A new species of Donlesia (Ceratophyllaceae) from the Early Cretaceous of Kansas, USA

Abstract

A new species of Donlesia (Ceratophyllaceae) from the Early Cretaceous Cheyenne Sandstone of Kansas, USA is reported. The fruits of Donlesia cheyennensis sp. nov. are achenes with four lateral spines, a stylar spine, and a long pedicel. The four lateral spines are arranged on two perpendicular planes. The leaves associated with D. cheyennensis fruits dichotomize three to four times. The fruit morphology of D. cheyennensis differs from Donlesia dakotensis, from the younger Dakota Formation, other fossil and extant members of Ceratophyllaceae in its tetra-radial symmetry, the presence of four lateral spines, and its long pedicel. The presence of Donlesia in the Cheyenne Sandstone extends the fossil record of Ceratophyllaceae to the earliest late Albian and this indicates that the Ceratophyllaceae clade probably diverged from its sister clade at least 105 million years ago in the Early Cretaceous.