Nicagus obscurus

Stag Beetle

Nicagus obscurus, Stag Beetle image from West Virginia


Family: Lucanidae

Subfamily: Aesalinae

Length: 5.5 - 9.5 mm in the genus

Nicagus is an unusual genus. Prior to 2005 there were only two species in the genus, one found in Japan and one in eastern North America. In that year a third species was described, this one from unvegetated sand dunes in west Texas (Paulsen and Smith 2005).

Morphologically, this is a Stag Beetle genus without the usual characteristics of Stag Beetles. The enlarged male mandibles are lacking. So too are the elbowed antennae. The elongated first segment of the antennae are also absent. The antennae resemble Scarab antennae more closely in any other beetles in Lucanidae. However, the antennae cannot close up tightly like Scarab antennae (Paulsen and Smith 2005).

In Nicagus spp. the females are generally darker and have less vestiture and smaller eyes. The shape of the pronotum is also sexually dimorphic. For example, in Nicagus obscurus the sides of the pronotum form an obtuse angle in males, while the margins of the female pronotum form a smooth arc. The beetle pictured here is a male.

Photo data: 8 May 2019. Arden, Barbour County, West Virginia. Along the Tygart Valley River.

The map below shows states and provinces with records of Nicagus obscurus in blue-green. The species is more common in the area between Iowa and Maryland—in other words, in the central part of its range.