A new species of <i>Triangocypretta</i> Ferreira, Higuti &amp; Martens, 2023 (Ostracoda: Cyprididae) from a Brazilian floodplain, with a key to the species of the genus

Abstract We describe a new species of ostracods, Triangocypretta mariae spec. nov. from lakes in the Upper Paraná River floodplain, Brazil. The genus is characterized mainly by its triangular shape in lateral view, the presence of anterior marginal septa on left and right valves, the smooth, not crenulated, posterior inner list on the right valve, and the short and narrow α and β setae on the mandibular palp. Triangocypretta mariae spec. nov. is allocated to this genus, but differs from its congeners by the almost circular shape of the carapace in dorsal and ventral views, the presence of two serrated claws on the third endite of maxillula, the four sub-apical setae on the protopodite of first thoracopod and by the fact that seta d2 on the second thoracopod is twice the length of seta d1. The populations found were all asexual. We provide an identification key for the five species in Triangocypretta Ferreira, Higuti &amp; Martens, 2023.