The monotypic genus Guamatela Donn. Sm. was originally described from Guatemala and has also been collected in Hondruas and Mexico. This taxon has been placed in tribe Neilleae of Rosaceae based on its follicular fruits and persistent stipules, but it is anomalous in the tribe due to lack of endosperm, while some of its other characters, such as opposite leaves and lack of a well-developed hypanthium, are unusual for the entire family. No other taxonomic placement has ever been proposed for Guamatela, however, and morphological characters alone do not point to any likely alternative. We extracted DNA from an herbarium specimen of G. tuerckheimii Donn. Sm., collected by Grady Webster and Gary Breckon in the state of Oaxaca, Mexico in 1969. Phylogenetic analyses of the chloroplast matK gene amplified from this material, along with matK sequences from representatives of most major angiosperm groups, suggest that Guamatela belongs within the Rosid clade, but to neither Eurosids I nor Eurosids II, and thus definitely not within Rosaceae. Further analyses of other genes will be undertaken in order to determine the phylogenetic position of this intriguing and enigmatic genus.

Key words: Guamatela, matK, Neillieae, Rosaceae, Rosids