New morphological aspects and taxonomical potential of the furca in the ostracod genus Neonesidea (Podocopida: Bairdioidea)

The chaetotaxy and microstructure of the furca were examined in three interstitial and one epifaunal species of the ostracod genus Neonesidea (Podocopida: Bairdioidea). Of the seven setae found on the furcae of the examined species, the thick and curved first to third setae from the distal end were relatively long and had two rows of serrations. The fourth and fifth setae, with intermediate lengths, were covered by numerous setulae of varying lengths and orientations. The sixth and seventh setae were shortest, with setulae and openings at the tips. These morphological variations suggest functional differences, that is the furca does not only have a mechanoreceptor function, but also a chemoreceptor function according to the direction of the setulae and the openings at the tips. Specific and sexual differences were observed when comparing the relative lengths of the seven setae on the furca. In contrast, there were no noticeable furcal characteristics that distinguished the three interstitials from the epiphytic species examined here.