DISTINCT GROUND BEETLE (COLEOPTERA: CARABIDAE) ASSEMBLAGES WITHIN A NEW YORK STATE WETLAND COMPLEX

Abstract

Carabid beetle communities were compared for adjacent marsh and bog biotopes at the McLean Bogs Preserve, Tompkins Co., New York by means of pitfall-trap sampling. Though the sampled marsh and bog habitats were only 200 m distant, with the umbrotrophic bog isolated from the marsh/fen complex by a Wisconsin-aged glacial esker of only 7 m ele- vation, the resident wetland carabid species assemblages differed significantly between the sites during the spring and summer seasons. Of 62 species observed in the wetlands, 36 were found exclusively in the marsh biotope, 17 were exclusive to the bog site, and only 9 were found at both sites. This level of wetland habitat fidelity was maintained in spite of potential colonization of the two sites each spring by adult beetles dispersing from overwintering sites in surrounding forest edge habitats. Pitfall sampling found 59 native carabid species, of which 52 were found during a survey conducted from 1916-1925, suggesting that the McLean Bogs Preserve sup- ports locally resident populations for the vast majority of carabid species found during this study. The McLean Bogs Preserve supports geographically southern, peripheral populations of the bog-specialist Platynus mannerheimiiDejean, as well as four marsh/fen-inhabiting species— Trechus crassiscapusLindroth, Bembidion muscicolaHayward, B. praticola Lindroth, and Bra- dycellus semipubescens Lindroth—emphasizing the role this preserve plays in maintaining the distributional ranges of both bog- and marsh-resident taxa. The distinct faunas observed in these two proximate biotopes clearly illustrate that comprehensive conservation of the carabid beetle fauna of northeastern North America should involve preservation of a variety of wetland types.