The current study is a revision of Leucoloma Brid. Subgenus Syncratodictyon Series Holomitrioidea (Ren.) La Farge-England that includes two new species–Leucoloma circinale La Farge sp. nov., endemic to Tanzania and Leucoloma marojeziense La Farge sp. nov., an endemic from the massif of Marojezy in northeastern Madagascar. The series includes four species that are characterized by having hyaline margins restricted to the lower portion of the leaf; differentiated, bulging, scalariform alar cells; strongly contorted, apiculate leaves; unusual biseriate papillae formation; and sharply differentiated, sinuose upper cells, with the basal cells extending up along the margins. The species are endemic to the lowland to elfin rainforests of Madagascar, East African Islands, and East African montane forests of central Tanzania. The phylogenetic and phytogeographic relationships of Series Holomitrioidea have been considered elsewhere (La Farge-England 1998).