Quantitative surveying of endogeic limbless vertebrates— a case study of Gegeneophis ramaswamii (Amphibia: Gymnophiona: Caeciliidae) in southern India

Many subterranean, limbless reptiles and amphibians are predators of invertebrate soil ecosystem engineers. The potential importance of these predators in soil ecology partly rests on whether they occur in high densities, but their abundance has rarely been measured, and there are no standard methods. The mostly tropical and fossorial caecilians (Amphibia: Gymnophiona) are often considered rare, but there are very few quantitative data, and some species, including Gegeneophis ramaswamii, have been reported as abundant in some situations. Using simple and repeatable survey methods with randomised 1 m2 quadrats, surveys of G. ramaswamii were conducted at five localities in southern India. Densities of 0–1.87 m−2 per survey were measured, with means of 0.51 and 0.63 m−2 at the beginning and middle of monsoon, respectively. These densities were far greater than for sympatric caecilians (ichthyophiids; uraeotyphlids) and fossorial snakes (typhlopids; colubrids). While ecological data remain very scant, establishing quantitative methods to assess the abundance of endogeic limbless vertebrates is an important step toward greater understanding of subterranean predator–prey relations, and of monitoring populations of these poorly known organisms. © 2003 Elsevier Science B.V. All rights reserved.