Two new species of Meliolaceae (black mildews) are described based on specimens recently collected in western Panama. Appendiculella lozanellae on leaves of Lozanella enantiophylla is the first species of Appendiculella known on Cannabaceae. Appendiculella chiriquiensis on leaves of Cupania guatemalensis is the first record of a species of Appendiculella on Sapindaceae. These species differ from known species on their respective host relationships by the presence of larviform appendages attached to the perithecia, as well as by characteristics of hyphae, appresoria and ascospores. Sequence data of 18S and 28S rDNA are published for A. lozanellae, which becomes the third species of Meliolales and the first species of the genus Appendiculella for which molecular data are available.