Polynesian ant (Hymenoptera: Formicidae) species richness and distribution: a regional survey

Thirteen Polynesian islands, including five true atolls, an uplifted atoll, and seven high volcanic islands of varying ages, were surveyed for ants by hand collecting techniques. Ten of the thirteen islands had been surveyed previously, and more and species were found in the present survey than were known from all earlier surveys combined, with two exception (Ducie Atoll and Easter Island).This represents the first report of the Argentine ant, Linepithema humile Mayr, from Easter Island. L. humile is a very successful pest species which has only recently invaded Easter Island, and is now very abundant and widespread, occurring at 16 of the 17 sample sites scattered across the island. The introduction of this species is almost certainly responsible for the apparent decline in species richness on Easter Island.In general, more species were present on high islands than atolls of a similar size, and elevation was significant while log (area) and latitude were not in a multiple linear regression with ant species number as the dependent variable. Not enough time was spent on the islands to survey their ant faunas completely, and extrapolations from species effort curves and jackknife estimators of earlier, thorough surverys for ants in the society Islands suggest that only about 50% of the total species were collected in the present survey, at least on the high islands. My collections were probably more complete on the atolls. The increase in species numbers from the present survey relative to known species richnesses (particularly when a large fraction of the species actually present were probably not included in the present survey) supports the hypothesis that remote Polynesian islands are not as depauperate in terms of ant species numbers as previously thought.