Student Research Projects

Interspecific Variation in Ovipositor Morphology Among Cosmetid Harvestmen

Student Eric Walker '14
Faculty Mentor(s)
Department Biology
Course BIO 489: Research in Natural Sciences


The morphology of the ovipositor of laniatorean harvestmen has largely been ignored in the taxonomic literature. As a result, relatively little is known about interspecific variation in female reproductive anatomy. In this study, I dissected 50 ovipositors from individuals representing 14 cosmetid species and used scanning electron microscopy to examine the microanatomy of the distal surface, the number, texture and shape of the large peripheral macrosetae, and the general appearance of the vagina. Ovipositors were carefully dissected, dehydrated in an ethanol series, dried with hexamethyldisilizane, mounted on aluminum stubs, sputter coated with 30 nm of gold, and examined with a Hitachi S-3400 SEM at an accelerating voltage of 10 kV. The results of my research indicate that there is considerable interspecific variation in female reproductive morphology of the Erginulus genus and that some of these structures could represent informative characters for taxonomic revisions. In particular, the morphology of the distal tips of the peripheral macrosetae displayed striking differences between genera. The functional significance of interspecific variation in setal structure is difficult to determine. Additional behavioral studies of oviposition behavior are needed to determine if there is a relationship between ovipositor morphology and egg laying behavior.