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Chalky Spreadwing



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Lestes sigma

Calvert, 1901


Order Odonata
Suborder Zygoptera
Superfamily Lestoidea
Family Lestidae
Genus Lestes
Species sigma Calvert, 1901 [Lestes]


Identification

This Mexican species ranges as far north as the Red River. Males have extensive blue on the face. Some individuals may have spots lateral to the posterior ocelli expanded into triangles. The rear of the head is yellow in young individuals, quickly becoming pruinos e and black with maturity. The eyes are blue dorsally fading to paler white below. The pterothorax is gray to tan with extensive black markings including an elongated antehumeral spot just above humeral suture. The middorsal and antealar carinae is often black. There is an irregular stripe half the length of the mesepimeron just below the humeral suture. The stripe along the interpleural suture is often extensive, covering the majority of the metepisternum. There are two black spots, which may be connected, above the anterior and posterior ends of the metapleural carina and another large spot below the carina. The black may become more extensive with age, eventually covering the entire pterothorax. The pruinescence may extend down to and include the legs. The pterostigma may be bicolored, dark brown or black anteriorly and yellow posteriorly. The abdominal segments 3-7 are dark dorsally and confluent with ventrolateral markings. Segments 8-10 are completely black, except for lighter br own posterodorsal and lateral spots on 10. Segments 1-2 and 8-10 become heavily pruinose with 10 remaining lighter than others. The paraprocts are distinctly sigmoid in form. The general color pattern of the female is like that of the male, but with black and pruinescence less extensive. Mature individuals become dark with age. The eyes are duller than in the male. Black on dorsum of abdominal segment 1 encompasses only apical half of segment. Black on ventrolateral parts of segments 3-5 is generally not confluent with the dorsal stripe. Segments 1-2 and 8-10 become heavily pruinose with age. The basal plate of the ovipositor has a distinct posterolateral acuminate tooth.

Size

Total length: 39-47 mm; abdomen: 31-37 mm; hindwing: 20-25 mm.

Similar Species

Older males of Rainpool Spreadwing (L. forficula ) are similar to Chalky Spreadwing, but the latter has distinctly sigmoid paraprocts and lacks a metallic green antehumeral stripe. Lyre-tipped Spreadwing (L. unguiculatus ) males also have sigmoid paraprocts, but are smaller in size and more northerly distributed. Lyre-tipped Spreadwing also lack dark marks posterior to the legs on the underside of the thorax.

Habitat

Temporary pools and ponds.

Discussion

This species has been eroneously reported from New Mexico, but this species doesn't reach that far northwest. Marshall County, Oklahoma is the farthest north this species has been documented and the only record north of the Red River. Variation in the caudal appendages of this damselfly are equal to differences between other spreadwing species. The basal tooth on the cerci can take the form of a distinct pointed tooth or a rounded lobe.

Distribution

Southern species found in Oklahoma and Texas south through Mexico to Costa Rica.