A Morphological Cladistic Analysis of Terpsichore (Polypodiaceae)

Terpsichore, a Neotropical genus of about 70 species, was shown in previous molecular phylogenetic studies to be polyphyletic. The present study assesses this conclusion using morphology and also examines the phylogenetic relationships of five informal species groups originally described within Terpsichore. A morphological matrix was constructed for 109 qualitative characters and 129 terminals. Maximum parsimony was used to analyze the complete data set and three different partitions of that data set which excluded characters of either leaf shape or indumentum position or both. Terpsichore is polyphyletic in all analyses, and the characters originally used to define the genus are either plesiomorphic or homoplastic. Whereas the analysis of the complete matrix recovered a clade similar to the original circumscription, analyses of the partitioned data sets yielded results similar to those of molecular phylogenetic studies. In all analyses, two of the five infrageneric groups of Terpsichore are resolved as monophyletic, whereas the others are either paraphyletic or polyphyletic. In all analyses, species from the Terpsichore taxifolin Group are recovered as diphyletic, a result corresponding to that found in the previous molecular phylogenetic studies. By scoring morphological characters for this study, it was found that two vascular bundles are present in many grammitid petioles and are not unique to Luisma, mesophyll composed of long-armed stellate parenchyma evolves at least three times and is not unique to Enterosora, and perforated dictyosteles are common in grammitids and not restricted to Zygophlebia.