When species with similar morphological and ecological characteristics occupy the same habitat, selection should minimize resource competition and promote coexistence by means of spatial partitioning. Competing species might exploit resources at different times or specialize in distinct resources. From July 2005 through May 2006 we examined the niche axes of two endemic sympatric desert species, Syspira tigrina Simon 1885 and Syspira longipes Simon 1885 in the State of Baja California Sur, looking for evidence that coexistence is fostered by differences in choice of microhabitat, temporal activity, occupation of space, or size. The results show high monthly microhabitat overlap (> 0.9). However, we found subtle differences in temporal activity and marked differences in juvenile and male body size, as well as some evidence of mutual spatial segregation. We conclude that body size and spatial segregation appear to be the dominant niche axes that facilitate coexistence of these species.