Lycinus caldera is a mygalomorph spider of Chile, named after its type locality: Caldera, Copiapó, Region III. 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.
Female: total length 35.95 millimetres (1.415 in); cephalothorax length 13.5 millimetres (0.53 in), width 10.8 millimetres (0.43 in); cephalic region length 8.35 millimetres (0.329 in), width 8.7 millimetres (0.34 in); fovea width 1.75 millimetres (0.069 in); medial ocular quadrangle length 0.86 millimetres (0.034 in), width 1.92 millimetres (0.076 in); labium length 1.7 millimetres (0.067 in), width 2.55 millimetres (0.100 in); sternum length 7.6 millimetres (0.30 in), width 6.5 millimetres (0.26 in). Its cephalic region is strongly convex, highand wide short. Its labium lacks cuspules; serrula is absent. The sternum is strongly rebordered. Chelicerae: rastellum is strong, formed by numerous blunt cusps on the anterior face (similar to the rastellum of L. longipes). The entire spider is a uniform dark blackish-reddish-brown colour, with no abdominal pattern.
Male: total length 27.14 millimetres (1.069 in); cephalothorax length 12.65 millimetres (0.498 in), width 11.49 millimetres (0.452 in); cephalic region 0.58 of the cephalothorax width; fovea width 0.08 of cephalothorax width; labium length 0.73 of width; sternum width 0.85 of length. Its labium possesses no cuspules. Its serrula is well evident, and the posterior sternal sigilla is long and well separated from margin. The entire spider is a uniform blackish brown colour, while the abdomen lacks a discernible pattern.
Distributionand Behaviour
Known only from provinces of Chañaral and Copiapó, in northern Region III, Chile.
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.
