Phoretic relationship between Lustrochernes grossus (Pseudoscorpionida: Chernetidae) and Odontotaenius striatopunctatus (Coleoptera: Passalidae)

摘要

: Phoresy is considered a non-parasitic partnership between a small animal (phoront) and a large one (host) that result in phoront transportation by the host. Throughout two years of observation and nursing of 16 family groups of the passalid Odontotaenius striatopunctatus, we noticed the presence of the pseudoscorpion Lustrochernes grossus within 11 of their 16 nests, which consisted of rotten wood logs (30 cm long ?— 15-20 cm in diameter) cut into 2 cm segments and secured with rubber bands to facilitate observation. The presence of pseudoscorpions became evident from the moment the passalids started building their nests creating space and food for their young. Evidence was found that pseudoscorpions can go under the elytra of passalids. Their presence did not prevent the reproduction of the beetles, performed in 13 of the 16 set nests (Fischer's exact test: P = 0.71, N = 16): neither was the number of passalids offspring modified (Mann Whitney U = 11.50, P = 0.2553). On three occasions during spring, L. grossus females carrying brood sac was documented. In this facultative relationship, phoresy and phagophilia could be involved; some hypotheses on the factors that may interfere with it are posed.