A number of mite species in the family Histiostomatidae inhabit phytotelmata, being found fully submerged and filtering organic material from the fluid. One such phytotelm habitat is the pitchers of species of Nepenthes, a carnivorous plant genus widely distributed in the South Pacific. Several histiostomatid genera are obligatory inhabitants of Nepenthes pitchers and adapted to withstand the digestive enzymes produced by the plant. As in most histiostomatid species, males seek quiescent tritonymphal females and guard them from other males. Such precopulatory mate guarding assures a mate when the female molts. While most species are ambulatory and move about on decomposing arthropods in the pitcher, one genus (Zwickia) is natatory as well as ambulatory, and the another genus (Creutzeria) is entirely natatory. Males of ambulatory species typically climb onto the dorsum of tritonymphal females, clasping the idiosoma with two pair of legs. The remaining two pair are used to walk about on the substrate while carrying the securely clasped female beneath. Swimming is a more laborious task, especially since the male must propel not only himself through the fluid but also the quiescent female. Natatorial activity therefore requires the use of all three pair of posterior legs, leaving only the first pair for clasping the female. Direct observation under the dissecting microscope as well as phase contrast and scanning electron microscopy were used to examine morphological and behavioral adaptations associated with mating. While legs I of both genera are highly modified for clasping females, they differ considerably in their morphological adaptations.