Interspecific variation in ovipositor morphology among Manaosbiid and Nomoclastid Harvestmen (Arachnida, Opiliones, Laniatores)

The external anatomy of the ovipositor has generally been overlooked as a source of informative characters in systematic studies of laniatorean harvestmen. In this study, we used scanning electron microscopy to examine the ovipositors of nine species representing the families Manaosbiidae (five species) and Nomoclastidae (four species). Similar to the ovipositor morphology of many gonyleptoidean families, the distal tips of the ovipositors of these harvestmen have four external lobes, with the margins most commonly adorned with 10 large peripheral setae. In manaosbiid and nomoclastid species, these peripheral setae have undivided bases, striated shafts and undivided distal tips. There are typically three setae on each anterior lobe and two setae on each posterior lobe. The medial setae on both anterior and posterior lobes insert into sockets that are slightly more dorsal. We observed small, surface denticles, usually associated with a pore, on the external surface of the lobes. There was interspecific and intraspecific variation in the number and shape of these surface denticles. The association of pores with denticles on the ovipositor appears to be a feature common to not only both families but is also a trait that has not been observed on ovipositors in other families of laniatorean harvestmen.