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Pronghorn Clubtail



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Gomphus graslinellus

Walsh, 1862


Order Odonata
Suborder Anisoptera
Superfamily Gomphioidea
Family Gomphidae
Genus Gomphus
Species graslinellus Walsh, 1862 [Gomphus]


Identification

This species has a largely northern distribution. Its face is greenish-yellow only scarcely marked with brown. The thorax is green with well-defined dorsal and lateral stripes. The middorsal thoracic stripe is parallel-sided. The antehumeral stripe is largely fused with the humeral stripe, but diverging at its upper end and becoming free. Only a thin pale line separates these two stripes medially. The remaining thoracic stripes are present an d well separated. The legs are brown, becoming black distally, with a yellow stripe externally on the tibiae. The abdomen is dark brown or black with a pronounced club. A yellow middorsal stripe is interrupted to appear as large spearheads on segments 1-7. Segment 8 has little yellow dorsally, but a wide stripe is present on segments 9-10. Laterally, segments 8-10 are all brightly marked with yellow. The male caudal appendages are dark brown.

Size

Total length: 44-54 mm; abdomen: 32-40 mm; hindwing: 28-35 mm.

Similar Species

Plains Clubtail (G. externus ) is similar and may not always be reliably separated. Some Plains Clubtails can be distinguished by the largely fused antehumeral and humeral stripes. The cerci in male Plains Clubtails lack teeth laterally. Ozark Clubtail (G. ozarkensis ) have segment 9 black dorsally or with at most a small pale yellow spot. The paler Sulphur-tipped Clubtail (G. militaris ) is yellow laterally on segment 7 and the pale yellow on segment 9 is only narrowly separated dorsally and laterally

Habitat

Ponds, lakes and slow-reaches of small and large streams.

Discussion

Adults rest on the ground, rocks or bushes near the water. Females lay eggs by flying low over the water and touching the abdomen to the surface every few feet. This species emerges between daybreak and sunrise. Females fly dipping and rising in a series of concave loops over the water when disturbed.

Distribution

Widespread from southern British Columbia and Ontario southward to Texas.