Natural history studies serve as important foundations for future investigations of behavioral ecology and provide biologists with critical information needed for the development of empirical research programs. Relatively little is known about the biology of most species of Neotropical harvestmen in Central America. In this field study, we investigated the activity patterns of two common species Cynorta marginalis (Cosmetidae) and Prionostemma sp. (Sclerosomatidae) in a wet tropical forest in Costa Rica. We used visual encounter surveys along randomly selected transects to compare the relative abundance of these species during morning, afternoon, evening, and late night sampling periods. To generate ethograms, we observed up to three individuals of each species for 10 min along each transect, generating 69 behavioral observations for C. marginalis and 51 for Prionostemma. Both species occupy perches on vegetation and are generally nocturnal with respect to activity. After dusk, individuals of C. marginalis actively climb, interact with conspecifics, and forage on the surfaces of small and large trees. During the day, adult Prionostemma form relatively inactive clusters of up to 40 individuals on arboreal perches and descend to the leaf litter after dusk to forage.

We describe multiple observations of epizoic cyanobacteria occurring on external surfaces of a species of sclerosomatid harvestman (Prionostemma sp.) in Costa Rica. In the field we collected four adults (three males, one female) that had green films growing upon the dorsal surfaces of the carapace and abdominal scutum. Examination by SEM revealed dense clusters of what appeared to be small prokaryotic cells ( 1-5 pm in diameter) covering the external surfaces of the carapace, abdominal scutum and coxae. We extracted DNA from the films of two specimens. The DNA was used as a template to amplify the intergenic spacer region (IGS) between the beta and alpha phycocyanin subunits (a signature DNA sequence, unique to cyanobacteria) by PCR. We successfully amplified an approximately 700 base pair product using DNA extracted from the film and did not obtain any product from the harvestman lacking the film. Our observation represents the second confirmed occurrence of epizoic cyanobacteria on Neotropical harvestmen. This is the first report of cyanobacteria associated with a sclerosomatid anywhere and the first known case from Central America.