''Ischnura gemina'' is a species of

damselfly Damselflies are flying insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies, which constitute the other odonatan suborder, Anisoptera, but are smaller and have slimmer bodies. Most species fold the wings along ...

in the family

Coenagrionidae The insect family Coenagrionidae is placed in the order Odonata and the suborder Zygoptera. The Zygoptera are the damselflies, which although less known than the dragonflies, are no less common. More than 1,300 species are in this family, making i ...

known by the common name San Francisco forktail. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the

San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area Go ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

in the United States. This uncommon insect has a total range of less than 500 square miles in the Bay Area, occurring only in greater

San Francisco San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...

and parts of San Mateo and Marin Counties.NatureServe. 2017
''Ischnura gemina''.
NatureServe Explorer Version 7.1. Accessed 5 August 2017. This species is "one of the rarest Odonates in the United States."

Biology

This damselfly is about 2.5 centimeters long. The male is mostly black with blue sides on the thorax and blue dots toward the tip of the abdomen. The female has dull green coloration on the sides of the thorax. This species is similar to ''

Ischnura denticollis ''Ischnura denticollis'', the black-fronted forktail, is a species of narrow-winged damselfly in the family Coenagrionidae. It is found in Central America Central America ( es, América Central or ) is a subregion of the Americas. Its b ...

'', and can be distinguished by the shape of the male genital appendages. The two species are thought to

hybridize Hybridization (or hybridisation) may refer to: *Hybridization (biology), the process of combining different varieties of organisms to create a hybrid *Orbital hybridization, in chemistry, the mixing of atomic orbitals into new hybrid orbitals *Nu ...

. This damselfly is active between March and November, and adults are known to live over 30 days, a relatively long adult life for damselflies. This species occurs in coastal regions of the Bay Area; it is thought that its long life and long flight season are

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...

s to the

fog Fog is a visible aerosol consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth's surface. Reprint from Fog can be considered a type of low-lying cloud usually resembling stratus, and is heavily influ ...

gy climate of the region. The natural habitat of the species is the various wetland ecosystems of the San Francisco Bay Area, including seepages and ponds. It can tolerate some disturbance, such as channelization of waterways, as long as there is marshy vegetation cover. The larvae develop in the cover of aquatic plants and the adults feed on other wetland arthropods.

Ecology

Populations of this damselfly have been

extirpated Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...

due to the destruction and degradation of habitat in the heavily urbanized area where it occurs. It lived in wetland habitat in

Glen Canyon Park Glen Canyon Park is a city park in San Francisco, California. It occupies about along a deep canyon adjacent to the Glen Park, Diamond Heights, and Miraloma Park neighborhoods. O'Shaughnessy Hollow is a rugged, undeveloped tract of parklan ...

in the city of San Francisco until these moist spots were fragmented too extensively to support populations. After patches of wetland in the park were restored, the damselfly was reintroduced and persisted for a short while before disappearing once more. Though the reintroduction failed, it provided data about the habitat requirements for the insect.Hannon, E. R. and Hafernik, J. E. (2007)
Reintroduction of the rare damselfly ''Ischnura gemina'' (Odonata: Coenagrionidae) into an urban California park.
''Journal of Insect Conservation'' 11(2) 141-49. This had been designated an

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

because of its very small range, small populations within that range, and extensive destruction of its habitat. It has been downgraded to vulnerable status because it has been located at a few more sites, it has good dispersal ability, and it is relatively resistant to some of the forms of habitat degradation that it faces, such as pollution.

References

External links

Photographs, ''I. gemina'' male and female.
Museum of Natural History, University of Puget Sound. {{Taxonbar, from=Q307167 Endemic fauna of California Endemic insects of the United States Ischnura Insects described in 1917 Fauna of the San Francisco Bay Area Taxonomy articles created by Polbot