Fallicambarus tenuis

Fallicambarus has traditionally been divided into two subgenera (Fallicambarus and Creaserinus). While these two subgenera form monophyletic groups, each is more closely related to other genera than to each other (Ainscough et al. 2013), with the subgenus Fallicambarus more allied with members of Procambarus and the subgenus Creaserinus more closely allied with species of Faxonius. Crandall and De Grave (2017) thus elevate the subgenus Creaserinus to full generic rank and retain the contained species.

This is a species with a fairly small range about which relatively little is known due to the scarcity of records. While portions of the range are protected by the Ouachita National Forest, other portions consist of large tracts of industrial timber land and pasture.

This species is restricted to the Ouachita Mountains, where is found in small streams, springs, seeps, and roadside ditches in portions of the Ouachita, Red River, and Arkansas River basins in Arkansas and Oklahoma (Hobbs 1989).

There are 27 known occurrences of this species based on a 2 km separation distance. While many of these collections come from streams, it has also been collected less frequently in burrows outside of stream channels (Rhoden et al. 2016, Dyer and Brewer 2018). This species was once assigned to the genus Procambarus and thought to be a tertiary burrower but has been reassigned to the genus Fallicambarus (Crandall and DeGrave 2017), all other members of which are primary burrowing species. Because this species may burrow more frequently than was formerly thought, previous reports of F. tenuis as rare within its range may be an artifact of sampling methods rather than small population size (Dyer and Brewer 2018).

While some of the range of this species is protected by the Ouachita National Forest, other portions consist of large tracts of industrial timber land and pasture.