Typical body deformations in earthworms exposed at subzero temperatures (the example of D. ghilarovi). For comparison, an intact worm is shown on the top.

Typical body deformations in earthworms exposed at subzero temperatures (the example of D. ghilarovi). For comparison, an intact worm is shown on the top.

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The northern range boundary of the earthworm, Drawida ghilarovi Gates 1969, a typical representative of the Amur fauna and the only species of the tropic Moniligastridae family in the territory of Russia, passes on the west from the Khingan river mainly along the mountain framing of the Priamurye plains to Evoron Lake (and possibly to the Amgun Riv...

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... worms survived cooling to -6°С without any visible damage. Exposure at -10 and -12°С was tolerr able for 60-70% of worms (Fig. 5), The proportion of fully intact individuals was lower, about 30%, but some other worms had only slight body constrictions that disappeared with time (Fig. 6). Only about 25% of worms remained intact after exposure at -14°С, and all of them had constrictions or hematomas after exposure at -16°С. Nevertheless, two out of 12 such worms survived and then lived in culture for 52 days. Taking into account the results of longgterm cultivaa tion after the experiment, LT 50% was estimated at ⎯ 12°С, ...

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... However, it soon turned out that there exists a variety of colorations in different populations of this species. Body color of different specimens was described as greenish-blue, black, brown, blueish-grey etc. [6][7][8]. These morphs are not easy to delimit, so this diversity is sometimes reduced to the grey, brown, and black morphs [9,10]. ...
Article
Drawida ghilarovi is an earthworm species with the northernmost distribution of all Monilidastridae in Asia. It includes multiple color morphs and has significant genetic diversity. In this study we used transcriptome sequencing to demonstrate that D. ghilarovi consists of three genetic clades that differ on both mitochondrial and nuclear genome levels. Pigmentation in D. ghilarovi appears to be labile, with frequent switching between different morphs. One of the clades of the complex is known from grey morphs only, the other consists of both grey and brown morphs, and the third one also has populations with black pigmentation. Two of the three clades are found only in the very south of the Russian Far East, while the third one has a distribution area that extends 800 km to the north, with the northernmost part of the distribution occupied by the black morph. We demonstrated that it would be phylogenetically unreasonable to divide the complex according to pigmentation, but splitting it according to genetic clades could be sensible.
... The SCP of the cocoons that did not pass acclima tion was -4.8 ± 0.4°C (n = 18). No frozen cocoons were recorded at -10°C, which indicated successful acclimation (Berman et al., 2010). ...
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A hypothesis of range formation of the earthworm Eisenia sibirica Perel et Graphodatsky 1984, which is an endemic species of the Altai–Sayan mountain system and is also found on the adjacent plains of Siberia across the valleys of the rivers, is suggested. The limited distribution of the species can be connected with the insufficient cold hardiness of the worm stage (–10 to–12°C). The plains of Western Siberia lie in an area of minimum soil temperature isotherms at a depth of 3 cm:–12 to–14°C, i.e., on average 2–4°C below the tolerable limits for this species. Foothill and mountain soils are warmer, since they obtain much more solid precipitation. Low soil temperatures of the plains apparently “lock up” this species within the Altai–Sayan system. At the same time, there are reasons to consider the northernmost locations of E. sibirica to be relict.
... Its genetic profile, on topotypes, would be most useful for comparison. Occurring as a litter species or subsoil geophage in forest soils, meadow-swamp and in peat to depths of 1 m (Ganin, 1023), its cold tolerance is found to be -16� C in worms to -20� C for cocoons (Berman et al., 2010). Nematode parasites are also reported (Ivanova et al., 2014) uniquely for two Drawida ghilarovi morphs supporting the current suggestion of separate species rather than just morphs or ecotypes. ...
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Moniligastrids are an important yet often ignored earthworm group commonly found in cultivated soils, especially paddy, in the tropical East. Seven new taxa are: Drawida koreana austri, D. koreana nanjiro, D. koreana shindo, D. odaesan, D. jeombongsan, D. companio and D. csuzdii Blakemore spp. or sub-spp. nov. from Korea. Drawida csuzdii is the first new species from North Korea since Lumbricidae Eisenia koreana (Zicsi, 1972). Historical East Asian moniligastrids are reviewed chronologically and Drawida barwelli (Beddard, 1886), D. japonica (Michaelsen, 1892) and D. siemsseni Michaelsen, 1910 are compared on their museum types. These three taxa were thought similar and related to D. nepalensis Michaelsen, 1907 and its possible synonym D. burchardi Michaelsen, 1903 (priority!) and both of these to prior D. uniqua (Bourne, 1887). Indian Drawida calebi Gates, 1945 is compared to new material of D. japonica from Japan, and D. willsi Michaelsen, 1907 to the new sub-species of D. koreana Kobayashi, 1938 from Korea. Where available, mtDNA COI gene barcodes are provided to help objective determinations and a phylogram is provided with outgroup Ocnerodrilidae Eukerria saltensis (Beddard, 1895) itself found in rice paddy/irrigation. The challenge now is comparison of all early taxa in their various homelands in order to assess the genetic variability and taxonomic boundaries acceptable, especially for unpigmented D. barwelli and also for pink/grey D. japonica and blue/grey D. koreana. A checklist of moniligastrids is appended showing 22 species from China (including Hainan and Taiwan), 21 from Korea, nine from Japan and the Drawida ghilarovi Gates, 1969 species-complex from far eastern Russian (Siberia). Recent Drawida dandongensis Zhang & Sun, 2014 from Sino-Korean border is misdescribed and cannot be meaningfully compared to any other Drawidas.
... Unlike other species of this group, the range of D. ghilarovi may be limited by insufficient cold resistance of both the worms and the cocoons. The life cycle of this species is incompletely studied, especially its winter phase (Berman et al., 2010b). There are grounds to believe that its cocoons do not overwinter ; if this is so, the soil temperature of −16°C can be considered critical for the species, since all the worms die at −18°C. ...
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Cold hardiness of 12 species and 2 subspecies of earthworms from Northern Eurasia was studied. Supercooling temperatures, the water content and the thresholds of tolerated temperatures of worms and their cocoons were determined. The threshold values varied within −1…−35°C for worms and within −1…−196°C for cocoons. Earthworms of 4 species and 2 subspecies survived freezing. Cocoons of all species except Eisenia fetida possessed a protective dehydration mechanism which prevented their freezing. During wintering at subzero temperatures, earthworms lost up to 20% of water, cocoons up to 37%. Species of the same life form can overwinter at different phases and have different cold hardiness values. On the whole, epigeic and epi-endogeic species (except for Eisenia fetida) were more resistant to cold than endogeic ones. The following preliminary classification of earthworms according to their tolerance to negative temperatures is proposed: (1) both onthogenetic phases are tolerant; (2) only cocoons are tolerant; (3) both onthogenetic phases are intolerant. The geographic distribution of all the studied species (except for Eisenia nordenskioldi nordenskioldi) is partially or completely limited by insufficient resistance of the worms to negative temperatures. A significant cold hardiness of cocoons of most species is nonadaptive, since the worms hatched from the eggs in spring die without having enough time to reach maturity and to lay cocoons before the onset of subzero temperatures. Only 3 species (Eisenia nordenskioldi nordenskioldi, Eisenia atlavinyteae, and Dendrobaena octaedra) can live in permafrost regions; this is the main reason for a drastically reduced diversity of earthworm assemblages in eastern Siberia except for its southern, mountain parts. In general, the reasons for the impoverishment lie in the modern climatic conditions correlated with the ecophysiological capacities of earthworms.
... The endemic D. ghilarovi has been found in the Sikhote-Alin Mountains and in the Amur floodplain. Berman et al. (2010) have shown that the geographic range of this earthworm species is probably at the northern boundary of the distribution range of Drawida spp.; they related this to the fact that this species demonstrates high levels of cold hardiness allowing the cocoons to overwinter in conditions at the limits of its cold tolerance. ...
... Drawida ghilarovi is thought to be represented by two morphs: anecic (deep burrowers) blue-grey forest morph (Vsevolodova-Perel, 1997) and endogeic (soil dwellers) tar-black meadow-swamp morph (Ganin, 1997). Yet recently Berman et al. (2010) reported that cocoons of the blue-grey morph are laid at depth about 15-20 cm in the surface soil horizon. Presently, Ganin et al. (2012) have shown that blue and black morphs occupy different positions in the Drawida spp. ...
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Drasico n. g. is erected to accommodate two new species of nematode, Drasico nemoralis n. sp. and D. paludigenus n. sp., recovered from coelomic cavities of Drawida ghilarovi Gates, endemic earthworms of the Russian Far East. The new genus is characterised by the following unique for the Synoecneminae characters: apical portion of the head attenuated, cephalic hooks displaced to the base of attenuated portion, amphids displaced posterior to cephalic hooks, excretory duct short and weak, males possessing several genital papilliform sensilla. The new species are differentiated by the size, number and disposition of the male genital sensilla (larger and more numerous in D. nemoralis n. sp.); the body shape of females (with thinner neck and wider mid-body in D. paludigenus n. sp.) and the ovarian tube arranged in transversal folds in D. paludigenus (vs longitudinal folds in D. nemoralis n. sp.). Nucleotide sequences of D2-D3 expansion segment of 28S rDNA for the two new species differed at 13 positions. Phylogenetic analysis revealed close relationships of Drasico n. g. with species of Siconema Timm, 1966. The host species was represented by two morphs (blue-grey forest and tar-black meadow-swamp morph) with intraspecific divergence of 16-17% for cytochrome c oxidase subunit 1 (COI) gene, and each host morph was found infected by a different nematode species. A co-infection with the plectid nematode Creagrocercus drawidae Ivanova & Spiridonov, 2011 was recorded together with D. nemoralis n. sp. in the blue-grey forest morph.
... Eisenia n. nordenskioldi populates the entire Asian Russia and eastern regions of the Russian Plain, from the lower reaches of the Volga and Don rivers to the Arctic Ocean coasts, while E. n. pallida is absent in European Russia and in the Urals but occurs in more southern regions. Its range covers southern Siberia, Amur and Khabarovsk regions, and Primorye (in Russ sia) and extends to Kazakhstan, Mongolia, China, and Korea (Kurcheva, 1977; Ganin, 1997; Vsevolodovaa Perel, 1997; Berman et al., 2010; Bessolitsyna, 2012). Such a pattern of geographic distribution may be due to differences in cold hardiness between the two c ˆ subspecies. ...
... The survival rate (the proportion of individuals that survived at a certain temperature), body water conn tent, and SCP were determined by standard methods (Berman et al., 2002Berman et al., , 2010 Leirikh et al., 2005). Groups of earthworms (15–20 ind.) were placed in a 2500mL plastic containers with soil (50–60% moiss ture) and acclimated at 5°С (14 days), 3°С (14 days), and 1, 0, and –1°С (7 days each). ...
... The SCP of freezeetoll erant organisms does not adequately reflect their cold hardiness, and the only criterion for evaluating this parameter is 50% lethal temperature (i.e., the temperr ature causing 50% lethality upon longgterm exposure), as in the case of organisms that use the mechanism of protective dehydration. To estimate SCP, the earthworms were placed in individual tubes without substrate and cooled to 0 and ⎯1°С (in the control, incubated at 18°С); the water contents in tissues were determined at the same temm peratures (Berman et al., 2010). The water content and SCP in the cocoons of E. n. nordenskioldi were measured at 5, –3, –20, and –40°С. ...
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The ranges of two earthworm subspecies, Eisenia nordenskioldi nordenskioldi (Eisen 1879) and E. n. pallida Malevic 1956, differ in area and partially overlap. E. n. nordenskioldi populates the entire Asian Russia and eastern regions of the Russian Plain, from the lower reaches of the Volga and Don rivers to the Arctic Ocean coasts, while E. n. pallida has not expanded to the Asian permafrost zone and does not occur in European Russia and in the Urals. These subspecies "hold the record" in cold hardiness: the worms and cocoons of the nominotypical subspecies withstand temperatures down to -34 and -40 degrees C, and those of E. n. pallida, to -28 and -23 degrees C, respectively. Hence, their distribution is independent of subzero temperatures, and their ability to overwinter at any phase of the life cycle makes them also independent of heat supply during the summer period. Differences in geographic range may also be due to biological features of the subspecies. The nominotypical subspecies feeds belongs to the epiendogeic morphoecological type (feeding on the ground surface), whereas E. n. pallida is a true endogeic earthworm. Both subspecies have similar requirements for soil acidity; however, conditions in coarse-humus organomineral horizons of frozen soils appear to be unfavorable for E. n. pallida, which accounts for the absence of this subspecies in the permafrost zone.
Article
The cold hardiness of soil invertebrates (37 species of insects and 27 species of other taxa) was studied in the continental areas of Northeast Asia, a region with extreme winter temperatures. Insects overwinter mostly (34 species) in a supercooled state surviving within the temperature range of –12 to –35°C. Thirteen species of invertebrates (including insects, centipedes, slugs, earthworms, and amphipods) can withstand temperatures within the range of –5 to –45°C in a frozen state. The eggs of slugs, cocoons of earthworms, and larvae of some species of elaterids use cryoprotective dehydration, which allows them to survive at temperatures from –20 to –40°C, down to the record minimum of –196°C. Most of the organisms studied can tolerate temperatures of –25 to –30°C, which correspond to the average minimal temperatures in the upper soil horizons in most habitats of the continental regions of Northeast Asia.
Article
The distribution of soil invertebrates from different taxa and the adaptive potential of all three cold hardiness strategies in the cold climate of northeastern Asia are analyzed. The correlation between the resistance to low temperatures and the overwintering conditions in habitats of some species is studied. The mechanisms and degree of cold hardiness are shown generally to be unrelated to the taxonomic proximity. The effect of the resistance to low wintering temperatures on the habitat distribution and faunogenesis of soil invertebrates in permafrost regions is discussed.
Article
Cold-hardiness of soil-dwelling invertebrates (37 species of insect and 27 species from other taxa) was studied in the continental parts of Northeast Asia, which represent a region with winter temperatures extreme for the Northern Hemisphere. Insects belonging to 34 species overwinter in the supercooled state, whereby they withstand temperatures of–12...–35°C. Thirteen species (insects, myriapods, slugs, earthworms, and an amphipod) spend winter in the frozen state and survive temperatures from–5 to–45°C. Cryoprotective dehydration is typical of slug eggs, earthworm cocoons, and certain click beetle larvae, which survive temperatures ranging from–20 to–40°C, down to the record value of–196°C. The majority of the studied organisms tolerate cooling to–25...–30°C, which corresponds to average temperature minima in the upper soil horizons of most biotopes in the continental parts of the Asian Northeast.
Article
Data on the occurrence and adaptive potential of three mechanisms of cold-hardiness are analyzed in different taxa of soil invertebrates under the conditions of the cold climate of Northeast Asia. The relationship between low temperature resistance and overwintering conditions in selected species is discussed. It is shown that taxonomically close species may have different mechanisms and values of cold-hardiness. The effect of winter low temperature resistance on the biotopical distribution and formation of the soil invertebrate fauna in permafrost regions is assessed.