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Southern Spreadwing



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Lestes australis

Walker, 1952


Order Odonata
Suborder Zygoptera
Superfamily Lestoidea
Family Lestidae
Genus Lestes
Species australis Walker, 1952 [Lestes]


Identification

This is the most widespread spreadwing in our region, occurring in all major watersheds and biotic provinces. The face and eyes of males are bright blue with a small, pale spot lateral to each posterior ocellus. There is a pale blue-green stripe on the mesopleural suture that extends the full-length of the suture and is confluent with the pale areas of the metepisternum at the border of the mesepimeron. The rest of the pterothorax varies from pale to black. Legs are dark brown. Older individuals become heavily pruinose ventrolaterally, occasionally obscuring the entire pterothorax (more common in northern populations). The abdomen is largely dark with a metallic green luster dorsally. There are distinct dark ventrolateral spots on segments 6-7. The spots may also be present on segments 3-5, but they are generally less defined. Heavy pruinos ity develops laterally on segments 1-2, ventrolaterally on segments 7-8 and completely on segments 9-10. The distal medial tooth of the cerci is acute, blunt and distinctly smaller than the basal tooth. Paraprocts are nearly as long as cerci. Females are generally similar to males with the pale stripe running along the mesopleural suture complete and confluent with metathoracic area. Females lack pruinosity on abdomen, but rear of head becomes pruinose, along with coxae and ventrolateral margins of the pterothorax. Laterally abdominal segments 7-10 are uniformly pale yellow, except for a ventrolateral rim of segment 9. Ovipositor with posterolateral corner of basal plate produced to form a distinct acute tooth, longer than its basal width. The ovipositor reaches well beyond margin of segment 10, but does not reach the tips of the paraprocts.

Size

Total length: 36-46 mm; abdomen: 28-36 mm; hindwing: 18-25 mm.

Similar Species

Southern Spreadwing is smaller than most other spreadwings in the region. The Northern Spreadwing (L. disjunctus ) generally does not extend south of north-central New Mexico, but it can be separated from the Southern Spreadwing by its darker color pattern, smaller size (33-40 mm ) and the more strongly developed distal tooth on the cerci. Females are similar to those of Slender Spreadwing (L. rectangularis ) and may be easily confused, but for the larger size, more robust and longer abdomen, and the yellow tarsi and tinted wingtips of Slender Spreadwing. The mid-dorsum of the thorax is generally darker than in Plateau (L. alacer ) and Rainpool (L. forficula ) Spreadwings. The abdomen of Lyre-tipped Spreadwing (L . unguiculatus ) is metallic green.

Habitat

Still, slow moving waters, including permanent or ephemeral ponds, marshes and lakes with moderate vegetation.

Discussion

This species has received considerable attention by workers due to both its abundance and taxonomic confusion. This species is found everywhere within the region except the extreme western edge where it is replaced by is northern counterpart, L. disjunctus Selys (Northern Spreadwing). Southern Spreadwing is colored similar to the more northern Sweetflag Spreadwing (L. forcipatus ) and their caudal appendages closely resemble one another. Early records for both of these species must be viewed with caution as a result. Southern Spreadwing emerges early in the south-central United States, mid-March, and flies throughout the rest of the year. This species does, however, seem to be most abundant in the fall. Males are not territorial and individuals are often seen a considerable distance, several hundred meters, from any body of water. Mating activity in this species tends to peak in the late afternoon, ca. 5 P.M. Egg laying occurs in tandem in green stems of cattails and similar plants, above the water line. Females will usually lay over a hundred eggs. The larvae can tolerate considerable salinity and may be a common inhabitant of saline lakes. A population study in eastern Ontario, Canada, on sexual size dimorphism and sex-specific survival in adults, found that there was no difference in the mass of mated and unmated males, but that females were more than 50% heavier than males. It was also determined that males were eight times more abundant than females; however, females were more active than males.

Distribution

Throughout all of much of the eastern and southern United States west of the Rocky Mountains.