OBSERVATIONS ON THE NATURAL HISTORY OF AN UMMIDIA TRAPDOOR SPIDER FROM COSTA RICA (ARANEAE, CTENIZIDAE)

Jason E. Bond and Frederick A. Coyle: Department of Biology, Western Carolina University, Cullowhee, North Carolina 28723 USA

ABSTRACT. An Ummidia trapdoor spider species near San Vito, Costa Rica, prefers steep slopes and open, sparsely wooded, early successional stage habitats. This habitat preference and the paucity of small juvenile burrows near adult burrows are consistent with spiderling dispersal by ballooning, known to occur in other Ummidia species. The entrance and burrow architecture and prey capture and defensive behavior of this species are similar to those of the few other observed Ummidia species. Ummidia’s door-holding defensive behavior is described in detail for the first time. Two enigmatic phenomena were observed; door hinges were often tilted well away from the horizontal plane, and one spider was found on two successive afternoons with the anterior half of its body fully exposed as it held onto the inner surface of its fully open trapdoor.