Epiophlebia is a genus of damsel-dragonfly native to the Indian subcontinent, East Asia, and Southeast Asia. It is the only living genus of Odonata to be neither a dragonfly nor a damselfly.
Description
The bodies of
Epiophlebia adults have a distinctive black and yellow striped colouration. Their bodies resemble those of dragonflies, while their wings more closely resemble those of damselflies,
with the wings being held over the back when resting like damselflies.
Like in true dragonflies (Anisoptera) the aquatic nymphs breathe through a rectal chamber, but jet propulsion (which is found in true dragonflies) has not been observed.
Epiophlebia flies relatively clumsily and is less manoeuverable than dragonflies, preferring to fly rapidly in straight lines in the shade, using a fast wingbeat with a wing motion intermediate between those of dragonflies and damselflies.
Distribution
Species of
Epiophlebia have a disjunct distribution, occurring in a narrow habitat of cold mountain streams at an altitude of with temperatures of around in winter to in summer.
The first two species described are
Epiophlebia superstes known from Japan and
Epiophlebia laidlawi from the northern Indian subcontinent and northern Vietnam.
In 2012, a third species,
Epiophlebia sinensis, was described from Heilongjiang province in northeast China, bridging
Epiophlebia distribution gap between Nepal and Japan.
A fourth species,
E. diana, has been claimed from larval material from South China, but this is not universally accepted,
with some authors considering it a synonym of
E. laidlawi. The distribution of the genus may have been continuous during Pleistocene
such as the Last Glacial Period, which may explain the genetic similarity of sequenced
Epiophlebia species to each other despite the broad geographical range of the genus.
Evolution
Genetic evidence suggests that
Epiophlebia is overall more closely related to dragonflies than damselflies, being placed along with dragonflies in the clade
Epiprocta. The lineage of
Epiophlebia is suggested to have split from that of living dragonflies around the end of the
Triassic, approximately 205 million years ago. Genetic evidence suggests that the lineage of
Epiophlebia arose from the ancient reticulate hybridisation of a lineage related to dragonflies and lineage related to damselflies in proportions of roughly 67% and 33%, respectively, which may explain why it combines features of both dragonflies and damselflies.
The genus was historically placed in the clade "Anisozygoptera" along with a variety of fossil odonatans, primarily from the
Jurassic period, but this grouping was later shown to be non-
monophyletic,
representing a
paraphyletic group, with many "anisozygopterans" more closely related to dragonflies than to
Epiophlebia.
The extinct family
Burmaphlebiidae from the mid Cretaceous
Burmese amber of Myanmar, dating to around 100 million years ago, may represent true close relatives of
Epiophlebia.
