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Allegheny River Cruiser



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Macromia alleghaniensis

Williamson, 1909


Order Odonata
Suborder Anisoptera
Superfamily Libelluloidea
Family Macromiidae
Genus Macromia
Species alleghaniensis Williamson, 1909 [Macromia]


Identification

This species is distinct in the region, with its entirely dark vertex, short tibial keels and vestigial pale antehumeral stripe. It has a yellowish-brown face that becomes black dorsally on the frons which has two small yellow spots. The wings are clear with a dark costa and pterostigma. The keel on the middle tibia is 1/7-1/5 as long as the tibia itself. A yellow ring on abdominal segment 2 is interrupted middorsally. Segments 3-6 each have a pair of spots dorsally. Segments 7-8 have pale basal middorsal spot, which may be absent in female s. Yellow on segment 7 encircles the abdomen, so that segments 7-9 each have the inferior basal margin of the segment yellow.

Size

Total length: 65-72 mm; abdomen: 51-56 mm; hindwing: 45-50 mm.

Similar Species

Illinois River Cruiser (M. illinoiensis ) is similar but with partial frontal thoracic stripes and a complete band around segment 2. Royal River Cruiser (M. taeniolata ) is noticeably larger and generally bears a pair of yellow spots on segment 7.

Habitat

Cool, upland streams

Discussion

This species has been reported from southwestern Arkansas. Nothing has been published about the behavior of this species, but it is presumably similar to Illinois River Cruiser. In the original description Williamson wrote, "...I recall nothing striking in its habits of life."

Distribution

Eastern U.S.