The first precinctive Carabidae from Moorea, Society Islands: new Mecyclothorax spp. (Coleoptera) from the summit of Mont Tohiea

James Liebherr

doi:10.3897/zookeys.224.3675

Abstract

Seven species of Mecyclothorax Sharp from Moorea, Society Islands are newly described; Mecyclothorax perraulti sp. n., Mecyclothorax pahere sp. n., Mecyclothorax menemene sp. n., Mecyclothorax mahatahi sp. n., Mecyclothorax popotioaoa sp. n., Mecyclothorax mapo sp. n., and Mecyclothorax fatata sp. n. These constitute the first Mecyclothorax species described from Moorea, and the first carabid beetle species shown to be geographically restricted to that island. Each of the newly described species is most similar to a different species on the island of Tahiti, suggesting that none of the seven Moorean taxa are evolutionary end-products of autochthonous speciation within Moorea. The occurrence of precinctive Mecyclothorax species on both Moorea and Tahiti demonstrates that radiation of Mecyclothorax in the Society Islands has been facilitated by speciation events implicating both islands. Whether this speciation has been preceded by vicariance or dispersal is discussed, with the generality of a dispersal hypothesis tested using information from Society Island Nabidae (Hemiptera). Salient morphological characters for taxa in the Society and Hawaiian Islands are compared to those representing a broad survey of southwest Pacific Mecyclothorax spp. This comparison supports the independent founding of each radiation in the Societies and Hawaii from an Australian ancestral propagule, likely drawn from the ecologically general, geographically widespread Mecyclothorax punctipennis (Macleay).

Highlights

The genus Mecyclothorax Sharp is distributed throughout Australia and associated landmasses and islands including New Guinea, the Greater Sundas of Java and Borneo, Lord Howe and Norfolk Islands, and St
It is on two Polynesian archipelagoes that Mecyclothorax has undergone radiations that are so rich in species that these radiations dwarf the levels of diversity observed over all other areas of the generic distribution
The Society archipelago, Tahiti, supports an impressively diverse radiation, with 67 species recognized from the island of Tahiti (Perrault 1992). Why have these two Polynesian archipelagoes been home to such diverse Mecyclothorax radiations? Based on shared attributes of Tahiti and the Hawaiian Islands, Mecyclothorax have thrived in these places in association with subtropical montane rain forest that is dissected by lava flows or by low-elevation erosionally formed valleys, with the islands’ orographic relief resulting in extensively subdivided habitats ranging from 1000–3000 m elevation

Summary

Introduction

The genus Mecyclothorax Sharp is distributed throughout Australia and associated landmasses and islands including New Guinea, the Greater Sundas of Java and Borneo, Lord Howe and Norfolk Islands, and St. Though some species are shared between adjacent ridges—e.g. the ridges culminating at Mont Marau and Mont Aorai—the majority of species are not so shared between different ridges (Perrault 1992: 211) These montane habitats receive anywhere from 4000–6000 mm of precipitation per year in Hawaii (Giambelluca and Schroeder 1998) and up to 8000 mm/yr in Tahiti (Mueller–Dombois and Fosberg 1998; Craig et al 2001). The high levels of diversity in these subtropical islands contrasts sharply with the low Mecyclothorax diversity resident in Australia and New Zealand (Moore et al 1987; Liebherr and Marris 2009), where species distributions are centered on open habitats including grasslands, moorlands, riparian corridors, and dry to mesic Eucalyptus forest. Characters presented by taxa across the Society Island Mecyclothorax radiation distinctively differ from those characterizing the more generalized members of the Hawaiian Mecyclothorax radiation, supporting independent colonization events from Australia and subsequent adaptive radiations for each of these lineages on their particular archipelagoes

Methods

Discussion