Nest density and other observations on a population of Aneuretus simoni Emery, 1893 (Formicidae, Aneuretinae) and other ants in Indikada Mukalana Forest Reserve in Sri Lanka

The Sri Lankan Relict Ant, Aneuretus simoni Emery, survives in several wet zone and intermediate zone forests in Sri Lanka. Nests of this species and other ants were surveyed at 159 m and 291 m elevations in Indikada Mukalana Forest Reserve by laying 20 quadrats of 1 m × 1 m at two plots of each locality in December, 2015. The number of ant nests within each quadrat was recorded; then the frequency of nest occurrence out of 40 quadrats, percentage nest abundance and mean nest density of A. simoni, as well as associated ant fauna were calculated. Percentage frequency of worker ant occurrence was also investigated using pitfall traps. Eighteen genera and 21 species in Aneuretinae, Dolichoderinae, Formicinae, Myrmicinae and Ponerinae were recorded from the two methods. Nests of A. simoni were found only in the locality at 291 m altitude in the forest; 17.5 % of quadrats with an A. simoni colonies, 9.7% of nest abundance in relation to that of other ant species and 0.18 m2 of mean nest density were observed. Nest density of A. simoni had the fourth rank among that of the other species. Frequency of occurrence of A. simoni workers in the pitfall traps at lower and upper elevations was 2% and 3%, respectively. An actualized map showing the current distribution of A. simoni is produced