Ischnura pumilio
Ischnura pumilio Charpentier, 1840
Local names: Small Bluetail, Scarce blue-tailed damselfly, Kleine Pechlibelle, Tengere grasjuffer, Agrion nain, Ischnure naine, Mindre kustflickslända
Species Information
Description
One of the smallest european species but an effective disperser, which swiftly colonises pioneer habitats. Young females are remarkably orange. Males have the typical Ischnura tail-light, but it is shifted to S9.
It can be easily separated from I. elegans and other Ischnura by:
- Pterostigma in forewing distinctly larger than in hindwing, especially in males.
- I males, the blue tail-light is on S9 and the adjacent half of S8, rather than concentrated on S8.
- Females always lack the tail-light, and when immature are bright orange, with limited black on the head, thorax and abdomen. Mature females are very different and inconspicuous.
Immature I. graelsii and I. fountaineae can also be orange but have more black on the head, enclosing postocular spots, and on the abdomen base (at least upper-side S2 partly black).
Mature females are separated by the bigger forewing pterostigma and the completely black upperside of the abdomen and pronotum.
Because of their size, greenish females may be confused with Nehalennia speciosa, which is metallic and more delicate.
Size
Habitat
As a pioneer species, I. pumilio is mostly found in habitats with shallow water and sparse vegetation which are either newly created or where vegetation has been removed, such as quarries, ephemeral ponds an agricultural fields and ditches. Typically, the number of adults increases sharply in the first years after colonisation and drops when the vegetation becomes denser and competition from other animals increases. Populations in more natural habitats are generally small but more long-lived. These latter types of habitats include swamps, Sphagnum peat bogs, springs and, mainly in the mediterranean, streams. The species is most common in the lowlands but populations have been found in mountains up to at least 1 800 m in southern Europe.
Distribution
Ischnura pumilio is largely confined to the Western Palearctic, although it extends across Mongolia up to the north-east of China. The species is common in south-west Asia although it is absent from the more arid parts of the region. In Africa I. pumilio is scattered in the north of the Maghreb, in both inland and coastal situations.
I. pumilio has a wide range in Europe, where it remains generally scattered and occurs at fluctuating densities due to its pioneer life style. It reaches north to parts of the British Isles, Denmark and the southern third of Fennoscandia. At mid and northern latitudes, populations are often short-lived and the presence of this species at the northern extent of its range depends on immigration from the south. The species has a strong dispersal power and is among the few which have successfully colonised the Azores and Madeira archipelago.
Flight Period
April to October
Behavior
In rare cases, tandem ovipositing have been recorded.
Conservation Status
Similar Species
Ischnura elegans, Ischnura graelsii, Ischnura genei
External Links
Genus: Ischnura
Ischnura is a genus of damselflies known as forktails in the family Coenagrionidae. Forktails are distributed worldwide, including various oceanic islands. The males have a forked projection at the tip of the abdomen which gives the group their common name.
Identification
Small delicate damselflies. The males are easily recognised by their contrasting blue 'tail-light' marking at the end of the abdomen. The abdomen is otherwise largely black or bronze-black dorsally, with the underside of S3-S& yellow.
Males have a bicoloured pterostigma in the forewing. The inner part is dark grey while the outer part is whitish. At the base of the ovipositor the females usually have a small vulvar spine on the underside of S8.
Separation from other genera
The dark abdomen with blue 'tail-light' may recall dark-bodied Coenagrion or Erythromma species, but both these have unicoloured dark pterostigmas. In Coenagrion S2 is mainly blue, and dark Erythromma have conspicuous red eyes. The vulvar spine feature of the Ischnura is shared only with Enallagma females, however these differ in their abdominal markings.
Behaviour
Females of Ischnura oviposit alone, unlike other small damselflies who often do thisin tandem. After emergence, many adults remain close to water, often creating high proportions of mating pairs and tenerals at a site.
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 it the largest damselfly family. The family Coenagrionidae has six subfamilies: Agriocnemidinae, Argiinae, Coenagrioninae, Ischnurinae, Leptobasinae, and Pseudagrioninae.
This family is referred to as the narrow-winged damselflies or the pond damselflies. The Coenagrionidae enjoy a worldwide distribution, and are among the most common of damselfly families. This family has the smallest of damselfly species. More than 110 genera of the family Coenagrionidae are currently accepted.
The family was named by William Forsell Kirby in 1890. The name may be derived from Greek coen meaning shared or common and agrio meaning fields or wild.