Northern emerald

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For the Australian moth species with this common name, see Prasinocyma rhodocosma.
Northern emerald
Specimen photographed in Ørland, Norway
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Odonata
Infraorder: Anisoptera
Family: Corduliidae
Genus: Somatochlora
Species:
S. arctica
Binomial name
Somatochlora arctica
(Zetterstedt, 1840)
Synonyms[1][2]
  • Aeshna arctica Zetterstedt, 1840
  • Cordulia subalpina Selys, 1840
  • Somatochlora gratiosa Bartenev, 1909

The northern emerald (Somatochlora arctica) is a species of emerald dragonfly found in the northern Palearctic realm, particularly in Europe. It was first scientifically described by Johan Wilhelm Zetterstedt in 1840 in the genus Aeshna. The dragonfly is assessed as least-concern globally on the IUCN Red List, but is threatened in Central Asia and parts of Europe.

Taxonomy

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The northern emerald is known scientifically as Somatochlora arctica and is placed in the family Corduliidae.[1] The genus Somatochlora, known as the "striped emeralds", includes 42 species found across the Holarctic realm. It is the largest genus of the family Corduliidae[3]: 1 

Taxonomic history

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The northern emerald was first scientifically described under the name Aeschna arctica in 1840 by Johan Wilhelm Zetterstedt. Zetterstedt provided a brief physical description and wrote he had discovered the dragonfly in August of 1821, noting it was found in sub-alpine parts of Finland and Norway. The original description was published in his thousand-page work Insecta Lapponica, a description of the insects of Lapland intended to add to Linnaeus' Fauna Svecica of nearly a century before.[4]

The very same year as Zetterstedt published his description, Edmond de Sélys Longchamps – considered a "founder of Odonatology"[5] – described a species he called Cordulia subalpina from Belgium.[6] In a paper in the journal Bulletins de l'Académie Royale des Sciences et Belles-Lettres de Bruxelles he described a species, discovered in June 1840 by Monsieur Putzeys, a Crown prosecutor in Arlon. He noted it was similar to Somatochlora alpestris (though he called it Cordulia alpestris).[7]

Ten years later, de Sélys published a comprehensive book, Review of the Odonates or Libellules of Europe,[a] in which he gave Zetterstedt credit for ths species, listing his own Cordulia subalpina as a junior synonym. However, he did reclassify Zetterstedt's species into the genus Cordulia, producing the new name Cordulia arctica. de Sélys also provided a detailed physical description and described its distribution: Belgium, Norway, Sweden, Finland, and, thanks to a specimen recorded by a Mr. Weaver, Scotland.[b][8]

In 1871, de Sélys published Synopsis des Cordulines and classified it in the subgenus Epitheca. He returned in 1887 to finally reclassify it in into Somatochlora, noting its range as cold and temperate Europe, Siberia, and Transcaucasia.[6][9] In 1909, Aleksandr Bartenev described a new species, Somatochlora gratiosa, from Siberia. This species would stand as separate until 1958 when Syoziro Asahina proposed it be synonymized with S. arctica.[6][2]: 69  According to the 1985 book The Dragonflies of the World, three forms of S. arctica are recognized: fuscoptera, infuscata, and ornata.[6][10] Ornata was described as an aberration from Finland in 1927.[6]

Phylogenetics

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Classification within the genus Somatochlora was traditionally based on physical characteristics, especially of the nymphs, the wing venation, and the morphology of the anal appendages (see § Description). However, these characteristics "are highly prone" to convergent evolution, making genetic-based research necessary to work out the true evolutionary relationships between species. A 2025 paper published in the journal Systematic Entomology did just that.[3]: 3  The phylogenetic tree their research suggested that Somatochlora arctica was most closely related to a clade comprising Somatochlora franklini, S. forcipata, S. dido, and S. incurvata. However, the exact placement of the species was unresolved and contradicted previous analyses. Their research also found that S. arctica, S. franklini and S. incurvata had all likely diverged approximately five million years ago, in the end of the Miocene epoch – the most recent divergences within the genus.[3]: 12 

Somatochlora arctica group
After Goodman et al. 2025[3]


Description

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Illustration of male (left) and female.

Members of the genus Somatochlora are generally medium-sized dragonflies with metallic green to black colouration and bright green eyes.[3]: 1  Northern emeralds (Somatochlora arctica) are smallish dragonflies with dark abdomens and lighter, hairy thoraxes,[11] usually measuring from 41 to 51 millimetres (1.6 to 2.0 in) long and a wingspan of around 67 millimetres (2.6 in).[12][13]: 138  The colour of the abdomen is blackish, while the head and thorax are bronzey green. Females have two characteristic oval yellow spots on the abdomen next to the thorax,[13]: 138–9  similar to spots on brilliant emerald females.[8] Both sexes have characteristic yellow spots on their faces next to the eyes, which are bright green in mature individuals.[12]

Northern emerald wings are not completely clear but rather are "suffused with a yellowish tint" which becomes strongest close to the leading edge of the wing.[13]: 138–9  The base of the wings is also pale ochre, especially the male inferior wing.[14] The pterostigmata – pigmented spots on the front corners of each wing[15] – are black-brown in males and dark brown in adult females, paler brown in immature ones.[13]: 139  The accessory membrane, a small membrane at the base of the wing next to the thorax considered useful for identification,[13]: 51–2 [16] is white in both sexes, but narrower in the female.[13]: 138–9  The legs are mixed black and brown in colour. The male legs are more predominantly black, with only one side of the first femur (third segment) brown; the females are more so, with all the femurs being brown.[14]

Males are distinctive because the two segments of the abdomen closest to the thorax, and the base of the third, are enlarged such that the dragonfly superficially appears to have a long thorax and a shortened abdomen. The abdomen has a narrow waist and then widens again, being widest in the middle. Females have abdomens without a narrowed waist: seen from above, they are a rectangular shape, tapering gently towards the top.[12][13]: 139 

The tip of the final, tenth segment of a dragonfly abdomen carries a set of short appendages. Both sexes have an upper pair called cerci or upper anal appendages but males additionally have a pair of lower appendages called the epiprocts. In females, the upper appendages are small and "leaf-like". The male upper appendages are rather long and shaped like calipers;[11] the epiprocts are smaller, short, triangular, and slightly curved. The female's vulvar scale – an organ possessed by some dragonflies similar to an ovipositor "used to 'throw' eggs rather less precisely"[17] – is "triangular, pointed, and spout-like."[13]: 139 

Northern emeralds are physically similar to alpine emeralds, Somatochlora alpestris, and must be distinguished mainly on the basis of the morphology of the anal appendages.[8] The physical similarity lead to the two species being traditionally grouped together. However, the 2025 phylogenetics study noted that the physical commonalities used to group S. arctica with S. alpestris were often subject to convergent evolution. Their molecular study found this classification incorrect, with S. arctica and S. alpestris belonging to quite different groups within the genus.[3]: 3, 17–8 

  • Male, identifiable by the caliper-shaped anal appendages and the narrow-waisted abdomen.
    Male, identifiable by the caliper-shaped anal appendages and the narrow-waisted abdomen.
  • Somatochlora alpestris male. The tips of the anal appendages are pointed, not round.[14]
    Somatochlora alpestris male. The tips of the anal appendages are pointed, not round.[14]
  • Female, identifiable by the straight, leaf-like anal appendages, paired yellow spots, and the unwaisted abdomen. Note also the yellowish tint towards the leading edges of the wings.
    Female, identifiable by the straight, leaf-like anal appendages, paired yellow spots, and the unwaisted abdomen. Note also the yellowish tint towards the leading edges of the wings.
  • Male showing the characteristically hairy thorax.
    Male showing the characteristically hairy thorax.

Habitat, distribution and conservation

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Habitat

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The northern emerald's preferred habitat varies across its range. In central Europe, it is restricted to alpine areas and moorlands; a related species, the alpine emerald, inhabits higher altitudes.[18]

The main threat to the northern emerald is loss of habitat through various means. The drainage of peat bogs for human agriculture, infrastructure, or for "industrial peat extraction", all threaten the dragonflies,[1] as does afforestation.[12] Climate change is likely to exacerbate habitat losses.[1][19]: 111 

Distribution and conservation status

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Northern emeralds are found throughout the northern Palearctic realm, holding a scattered distribution from Ireland to Japan between approximately the 40th and 74th parallels. The IUCN Red List describes a scattered distribution in Europe, broadly centred on a diamond cornered by Switzerland, the Netherlands, Slovakia, and the northern Scandinavian Peninsula. Its distribution in the south is especially patchy due to the mountains.[1] It is common in Scandinavia and Finland but rarer in continental (non-Nordic) countries. It is rare in western Europe but common in upland areas of central Europe.[18] It is known from a few alpine peat bogs in Romania, where its habitat is threatened from climate change.[19]: 111 Its distribution outside of Europe is even sparser, with patchy observations throughout Russia, as well as in northern Japan, North Korea, Manchuria, and southern Kazakhstan.[1] In Japan, northern emeralds have been recorded from Nagano in central Honshū[20]: 105  and Hokkaido.[21] In the Russian Far East, it is found in the disputed islands of Kunashir and Iturup the Kamchatka Peninsula and the isle of Sakhalin.[2]: 69 [22]: 235 

In Central Asia, northern emeralds are naturally scarce, found only in vulnerable, isolated populations. The IUCN has warned that climate change could decimate these small amounts of available habitat for the dragonflies in Central Asia and thus significantly endanger them there. The dragonflies are already endangered in several European countries: they are assessed as vulnerable in Austria and Poland and critically endangered in Germany and Denmark. However, at the global level, the IUCN considers the species as of least concern due to the breadth and diversity of its range and its commonality; in much of its Eurasian range, it is not endangered.[1]

In Great Britain, the species is considered near-threatened, and restricted to the Scottish Highlands north of the Firth of Clyde and west of the Cairngorms.[12] The dragonflies are endangered in Ireland,[12] where they are only found in counties Kerry and Cork, inhabiting "moorland pools and bogs".[23] A 1900 book by William John Lucas describes a roughly similar distribution.[13]: 140  According to Steve Brooks and Steve Cham in their 2014 edition of the Field Guide to the Dragonflies and Damselflies of Great Britain and Ireland, the species' range of occurrence in Scotland has doubled since 1982, but due likely to more extensive recording fieldwork – the dragonfly is nonetheless threatened by habitat loss and "undoubtedly is still under-recorded".[11]

Notes

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  1. ^ Revue des Odonates ou Libellules d'Europe
  2. ^ Specifically, from Loch Rannoch in Perthshire

References

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  1. ^ a b c d e f g h Boudot, J.-P. (2020). "Northern Emerald". IUCN Red List of Threatened Species. 2020 e.T165490A140528834. doi:10.2305/IUCN.UK.2020-3.RLTS.T165490A140528834.en. Retrieved 1 Dec 2025.
  2. ^ a b c Asahina, Syoziro (March 1959). "A revision of the Odonata of the Kurile islands" (PDF). Insecta Matsumurana. 22 (3): 63–70. hdl:2115/9636.
  3. ^ a b c d e f Goodman, Aaron; Abbott, John; Breinholt, Jesse W.; Bybee, Seth; Frandsen, Paul B.; Guralnick, Rob; Kalkman, Vincent J.; Kohli, Manpreet; Newton, Lacie; Ware, Jessica L. (July 2025). "Systematics and biogeography of the Holarctic dragonfly genus Somatochlora (Anisoptera: Corduliidae)". Systematic Entomology. 50 (3): 585–610. doi:10.1111/syen.12672. ISSN 0307-6970.
  4. ^ Zetterstedt, Johan Wilhelm (1840). Insecta Lapponica. Lipsiae: Voss. pp. 10 & 1024.
  5. ^ Wasscher, Marcel; Dumont, Henri J. (December 2013). "Life and work of Michel Edmond de Selys Longchamps (1813-1900), the founder of Odonatology". Odonatologica. 42 (4): 369–402.
  6. ^ a b c d e Steinmann, Henrik (2013). World Catalogue of Odonata II: Anisoptera. Das Tierreich. Berlin: De Gruyter. pp. 268–9. ISBN 978-3-11-082444-5.
  7. ^ de Sélys Longchamps, Michel Edmond. "Additions à deux notices sur les Libellulidées, insérées précédemment dans les Bulletins de l'Académie". Bulletins de l'Académie Royale des Sciences et Belles-Lettres de Bruxelles. 7: 90–91 – via Biodiversity Heritage Library.
  8. ^ a b c Selys-Longchamps, Edmond de (1850). Revue des odonates ou libellules d'Europe. Mémoires de la Société royale des sciences de Liége. Hermann August Hagen. Bruxelles Leipzig Paris: C. Muquardt Roret. pp. 71–3.
  9. ^ de Sélys Longchamps, Michel Edmond (1887). "Odonates de l'Asie Mineure". Annales de la Société Entomologique de Belgique. 31: 24.
  10. ^ Allen, D.; Davies, L.; Tobin, Pamela (1984-01-01). "The dragonflies of the world: A systematic list of the extant species of Odonata" (PDF). Rapid communications (supplements). 2: 66.
  11. ^ a b c Brooks, Steve; Cham, Steve (2014). Field Guide to the Dragonflies and Damselflies of Great Britain and Ireland. Illustrated by Richard Lewington (5th ed.). Bloomsbury. pp. 73 & 154–5. ISBN 978-1-4729-6453-3.
  12. ^ a b c d e f Northern Emerald: Somatochlora arctica (PDF). BDS Species and Habitat Management Sheet #2. British Dragonfly Society & Scottish Natural Heritage. 2019.
  13. ^ a b c d e f g h i Lucas, William John (1900). British dragonflies (Odonata). London: L.U. Gill.
  14. ^ a b c Selys-Longchamps, Edmond de (1871). Synopsis des Cordulines (in French). F. Hayez. pp. 63–4.
  15. ^ "Dragonfly and damselfly anatomy". Queensland Museum Collections Online. Retrieved 2025-12-08.
  16. ^ Latter, Oswald H. (1904). The Natural History of Some Common Animals. Cambridge University Press. p. 112.
  17. ^ "Dragonfly Anatomy". Odo-nutters. 2020-02-26. Retrieved 2025-12-08.
  18. ^ a b Askew, R. R. (2021). The Dragonflies of Europe. Brill. pp. 150–1. ISBN 978-90-04-47438-3.
  19. ^ a b De Knijf, Geert; Flenker, Ulrich; et al. (June 2011). "The status of two boreo-alpine species, Somatochlora alpestris and S. arctica , in Romania and their vulnerability to the impact of climate change (Odonata: Corduliidae)". International Journal of Odonatology. 14 (2): 111–126. doi:10.1080/13887890.2011.578565. ISSN 1388-7890.
  20. ^ Karube, H.; Futahashi, R.; et al. (2012). "Taxonomic revision of Japanese odonate species, based on nuclear and mitochondrial gene genealogies and morphological comparison with allied species. Part I". Tombo. 54: 75–106. ISSN 0495-8314.
  21. ^ Tenthredo: Acta Entomologica. Takeuchi Entomological Laboratory. 1938.
  22. ^ Kiauta, Bostjan (1964). "Over het voorkomen van Somatochlora arctica (Zetterstedt 1840) in Nederland (Odonata: Corduliidae)" [On the occurrence of Somatochlora arctica (Zetterstedt 1840) in the Netherlands (Odonata: Corduliidae)]. Entomologische Berichten. 24.
  23. ^ "Odonata (Dragonflies & Damselflies)" (PDF). Scottish Invertebrate Species Knowledge Dossier. Buglife – The Invertebrate Conservation Trust.