1898)

Genus Agrenia A. bidenticulata (Tullberg, 1876) s.l. A. riparia Fjellberg, 1986

Genus Vertagopus Börner

In the conception of European Isotominae the genus is well defined with the presence of clavate tenent hairs on tibiotarsi, a full set of chaetae in apical tibiotarsal whorl (11), and two last abdominal segments separated. Two species of Buryatia show an incomplete set of the key characters mentioned above: V. asiaticus sp. nov. lost two T- chaetae in apical whorl (deficient set) while V. larici s has two last abdominal segments fused. Thus, Asiatic species make the status of the genus more questionable although the value of differentiating characters of Vertagopus were already doubted long before (Fjellberg 1978). The local species of the species can be classified by the ecology into two groups: xylophilic species related with rotten wood (asiaticus sp. nov., pseudocinereus) and xerophilic species inhabiting dry litter, mosses and lichens (ceratus sp. nov., laricis, westerlundi).

Vertagopus ceratus sp. nov. Figs 1–8, 18, 22, 25, 26

Type material. Holotype, Russia (East Siberia): N Buryat Republic, Dzergynsky Nature Reserve, upper flow of Barguzin River, Balan-Tamur Range, ca. 1800 m alt., 55.36698°N, 111.55280°E, moss-lichen tundra, 09.ix.2012, coll. A.Gulgenova and M.Potapov (MSPU). Twenty paratypes, 10 specimens on slides and 10 specimens in alcohol, ibidem (MSPU and BSU). Other material. Russia (East Siberia): N Buryat Republic, Dzergynsky Nature Reserve, upper flow of Barguzin River, Balan-Tamur Range, ca. 1800 m alt., 55.36698°N, 111.55280°E, mossy sites, litter under Pinus pumila, dry stony slope with lichens and Empetrum, 09.ix.2012, coll. A.G. and M.P.; NW Buryat Republic, northern shore of Baikal Lake, peak nearby Goudjekit, subalpine belt with Pinus pumila, ca. 1600 m. alt., thick lichen spots, 15.viii.2013, coll. A.G. and M.P.; NW Buryat Republic, Barguzinsky Range, ca. 10 km W Barguzin, upper flow of Bol'shoi Chevyrkuy Stream, alpine belt, ca. 1970 m. alt., cold mosses in shadow between rocks, 19.viii.2008, coll. A.G. and M.P. Description. 8+8 ommatidia of which G and H much smaller and hardly visible (Fig. 1). PAO elliptical, about twice as long as nearest ommatidium (1.9–2.5). Maxillary outer lobe with 4 sublobal hairs and bifurcate palp. Labrum with 4 prelabral chaetae and about 6–7 on front, labral edge with four sharp ridges. Labial palp with all usual papillae and complete set (16) of guards (e7 present), 4 proximal, 4 basomedian and 5 basolateral chaetae. Ventral side of head with 4–6+4–6 postlabial chaetae. Maxillary head with unmodified lamellae. Ant.I with 2

ISOTOMIDAE OF BURYAT REPUBLIC Zootaxa 4088 (1) © 2016 Magnolia Press · 113 ventral microsens at base and 5–7 ventral sens of which 2–4 short in distal row (Fig. 1). Ant.II with about ten sens. Ant.IV with bifurcate subapical pin-chaeta and big globular organite.

FIGURES 1–8. Vertagopus ceratus sp. nov.: 1, anterior part of head; 2, ventral tube, front view; 3, manubrium, lateral view; 4–5, distal part of tibiotarsus 3 (4) and 2 (5); 6, furca, anterior view; 7, dens, lateral view; 8, distal part of furca. di, de—dorso- internal and dorso-external chaetae, l.ch.—lateral chaetae of manubrium.

Body with differentiated smooth macrochaetae. Macrochaetae on Abd.V about as long as this segment length (0.9–1.1). Number of macrosens in full grown specimens as 4–5,4–5/4(3–5),6(5–7),6(5–7),7(6–8),6 (Figs 18, 22). Th.II–III with 2–3 accp and 2 al. On all segments accp in p-row, sometimes one or two moved forward. On Abd.V six sens arranged as two in anterior position and four in p-row. Microsens 1,0/0,0,1 in number, on Abd.III ms associated with p-row. Th.III without ventral chaetae, Abd.II without ventromedial group of chaetae. Legs with claws of normal shape, with lateral teeth and minute inner tooth. Empodium with indistinct corner inner tooth. Tibiotarsi with 11 chaetae in distal whorl, all T-chaetae present (Figs 4, 5). 2,3,3 clavate tenent hairs of

114 · Zootaxa 4088 (1) © 2016 Magnolia Press POTAPOV ET AL. medium size, about as long as inner edge of claw (0.8–1.0). Retinaculum with 4+4 teeth and 5–7 chaetae. Chaetotaxy of ventral tube (Fig. 2) invariably with 4+4 laterodistal, 1+1 anterior and 3 posterior chaetae (2 in distal transversal row and one at base). Furca rather long, 1.2–1.4 times longer than length of antennae. Manubrium densely covered by chaetae, with more than 40 on anterior side (Fig. 6). With "double" row of chaetae on lateral sides (l.ch. in Fig. 3). Manubrial thickening simple. Dens gradually narrowed towards apex, crenulated (Fig. 7), with 10–12 chaetae on posterior side (4–6 basal and 3+3 di-de). Anterior side of dens with more than 70 chaetae. Mucro with four teeth as common for the genus, "apical" tooth small (Fig. 8). Ratio dens : manubrium as 1.8–2.1. Body size 1.1–1.3 mm. Pale, often totally yellowish-white (Figs 26), with dark pigment on ommatidia, at antennal bases and front of head; distal half of antennae darker. Darker specimens with weak diffuse bluish pigmentation, more concentrating on mid-dorsal area and at posterior borders of tergites (Figs 25). Feet pale. Discussion. This species is readily defined due to pale coloration, long furca, the presence of chaetae on anterior side of ventral tube, and unusual sensillar chaetotaxy. Sharp apical folds on the labrum and the presence of e-7 in labial palp are also uncommon for the genus. Presence of anterior chaetae on the ventral tube are shared with the corticolous V. arboreus (Europe), which differs by dark pigmentation and less abundant sensillar chaetotaxy. The new species shares the presence of e-7 in labial palp and long furca with V. helveticus Haybach and V. alpinus Haybach (both from high mountains of Austria). In contrast with V. ceratus sp. nov., these two European forms have no anterior chaetae on ventral tube, show more common sensillar chaetotaxy and are intensively pigmented. The new species does not belong to either 'westerlundi' or 'arboreus' groups since it has more s-chaetae on abdominal segments. Considerable difference in the number of sens on Abd.I (4) and Abd.II and III (6 on each) is notable. Pale coloration is known also in 'pallidus' form of V. arcti cus Martynova (transholarctic species distributed in more northern areas), which differs from V. ceratus sp. nov. in many significant characters, such as ventral chaetotaxy of thorax, number of chaetae on dens and s-chaetae on body. Distribution and ecology. V. ceratus sp. nov. is a local species (Fig. 29). It inhabits lichen tundra in the alpine belt of northern areas of Buryatia (Balan-Tamur Range, Barguzinsky Range, Baikal'sky Range). Etymology. The name reflects the ceral coloration of the type population of the new species.

Vertagopus asiaticus sp. nov. Figs 9–17, 19, 20, 21, 27

Type material. Holotype, NW Buryat Republic, at northern shore of Baikal Lake, ca. 25 km west from Severobaikal'sk, Goudjekit, 55.71031°N, 109.03793°E, larch forest, ca. 600 m. alt., rotten wood, 20.viii.2013, coll. A. Gulgenova and M. Potapov (MSPU). Paratypes, 10 specimens on slides and 10 specimens in alcohol, ibidem (MSPU and BSU). Other material. Buryat Republic: NW Buryatia, Barguzinsky Range, ca. 10 km W Barguzin, upper flow of Gremyachaya Brook, ca. 1400 m alt., subalpine belt, mosses and lichens on wind erosion areas, 20.viii.2008, coll. M.P. and A.G.; N Buryat Republic, Dzergynsky Nature Reserve, upper flow of Barguzin River, at "81 km" Station, 1076 m alt., 55.34881°N, 111.49967°E, larch wood in river valley, in rotten wood, under bark of larch tree and in litter, 10–12.ix.2012, coll. A.G. and M.P.; NW Buryat Republic, northern shore of Baikal Lake, Goudjekit, larch forest, ca. 600 m. alt., rotten wood, 20.viii.2013, coll. A.G. and M.P.; Ibidem, lake nearby Goudjekit, ca. 700 m alt., Sphagnum at water edge, 16.viii.2013, coll. A.G. and M.P.; Ibidem, Akulikan Stream, ca. 700 m alt., mosses on river bank, 15.viii.2013, coll. M.P. and A.G.; Ibidem, mosses at bank of Goudjekit River, 15.viii.2013, coll. M.P. and A.G.; S Buryat Republic, at Zagansky Range, Arshan, SE slope, 985 m alt., 50.81451°N, 107.78026°E, larch- birch forest, under bark, 20.viii.2011, coll. A.G. & L.V.; E Buryat Republic, Eravninsky District, nearby Telemba, larch forest, rotten wood and under looser bark, 15.viii.2008, coll. M.P.; S Buryat Republic, Dzidinsky District, nearby Borgoi, grass meadow in depression, soil; ibidem, under bark of dead larch tree. 1.viii.2014, coll. M.P. Russia: Irkutskaya Region: W Khamar-Daban Range, Slyudyanka River, taiga belt, under looser bark of poplar-tree, 25.viii.2008, coll. M.P.; Irkutsk, botanic garden, under bark, 01.ix.2008, coll. V. Kadnikov. Russia: Ural: Middle Ural Mts., Sverdlovskaya Region, nearby Revda, impact zone of copper pollution, under bark of dead poplar trees, 29.vii.2002, coll. M.P.; Sverdlovskaya Region, flow of Serga River, nearby Katnikova Cave, floodplain, on fallen trunk, 03.viii.2002, coll. M.P. Russia: East Siberia: Zabaikal'sky Krai: Alkhanai National Park, valley of Ilya River, nearby Ara-Ilya Station,

ISOTOMIDAE OF BURYAT REPUBLIC Zootaxa 4088 (1) © 2016 Magnolia Press · 115 ca. 880 m alt., 50.925133°N, 113.173417°E and 50.930433°N, 113.213783°E, litter of birch forest with larch, litter of pine forest, mosses at bank of Ilya River, 7–12.vii.2014, coll. A.G. Russia: East Siberia: Yakutia: Suntar-Khayata Range, upper flow of Kyubyume River, "Vostochnaya" meteorological station, greenhouse, 23.vii.2002, coll. O. Makarova. Russia: Far East: Primorsky Krai: South Primorye, Shkotovsky area, valley near Vorobey Mt., under bark, 11.ix.2011, coll. M.P.; Shkotovsky area, Anisimovka, under bark of dead poplar tree and tree stump, 20.ix.2004, coll. M.P.; Shkotovsky area, Livadiysky Range, Khualaza Mountain, under bark of logs, 18–19.ix.2004, coll. M.P.; Primorye, Lazovsky area, in mountains nearby Preobrazheniye, ca. 500 m alt., grass turf in coniferous forest, 21.ix.2011, coll. M.P.; South Primorye, Khasansky area, near Barabash, valley forest, litter and under bark of dead tree, 27.ix.2004, coll. M.P.; South Primorye, Khasansky area, Kedrovaya Pad' Nature Reserve, forest litter, 2.x.2009, coll. O. Smirnova; Ussuriysky area, Ussuriysky Reserve, near water edge of Kamenushka River (sedge turf), 05.x.2004, coll. M.P.; middle flow of Bikin River, nearby mouth of Amba River, 46.69949°N 135.77142°E, under maple tree, 20.ix.2009, coll. O. Smirnova; Kirovsky district, Gornye Klyuchi (Shmakovka), mixed forest, coll. E. Sokolova. Russia: Far East: Kamchatka: Surroundings of Petropavlovsk-Kamchatsky, Elizovo, on tree stump in garden, 2004, coll. L.Lobkova; Kamchatka, Bystrinsky area, Anavgai village, ca. 450 m alt., 56.06059°N, 158.93608°E, floodplain of Bystraya River, under bark of dead tree, 3.vii.2012, coll. M.P.; ibidem, mouth of Razdelny Stream, 494 m alt., mixed taiga, from pitfall-traps, 3–5.vii.2012, coll. M.P. Russia: Far East: Khabarovsky Krai: Bureinsky Nature Reserve, middle flow of Pravaya Bureya, Medvezye Station, ca. 950 m alt., ~52.15°N, ~134.316667°E, larch and willow litter, 16.vii.2005. coll. I. Lyubechansky; Middle flow of Amur River, ca. 25 km S Khabarovsk, Khekhtsyr Range, near Korfovsky, coniferous and mixed forests, litter, in rotten wood, under looser bark, 24–25.iv.2010, coll. E.Sokolova and M.P.; Ibidem, Khekhtsyr Range, mixed forest (Pinus sibirica), 17.ix.1988, coll. V.Behan; Ibidem, 10 km N Korfovsky, mixed forest, 24.ii.2007, coll. E. Sokolova; Low flow of Amgun' River (not far from Nikolaevsk-na-Amure), forest with poplar and birch, 01.vii.1990; Ca. 100 km N Komsomol'sk-na-Amure, Evoron Lake, silver fir forest, 03.viii.1988, coll. N. Ryabinin; Suburbs of Khabarovsk, Voronez highlands, gorge of spring, mosses on stones sprinkled with water, 26.iv.2010, coll. M.P.; Verknebureyskoye Reservoir, Nizniy Mel'gin Bay, mixed forest on southern slope (Larix, Betula, Abies), 12.ix.2009, coll. M. Babykina. Russia: Far East: Amurskaya Region: Zeysky Reserve, 52 km of road Zeya–Beregovoy, ca. 300 m alt., "52 km" Station, valley of Erakingra River and open larch forest on northern slope, under bark of fallen branch, 21– 22.viii.2014, coll. M.P. and N.K.; ca. 3 km N Zeya City, oak wood on southern slope, under bark, 22.viii.2014, coll. M.P. and N.K.; nearby Antonovka (ca. 15 km NW Arkhara), under willow, 22.v.2008, coll. M. Babykina; Arkhara, under bark of dead willow, 17.viii.2014, coll. M.P. and N.K.; Ca. 3 km W Arkhara, northern slope, oak forest, under bark. 17.viii.2014, coll. M.P. and N.K.; Khingansky Reserve, ca. 15 km SE Uril, oak forest, 08.x.2009, M. Babykina; Khingansky Reserve, ca. 10 km E Uril, coniferous forest on northern slope, 07.x.2009, M. Babykina; Khingansky Reserve, near (3 km W) Kundur, valley of Karapcha River, southern slope, dry oak forest, under bark. 19.viii.2014, coll. M.P. and N.K. Russia: Far East: South Kuril Isls: Kunashir Isl., caldera of Golovnina Vulcano, Goryachee Lake, debris on lake shore, 24.viii.2008, coll. K. Makarov. China. Heilongjiang Province (NW China), Small Hinggan Range, ca. 50 km W Heihe, rotten wood in mixed forest, and litter in wet grassy birch-forest, 15.viii.2014, coll. M.P., C.-W. Huang, Y. Luan; Inner Mongolia Province, Da Hinngan Ling Mts, ca. 5 km NW BaLin, floodplain forest, under loose bark, Ibidem, ca. 3 km SE BaLin, floodplain pasture, in bushes, under loose bark, 12.viii.2014, coll. M.P., C.-W. Huang, Y. Luan; NE China, Jilin Province, nearby Changchun, Changchun-Jingyue Lake, mixed forest, under bark of willow, 20.IV.2010, coll. M.P. and D. Wu. Description. 8+8 ommatidia of which G and H much smaller (Fig. 9). PAO elliptical, about twice as long as nearest ommatidium and shorter (0.6–0.7) than Ant.I width. Maxillary outer lobe with 4 sublobal hairs and bifurcate palp. Labrum with 4 prelabral chaetae, labral edge with four sharp ridges. Labial palp with all usual papillae and 15 guards (e7 absent), 4 proximal, 4 basomedian and 5 basolateral chaetae. Ventral side of head with 4–5+4–5 postlabial chaetae. Maxillary head with unmodified lamellae. Ant.I with 2 ventral bms at base and 4–5 ventral s of which 1–2 short in distal row (Fig. 9). Ant.III with several sens, one of which in lateral position thick. Ant.IV with bifurcate subapical pin-chaeta and very small peg-like organite.

116 · Zootaxa 4088 (1) © 2016 Magnolia Press POTAPOV ET AL. FIGURES 9–17. Vertagopus asiaticus sp. nov.: 9, anterior part of the head; 10, ventral tube, lateral view; 11, manubrium, lateral view; 12–13, distal part of tibiotarsus 3 (12) and 2 (13); 14, furca, anterior view; 15, dens, posterior view; 16, distal part of furca; 17, mucro. l.ch.—lateral chaetae of manubrium.

Body with almost smooth, sometimes indistinctly serrated, macrochaetae. Macrochaetae on Abd.V longer than this segment length (1.05–1.35, Fig. 21). Number of macrosens in full grown specimens as 4,4/3,3,3,4,6 (Figs 19, 21). Th.II–III with 2 accp-sens and 2 al-sens. On all segments accp-sens in p-row. On Abd.V six sens arranges as two in anterior position and four in p-row. Microsens 1,0/0,0,1 in number, on Abd.III ms associated with p-row. First instar has principally the same sensillar chaetotaxy (Fig. 20). Th.III without ventral chaetae, Abd.II without ventromedial group of chaetae. Legs with claws of normal shape, with two lateral and one inner tooth. Empodium with minute inner tooth. Tibiotarsi with 9 chaetae in distal whorl, T2 and T3 chaetae absent, T1 and T4 present (Figs 12, 13). Clavate tenent hairs present, usually 1(2),2,2 in number: A1 on tibiotarsus 1, A1 and A7 on tibiotarsus 2, and A1 and A2 on tibiotarsus 3. Tenent hairs on tibiotarsi 2 and 3 clearly different in size, A1 always being longer and more distinctly clavated. Length of A1 about as long as inner edge of claw (0.8–1.2). Retinaculum with 4+4 teeth and 6–9 chaetae. Ventral tube (Fig. 10) with 4+4(5+5) laterodistal, without anterior and with 5 posterior chaetae (4 in distal

ISOTOMIDAE OF BURYAT REPUBLIC Zootaxa 4088 (1) © 2016 Magnolia Press · 117 transversal row and one at base). Furca rather long, 1.05–1.30 times longer than length of antennae. Manubrium with 21–26 chaetae on anterior side (Fig. 14), with "single" row of chaetae on lateral sides (Fig. 11). Manubrial thickening simple. Dens continuously narrowed, crenulated, with 8 chaetae on posterior side (4 basal and 2+2 di- de), rarely 3 on one side in middle group (Fig. 15). Anterior side of dens strongly chitinized, with more than 50 chaetae (up to 70 in large individuals). Mucro with four teeth, "apical" tooth very small (Figs 16, 17). Ratio dens : manubrium as 1.8–2.2. Body size up to 1.6 mm. Regularly bluish, sometimes dark (Fig. 27).

FIGURES 18–20. Chaetotaxy: 18–19, sensillar chaetotaxy of adult stage of V. ceratus sp. nov. (18) and V. asiaticus sp. nov. (19); 20, 1-st instar of V. asiaticus sp. nov.

Discussion. The species is characterized by the absence of two T-chaetae (T2 and T3) on tibiotarsi, a character unknown for the genus. Due to this peculiarity V. asiaticus sp. nov. is somewhat in an intermediated position between genera Vertagopus (all T-chaetae present) and Pseudisotoma (T2, T3, T4 absent). Due to the shape of the

118 · Zootaxa 4088 (1) © 2016 Magnolia Press POTAPOV ET AL. mucro and independence of two last abdominal segments V. asiaticus sp. nov. is classified by us with Vertagopus while further study is needed. Another peculiarity of the new species is few posterior chaetae in di-de group combined with long and dorsally polychaetotic dens. After sensillar pattern V. asiaticus sp. nov. formally belongs to 'westerlundi' group. Another closely related new species was collected by us in Western Caucasus, which also has no T2 and T3 chaetae but differs by more sens on body tergites. One species from NE China, V. arborata Fusheng, Huifen & Yueling, also has 1,2,2, clavate tenent hairs and differs by large apical tooth on mucro, two inner teeth on claw, and presence of either T2 or T3 on tibiotarsi. The last character is evident from the figure given in first description of V. arborata. Etymology. The name reflects wide geographical distribution in Asia. Distribution and ecology. V. asiaticus sp. nov. is distributed widely in the Asiatic part of Russia, but no records exist for the Arctic (Fig. 29). Literature records of V. arboreus in Asia (Uchida 1969, Martynova 1979) may refer to this species. The species lives under loose bark of dead trees and in rotten wood where it can occur together with V. pseudocinereus. Unlike the latter, V. asiaticus sp. nov. also often inhabits forest litter and organically enriched sites.

FIGURES 21–22. Chaetotaxy: 21, Abd.III–VI in V. asiaticus sp. nov.; 22, Abd.I–II in V. ceratus sp. nov.

Vertagopus laricis Martynova, 1975 Figs 23, 28

Material examined. Russia: Buryat Republic: NW Buryatia, Barguzinsky Range, ca. 5 km W Barguzin, middle flow of Gremyachaya Brook, 500–900 m alt., forest belt, mosses on stones and trunks, ibidem, upper flow of Bol'shoi Chevyrkuy River, mountain tundra and lichen wasteland after fire, ca. 1750 m alt., 17–20.viii.2008, coll. M.P. and A.G.; NW Buryatia, SE shore of Baikal Lake, at Ust'-Barguzin, dry pine forest on dunes, litter,

ISOTOMIDAE OF BURYAT REPUBLIC Zootaxa 4088 (1) © 2016 Magnolia Press · 119 5.viii.2014, coll. M.P.; NW Buryatia, NW shore of Baikal Lake, ca. 30 км N Severobaikalsk, nearby Slyudyanskoye Lake, stony steppe on steep SE slope, vegetation in crevices of rocks, ca. 700 m alt., ibidem, dry pine forest with Vaccinium vitis-idae, ca. 700 m alt., litter and moss on stones, 19.viii.2013, coll. M.P. and A.G.; S Buryat Republic, nearby Gusinoozersk, dry grassy pine forest with Fabaceae, litter, 1.viii.2014, coll. M.P.; S Buryat Republic, Zagansky Range, eastern slope, 50.92895°N, 107.91876°E, 1074 m alt., dry pine forest with Vaccinium vitis-idae, sand soil, 21.viii.2011, coll. A.G. and L.V.; S Buryat Republic, Bichurinsky District, Khilokskaya Basin, nearby Shibertuy, mossy spruce wood surrounded by steppe, 50.79364°N, 107.87653°E, 725 m alt., 20.viii.2011, coll. A.G. and L.V.; S Buryat Republic, Dzidinsky District, nearby Borgoi, birch forest in depression, litter, 1.viii.2014, coll. M.P.

FIGURES 23–24. Appearance and macrochaetotaxy of V. laricis (23) and V. westerlundi (24).

Russia: East Siberia: Zabaikal'sky Krai: Alkhanai National Park, valley of Ilya River, nearby Ara-Ilya Station, slope of Mogotuyski Range, 50.926033°N, 113.226467°E, 930 m alt., dry lichen-mossy larch and pine woods with Rhododendron, Vaccinium vitis-idaea, 7.vii.2014, coll. A.G. Russia: East Siberia: Irkutskaya Region: Bratsk (Gidrostroitel' area), dry pine forest (V. vitis-idaea, moss, Rosa), litter, 14.viii.2013, coll. M.P.; W shore of Baikal Lake, Peschanaya Bay, lichens on stony place, 6.vii.1963, coll. S.Stebaeva. Russia: East Siberia: the Republic of Tuva: Sangilen, mouth of Ular River, spruce-larch forest, lichens (Hypogymnia) on larch trunk, 5–6.viii.1995, coll. S. Stebaeva. Russia: Far East: Amurskaya Region: ca. 3 km W Arkhara, southern slope at top of hill, dry young oak forest, litter, 17.viii.2014, coll. M.P. and N.K.; Zeysky Reserve, 52 km of road Zeya-Beregovoy, ca. 800 m alt., mixed forest on northern slope, mosses and lichens on stones, 21.viii.2014, coll. M.P. and N.K. Mongolia. Arhangay Aymag, 5.vii.1971. coll. E.Martynova (probable type locality) China. Inner Mongolia Province, Da Hinngan Ling Mts, nearby BaLin, Balin Lama Mountain Forest Park, 48.33302°N, 122.31580°E, 538 m alt., southern slope, young mixed deciduous forest (oak, poplar, birch), thick moss under rock in shadow hollow, moss and lichens on stones. 12.viii.2014, coll. M.P., C.-W. Huang, Y. Luan. Discussion. This species belongs to the 'westerlundi' group. V. larici s was briefly redescribed based on type specimens (Potapov 2001), concluding that it differed from V. westerlundi by darker and uniform pigmentation

120 · Zootaxa 4088 (1) © 2016 Magnolia Press POTAPOV ET AL. (Fig. 28) and fewer chaetae on ventral side of Th.III (Martynova 1979, Potapov 2001). According to our new observations, the dens of V. laricis always has more than 24 anterior chaetae, also in type specimens (20–23 ones were incorrectly indicated in first description), the dens normally has 9 chaetae on the posterior side (3 basal and 3+3 di-de), furca as long as or longer than antennae (1.0–1.1), macrochaetae ca. 4 times longer than inner edge of the claw. In contrast, V. westerlundi has 19–23 (rarely 25) anterior and 2+2 (more rarely 3+2) di-de posterior chaetae on dens, furca shorter than antennae (0.7–0.9), macrochaetae ca. 3 times longer than inner edge of the claw. Habitus of V. laricis and V. westerlundi are given in Figs 23 and 24. The last two abdominal segments are fused in V. laricis (vs. separated in V. westerlundi). With this character V. laricis is a unique member of the genus and is similar to Pseudisotoma Handschin. Other principal characters of the species (11 chaetae in apical tibiotarsal whorl, quadridentate mucro) indicate the genus Vertagopus. Distribution and ecology. Inner areas of the eastern Asia including Mongolia and several surrounding territories of Eastern Siberia and China (Fig. 29). It is a rather common species in the south and centre of Buryatia. V. laricis prefers xeric sites and inhabits coniferous litter of dry forests and sparse vegetation on exposed objects.

Vertagopus pseudocinereus Fjellberg, 1975

Material examined (only records from Buryat Republic and adjoining areas of Irkutskaya Region are listed below). Buryat Republic: Ulan-Ude, valley of Selenga River, under looser bark of died big willow, 31.viii.2008. coll. M.P. and A.G.; N Buryat Republic, Dzergynsky Nature Reserve, upper flow of Barguzin River, at "81 km" Station, 1076 m alt., 55.34881°N, 111.49967°E, larch wood in river valley, under bark of larch tree, 10.ix.2012, coll. A.G. and M.P.; S Buryatia, Khamar-Daban Range, nearby Babushkin, northern slope, litter of forest with Pinus sibirica, 11.x.2013. coll. N. Makeeva; NW Buryatia, NW shore of Baikal Lake, ca. 30 км N Severobaikalsk, nearby Slyudyanskoye Lake, ca. 400 m alt., boggy larch wood, under looser bark of tree, 19.viii.2013, coll. M.P. and A.G.; Ibidem, nearby Slyudyanskoye Lake, dry pine forest with Vaccinium vitis-idae, ca. 600 m alt., under looser bark of fallen pine-tree, 19.viii.2013, coll. M.P. and A.G.; NW Buryatia, northern shore of Baikal Lake, nearby Goudjekit, floodplain of Goudjekit River (Chosenia, Abies), ca. 600 m alt., under bark, 16.viii.2013, coll. A.G. and M.P.; NW Buryatia, Barguzinsky Range, ca. 5 km W Barguzin, middle flow of Gremyachaya Brook, forest belt, ca. 1100 m alt., under looser bark, 18.viii.2008, coll. M.P. and A.G.; E Buryat Republic, Eravninsky District, nearby Telemba, larch forest, rotten wood and under looser bark, 15.viii.2008, coll. M.P.; W Buryatia, Tunkinskiye Gol'tsy Range, Khulugaisha Mount, 1735 m alt., under bark of birch and larch, 27.vii.2009, coll. A.G.; S Buryat Republic, Dzidinsky District, nearby Borgoi, under bark of dead larch tree. 1.viii.2014, coll. M.P. Russia: Irkutskaya Region: W Khamar-Daban Range, nearby Cherskogo Peak, ca. 1 km away from meteorological station, taiga belt, in dry decaying wood and under the looser bark, 1372 m alt., 27.viii.2008. coll. V. Kadnikov; Ibidem, Slyudyanka River, 753 m alt., mixed forest, under bark of different trees, 27.viii.2008. coll. M.P. Distribution and ecology. After our collections V. pseudocinereus is widely distributed in northern Asia and is very common all over the Buryat Republic. The species lives only under looser bark of dead trees. The Buryatian records are among the most eastern ones, thus so far in the eastern Palearctic it has been recorded only in Wrangel Island situated in north-eastern corner of Far East of Russia (Babenko 2010). According to catalogue of Babenko & Fjellberg (2006), the few ancient records of V. cinereus (Nicolet), a very common European species, from the same region might belong to V. pseudocinereus. The former species was absent in our materials from Buryatia.

Vertagopus westerlundi (Reuter, 1898) Fig. 24

Material examined. Buryat Republic: Dzerginsky Nature Reserve (N Buryatia), vicinities of Reserve station 81 km (upper flow of Barguzin River), at ridge of Balan-Tamur Range, northern slope, ca. 1500 m alt., 55.36062°N, 111.53727°E, thick lichens on talus, 09.ix.2012, coll. M.P. and A.G. Distribution and ecology. It is distributed in Western Palearctic with only a few references from the Asiatic

ISOTOMIDAE OF BURYAT REPUBLIC Zootaxa 4088 (1) © 2016 Magnolia Press · 121 part (Martynova 1979, Babenko 2007). It was singly collected in the northern part of the Buryat Republic. This record is new for the area under study and is also the most eastern one for the species.

FIGURES 25–28. Coloration of Buryatian species of Vertagopus: 25–26, V. ceratus sp. nov., populations from Barguzin Range (25) and Balan-Tamur Range (26); 27, V. asiaticus sp. nov.; 28, V. laricis.

Key to Buryatian Vertagopus species

1 Th.III and Abd.II without ventral chaetae, no balloon-like apical papillae on Ant.IV ...... 2 - Th.III and Abd.II with ventral chaetae, with two balloon-like apical papillae on Ant.IV ...... 4 2 Dens with more than 50 anterior chaetae ...... 3 - Dens with less than 30 anterior chaetae ...... V. pseudocinereus 3 Apical whorl of tibiotarsi with 9 chaetae (two small T-chaetae between tenent hairs absent). Ventral tube without anterior chae- tae. 3 sens on each half of Abd.I–III...... V. asiaticus sp. nov. - Apical whorl of tibiotarsi with 11 chaetae (with small T-chaetae between tenent hairs). Ventral tube with a pair of anterior chae- tae. 4 or more sens on each half of Abd.I–III...... V. ceratus sp. nov. 4 Dens with 2+2 (more rarely 3+2) di-de posterior chaetae on dens, furca shorter than antennae. Two last abdominal segments separated. Normally pale coloration ...... V. westerlundi - Dens with 3+3 di-de posterior chaetae on dens, furca as long as antennae. Two last abdominal segments fused. Dark coloration ...... V. laricis

122 · Zootaxa 4088 (1) © 2016 Magnolia Press POTAPOV ET AL. FIGURE 29. Records of of three species of Vertagopus occurring in Buryat Republic. For V. laricis the papers of Martynova (1975), Dunger (1982), Stebaeva & Sedelnikova (1999), Stebaeva et al. (2001), and Gulgenova (2012) were also used.

Genus Agrenia Börner

The genus is well defined and was reviewed by Fjellberg (1986) and Fjellberg & Bernard (2009). In the course of our study of neustonic fauna two species were collected. One of them, supposedly a new species, belonged to 'bidenticulata' group and differed from the widely distributed arctic species A. bidenticulata by longer claws. To clarify the independence of the Buryatian form we have studied other populations of A. bidenticulata from Russian Arctic and Siberian mountains.

Agrenia riparia Fjellberg, 1986

Material examined. Buryat Republic: NW Buryat Republic, northern shore of Baikal Lake, nearby Goudjekit, ~

ISOTOMIDAE OF BURYAT REPUBLIC Zootaxa 4088 (1) © 2016 Magnolia Press · 123 600 m alt., under stones along bank of Goudjekit River, 16.viii.2013, coll. A.G. and M.P.; N Buryat Republic, Dzergynsky Nature Reserve, upper flow of Barguzin River, Turakina spring, ca. 1080 m alt., 55.34875°N, 111.49867°E, green mosses along bank, 10.ix.2012, coll. A.G. and M.P. Distribution and ecology. It is a transholarctic species (Fjellberg 1986, Babenko 2002, Babenko & Fjellberg 2006). The Buryatian records are new for the area under study and are the most southern for the species. Ecology as common for the genus. It was not recorded in southern areas of the republic.

Agrenia bidenticulata (Tullberg, 1876) sensu lato Figs 30–37

Material examined. Russia: Buryat Republic: NW Buryatia, northern shore of Baikal Lake, Baikalsky Range, ~ 600 m alt., under stones along bank of Goudjekit River, 16.viii.2013, coll. A.G. and M.P. (together with A.riparia); Ibidem, nearby Goudjekit, 700–900 m alt., mosses along bank of Akulikan Stream, 15.viii.2013, coll. A.G. and M.P.; NW Buryatia, Barguzinsky Range, ca. 5 km W Barguzin, middle flow of Gremyachaya Brook, forest belt, moistened mosses along brook, 17.viii.2008, coll. M.P. and A.G. Russia: Irkutskaya Region: W Khamar-Daban Range, Slyudyanka River, taiga belt, in moistened mosses on stones in river, from 800 to 1300 m alt., 28–29.viii.2008, coll. M.P.; W Khamar-Daban Range, near Cherskogo Peak, Serdtse Lake, in wet mosses near water edge, ~ 1800 m alt., 26.viii.2008. coll. V. Kadnikov For quantitative analysis the individuals from the following localities were studied: Arctic: Russia: Graham Bell Isl. (Franz Josef Land, 5 ex., coll. V.B.); Kheysa Isl. (Franz Josef Land, 34 ex., coll. V.B.); Franz Josef Land (an island not precised, 23 ex., coll. V. B.); Uboynaua River (Taimyr Peninsula, 2 ex., coll. A.B.); Pyasina River (Taimyr Peninsula, 1 ex., coll. A.B.); Bol'shevik Isl. (Severnaya Zemlya Archipelago, 1 ex., coll. V.B.); mouth of Olenek River (N Yakutia, 2 ex., coll. A.B.); Stolbovoy Isl. (Novosibirskiye Isls, 4 ex., coll. V.B.); Zemlya Bunge (Novosibirskiye Isls, 4 ex., coll. V.B.); Canada: Devon Isl., two localities (Nunavat province), 11 ex., coll. A.B.). Subarctic: Zelentsy (Kolsky Peninsula, northern coast, 3 ex., coll. A.B.); Khibin Mts (Kolsky Peninsula, 6 ex., coll. A.B. and M.P.); Dynkengda Mts. (Putorana Plateau, 10 ex., coll. A.B.); Lavrentiy Bay (E Chukotka, 3 ex., coll. A.B.) Mountains of boreal zone: Komi Republic (Middle Ural Mts, Pechora River, 2 ex., coll. M.P.); Bol'shoy On River (Khakasiya, W Sayan, 1 ex., coll. S.Bugrov); Goudjekit River (NW Buryatia, 16 ex., coll. M.P. and A.G.); Gremyachaya Brook (NW Buryatia, Barguzin Range, 2 ex., coll. M.P. and A.G.); Slyudyanka River and Serdtse Lake (Irkutskaya Region, W Khamar-Daban Range, 9 ex., coll. M.P. and V.Kadnikov); Ola River (Magadan Region, 1 ex., coll. A.B.). Description of populations from Buryatia and Irkutskaya Region. Ground colour yellowish or greenish. Dorsum much darker, pigmentation more developed on thorax and anterior half of abdomen. Antennae 1.4–2.4 (mostly 1.6–2.1) as long as head diagonal. Frontoclypeal field without a distinct "moustache", chaetae stronger over labral base. Chaetae of body subequal, short and fine. Ventral tube with more than 20 posterior chaetae, 11– 18+11–18 lateral, and 3–8+3–8 frontal chaetae. Tenaculum with more than 20 chaetae. Claw index 2.5–3.8 (see below). Furca 2.0–2.7 as long as head diagonal. Dens 1.6–2.1 as long as manubrium. Mucro with lateral chaeta, apical and subapical teeth subequal. Proportions of body limbs, chaetae covering and integument are not affected by maturity and sex. Morphology of winter form unknown. Distribution and ecology. A. bidenticulata is a transholarctic species (Babenko & Fjellberg 2006, Fjellberg & Bernard 2009). Typical form is a common component of Arctic desert and wet tundra. In more southern parts of Asia the species comprises the closely related populations/species of unclear status and is very common along water streams both in alpine and forest zone. In Nearctic the species probably occurs only in high latitudes being absent in southern areas (Fjellberg & Bernard 2009). A. bidenticulata sensu lato is common all over the Buryatian mountains. In Scandinavia A. riparia tends to replace A. bidenticulata in the forest belt (Fjellberg & Bernard 2009). We did not find such regularity in Buryatia so far but the current material along latitudinal gradients is not sufficient to make a final conclusion.

124 · Zootaxa 4088 (1) © 2016 Magnolia Press POTAPOV ET AL. FIGURES 30–36. Claw index in populations of Agrenia bidenticulata complex: 30–32, distal half of Leg III in specimens from S Buryatia (Boreal zone of East Siberia) (30), Putorana Plateau (Subarctic zone of East Siberia) (31), and Franz Josef Land (High Arctic) (32), 33, relationship of Claw index, ratio Tibiotarsus length/outer edge of claw, and size of , plotted for 141 individuals, open circles—Baikal populations, plain circles—other populations, diameter of a circle is representative of Tibiotarsus length (smaller circles: juveniles, large circles: adults or large juveniles); 34–36, plots of Claw index against length of tibiotarsus 3 in individuals from all localities under study (34), in Arctic (35), and Boreal mountain populations (36). In figs 35 and 36 only the specimens with the length of tibiotarsi 3 > 0.2 mm are plotted. tun—tunica.

ISOTOMIDAE OF BURYAT REPUBLIC Zootaxa 4088 (1) © 2016 Magnolia Press · 125 FIGURE 37. Average values of Claw index against latitude in populations of Agrenia bidenticulata complex. Locations are marked according to zonal division, only the specimens with the length of tibiotarsi 3 > 0.2 mm were used to average. Habitus of an individual with long claws (Khamar Daban Mts) is shown.

Claw index in Asiatic population

General view of the Claw index. Claw index is the length of free part of the claw divided by the length of the claw tunica (Fig. 3 in Fjellberg 1986). In fact, the index reflects the length of the claw and roughly classifies the species of the genus to short-claw and long-claw groups. "Short-claw" species have the value below 2.7 while "long- claw"—above 2.8 (2.6–3.2 in A. lamellosa Fjellberg). At whole, the Claw index varies widely within one species, for example in A. bidenticulata it varies from 1.8 to 2.7 (Fjellberg 1986). In two species the index depends on season: A. riparia Fjellberg shows its ranging 1.2–1.3 in winter and 2.1–2.5 in summer form, A. parkeri Fjellberg & Bernard—2.0–2.7 in winter and 2.8–4.5 in summer. In the latter example, winter form formally belongs to "short-claw" group while summer form—to "long-claw". In adaptive terms, it was proven that the elongate claw is the characteristic shared by aquatic Collembola (Christiansen 1961). Baikal populations. According to the modern taxonomy of the genus the four populations from surrounding

126 · Zootaxa 4088 (1) © 2016 Magnolia Press POTAPOV ET AL. of Baikal Lake (Goudjekit River, Gremyachaya Brook, Slyudyanka River, and Serdtse Lake) belong to 'bidenticulata' group being most similar to the widespread A. bidenticulata although clearly differ from the latter by much longer claws. Claw index in these populations ranges from 2.5 to 3.8 vs. 1.8–2.7 in bidenticulata sensu Fjellberg 1986 (Fig. 30 vs. Fig. 32 and Fig. 36 vs. Fig. 35). Age dependence. In our materials the Claw index is only weakly dependent on age instar (Figs 33, 34) that make possible to include non-adult specimens into analysis. The smallest juveniles have lower values of the index indeed (Fig. 34) but starting from the individuals with the length of tibiotarsi III higher than 0.2 mm, the dependence of the index on size is not significant, that is true for both forms, the arctic "short-claw" A. bidenticulata (Fig. 35) and the boreal "long-claw" populations (Fig. 36). Thereby we could use the retrievals having tibiotarsi from 0.2 (middle-sized juveniles) to ca. 0.4 mm (adult individuals). The whole variability of claw in Asiatic populations. We have analyzed available materials of A. bidenticulata from 20 localities in the Arctic, sub-Arctic and Boreal forests zone (19 in Palearctic and 1 in Nearctic, 141 individuals at whole, see the Material part in detail). We also used the ratio of length of tibiotarsi to whole length of Claw measured along dorsal side (Tibio/Claw) which correlates with Claw index. Considering all the populations, the Claw index varies from 1.2 to 3.8, all values of the two characters plotted (Fig. 33) does not reveal any groups. Concerning the climatic zones, in the Arctic populations the index varies as 1.2–2.7 (1.9, on average), in sub-Arctic—1.8–2.8 (2.4, on average), in boreal—2.4–3.8 (3.1). The zonal trend can be illustrated by the average values for the populations plotted against latitude, from South Siberia (ca. 50 N) to the High Arctic (ca. 80 N) (Fig. 37). The same but less distinct trend can be revealed in ratio Tibio/Claw. Fjellberg (1986) mentioned the shorter antennae in the Arctic populations in Europe. The same is confirmed by us on Asiatic material: the mountain populations have, on average, longer antennae than in the Russian Arctic ('a/b' index 1.9 vs. 1.5), but the overall variability of this character is too high (1.4–2.4 vs. 1.1–2.1). So far no conclusions on the status of the Asiatic populations under study can be made. Type specimens of ' bidenticulata' of Tycho Tullberg came from Novaya Zemlya (High Arctic), thus the Arctic populations can be considered as typical "short-claw" A. bidenticulata sensu stricto. We temporarily join all the populations including the more southern ones under A. bidenticulata sensu lato name.

Acknowledgements

We would like to express our sincere thanks to V. Alpatov, A. Babenko, A. Bedos, V. Behan, Y. Bu, S. Bugrov, V. Bulavintsev, L. Deharveng, S. Dmitriev, S. Gulgenov, C.-W. Huang, V. Kadnikov, N. Kuznetsova, L. Lobkova, Y. Luan, I. Lyubechansky, K. Makarov, O. Makarova, N. Nefed'eva, N. Ryabinin, O. Smirnova, E. Sokolova, S. Stebaeva, L. Vanyavina for kindly providing material on Collembola or field assistance. The authors are grateful to the management and staff of the Zabaikalsky Park (Buryatia), Jerga Wildlife Preserve (Buryatia), Alkhanai National Park (Zabaikal'sky Krai), Khingansky State Nature Reserve (Amurskaya Region), Zeysky State Nature Reserve (Amurskaya Region), and State Reserve of Laso (Primorsky Krai), who provided the collecting permit and the favourable conditions to our field work. K. Makarov kindly helped to take photographs. We are also much indebted to С. Janion (South Africa) for having edited the English of a draft manuscript and two reviewers for their corrections and suggestions. The paper has been supported through the Ministry of Education and Science of the Russian Federation, for the first author with the project No 6.632.2014/K, for the second author with the project No 3834.

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