Westfall's Snaketail
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Ophiogomphus westfalli
Cook & Daigle, 1985
Order Odonata
Suborder Anisoptera
Superfamily Gomphioidea
Family Gomphidae
Genus Ophiogomphus
Species westfalli Cook & Daigle, 1985 [Ophiogomphus]
Identification
This species occurs in the Interior Highlands of the Arkansas Ozarks and Ouachita Mountains. It is green with conspicuously absent dark thoracic markings. Only a faint brown middorsal stripe is present. The female has prominent occipital spines and occasionally vestigial postoccipital spines. The wings have the basal third flavescent and a yellow costa. The pterostigma is black. The abdomen is pale yellow dorsally, with an interrupted dark brown dorsolateral stripe on segments 1-6. Segments 7-9 are yellow dorsally with black apically and a reddish-brown full-length dorsolateral stripe. Segment 10 is mostly yellow.
Size
Total length: 48-50 mm; abdomen: 31-35 mm; hindwing: 29-31 mm.
Similar Species
Pond clubtails (Arigomphus
) that may be confused with this species have dark humeral and antehumeral stripes. Eastern Ringtail (E. designatus
) is similar, but has a dark midfrontal thoracic stripe and distinct humeral and antehumeral stripes. There are also pale abdominal rings in that species.
Habitat
Clear forest mountain streams with strong riffles and cobble substrate.
Discussion
Rusty Snaketail (O. rupinsulensis (Walsh
) was reported from Arkansas before this species was described. Those specimens have all been reexamined and found to be Westfall's Snaketail. Males regularly visit areas of streams with riffles where they may perch on exposed rocks. They patrol around midday.
Distribution
Ozark region of Arkansas, Kansas and Missouri.
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