Fossil fruits of <i>Trapa</i> L. from the late Miocene of southeastern Qaidam Basin (Qinghai, China)

<i>Trapa</i> L. (Lythraceae J. ST.-HIL) is a genus of annual free-floating plant, widely distributed in the Northern Hemisphere. The Qaidam Basin is regarded as an ideal region to understand the Cenozoic palaeoclimatic and palaeobiological evolution of the northern Tibetan Plateau. A few records of <i>Trapa</i> have been previously mentioned from the Cenozoic deposits of the Qaidam Basin, northern Tibetan Plateau. Here, we describe some fossil fruits of <i>Trapa</i> from the late Miocene Shangyoushashan Formation of southeastern Qaidam Basin (Tuosu Lake area), which were identified as <i>Trapa qaidamensis</i> sp. nov. based on their morphology. Extant species of <i>Trapa</i> usually live in the environments with mean temperature of warmest quarter (MTWQ) ranging from 14.9°C to 30.9°C, as well as mean temperature of warmest month (MTWM) ranging from 19.6°C to 37.3°C in the living areas of <i>Trapa</i>. Compared with MTWQ 16.5°C and MTWM 17.5°C in current fossil locality, the present fossil site was warmer during the Miocene than in the present day. urn:lsid:zoobank.org:act:9F7DAD1B-DA2D-4734-BE27-99276F57DD2A