Leiocanthus quinquenudus sp. nov. and L. satanicus sp. nov., two new species of pycnophyid Kinorhyncha (Allomalorhagida: Pycnophyidae) from the Gulf of Mexico

Two new species of pycnophyid Kinorhyncha, Leiocanthus quinquenudus sp. nov. and L. satanicus sp. nov., are described from soft seafloor sediment samples in the Gulf of Mexico. Leiocanthus quinquenudus sp. nov. is easily distinguished from the other congeners by the absence of ventromedial setae on segment 5, a structure otherwise present in all the other known Leiocanthus. Leiocanthus satanicus sp. nov. lacks lateral terminal spines, a feature only shared by L. langi and L. mainensis among the congeners; otherwise the new species is easily discernible by the arrangement of the paradorsal, laterodorsal and ventromedial setae, and the number of ventral sensory spots per segment. These findings are a significant contribution to the knowledge of the Kinorhyncha biodiversity from the Gulf of Mexico, which has recently been explored in several taxonomical and ecological studies mainly focused on cyclorhagid Kinorhyncha, not pycnophyid kinorhynchs.