Ecologica Montenegrina 34: 49-63 (2020) This journal is available online at: www.biotaxa.org/em http://dx.doi.org/10.37828/em.2020.34.6 Dragonflies from hot springs in Russia with a country-level checklist of species known to occur in geothermal environments OLGA V. AKSENOVA, GRIGORY S. POTAPOV*, YULIA V. BESPALAYA, YULIA S. KOLOSOVA, ILYA V. VIKHREV, ALEXANDER V. KONDAKOV, MIKHAIL YU. GOFAROV & IVAN N. BOLOTOV N. Laverov Federal Center for Integrated Arctic Research of the Ural Branch of the Russian Academy of Sciences, Northern Dvina Emb. 23, 163000, Arkhangelsk, Russia *Corresponding author: [email protected] Received 28 August 2020 │ Accepted by V. Pešić: 12 September 2020 │ Published online 15 September 2020. Abstract Geothermal springs are known to harbor unusual assemblages of dragonflies and damselflies worldwide. A review of original records and the body of available literature revealed that 27 Odonata species were recorded from hot springs in Russia so far and that the successful larval development in geothermal environments was discovered for 17 species. Among them, four species exclusively inhabit hot springs, i.e. Mnais costalis, Anotogaster sieboldii, Orthetrum melania (Kunashir Island), and O. albistylum (Eastern Siberia). In Russia, these southern species are unable to develop beyond geothermally heated water bodies due to cold climate, and they exist as local geothermal populations there. Here, we report on several novel records of Odonata species from geothermal springs in eastern Russia. Four species were recorded on the Kunashir Island (Kurile Archipelago): Mnais costalis (adults), Anotogaster sieboldii (adults and larvae), Orthetrum melania (adults), and Sympetrum pedemontanum elatum (adults and larvae). Two species were found in the Kamchatka Peninsula, i.e. Libellula quadrimaculata (freshly emerged imago and exuvia) and Aeshna juncea (larvae). To explain the origin of isolated geothermal populations of Odonata, three alternative hypotheses can be proposed as follows: (1) pre-glacial relicts; (2) mid-Holocene relicts (since the Holocene Climate Optimum); and (3) recent (late Holocene) populations founded by long-distance dispersal events. These scenarios are yet to be tested by means of a molecular approach. Key words: Odonata, Eastern Siberia, Russian Far East, Kurile Archipelago, geothermal habitat, extreme environment, larval development, isolated population. Introduction Hot springs house distinctive animal communities because of stable temperature regime and high concentration of dissolved solids compared with those in non-geothermal habitats (Corbet 2004; O’Gorman et al. 2012). Geothermal sites in cold high-latitude and high-altitude areas could serve as local refugia for thermophilic animals and plants (Pleshanov et al. 2002; Kornobis et al. 2010; Bolotov et al. 2012). In temperate areas and high mountain ranges, various southern species of dragonflies and damselflies are Ecologica Montenegrina, 34, 2020, 49-63 DRAGONFLIES FROM HOT SPRINGS IN RUSSIA known to establish local populations in warm springs (Leggott & Pritchard 1986; Corbet 2004; Borisov & Haritonov 2004; Borisov 2009, 2014, 2015a; Haritonov & Borisov 2013). Occurrences of Odonata species from geothermal sites attracted a full attention of scientists since the end of the 19th century (Kellicott 1897). In a global summary, 38 species of Odonata were listed as permanent inhabitants of hot springs that can complete their life cycle in geothermal environments (Corbet 2004). This list contains 10 species that were thought to be recorded from hot springs in Russia (Corbet 2004), although most of these records are doubtful (Borisov 2014). Two species are known to occur near hot springs of the Kamchatka Peninsula, i.e. Aeshna juncea (Linnaeus, 1758) and Somatochlora graeseri Selys, 1887, although only adult dragonflies were collected there (Dumont et al. 2005). Recently, 23 Odonata species were recorded from hot springs around Lake Baikal based on comprehensive field surveys (Borisov 2014, 2016, 2017). Occurrences of three Odonata species from hot springs of the Kurile Archipelago were also registered, i.e. Mnais costalis Selys, 1869, Orthetrum melania (Selys, 1883), and Anotogaster sieboldii (Selys, 1854) (Paulson et al. 1998; Corbet 2004; Kotlyakov et al. 2009; Palatov 2014; Sasamoto et al. 2017). This study aims to describe several new records of Odonata species from geothermal springs of eastern Russia and to provide further notes on their biology and ecology based on the field observations. A complete checklist of Odonata species that are known to occur in geothermal environment in Russia is compiled based on published and original occurrence data and a critical revision of Corbet’s (2004) list of species. Materials & Methods Field surveys of dragonflies in geothermal habitats were conducted on the Kunashir Island in July 2011, and at the Kamchatka Peninsula in June 2013 and August 2014 (Table 1 and Figs. 1-4). Adult Odonata specimens were collected randomly by a butterfly net near hot springs and warm streams (Fig. 2), while larvae were sampled using a sieve and a standard hydrobiological net (mesh size 0.1 mm). Altogether 100 adult specimens, 12 larvae, and 2 exuvia were collected. The samples were deposited in the Siberian Zoological Museum [SZM], Institute of Systematics and Ecology of Animals of the Siberian Branch of the Russian Academy of Sciences (Novosibirsk, Russia), and the Russian Museum of Biodiversity Hotspots [RMBH], N. Laverov Federal Center for Integrated Arctic Research of the Ural Branch of the Russian Academy of Sciences (Arkhangelsk, Russia). Table 1. Sampling localities of Odonata in eastern Russia. Stolbovsky hot Neskuchensky hot The Valley of Karymshinsky hot springs, Kunashir springs, Kunashir Geysers, Parameters springs, Kamchatka Island, South Island, South Kamchatka Peninsula Kuriles Kuriles Peninsula Latitude 44.0072°N 44.4856°N 52.8125°N 54.4376°N Longitude 145.6831°E 146.0981°E 158.0975°E 160.1389°E Environment Warm springs and a Warm springs and Warm pool Warm lakelet warm stream warm streams Water temperature range (°C) 14.4-72.5 14.8-70 19-22.5 30-38 Mineral content of geothermal waters (mg×L-1): Na+ 101.3 51.8 128.0 N/A Ca2+ 16.0 43.1 10.7 N/A Mg2+ 2.93 17.05 0.24 N/A K+ 7.91 15.88 2.97 N/A 2– SO4 66.0 97.5 141.0 N/A Cl– 155.9 16.1 92.6 N/A Nitrogen content of geothermal waters (mg×L-1): + NH4 1.72 4.59 0.57 N/A – NO3 0.31 0.20 0.00 N/A N/A – not available. 50 AKSENOVA ET AL. Figure 1. Map of sampling localities of Odonata in eastern Russia: Stolbovsky hot springs (1); Neskuchensky hot springs (2); Karymshinsky hot springs (3); and the Valley of Geysers (4). Field observations on behavior and biological features of dragonfly populations associated with geothermal habitats were conducted. A digital thermometer (TK.5.05, TekhnoAS, Russia) was used for measuring of water and ground temperatures of geothermal sources in situ. Water samples for chemical analysis were obtained using 0.5 L polyethylene bottles that were kept cool and dark until transfer to the laboratory. In each site, the water samples were collected from an outflow stream or a pool accumulating geothermal waters from surrounding hot springs. Hydrochemical analyses were performed in the core facility center of the Northern Arctic Federal University, Arkhangelsk, Russia. Geographic position, hydrochemical content, and temperature range of geothermal waters at the sampling localities are presented in Table 1. Ecologica Montenegrina, 34, 2020, 49-63 51 DRAGONFLIES FROM HOT SPRINGS IN RUSSIA Figure 2. Hot spring habitats and a live dragonfly on the Kunashir Island. (A) Neskuchensky hot springs, a habitat of Sympetrum pedemontanum elatum, Anotogaster sieboldii, and Orthetrum melania, 26 July 2011. (B) Stolbovsky hot springs, a habitat of Mnais costalis, Anotogaster sieboldii, and Orthetrum melania, 29 July 2011. (C) Male of Orthetrum melania near the Neskuchensky hot springs, 26 July 2011. (Photos: Yu. S. Kolosova [A, C] and O. V. Aksenova [B]). The adult specimens from the Kunashir Island were identified by the late Dr. Anatoly Yu. Haritonov (Novosibirsk, Russia). Other imago samples were identified using an appropriate key (Haritonov 1986). The larvae were identified based on morphological features using available guides (Haritonov 1997; Lee and Jung 2012). Images of larvae samples were obtained using a stereomicroscope (Leica M165C, Leica Microsystems, Germany). Images of adult specimens were taken by a digital camera (Canon EOS 60D, Canon Inc., Japan). Results In total, our samples contain six Odonata species from geothermal habitats in eastern Russia: Mnais costalis, Anotogaster sieboldii, Orthetrum melania, and Sympetrum pedemontanum elatum from Kunashir Island, and Libellula quadrimaculata, and Aeshna juncea from Kamchatka (see Taxonomic Account and Figs. 2-5 for detail). Larvae of Anotogaster sieboldii, Sympetrum pedemontanum elatum, and Aeshna juncea were collected from warm geothermal waters (Figs. 2-4). Exuvia and a freshly emerged adult specimen of Libellula quadrimaculata supported its successful development in a warm pool of the Karymshina hot springs, Kamchatka (Fig. 4A-B). On the Kunashir Island, four species were recorded from geothermal areas (Table 2 and Figs. 3 and 5). Based on our randomly collected samples of adult specimens (Table 2), Sympetrum pedemontanum 52 AKSENOVA ET AL. elatum was the most abundant species in the Neskuchensky hot springs. Orthetrum melania was abundant in the Stolbovsky and Neskuchensky hot springs. Table 2. Number and proportion of Odonata imago collected from geothermal sites of the Kunashir Island in July 2011 Stolbovsky hot springs Neskuchensky hot springs Number of Number of Species Proportion of Proportion of specimens specimens specimens (%) specimens (%) [♂/♀] [♂/♀] Mnais costalis Selys, 1869 6 [6♂] 20.7 0 0.0 Anotogaster sieboldii (Selys, 1854) 2 [1♂, 1♀] 6.9 5 [4♂, 1♀] 7.1 Orthetrum melania (Selys, 1883) 21 [18♂, 3♀] 72.4 21 [20♂, 1♀] 30.0 Sympetrum pedemontanum elatum (Selys, 1872) 0 0.0 44 [26♂, 18♀] 62.9 Total sample 29 100.0 70 100.0 Altogether 27 Odonata species are known to occur in geothermal springs in Russia (Table 3).