<i>Paranthura oriens</i> sp. nov. (Isopoda: Anthuroidea: Paranthuridae) from Tateyama, Chiba, Japan

We describe Paranthura oriens sp. nov. based on specimens collected from Tateyama, Chiba, Japan. Paranthura is the most speciose genus in Anthuroidea, with five groups defined by the condition of the pleonites. Our new species belongs in Group E, defined by having dorsally fused pleonites 1–5. It differs from the other 17 species in Group E in the following combination of characters: (1) the apical edge of the telson is rounded, not sharp, (2) the uropodal endopod is triangular and tapering, and (3) the uropodal exopod is narrow, 2.72–2.84 times longer than wide. We determined a partial cytochrome c oxidase subunit I (COI) nucleotide sequence for the new species.