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Leonora's Dancer



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Argia leonorae

Garrison, 1994


Order Odonata
Suborder Zygoptera
Superfamily Coenagrionoidea
Family Coenagrionidae
Genus Argia
Species leonorae Garrison, 1994 [Argia]


Identification

The male has a dark head and pale postocular spots that may vary in size. Sometimes there is a blue line at the rear of the occiput, but when present, the postocular spots never touch this line. Garrison (1994a ) reported that specimens from Reeves County, Texas, had these postocular spots considerably reduced and lacked the blue line at the rear of the occiput. The pterothorax is blue gradually becoming paler laterally. There is a broad, black middorsal stripe and a dark humeral stripe forked at its upper third. The lower fork is half the width of the upper fork and both of these may be broadly joined at their upper end. The legs are blue, becoming paler medially with the inner and outer surfaces of the femora black. There are postquadrangular cells in both fore- and hindwings. The abdomen is blue with black markings that become more pronounced posteriorly. Segment 1 is blue with a single antehumeral black spot on each side, as well as a black spot dorsally on the basal half of the segment. Segment 2 has an irregular dorsolateral stripe that is constricted medially and expanded in the posterior quarter of the segment so that it becomes confluent with that of other side. There is a small bla ck spot laterally on half of segment 2. The apical third to 1/2 of segments 3-5 are black narrowing to a point. Segments 6 and 7 are similar to 3-5, but with the black covering most of the segment. The appearance of these segements when viewed dorsolaterally is of spear tips directed toward the head. Segments 8-10 are blue with black on segment 8 extending ventrally to the anterior half of the segment. The cerci are dark and the paraprocts are small and quadrad in shape. The cerci each bear a small lobe posteromedially followed by smaller, distal tooth. The paraprocts are forked and twice the length of the cerci with the lower lobe rounded. The female is similarly patterned to the male and may be blue or tan. The pale postocular spots are larger and the dark humeral stripe is forked at half its length. The mesostigmal plates are triangular and with a costate rim. There is a poorly developed mesostigmal lobe present. There is a small dorsobasal black spot on abdominal segment 1. Segment 2 has a black dorsolateral stripe, as in the male, but reduced and separated dorsally and medially. Segments 3-5 are pale with the distal third of each segment black and with dorsolateral extensions to the basal part of segment. Segments 6 and 7 are like 3-5, but black dorsolateral areas are confluent dorsally, obscuring the pale middorsal stripe. Segments 8 and 9 are pale with a black dorsolateral stripe and a narrow pale middorsal line becoming wider on 9. Segment 10 is nearly all pale with brown areas restricted to the dorsolateral areas. Some specimens in Texas have segments 3-7 all black dorsally, except for the extreme bases.

Size

Total length: 28-32 mm; abdomen: 21-26 mm; hindwing: 15-19 mm.

Similar Species

Aztec Dancer (A. nahuana ) is similar but the dark rings on the middle abdominal segments are truncate and don't taper to points as in Leonora's Dancer. Double-striped Blue (Enallagma basidens ) has a dark humeral stripe divided by a thin pale stripe. Female Variable Dancer's (A. fumipennis ) are essentially identical and can only be reliably separated from Leonorae's Dancer where they are found together, by examination of the mesostigmal plates.

Habitat

Small streams and seepages.

Discussion

This is a small blue uncommon but widely distributed species in south-central and western Texas. Leonora's ancer was first collected in Brooks County, Texas, in 1928. T.W. Donnelly and G.H. Beatty collected it in 1954 at Balmorhea State Park in Reeves County, Texas and was known as the "Balmorhea Damselfly" until Garrison formally described it in 1994. Little is known about its biology. It frequents small streams and seepages such as the "muddy banked rivulets" of Mustang Creek in Williamson County, Texas, and scattered sedge-ridden swales above the Rio Sabinal in Bandera County, Texas. I have found it associated with sedges in western and central Texas. Females are generally not found with males around water unless they are mati ng or laying eggs. The latter of which they do accompanied by the male.

Distribution

Texas and Nuevo Leon, Mexico.