Amblyderus triplehorni

Amblyderus triplehorni is the largest North American Amblyderus species with its length ranging from 4.5 to 6.1 mm. This light yellowish brown beetle varies in colour from yellow to orange-brown, with males typically darker than the females. It can also have a large brown blotch centered on each elytron occasionally. For the males, generally most of the head, pronotum, and abdomen are dark, with the anterior margins of these parts being lighter coloured. The ventral abdomen is the darkest. The antennae, legs, anterior portion of the head, and ventral region of the prothorax are the lightest coloured. The hairs are white to silvery. For the females, they are a lighter colour overall. Usually the head has a uniform colour and the central thorax is light coloured, which differs from the males.

Technical description. The head is triangular, wider than it is long. Its eyes are large, black, and oval. The head is light brown anteriorly and dark brown posteriorly. Generally the surface of the head integument is coarsely tuberculate over entire disc with the exception of the median smooth line. The antennae are almost double the length of the head, with the last antennomere conical and pubescent on distal 2/3. The prothorax is wider than the base of the head, and tapers evenly to base. The width of the prothorax at the base is approximately 2/3 the width of the prothorax apex. …

Amblyderus triplehorni is a sand dune specialist, preferring to inhabit the most barren dunes. This species can usually be observed on high bare dune ridges, especially in windswept debris pockets.

Adults are scavengers that feed on dead insects. They forage in the evenings near the dune crest or in debris pockets further down the dunes. Debris pockets trap small dead insects, such as aphids and cicadellids that the adults feed on. When the wind is calm, the adults travel quickly in a circuitous pattern in search of food. When there are strong gusts of wind, they lie flat against the sand to prevent being picked up by the wind. Two feeding methods are known. The first method uses their middle and hind legs to anchor themselves to the ground and their forelegs and palps to manipulate their food. The second method is to feed while on its back and use all six legs to manipulate the food. Occasionally, these beetles hold their food with their mouths and forelegs, and travel erratically. The adults are most active in early summer, but have been detected up to September.

Amblyderus triplehorni was named after Charles A. Triplehorn due to his work with W.A. and B.W. Triplehorn that collected the type specimens in 1974 in Great Sand Dunes National Monument.

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