Mega-transect studies in Brazil and tropical Africa: gathering data to estimate global pholcid diversity

BERNHARD A. HUBER; ABEL PÉREZ GONZÁLEZ; CRISTINA RHEIMS; ALESSANDRO GIUPPONI; JANAEL RICETTI; MARCELO ALVES DIAS; GERALD EILU; PETER KWAPONG; PHILIPPE LE GALL; JACQUES MAVOUNGOU; MAMADI SIDIBE; CHARLES WARUI

Congreso; 19th International Congress of Arachnology; 2013

Estimates of global species diversity rely on collected specimens. However, the large majority of material currently available in museum collections suffers from the usual problems of generalist collections. Among these, the most common bias is probably one towards widespread species that usually tolerate a wide range of ecological conditions. The more exigent and often locally endemic species are much more challenging to collect and much less likely to end up in collections. At the same time, extrapolation from single-site studies ignores distribution patters and is thus problematic. For these reasons we have started two long-term projects with the aim of producing reasonable estimates of the actual pholcid diversity in at least two megadiverse regions. The basic aim is to provide close-to-complete inventories of the pholcid fauna in dozens of localities spread over the Atlantic Forest in Brazil (N-S transect) and across tropical Africa (W-E transect). The combination of data about species per locality, endemism levels, distributions patterns, and vegetation data will produce a first hypothesis of overall diversity based on more than just speculation. Current data (after five expeditions to Brazil and six expeditions to tropical Africa) provide among-locality species accumulation curves that do not seem to level off. Both mega-transects provided similar percentages of new species (70.1% and 79.8%), suggesting that a global total of 5000 pholcid species (current total: 1350) may be a reasonable estimate.