Altitudinal distribution of native and alien landhoppers (Amphipoda: Talitridae) in the Ko'olau Range, O'ahu, Hawaiian Islands

Abstract

Landhoppers were sampled by hand, pitfall and tree trunk traps on a 500 m altitudinal transect in the Ko'olau Range, O'ahu, in the Hawaiian Islands. Five species were present. The circumtropical tramp Talitroides topitotum was abundant in ground litter from 300 m (above sea level) to the summit of the ridge (800 m). Although common in damp situations nearer sea level, the other introduced species, T. alluaudi, was rare on the transect. Of the native species, Hawaiorchestia gagnei was found from 320 m to the summit of the ridge in ground litter, and in moss and leaf axils well above ground. Platorchestia lanipo was not found below 440 m, and was also found on the ground, in axils and perched moss. Platorchestia pickeringi was only found above 550 m and almost always in the leaf axils of Freycinetia arborea. Pitfall traps caught fewer T. topitotum than expected from quadrat sampling at the higher sites, where T. topitotum and P. lanipo were the most abundant litter species. Trunk traps caught many P. lanipo...