Temperature and Humidity Relations of Some Bog Pselaphid Beetles

Of the many microclimatic variables, temperature and moisture exert a considerable influence upon the numbers and kinds of arthropods found in particular habitats. Experimental temperature and humidity gradients permitted determinations of the responses of five bog—inhabiting species of pselaphid beetles to these factors. Significant differences were found between species with respect to their temperature preferenda and preferred temperature ranges: Bythinopsis tychoides, 21.5 ° 0.81, 25.9 — 15.3°C; Decarthron defectum, 28.5 ° 0.55, 31.4 — 24.0; Pselaphus ulkei, 19.5 ° 0.86, 24.7 — 13.0; Reichenbachia borealis, 21.+ ° 0.99, 26.2 — 14.4; Rybaxis clavata, 28.3 ° 0.41, 29.9 — 25.1. Species reactions were correlated with the natural environmental conditions of their microhabitats and predilection of ᵢndex" species for unique microhabitats within the bog sere. The consistent response of all species toward saturated humidities (95—100% relative humidity) was paralleled by the near—saturated humidities of the interstices of moss microhabitats. Temperature stratification within moss microhabitats and differential species responses to temperature are postulated as mechanisms restricting certain species to different seral stages and isolating sympatric species in similar habitats.