Student Research Projects

Reproductive Morphology of Three Species of Neotropical Harvestmen (Opiliones, Laniatores, Gonyleptoidea)

Student Katie Bennett, ‘13
Faculty Mentor(s)
Department Biology
Course BIO 489: Research in Natural Sciences


In harvestmen of the suborder Laniatores, males possess sclerotized penises that exhibit a generally, complex morphology. In contrast, females have flexible, relatively short ovipositors that are generally unarmed. While descriptions of male genitalia are standard in modern taxonomic descriptions for harvestmen, relatively little is known about intraspecific variation in penis morphology. In contrast, descriptions of female genitalia are rarely included in species descriptions and remain unexamined for most species. In this study, we used a Hitachi S-3400N SEM to examine intraspecific variation in the reproductive morphology of Cynortula granulata (Cosmetidae), Rhopalocranaus albilineatus (Manaosbiidae), and Phareicranaus calcariferus (Cranaidae). For male genitalia, we compared the distal margin of the ventral plate, the number and morphology of marginal setae, the shape of the glans penis, the morphology of the stylus, and the orientation of the glans penis and stylus. For ovipositors, we examined the number and morphology of setae on the distal tip of the ovipositor as well as the overall surface texture and symmetry. We observed considerable intraspecific as well as interspecific variation for ovipositor morphology, especially with respect to the total number of setae, morphology of distal tip of the setae, and surface texture. For males, we observed relatively little intraspecific variation. The discovery of informative characters is vital for future taxonomic and systematic studies of harvestmen and may lead to remarkable new insights into the function and biological roles of previously overlooked structures, such as the ovipositor.