Insensitive blueberries: a total-evidence analysis of Disterigma s.l. (Ericaceae) exploring transformation costs

Disterigma sensu lato (s.l.) is a polyphyletic genus of neotropical blueberries that comprises 37 species found in Central and South America, mostly in Andean cloud forests and páramos. The present phylogenetic analysis, based on molecular and morphological data for 84% of the species of Disterigma s.l., addressed the monophyly of the genus and identified the putative morphological synapomorphies of the main clades. The sensitivity of the phylogenetic hypotheses to the choice of analytical parameters was addressed in detail, by varying all possible parameters and applying different treatments for indel coding. A total of 29 transformation cost matrices were investigated and all these analyses were performed in POY 4, using direct optimization. A diagnosable Disterigma sensu stricto (s.s.) clade was recovered in all analyses, despite changes in the transformation costs. Additionally, none of the analyses refuted the segregation of D. trimerum, D. ulei, D. pentandrum, D. rimbachii, and D. bracteatum from Disterigma s.s. Although measurements of congruence are used to choose among alternative analytical parameter sets, the behaviour of the RILD index (rescaled incongruence length difference) in this study suggested that it may not be a good measure of congruence and that further studies are necessary to better understand its performance.  © The Willi Hennig Society 2009.