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Cherry Bluet



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Enallagma concisum

Williamson, 1922


Order Odonata
Suborder Zygoptera
Superfamily Coenagrionoidea
Family Coenagrionidae
Genus Enallagma
Species concisum Williamson, 1922 [Enallagma]


Identification

The front of the male's head is bright red-orange with a narrow black stripe. The top is black with two transverse orange postocular spots confluent with occipital bar to form a single narrow orange band. The mddorsal carina and stripe are both black, with the latter no more than a third the width of the mesepisterna. The antehumeral stripe is red-orange and nearly half as wide as the middorsal stripe and more than half as wide as the humeral stripe. There is an abbreviated black line on the interpleural suture and a slightly wider line on the metapleural suture. The remainder of the pterothorax is red-orange, quickly fading to yellow or cream color. The legs are entirely orange armed with dark spurs. The abdomen is red-orange dorsally, becoming paler laterally, and marked with black. Except for the apical margin the entire dorsum of segment 1 is black. A full-length black stripe extends dorsally on segment 2 that is thin basally, widening considerably to a large spot over the apical half of the segment. There is a dorsal black stripe on the apical 1/3 to 4/5 of segment 3 that is truncated basally. The entire dorsum of segments 4-7 is black except for a broad, pale band basally. Segment 7 also bears a narrow pale apical ring, dorsally. Segments 8-10 are black dorsally except for a pale narrow apical rings that is sometimes present. The cerci are longer than segment 10 and orange or tan later ally, but distinctly white medially with dark tips. The pale paraprocts are 1/2 to 2/3 the length of the cerci with their upper surface straight when viewed laterally. Females are similar to males, but with darker heads. The pale areas are more yellow and there are distinct small pits medially on the middle lobe of prothorax. The rest of the thorax is patterned as in the male, but with a slightly wider humeral stripe and pale areas yellow or yellow-green. The mesostigmal plates are generally triangular with a distinct pale tubercle on the posteromedial corners. The posterior and lateral borders are also pale. The legs are paler, more yellow or tan, and the femora have a dark stripe. The pale areas of the abdomen are more yellow-green or tan. Segments 1-2 are like those of the male, but with the black stripe on the latter not as narrowed basally. The dorsum of segments 3-10 is nearly all black, only interrupted by a pale ring on segments 7-10 and basal ring on segments 3-7. There is a s light subapical expansion of the stripe on segments 3-6.

Size

Total length: 27-32 mm; abdomen: 22-25 mm; hindwing: 13-17 mm.

Similar Species

The red coloration of Cherry Bluet is unusual among our bluets, making it easier to identify. Burgundy Bluet (E. dubium ) is smaller and has an orange not red antehumeral stripe. The metapleural suture is pale in Orange Bluet (E. signatum ) while in Cherry Bluet there is a distinct dark stripe on this suture.

Habitat

Sand-bottomed lakes and ponds, generally with ample emergent vegetation and lily pads.

Discussion

This species is closely related to Orange Bluet, but little is known of its reproductive behavior and ecology. It is usually seen on emergent vegetation and lily pads, where females curl their abdomens to oviposit on the underside of the latter's leaves. It is relatively uncommon in our area, limited to the extreme southeatern parts of the region.

Distribution

Southeastern U.S. from Florida north to North Carolina west to Louisiana.