Unimeria gen. nov.

Diagnosis. Body inflated. Prosome unsegmented, gradually broadening posteriorly. Urosome small, wider than long, unsegmented, and directed perpendicular to prosomal axis. Caudal ramus small, notarticulated from abdomen, armedwith 6 setae. Rostrum present.Antennule incompletely 2-segmented. Antenna 3-segmented, consisting of short coxa, basis and unsegmentedendopod with small terminal claw. Labrum simple. Mandible with pectinate medial margin on coxal gnathobase; palp biramous; exopod incompletely articulated from basis, bearing 4 setae; first endopodal segment fused with basis, with 2 setae onmedial margin; secondendopodal segment incompletely articulated from first, armed with 4 setae. Maxillule as lobe bearing 10 setae. Maxilla incompletely 3-segmentedwith 4, 1, and 2 setaeonfirst to third segments, respectively. Maxilliped absent. Legs 1–4 biramous, unsegmented with elongate, digitiform rami; setae small and naked. Leg 5 absent.

Type and only species. Unimeria longipedata gen. et sp. nov. by original designation.

Etymology. The generic name is derived from the Greek uni (=one) and mer (=a part) and refers to the unsegmented body of the type species. Gender feminine.

Remarks. The type species could not be assigned to any known notodelphyid genera because it exhibits a unique combination of highly derived and plesiomorphic character states. The derived states include: the urosome is small and unsegmented, the medial margin of mandibularcoxais pectinate, themaxillule isvery reduced (represented by a lobe bearing setae), the maxilliped is absent, the swimming legs are unsegmented but retain elongate rami, and leg 5 is absent. However, the presence of 6 caudal setae and the setation of the mandibular palp are both relatively plesiomorphic features. Unimeria gen. nov. is established to accommodate U. longipedata gen. etsp. nov.