Comparative study of the microanatomy of four species of harvestmen (Opiliones, Eupnoi)

Abstract

Most species descriptions of harvestmen from Central America that belong to the suborder Eupnoi are based on characters such as total body length, relative size of leg segments, coloration of the body and legs, and armature of the eye mound and dorsal scutum. Characters based on reproductive morphology and microanatomical structures are generally absent from most taxonomic works. Not surprisingly, the taxonomy of these harvestmen from this region requires extensive revision. In an effort to identify novel characters, we used scanning electron microscopy to compare the morphology of somatic and reproductive structures of Prionostemma vittatum (Roewer, 1910), Metopilio niger (Goodnight and Goodnight, 1942), and Metopilio ornatipes (Banks, 1909). Specifically, we investigated the morphology of the ocularium, ozopore, dorsal scutum, genital plate, pedipalp, spiracular opening on tibia II, ovipositor, and penis. We compared the morphology of these Neotropical taxa with that of a temperate sclerosomatid species, Leiobunum formosum (Wood, 1870). In general, we observed interspecific variation in the surface texture of the cuticle and the distribution of setae on the body and appendages. Potentially informative characters include cuticular structures associated with the ocularium, anterior propeltidium, meso- and metapeltidium, dorsal scutum, genital plate, pedipalp, and penis. We also observed intersexual variation with respect to morphology of Spicer's tarsal organ and the claw of the pedipalp. © 2014 Entomological Society of America.