Ecological Entomology, in press.

Local versus regional species richness in tropical insects (Auchenorrhyncha, Hemiptera): one lowland site compared to the island of New Guinea

Vojtech Novotny and Olivier Missa

Abstract. 1. The overlap in species composition of Cercopoidea (Aphrophoridae, Cercopidae and Machaerotidae), Flatidae and Ricaniidae between two data sets, an almost exhaustive census from 13 Ficus species and a sample from diverse vegetation in the same area, lead to the estimate of the local species richness of 113 species (46 species of Cercopoidea, 37 species of Flatidae and 30 species of Ricaniidae) at a lowland rain forest site.

2. Another, independent estimate of the local species richness of 116 species was obtained by fitting an asymptotic function to the species accumulation curve for the samples from diverse vegetation.

3. Samples restricted to 13 species of Ficus contained 66 species, i.e. 57-58% of the estimated local species richness. This high proportion probably results from the high proportion of polyphagous and tourist (transient) species in the Cercopoidea, Flatidae and Ricaniidae.

4. The two largest museum collections of New Guinean insects contained 327 species of Cercopoidea from New Guinea, including 23 of the 34 species collected in the field samples. This overlap lead to the estimate of 483 species of Cercopoidea present in New Guinea.

5. The species found in the field samples were also 2.6 times more likely to be found in the museum collection than other species. This sampling bias probably results from a positive correlation between species local abundance and geographic distribution. Such correlation was found between the abundance of species in the Ficus samples and the number of New Guinean localities recorded for them in the museum collection.

6. The estimate of species richness of Cercopoidea in New Guinea increased to 1,222 species when corrected for this sampling bias. Thus, only 4 % of the New Guinean species were present locally, in the study area. Such high beta diversity is probably a consequence of the exceptional habitat and vegetation diversity in New Guinea, as well as its complex geological history since several tectonic blocks that now compose the island remain distinct centers of endemism.