Ischnura graellsii
Ischnura graellsii (Rambur, 1842)
Local names: Iberian bluetail, Spanische Pechlibelle, Iberisch lantaarntje
Species Information
Description
A member of the elegans-group, confined to the westernmost parts of Europe and North Africa. Overlaps and hybridises with I. elegans locally in Iberia, especially in the north and west, while only I. elegans occurs in the Balearics. Meets I. saharensis very locally on the edge of the Sahara, but hybrids are unknown. Some mature females in particular may not be reliably identifiable in areas of overlap.
Smaller on average than I. elegans. Unlike it, postocular spots and antehumeral stripes are often reduced or totally lacking in both sexes, while the majority of gynomorph females (B and C) have variable black markings on S8. In Iberia, larger well marked (postocular, antehumeral) males should be carefully checked as they may be I. elegans. Females without postocular spots may be confused with Erythromma viridulum, but have a vulvar spine.
Unlike I. elegans, the tips of the male's lower appendages are directed towards each other (viewed from above). The inner branches of the upper appendages diverge (view from behind). Hind borde of the pronotum is weakly arched, without an upright projection as in I. elegans.
As in I. elegans, female forms A, B and C all occur, but the teneral thorax colours are distinctive (greenish) yellow in A, whitish lilac in B, orange in C. The later may recall I. pumilio, black on S2 is restricted to the distal quarter. Pink individuals, as often seen in I. elegans, and burgund ones are rare.
Size
Habitat
Ischnura graellsii is found in a wide variety of habitats, including running, standing and brackish waters. The species has been found up to 1 300 m.
Distribution
Ischnura graellsii is endemic to the Iberian Peninsula and the Maghreb. In northern Africa it is limited to the northern parts of Morocco, Algeria, Tunisisa and the north-west of Libya, being replaced by I. saharensis in the more arid inland areas to the south.
The European population are presently confined to the Iberian Peninsula. In 2015 a population was found in French part of Cerdagna, eastern Pyrenees. Records published for Sardinia is believed to be misidentifications.
In northern Spain hybridisation between I. elegans and I. greallsii has been observed. Hybrids are fertile and backcross with I. elegans.
Flight Period
March to November
Conservation Status
Similar Species
Ischnura elegans, Erythromma viridulum
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.