Somatochlora flavomaculata
Somatochlora flavomaculata (Vander Linden, 1825)
Local names: Yellow-spotted emerald, Gevlekte glanslibel, Cordulie à taches jaunes, Gulfläckad glanstrollslända
Species Information
Description
A slender Somatochlora, easily distinguished from the other emeralds thanks to the yellow spots on the side of the abdomen and rear of thorax, larger on females and brighter in immature individuals. S2-S3 has large lateral spots and S4-S8 each has large yellow triangular paired spots. The spots tend to darken and in some mature individuals they become almost invisible. Males are metallic dark-green, females similar but more brown. Young individuals have yellow bands on the side of thorax, but these darken quickly and is most often invisible. Frons is dark with two big yellow spots on each side. Teneral and very fresh females can, due to the abdominal markings, be confused with Epitheca bimaculata, but the latter is bigger, has different terminal appendages and has dark patches on the base of the hind wings. Rarely, the wing bases of S. flavimaculata can have yellow patches. Oxygastra curtisii has dorsal yellow streaks on the abdomen but has no yellow spots on both side of the frons.
Size
Habitat
Somatochlora flavimaculata generally prefers oligotrophic to weakly eutrophic peaty water bodies with abundant and dense vegetation. Suitable habitats can be found at fens, marshes, oxbow lakes, wet meadows, ponds, peaty pools including abandoned excavations, Sphagnum peat bogs, and, more rarely, at slow-flowing waters such as ditches and canals. Most of its habitats have a reduced surface of open water due to the density and expanse of the vegetation. In many cases, a layer of at least 10 cm organic material is present at the bottom, while the water is generally shallow. Larvae are capable of surviving an absence of free water for a period of a few weeks. Favoured habitats are fish free and largely unshaded., but often near forest. At such sites, adults are mostly found at the periphery of their breeding habitat, often foraging in meadows and sunny spots in, or along, the forest edges. Most records are from below 600 m, but populations have been found up to 1 270 m in the south of its range.
Distribution
Somatochlora flavimaculata is fairly common in southern Fennoscandia and central and north-eastern Europe. It is less common in western and southern parts of its range, where populations are often small and isolated. It occurs locally at high densities and in some areas it is the most common species of Somatochlora. Suitable habitats and climate seem to occur in Great Britain and the species absence from this country is surprising.
Flight Period
May to September
Conservation Status
Similar Species
Cordulia aenea, Somatochlora metallica
External Links
Genus: Somatochlora
Somatochlora, or the striped emeralds, is a genus of dragonflies in the family Corduliidae with 48 described species found across the Northern Hemisphere. This is a large genus, especially in North America from where the not so apt name 'striped emeralds' originates, and the only corduliid genus with more than a single species in Europe.
Identification Diagnosis
Somatochlora are medium-sized dragonflies, with largely dark bodies that have a metallic green lustre. Eyes are reddish brown at emergence, but becomes brilliant green. Frons are dark metallic green with yellow spots on both sides.
Abdomens of males generally have a diagnostic shape (exept S. borisi who more resemble a *Cordulia). S1-S2 is bulbous, S3 is waisted, S4-S10 gradually widens up to about halfway, around S6-S7, and then gradually narrowes. They are not clubbed near the end. The abdomen is dark green to almost black, with minor yellowish markings on the sides. Male appendages are rather long, often with upcurled tips and several irregular ventral teeth. Lower appendage is triangular, with a narrow, upcurved tip. Female appendages are very long. Their vulvar scale is large, visible when viewed from the side, often shaped like a spout or trough, and distinctly projecting in most species.
Separation from other genera
Both Cordulia and Oxygastra have a uniformly dark frons, the male of these genera has a conspicuously clubbed abdomen, with S7 and/or S8 widest, and a deeply notched lower appendage. Their females have inconspicuous vulvar scales. Moreover, Cordulia has only one cross-vein between the hindwing triangle and base (not two) and Oxygastra has deep yellow streaks down the middle of the abdomen.
Separation of the species
The seven species found in Europe may be most easily determined in the hand by the shape of the anal appendages in males and by the vulvar scale in females. The patterns of yellow spots on the face, thorax and abdomen are also distinctive features.
Behaviour
Male patrols are swift and often stealthy or erratic. Females are especially shy, but may be detected by the rustling of wings while ovipositing alone under the cover of dense vegetation. Both sexes rarely perch near the waterside, but rather up in trees.
Family: Corduliidae
The Corduliidae, also knowns as the emeralds, emerald dragonflies or green-eyed skimmers, is a family of dragonflies. These dragonflies are usually black or dark brown with areas of metallic green or yellow, and most of them have large, emerald-green eyes. The larvae are black, hairy-looking, and usually semiaquatic. They are not uncommon and are found nearly worldwide. The Treeline Emerald (Somatochlora sahlbergi) belongs to this family and is not (yet) rare but considered extremely hard to see as an adult. It is one of the species most endangered by the global warming.