A new species of cycad allied to theC. circinalis group,Cycas pranburiensis, is described from the southeast karst area of Thailand near Pranburi, Prachuap Khiri Khan province. It is distinguished by its short leaves with broad, coriaceous leaflets and mostly unarmed petioles, and the extended, gently curved sterile apices of the microsporophylls. The cone beetle fauna of the new species, believed to be involved in pollination, is distinct from that of other southeast Asian species ofCycas.