| Popis: |
We describe Terrestricythere proboscidis sp. nov. from a littoral interstitial habitat at Orito Beach, Matsumae, southern Hokkaido, Japan, a site characterized by coarse sand with many pebbles. This is the fifth known species of the ostracod superfamily Terrestricytheroidea, the first interstitial species of the superfamily, and the first record of the superfamily from Japan. The new species is clearly distinguished from its four known congeners by its small carapace with a transversely flat ventral margin, and the seventh limb consisting of four podomeres; its hemipenis has a long, S-curved process. We also report here the habitat, microdistribution, and locomotory behavior of the new species. Quantitative sampling revealed that the species lives in an interstitial environment. T. proboscidis is euryhaline. Behavioral observations showed that T. proboscidis cannot swim, but uses its appendages to push itself among sediment grains. An analysis of variance showed temperature and grain size, as well as temperature-depth and temperature-grain size interactions, to be significant influences on variation in population density. Sediment moisture content is correlated with these variables and likely is a primary factor in this species’ microdistribution. |
