The epizoic occurrence of algae on the Neotropical harvestman Metarthrodes longipes (Opiliones: Gonyleptidae)

Pre-print manuscript. A male individual of Metarthrodes longipes showing dark green tussocks on the tibiae and femura of its legs IV was found in a fragment of Atlantic Forest in Brazil. The tussocks are formed by an unidentified species of filamentous algae of the order Coleochaetales. To our knowledge, this is the first record of the epizoic occurrence of a Coleochaetales algae in terrestrial habitats. It is likely that the lengthy legs of M. longipes have been colonized by the filamentous algae while it was moving through the vegetation. The harvestman seemed to be unhealthy, for it showed very slow movements, lack of defensive responses when handled, and we found a large amount of ectoparasite mites on its legs. The unique characteristics of the colonization and the fact that we found only one individual with algae on its integument made us conclude that this may be the case of an opportunistic colonization.