Tropical subterranean biodiversity; A new method for studying an undersampled ant fauna
Kari T. Ryder Wilkie, Amy L. Mertl, and James F.A. Traniello. Biology, Boston University, 5 Cummington St., Boston, MA 02215
Subterranean ants are underrepresented in biotic surveys. We developed a novel probe that permits the vertical sampling of tropical ants beneath the soil. The probe consists of two 50 cm-long plastic cylinders implanted in the ground within a drilled hole of the same dimension. The outer cylinder is perforated and receives a second removable cylinder with aligning holes. The inner cylinder is easily removed and can be replaced without disturbance. Underground ants enter four separate baited sections 12.5, 25, 37.5, and 50cm below the surface. Probes were implanted along five transects at the Tiputini Biodiversity Station in Amazonian Ecuador and checked at 24, 48 and 72 hour intervals. Results were compared to traditional surface sampling using the ALL protocol. Forty-five species and 19 genera of ants were collected, 22 of which were rare (present in only 1 of the 50 probe samples). At least 5 species -- Acanthostichus quadratus, Centromyrmex alfaroi, Neivamyrmex spinolai, Pachycondyla impressa, and Tranopeltagilva -- of the 45 collected (11.1%) were unique to probe samples. The highest species richness (41 species) and the greatest number of unique species (17 species) were found at a depth of 12.5 cm. The deepest levels (37.5 and 50 cm) contained 11 and 9 species, respectively, with no unique species. All 44 species collected were present in the top two levels of the soil. The total number of species and species composition recorded during each sample interval was similar. The majority of species were collected during the first 24 hour sample. Michaelis-Menton predicts that additional sampling days would result in an expected species richness of 55, compared to an expected species richness of 74 predicted by sampling with additional probes. The use of the probe will increase our understanding of the subterranean vertical stratification and ecology of tropical ants.