The Brazilian Atlantic Forest is one of 25 biodiversity hotspots with a rich liverwort diversity, especially of Lejeuneaceae. Rectolejeunea truncatilobula C.J.Bastos endemic to Brazil's Atlantic Forest was one member of the subtribe Lepidolejeuneinae of Lejeuneaceae. Recent a field trip to the area permitted us to study living samples of the plant, and we found that the species is characterized by the granular oil bodies in median and basal chlorophyllose cells of the leaf lobe and presence of Allorgella-type marginal denticulations, which are striking characters of the subtribe Echinolejeuneinae. Our phylogenetic analyses based on the nuclear ribosomal ITS region and two chloroplast regions (rbcL, trnL−trnF) also suggest that this species belongs in the subtribe Echinolejeuneinae rather than the subtribe Lepidolejeuneinae. On the basis of the combined molecular phylogenetic and morphological data, a new genus Yanoella is proposed for accommodating the remarkable Brazilian species. Molecular evidence of Stenolejeunea thallophora (Eifrig) R.M.Schust. (type species of Stenolejeunea R.M.Schust.) supports the earlier reduction of Stenolejeunea to synonymy under Lejeunea Lib.