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Blue-ringed Dancer



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Argia sedula

Hagen, 1861


Order Odonata
Suborder Zygoptera
Superfamily Coenagrionoidea
Family Coenagrionidae
Genus Argia
Species sedula (Hagen, 1861) [Agrion]


Identification

Head of the males is dark and often the blue postocular spots are obscured. The middorsal stripe are black. The broad humeral stripe is black and nearly tw ice as wide as the pale antehumeral stripe. The black stripe on the metapleural suture widens. The rest of the pterothorax is blue, becoming paler and almost yellow ventrally. The legs are largely black except for the medial surfaces of the femora and lateral surfaces of the tibiae and tarsi. There are 4 and 3 postquadrangular cells in the fore- and hindwings, respectively. Abdominal segment 1 is blue with dark brown dorsobasally and laterally. Abdominal segment 2 is black dorsally with a small pale blue spot basally or on each side of the midline. Segments 3 through 7 are black dorsally with a blue basal ring. Ventrolateral areas of the segments are paler and confluent. Segments 8-10 are blue with a black ventrolateral stripe extending to the apical portion of segment 10. The cerci are straight in lateral view, with a ventrally projecting tooth. The paraprocts are bifid with a superior lobe rounded and directed dorsally. The inferior lobe is strongly serrated and projecting posteroven trally. The head of the female is largely a combination of pale brown and olivaceous markings. The pterothorax is brown dorsally, becoming paler ventrally. The middorsal and humeral stripes are reduced to thin black hairlines and often the latter is absent entirely. The legs are pale brown with dark stripes on the outer surfaces and armed with black spurs. The mesostigmal plates are long and strongly erect appearing almost perpendicular to the mesepisternum, when viewed laterally mesepisternal tubercles are small or absent entirely. The abdomen is pale brown dorsally on segments 2-7. The ventrolateral stripes and basal rings are often ill-defined, but with touches of blue or green evident. Segments 8-10 are pale and lack dark markings.

Size

Total length: 29-34 mm; abdomen: 22-28 mm; hindwing: 17-21 mm.

Similar Species

Golden-winged Dancer (A. rhoadsi ) has deeper amber colored wings and a bluer abdomen. Golden-winged Dancer also lacks dark ventrolateral stripes on segments 8-10. Dorsally, the dark middorsal stripe on abdominal segments 3-6 is divided by a pale area in Kiowa Dancer (A. immunda).

Habitat

Lakes, ditches, streams and rivers with gentle current and dense vegetation.

Discussion

This species is more prone to perching on vegetation, often in the shade, than most dancers. Pairs require 10-15 minutes to mate and egg laying occurs in tandem, often in large numbers. A mark-recapture study on adult Blue-ringed Dancers at a small creek on the campus of the University of Texas at Arlington revealed that males had an average daily probability of survivorship of 0.79 and that activity was closely correlated with bright sun.

Distribution

From Florida north to Pennsylvania west to California and south into Mexico.