Arachnologists of the UNAM

Biological inventories serve to document the species inhabiting an ecosystem so we can begin to understand their interactions, importance and use of resources. Spiders form part of the order Araneae, which is recognized as one of world’s richest in terms of number of species: approximately 42,000 recorded species, representing half to one fifth of the estimated quantity of species. Most new discoveries inhabit subtropical and tropical regions. Mexico is of prime biological importance for this and other groups of organisms given that it is a transitional region between temperate and tropical zones, with highly variable terrain, and also because there have been few inventories of its spider population. Thus, it is likely that future studies will discover new species and extend the distribution range of previously identified species.

Woodland conservation and responsible management of natural resources is of key importance to the preservation of such biodiversity. Las Pozas is a high evergreen forest, under conservation for at least the past twenty years, and surrounded by human settlements. It functions as a refuge for a number of species whose natural habitats have been altered. This was the motive of four visits to the region made in 2011 and 2012.

A total of 10,716 spiders were collected in Las Pozas, of which 4017 were adult specimens representing approximately 250 species. Experts estimate that this represents between fifty and seventy-five percent of the species that may inhabit the zone, rated by the Shannon-Wiener and Simpson diversity indices as H’=3.69 and D=0.954 respectively, indicating a high degree of diversity. Studies realized in other parts of the Sculpture Garden and surrounding areas complement this information. Previously, 155 species had been recorded in San Luis Potosí (Hoffmann 1976). The 250 species collected in Las Pozas are currently being identified to determine which ones are new sightings in the state, and which ones are entirely new species. Preliminary data indicate that there may be ten new species for science, and many species recorded for the first time in this state.