The Fijian Nesobasis: a further examination of species diversity and abundance (Zygoptera: Coenagrionidae)

Recently, an overview of the diversity, abundance, distribution and morphological characteristics of spp. of the genus Nesobasis, endemic to Fiji, was presented for spp. occurring on the 2 largest islands of the archipelago: Viti Levu and Vanua Levu. Here, this knowledge is extended by providing more extensive diversity and abundance data for the island of Vanua Levu, as well as for 4 smaller islands in Fiji: Taveuni, Koro, Ovalau and Kadavu. Previous research indicated that the Nesobasis spp. inhabiting Viti Levu and Vanua Levu are unique, with these islands having no species in common. The new data confirm this proposal and also show that smaller islands in proximity to these 2 larger islands usually contain a subset of the large island’s Nesobasis fauna. The island of Koro, however, is unusual in that, while its Nesobasis spp. are predominantly those found on Vanua Levu, it also harbours N. rufostigma, a sp. occurring on Viti Levu. Further, N. recava is endemic to Kadavu and is not found on Viti Levu, the nearest large island. Species richness is higher on large than small islands while mean species abundances were consistently higher on large islands compared to small islands. The pattern of distribution and speciation in this genus is quite complex, and is the subject of ongoing research.