Boyeria cretensis
Boyeria cretensis Peters, 1991
Local names: Cretan spectre, Kretaschemerlibel
Species Information
Description
This species is endemic to the island of Crete, where it replaces B. irene. It is very similar in general appearance, size and behaviour to B. irene. It can be distinguished from B. irene by some details; colouration in general is darker and light portions on the body tends to be greenish yellow rather than green. The pterostigma of the hind wing is slightly larger. The frons is more pointy seen in profile.
Size
Habitat
Limited to running waters and is mainly found near the upper courses of permanent streams with a moderate to strong current. It is largely confined to streams with extensive gallery forests of Plane trees where the water is partly shaded. The species has been recorded up to 450 m.
Distribution
Boyeria cretensis range is confined to the island of Crete, where it is know from fifteen river systems. The populations are concentrated in two areas, with five populated rivers at Lefka Ori mountains in the westernmost of Crete and nine populated rivers in the region between the Lefka Ori and the Psiloritis mountains (Mount Idi) and north of the latter in central Crete. In addition to these, there is a single isolated locality known east of the Dikti mountains in the easternmost part of Crete.
Flight Period
From the end of May to August.
Behavior
Like B. irene it is a powerfull and untiring flyer, capable of flying for long periods of time without perching. Just like B. irene and Calaeshna microstigma, it tends to be more active and visible late in the afternoon and has twilight habits. There are reports of it flying late in the evening and attracted by artificial lights.
Conservation Status
Similar Species
Boyeria irene
External Links
Genus: Boyeria
Boyeria is a genus of dragonfly in the family Aeshnidae, commonly called spotted darners. The name Boyeria commemorates the French entymologist Etienne Laurent Joseph Hippolyte Boyer de Fonscolombe.
Identification
Boyeria is not a colourfull genus, rather they are somewhat dull and blotchy, like military camouflage. Most males and some females have wings with darker tips (especially the hindwing). Pterostigma are moderately long, covering 4-7 cells below it.
Separation from other genera
In the field it is important to observe habitat, behaviour and colour. In the hand hand wing venation can rule out any confusion. Caliaeschna has similar habits, but their ranges does not overlap. Caliaeschna also are much smaller, with more contrasting markings and has a short pterostigma. Most Aeshna species have more conspicuous markings. Both Caliaeschna and Aeshna species never have dark wing tips.
Separation of the species
Boyeria is a genus with isolated relict populations. It contains two species in eastern North America and three in eastern Asia. Two species are endemic to Europe.
Behaviour
Males patrols long routes, slowly flying low over the water. They tend to keep in the shade along the edge of the water and often stop mid-air to inspect dark corners, e.g. under tree roots. They avoid sunlight (still they tend to stop patrolling when the sun is clouded). They become more active towards the late afternoon and aggregate at dusk when they hunt in fast, zig-zagging flight over clearings. They remain on the wing until nightfall and may be attracted to light thereafter. The behaviour of B. cretensis is poorly known. Males are said to patrol fast over streams in the afternoon, passing low between rocks.
Family: Aeshnidae
The Aeshnidae, also called aeshnids, hawkers, or darners, is a family of dragonflies. The family includes the largest dragonflies found in Europe and North America and among the largest dragonflies on the planet.
Description
Common worldwide or nearly worldwide. Genera are Aeshna and Anax. The African Anax tristis has a wingspan over 125 mm, making it one of the world's largest known dragonflies. Most European species belong to Aeshna. Their American name darner stems from the female abdomens looking like a sewing needle, as they cut into plant stem when they lay their eggs.
The dragonflies mate in flight. The eggs are deposited in water or close by. The larvae (nymphs or naiads) are generally slender compared to those of other families, with a long and flat extensible lower lip (labium). The larvae are aquatic predators, feeding on other insects and even small fish.
The adults spend large amounts of time in the air and seem to fly tirelessly. They can fly forwards or backwards or hover like a helicopter. The wings are always extended horizontally.
The abdomen are mostly colored blue and or green, with black and occasionally yellow. The large, hemispherical, compound eyes touch in the midline. Individuals of this family have an extremely good sight, and are voracious insect predators.
A proposal has been made to split this family into Aeshnidae and Telephlebiidae.
The name may have resulted from a printer's error in spelling the Greek Aechma, a spear. The spelling Aeschnidae has been intermittently used over a period of time, but is now abandoned for the original name Aeshnidae. However, derived genus names (such as Rhionaeschna) retain the 'sch' spelling, as this is how they were first cited.