A new neotropical genus, Sumacoa, with a single species, S. barbata J. L. Clark & D. A. Neill, is described from the Cordillera del Cóndor, Cordillera Galeras, and eastern slopes of the Andes in Ecuador and is placed in the family Gesneriaceae and tribe Beslerieae. The placement of Sumacoa in the tribe Beslerieae is strongly supported by molecular sequence data generated from analyses of nuclear ribosomal DNA internal transcribed spacer region (ITS). Sequence data were evaluated from 34 taxa representing all genera from the tribes Beslerieae and Napeantheae. Sumacoa is characterized by the following unique combination of relatively uncommon characters in the Gesneriaceae: arborescent habit, a tardily dehiscent globose bivalved capsule, and elongate multicellular trichomes clustered apically in the throat. Sumacoa is endemic to the provinces of Napo and Morona-Santiago and in lower montane cloud forest from the Cordillera del Cóndor and Cordillera Galeras at 1200–1800 m elevation, as well as one locality on the eastern slopes of the Eastern Cordillera of the Andes. A key and a table are presented for differentiating Sumacoa from other genera. Based on IUCN guidelines, a preliminary conservation status of Vulnerable (VU) is provided for S. barbata.

DNA Extraction, Amplification, and Sequencing—All the tissue samples included in the analysis were collected in the field and dried in silica gel. Leaf samples were ground using a ThermSavant FastPrep FP120 cell disrupter (Qbiogene, Carlsbad, California). DNA was isolated using the Qiagen DNeasyTM DNA isolation kit (Qiagen, Valencia, California). 

Templates of the nrDNA internal transcribed spacer region (ITS) were prepared using the primers ITS5HP (5’ –GGA AGG AGA AGT CGT AAC AAG G-3’; Suh et al. 1993) and ITS4 (5’ –TCC TCC GCT TAT TGA TAT GC-3’; White et al. 1990). 

Polymerase chain reaction (PCR) amplifications followed the procedures described by Baldwin et al. (1995) utilizing Taq DNA polymerase (Promega, Madison, Wisconsin). To reduce within-strand base pairing that can result in interference with Taq polymerase activity, we found it essential to use 5% DMSO and 5% BSA in PCR reactions for ITS. The PCR products were electrophoresed using a 1.0% agarose gel in 13 TBE (pH 8.3) buffer, stained with ethidium bromide to confirm a single product, and purified using PEG 8000 (polyethylene glycol) in 2.5 M NaCl under the conditions described in Johnson and Soltis (1995). Direct cycle sequencing of purified template DNAs followed the manufacturer’s specifications using the ABI PrismVR BigDyeTM Terminator Cycle Sequencing Ready Reaction Kit (PE Biosystems, Foster City, California). 

DNA chromatograms were edited and contigs were assembled using Sequencher version 5.4.6 (Gene Codes Corporation, Ann Arbor, Michigan). The sequences include only ITS1, 5.8S, and ITS2 regions. Identification of the ends of ITS1, ITS2, and 5.8S were determined by comparisons with sequences of Daucus carota and Vicia faba from Yokota et al. (1989). All sequence data are available in GenBank.