Sympetrum striolatum (Common Darter)
The common darters recorded in the Outer Hebrides are the usually melanic form which is typically found in extreme west and north of Europe, in Ireland, Scotland and Norway. This form was formerly classified as a separate species, the highland darter (Sympetrum nigescens) but the reliability of the characters have been questioned and it is treated in most publications as a form of common darter.
The latest DNA research indicates that it is not a separate species but just a dark morph of Sympetrum striolatum, the darker colouring benefiting survival in a colder, northern climate.
Although, it still appears as Sympetrum nigrescens (Lucas, 1912) on the Natural History Museum list of British species, the records on NBN are treated as S. striolatum.
The highland darter has more extensive black markings on the thorax and underside of the abdomen than the common darter. Immature males and females have a light brown to yellowish abdomen. Old females tend to be reddish, whilst males have an orange-red abdomen.
Distinguishing features
centre side panel of thorax encloses two/three paler “windows”
black on frons extends further along eye margins than typical S. striolatum
side of abdomen with extensive areas of black
legs can be almost completely black as opposed to with yellow stripes in typical S. striolatum
British Dragonfly Society UK species description
Field Guide to the Dragonflies of Britain and Europe (Klaas-Douwe B Dijkstra 2006)
he latest DNA research states that this is not actually a separate species [what a shame, say I] but just a dark morph of Sympetrum striolatum (Common Darter), the darker colouring benefiting survival in a colder, northern climate. However, since Djikstra/Lewington shows and describes them separately
