Diversidad de arañas (Araneae, Araneomorphae) en la selva de montaña: Un caso de estudio en las Yungas Argentinas

Abstract

The spider diversity from yungas vegetation in northwestern Argentina is studied, integrating two levels: local (α diversity, community structures) and a projection at regional level of diversity (β diversity). Twenty six sites in Salta Province were sampled, representing different ambient/altitudinal strata of yungas sensu stricto (SP= pedemontane rainforest, SM= montane rainforest and BM= montane forest), yungas sensu lato (Cc-s= yungas central and southern sectors connectivity areas, YT= transitional yungas), and Chaco Serrano sites (ChS) as contrast. The sampling was carried out seasonally for one year taking 10 samples of vegetation with G-Vac method. A total of 6412 spiders, 188 species and 34 families were obtained (only yungas). Theridiidae, Anyphaenidae and Linyphiidae were dominant. The highest richness was observed in Araneidae, Salticidae and Theridiidae. Chibchea salta (Pholcidae), Dubiaranea msp111 (Linyphiidae) and Mysmena msp110 (Mysmenidae) were dominant species. Relevant differences in species composition and abundance highlighted two groups of environment (Cc-s+SP+YT+ChS) vs. (SM+BM). Dictynidae, Oxyopidae and Philodromidae are associated with lower altitudinal floors (Cc-s, YT, ChS). The greatest species richness and diversity were recorded in SP and YT. The highest similarity was recorded in SM and BM; the major differences were observed in Cc-s and ChS compared with the other ambient, except with SP. Complementarity and similarity indices and coefficients revealed high β diversity in the region. Thus, it is suggested that besides reinforcing protection in transitional levels Yungas (the most disturbed and diverse habitats for spiders), conservation management in the area should be directed towards promoting natural spatial heterogeneity of Yungas, giving special emphasis to habitat mosaics that constitute each different stratum.