Adults of the nominate subspecies have a sooty brown head that is lighter on the forehead, chin, and around the eyes.

The wing and tail feathers are blackish on their outer webs and pale gray brown on the inner ones.

Juveniles are similar to adults with the addition of grayish white edges to the belly feathers and the tips of the tail.

[5] The nominate subspecies of biscutate swift is found from Minas Gerais in southeastern Brazil into Argentina's Misiones Province; at least one record has also been confirmed in Bolivia.

Details of its diet are lacking but it is assumed to be similar to that of others of its genus; insects of many orders are their prey.

It builds a nest of lichen, bryophytes, other plant material, and soil on a ledge or adhering to a vertical wall.