Enallagma ebrium
| Enallagma ebrium | ||||||||||||
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Enallagma ebrium , male |
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| Scientific name | ||||||||||||
| Enallagma ebrium | ||||||||||||
| ( Hagen , 1861) |
Enallagma ebrium is a species of dragonfly from the family of the common dragonflies (Coenagrionidae), which is widespread in Canada and northern North America and can become very common in the northern latitudes. The habitat is formed by lakes and ponds of all sizes, often located in forest areas and typically surrounded by dense aquatic vegetation. Enallagma ebrium is a typical representative of the species-rich group of blue-colored cup maids . It is confusingly similar to the other members of the genus, especially the Enallagma hageni, which also has almost the same ecological standards. Thespecies was first described in 1861 by Hermann August Hagen .
features
Enallagma ebrium is a typical slender dragonfly with a body length of 28 to 34 millimeters and a length of the hind wings of 16 to 21 millimeters and thus belongs to the smaller representatives within the group of blue-colored cup maids. The males have a light blue basic color with drop-shaped and also blue postocular spots on the body-facing side of the compound eyes . These are aligned with one another with the tip and connected to one another via a line. The eyes are dark on top, so that they appear to be covered by a cap. On the upper side of the thorax there is a broad black median stripe with slightly narrower, light ante-humeral stripes on both sides. The following dark humeral stripes are of similar width. On the light blue sides of the thorax underneath there are two short black stripes, the upper one is, as is typical for the cup maids, only very rudimentary or not at all, so that the side surfaces appear as if they were not marked. The elongated abdomen is provided with a typical slender vial mark. At the lower end of the second segment there is a black point, which in most specimens merges with the adjacent caudal ring. There are also narrow black rings on the other segments three to five, which expand dorsally and increase in width towards the rear segments. The sixth segment is mostly black on the top and the seventh is predominantly black. The eighth and ninth abdominal segments are unmarked and therefore blue, the tenth completely black on top. Specimens with extensive black markings of the middle abdominal segments are rare.
The abdomen of the females is more powerfully built than that of the males and the top is completely covered with a black torpedo-shaped drawing, so that the abdominal segments only show a light ring at the front edge of segments three to eight. There is a protruding spike in front of the ovary on the eighth abdominal segment. The chest drawing corresponds to that of the male. As is not uncommon in the subfamily of the Ischnurinae , the females come in different color variants. There is an androchromic blue form, colored like the males, as well as the either pale brown or greenish colored heterochromic forms. The eyes of the females are divided horizontally in color, the lower part is brownish or greenish, the upper part brown. On the lower light part there is usually a dark horizontal stripe.
Similar species
A relatively recent evolutionary split has led to a large number of species, some of which are very similar and difficult to distinguish, in North America. However, the cup youngsters are often formed from only one species, and once determined, it can be assumed that all specimens of this population only belong to this species. Preferences for different habitat types, which at first glance appear very similar, seem to separate them, even if these mechanisms are not yet fully understood.
Males of Enallagma ebrium can hardly be distinguished from those of Enallagma hageni , a differentiation can only be made on the basis of the male abdominal appendages, the details of which can possibly be perceived when viewed from close up. In E. hageni , only a single horizontal spine can be seen in the lateral view, while in E. ebrium the cerci fork into two outgrowths of about the same length.
The females, too, are practically identical to the females of E. hageni and can only be distinguished by the shape of the prothorax and its typical shape of the rear edge. In E. hageni , this is largely upward and bulges clearly above the thorax, while in E. ebrium the areas are flat.
The very similar males of Enallagma annexum , Enallagma boreale , Enallagma civile and Enallagma vernale are also very difficult to distinguish from Enallagma ebrium , as well as from E. hageni . However, these are significantly larger and with the exception of E. civile , the mushroom-shaped pattern of the second abdominal segment does not merge with the adjoining ring , at least in the area where the distribution overlaps with E. ebrium . Other common blue slender vials are characterized by larger black portions on the middle abdominal segments. The females of E. ebrium can also be confused with the females of Enallagma anna , Enallagma carunculatum , Enallagma civile and Coenagrion resolutum , which also have a completely black upper side of the abdomen.
distribution
Enallagma ebrium is distributed far from western Canada to Idaho and Wyoming and west of the Rocky Mountains to Newfoundland , and south to Tennessee and West Virginia .
Odonatological records by Francis Whitehouse from 1918 for Alberta , in which species that are actually not difficult to find such as Enallagma carunculatum , Enallagma clausum and Enallagma hageni and also Enallagma ebrium , suggest that they have expanded their territory significantly to the north in the last few decades need to have.
The IUCN classifies Enallagma ebrium as “not endangered” ( least concern ).
Way of life
Enallagma ebrium can become very common in northern latitudes. The habitat is formed by lakes and ponds of all sizes, often located in forest areas and typically surrounded by dense aquatic vegetation. In contrast to the similar Enallagma hageni , bog pools or other acidic waters are usually avoided.
The males rest, sometimes in very large numbers, on stalks of the bank vegetation or algae mats near the waters. Atypical for cup maids they stay in the cover of the vegetation and avoid the open water. The first pairs in the bike reach the breeding water around noon, the eggs are laid, alone or with the male attached, in flooding or submerged water plants. The female can reach a depth of more than 30 centimeters, and in individual cases spend up to five hours under water without surfacing. The larvae overwinter in one of the last larval stages.
The flight time of the adults differs with the distribution. In the northwest of the distribution area in the Yukon Territory , it begins in June and ends in July, in British Columbia it begins in May and extends into August, as well as in Alberta and Montana , where it does not begin until June. In southern Nebraska , specimens can be found until September. E. hageni hatches in Ontario , Québec and Wisconsin in May, in Nova Scotia , Iowa and Maine from June and flies into September, in Ohio even into October.
Naming
The specific epithet ebrium ( Latin ) means "intoxicated". Since Hermann August Hagen , of the type in 1861 described , this could not have observed alive because he had never been in the Americas until then, we can only speculate why he chose this name.
swell
literature
- John Acorn: Damselflies of Alberta, Flying Neon Toothpicks in the Grass. University of Texas Press, Austin 2011, ISBN 978-0-88864-419-0 .
- Dennis Paulson: Dragonflies and Damselflies of the East, Princeton Field Guides. Princeton University Press, New Jersey 2011, ISBN 978-0-691-12283-0 .
- Dennis Paulson: Dragonflies and Damselflies of the West, Princeton Field Guides. Princeton University Press, New Jersey 2000, ISBN 0-691-12281-4 .
- Robert DuBois: Dragonflies & Damselflies of the Rocky Mountains. Kollath + Stensaas Publishing, Duluth 2010, ISBN 978-0-9792006-8-7 .
Individual evidence
- ↑ a b c d e f g Dennis Paulson: Marsh Bluet. In: Dragonflies and Damselflies of the East. Pp. 103-104.
- ^ Jill Silsby: Subfamily Ischnurinae (Blue-tailed Damselflies). In: Dragonflies of the World . Smithsonian, Washington 2001, ISBN 1-56098-959-9 , pp. 110-112.
- ^ A b Dennis Paulson: American Bluets. In: Dragonflies and Damselflies of the East. P. 85.
- ^ Dennis Paulson: Vernal Bluet. In: Dragonflies and Damselflies of the East. Pp. 97-98.
- ↑ Robert DuBois: Hagen's Bluet. In: Dragonflies & Damselflies of the Rocky Mountains. Pp. 116-117.
- ^ A b Robert DuBois: Marsh Bluet. In: Dragonflies & Damselflies of the Rocky Mountains. Pp. 114-115.
- ^ A b Dennis Paulson: Marsh Bluet. In: Dragonflies and Damselflies of the West. P. 90.
- ↑ John Acorn: Hagen's Bluet. In: Damselflies of Alberta. Pp. 92-94.
- ↑ Enallagma ebrium in the IUCN Red List of Threatened Species 2012.1. Posted by: DR Paulson, 2009. Retrieved July 23, 2012.
- ^ A b John Acorn: Marsh Bluet. In: Damselflies of Alberta. Pp. 95-97.
Web links
- Photos of "Enallagma ebrium" - Marsh Bluet on odonata.bogfoot.net, with pictures