Southern blue arrow
| Southern blue arrow | ||||||||||||
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Southern blue arrow ( Orthetrum brunneum ) |
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| Scientific name | ||||||||||||
| Orthetrum brunneum | ||||||||||||
| ( Fonscolombe , 1837) |
The southern blue arrow ( Orthetrum brunneum ) is a dragonfly species from the family of the sail dragonflies . It is divided into two subspecies , with Orthetrum brunneum brunneum mainly in the Palearctic and Orthetrum brunneum cycnos in Corsica and Sardinia .
features
Imago
The southern blue arrow is a relatively small dragonfly whose abdomen in males is between 29 and 31 millimeters long. The females measure 29 to 30 millimeters here. In the young adults , the body of the male is brownish gray with a purple undertone or pale gray mixed with a pale yellowish brown. The female, on the other hand, is more of an ocher brown. The abdomen tends to be a little more greyish with a light yellowish and pale purple coating. In the course of the development of the male, the initially very fine black delimitation lines of the abdomen expand and turn light blue. The colored male is completely provided with blue hoops, which are denser and lighter than the little blue arrow . The female, however, takes on a grayish brown tone. The sides of the first three abdominal segments and the face are whitish purple. The transparent hind wings measure 34 to 35 millimeters in both sexes. The pterostigma in the males is 2.8 to 3.3 millimeters but significantly smaller than in the females, where it measures 3.5 to 3.8 millimeters.
larva
Like the adults, the larvae also undergo a color change. The larvae that have just hatched from the egg are still light gray and only measure one millimeter. The front of the head and legs are dark gray. As the larva develops, it turns greenish brown, with the wing sheaths being dark brown. The lateral spines on segments eight to nine, which are already weakly pronounced in the small blue arrow, are completely absent in the southern blue arrow. There are three to six very small dorsal spines on the segments . In the last larval stage, they measure 18 to 20.5 millimeters.
habitat
The habitat of the southern blue arrow mostly consists of ditches, meadow streams, canals or shallow ponds whose banks are not overgrown.
Reproduction
During the mating season, the males choose areas along the river that can be between 25 and 50 meters long and are defended by them. Once they have chosen a territory, the animals often keep them for weeks and days. If a female flies by, the male flies there and couples in flight. The resulting pairing wheel then usually lands for one to two minutes. After mating, the male flies around the female until the female flies off to lay eggs. During the egg-laying, the female is always guarded by the male flying nearby. The female lays her eggs, which measure an average of 0.32 × 0.48 millimeters, within five minutes. Compared to other dragonfly species, the shape shows an extraordinary variability.
Research history
The species was first described in 1837 by Fonscolombe using a male from Aix-en-Provence . He gave the animal the name Libellula brunea . All further descriptions were then made in the genus Orthetrum . The second subspecies was first described by Selys in 1848 . He named his female from Corsica Libellula cycnos . It was also Selys who downgraded the species to a subspecies in 1864 and placed it next to Orthetrum brunneum .
Individual evidence
- ^ A b Henrik Steinmann: World Catalog of Odonata. Volume II: Anisoptera. de Gruyter, 1997, ISBN 3-11-014934-6 , p. 412.
- ↑ a b c Paul-A. Robert: The dragonflies (odonates). Authorized translation by Otto Paul Wenger. Kümmerly & Frey, Geographischer Verlag, Bern 1959, DNB 454062648 , p. 304ff.
- ↑ a b Wolfgang Dreyer: Die Libellen -The comprehensive handbook on the biology and ecology of all Central European species with identification keys for adults and larvae. Gerstenberg Verlag, Hildesheim 1986, ISBN 3-8067-2022-3 , pp. 85f.
literature
- K. Sternberg, R. Buchwald: Orthetrum brunneum. Fonscolombe, 1837 - flat belly. In: K. Sternberg, R. Buchwald (Ed.): Die Libellen Baden-Württemberg. Volume 2: Dragonflies (Anisoptera). Ulmer, Stuttgart 2000, ISBN 3-8001-3514-0 , pp. 477-492.
Web links
- Orthetrum brunneum in the Red List of Endangered Species of the IUCN 2013.2. Listed by: Dow, RA, 2007. Retrieved February 22, 2014.