Lycinus caldera is a mygalomorph spider of Chile, named after its type locality: Caldera, Copiapó, Region III.[2] Males are distinguished from L. gajardoi by the larger cymbium, the thinner and more numerous modified cymbial setae and the shorter embolus, and from those of all other species in the tribe by having cymbial setae directed backwards. Females are distinguished from other Chilean species of Lycinus by the spermathecae with two or three receptacula on each side.
The spider is found in long, deep burrows (closed with a double flap typical of the Chilean Lycinus) in sandy, desertic locations. The internal burrow's lining forms a dense, thick tube which prevents sand from collapsing. The burrows are typically between 20 and 25 millimetres (0.79 and 0.98 in) wide. They start a vertical path, becoming more horizontal after approximately 25 centimetres (9.8 in), widening at a bottom chamber.