''Dolania'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus of

mayfly Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the ord ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Behningiidae Behningiidae is a family of mayflies. It is a primitive family; the nymphs burrow in the sediment but lack tusks on their mandibles, and the forelegs are not modified for burrowing. The gills are ventral, and the ones on the first abdominal segme ...

containing the single species ''Dolania americana''. It is found in the southeastern United States, as far south as Florida, and is generally uncommon. The adult insects emerge before dawn in early summer, mate and die within the space of about thirty minutes. The female deposits her eggs in the water and dies within five minutes of emergence, believed to be the shortest adult lifespan of any insect.

Description

The adult ''Dolania americana'' has a pale brownish-purple body and membranous wings that are in length. The legs of both male and females are vestigial, thin and twisted, but appear to retain some function. The cerci are longer and more robust than the terminal filaments. The

penis A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during copulation. Such organs occur in many animals, both vertebrate and invertebrate, but males do n ...

of the male is twice as long as the genital forceps. The body of the

nymph A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are ty ...

is cylindrical with a flattened head. The antennae are on the ventral side of the head and the small mandibles do not bear any tusks. The sides of the head and the prothorax are spiny. None of the legs have claws; the front pair are palp-like and the remaining pairs are spiny and protect the

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

s, which are on the ventral surface of the abdomen. The abdomen is densely covered with bristles. The first abdominal segment has a pair of single gills and the other segments bear further pairs of rather smaller, bifid gills. There are three tail filaments at the tip of the abdomen.

Distribution and habitat

''Dolania americana'' is found in the streams and rivers of the coastal plains of the southeastern United States. The nymph burrows into the sandy riverbed and the adults appear briefly flying over the water surface.

Biology

In Florida, the adults emerge at the end of April or in early May, and in South Carolina, in the first half of June. When ready to transform, the nymphs swim to the surface, split their skin, transform into the

subimago Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the orde ...

winged form, and fly off, all in the course of ten to twenty seconds. The

exuvia In biology, exuviae are the remains of an exoskeleton and related structures that are left after ecdysozoans (including insects, crustaceans and arachnids) have moulted. The exuviae of an animal can be important to biologists as they can often b ...

e (nymphal skin) float away downstream. Their emergence is synchronised and the males emerge first, about one and a half hours before sunrise. Male subimagos moult but the females, which emerge soon after the males, remain in the subimago form. Having moulted into the adult form within about five minutes of emergence, the males patrol a stretch of river about long, seeking out females with which to mate. They continue to do this until they drown, having fallen into the water from exhaustion. Upon emergence, the females mate, deposit their eggs into the water and die within the course of about five minutes. All the mayflies die within about thirty minutes of emergence. The eggs are about in diameter, among the largest of eggs laid by mayflies. The nymphs that hatch out of these burrow into the sediment on the bed of the river using their forelegs and head. Their usual habitat is fairly clean sand in an area with rapidly moving water. They feed on the larvae of

chironomids The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nematoceran flies with a global distribution. They are closely related to the Ceratopogonidae, Simuliidae, and Thaumaleidae. Many species s ...

and ceratopogonids. By autumn they are about one third grown and complete their development within a year.

References

{{Taxonbar, from1=Q13573762, from2=Q10475391 Mayflies Fauna of the Southeastern United States Monotypic insect genera Mayfly genera