Cerdia, Prodr. 3: 377. 1828 sec. Sosa & al. (2006)
Monotypic; endemic to Mexico. Placement within the Polycarpeae is probable (near Cardionema and Scopulophila?), but Sosa & al. (2006) suggest that further study is needed. In a broader survey using a different voucher, Greenberg & Donoghue (2011) found Cerdia clustering near Drymaria.