[3] D. nubeculosus is a small to medium-sized poison dart frog; larger than many of its contemporary Ranitomeya species, but smaller than the other members of the genus Dendrobates.

The holotype specimen measures 2.5 centimetres in length, and the species' size range is unknown.

It is reasonably certain that, like other members of the genus Dendrobates, D. nubeculosus females are larger than males, but even this is open to speculation.

It is assumed that the breeding habits of Dendrobates nubeculosus are similar to that of its sister taxon, D. leucomelas.

[5][6] No precise habitat data exist but the vegetation in the area of the type locality, near Rockstone, a town on the Essequibo River, lowland jungle.