Seasonal activity and habitat associations of Mecodema howitti and Megadromus guerinii, two endemic New Zealand ground beetles (Coleoptera: Carabidae)

Abstract

Seasonal activity and habitat associations of the threatened endemic forest carabid Mecodema howitti Castelnau, and the sympatric but common endemic Megadromus guerinii (Chaudoir), were studied by pitfall trapping in a montane podo‐carp/hardwood forest remnant on Banks Peninsula, Canterbury, New Zealand. The main surface activity period for adult M. howitti and Mg. guerinii was the austral spring and summer. Megadromus guerinii was active across a wider temperature range than M. howitti, and was less inhibited by rain during the night. Both species were reproductively active in spring and summer, and a teneral Mg. guerinii was recorded in autumn. Mecodema howitti appeared to be randomly distributed and associated with logs. Megadromus guerinii showed spatial clustering, partly due to associations with topography and the proportion of stones in the substrate. © The Royal Society of New Zealand 2004.