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Rubiaceae are one of the largest families of plants, with ;13,000 species. In this study, we have estimated the phylogeny for 534 Rubiaceae taxa from 329 genera with up to five different chloroplast regions by Bayesian analysis. It resulted in a highly resolved tree with many strongly supported nodes. There is strong support for the three subfamilies (Cinchonoideae, Ixoroideae, Rubioideae) and most of the 44 included tribes. A scaled-down data set of 173 Rubiaceae taxa was used with a Bayesian approach to estimate divergence times for clades classified as tribes and subfamilies. Four fossils were used as minimum age priors, one inside each subfamily and one for Rubiaceae as a whole (Faramea-type pollen, Scyphiphora pollen, Cephalanthus pusillus fruits, and Paleorubiaceophyllum eocenicum leaves). The estimated lineage (stem) divergence time for Rubiaceae is 90.4 Ma. The estimated lineage divergence times for the subfamilies are 84.4 (86.6) Ma for Rubioideae, 73.1 Ma for Ixoroideae, and 73.1 Ma for Cinchonoideae. The estimated lineage divergence times for the tribes vary between 86.6 and 14.2 Ma. Classification, relationships, geographical distribution, and age estimates are presented and discussed for all tribes.

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The phylogeny of Rosoideae was investigated using 44 species. Here we report new sequence data from the chloroplast trnL/F region as well as an increased sample of species. The analysis of these new data, along with previously used data from the nuclear ribosomal internal transcribed spacers (ITS), significantly increased resolution as well as confidence for Rosoideae phylogeny. Using both Bayesian inference and parsimony methods, we conducted analyses on the data sets separately and in combination. The resulting phylogenies are congruent with all well-supported clades of Rosoideae found in previous analyses of ITS or rbcL data. The support for these and other clades is improved, and we consider several clades to be supported well enough to be named. The following clades are given phylogenetic definitions: Sanguisorbeae and its subclades Agrimoniinae and Sanguisorbinae, Potentilleae and its subclades Fragariinae and Potentilla, Roperculina (Rosa + Sanguisorbeae + Potentilleae), and Sanpotina (Sanguisorbeae + Potentilleae). Potentilla includes the Potentilla anserina clade (Argentina) in our trnL/F and combined analyses, but this relationship is not resolved by ITS alone. The previously used genera Duchesnea (Potentilla indica), Horkelia, and Ivesia are strongly supported as nested within Potentilla. Comarum (Potentilla palustris and Potentilla salesowianum), Sibbaldiopsis (Potentilla tridentata), Dasiphora (Potentilla fruticosa), and Drymocallis (Potentilla arguta) join Alchemilla, Aphanes, Sibbaldia, Chamaerhodos, and Fragaria in the well-supported Fragariinae clade outside of Potentilla. The monophyly of both Potentilleae and Sanguisorbeae is well supported, and the clades correspond to previously named tribes with the exception of Alchemilla and its segregate Aphanes, which are nested within Potentilleae instead of in Sanguisorbeae. The position of Rubus is still not securely resolved.

Although recent methodological advances have allowed the incorporation of rate variation in molecular dating analyses, the calibration procedure, performed mainly through fossils, remains resistant to improvements. One source of uncertainty pertains to the assignment of fossils to specific nodes in a phylogeny, especially when alternative possibilities exist that can be equally justified on morphological grounds. Here we expand on a recently developed fossil cross-validation method to evaluate whether alternative nodal assignments of multiple fossils produce calibration sets that differ in their internal consistency. We use an enlarged Crypteroniaceae-centered phylogeny of Myrtales, six fossils, and 72 combinations of calibration points, termed calibration sets, to identify (i) the fossil assignments that produce the most internally consistent calibration sets and (ii) the mean ages, derived from these calibration sets, for the split of the Southeast Asian Crypteroniaceae from their West Gondwanan sister clade (node X). We found that a correlation exists between s values, devised to measure the consistency among the calibration points of a calibration set (Near and Sanderson, 2004), and nodal distances among calibration points. By ranking all sets according to the percent deviation of s from the regression line with nodal distance, we identified the sets with the highest level of corrected calibration-set consistency. These sets generated lower standard deviations associated with the ages of node X than sets characterized by lower corrected consistency. The three calibration sets with the highest corrected consistencies produced mean age estimates for node X of 79.70, 79.14, and 78.15 My. These timeframes are most compatible with the hypothesis that the Crypteroniaceae stem lineage dispersed from Africa to the Deccan plate as it drifted northward during the Late Cretaceous.

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Abstract.•Linnaean binomial nomenclature is logically incompatible with the phylogenetic nomenclature of de Queiroz and Gauthier (1992, Annu. Rev. Ecol. Syst. 23:449-480): The former is based on the concept of genus, thus making this rank mandatory, while the latter is based on phylogenetic definitions and requires the abandonment of mandatory ranks. Thus, if species are to receive names under phylogenetic nomenclature, a different method must be devised to name them. Here, 13 methods for naming species in the context of phylogenetic nomenclature are contrasted with each other and with Linnaean binomials. A fundamental dichotomy among the proposed methods distinguishes those that retain the entire binomial of a preexisting species name from those that retain only the specific epithet. Other relevant issues include the stability, uniqueness, and ease of pronunciation of species names; their capacity to convey phylogenetic information; and the distinguishability of species names that are governed by a code of phylogenetic nomenclature both from clade names and from species names governed by the current codes. No method is ideal. Each has advantages and drawbacks, and preference for one option over another will be influenced by one's evaluation of the relative importance of the pros and cons for each. Moreover, sometimes the same feature is viewed as an advantage by some and a drawback by others. Nevertheless, all of the proposed methods for naming species in the context of phylogenetic nomenclature provide names that are more stable than Linnaean binomials. {Phylogenetic nomenclature; species names; binomial nomenclature.)

The Begoniaceae consist of two genera, Begonia, with approximately 1400 species that are widely distributed in the tropics, and Hillebrandia, with one species that is endemic to the Hawaiian Islands and the only member of the family native to those islands. To help explain the history of Hillebrandia on the Hawaiian Archipelago, phylogenetic relationships of the Begoniaceae and the Cucurbitales were inferred using sequence data from 18S, rbcL, and ITS, and the minimal age of both Begonia and the Begoniaceae were indirectly estimated. The analyses strongly support the placement of Hillebrandia as the sister group to the rest of the Begoniaceae and indicate that the Hillebrandia lineage is at least 51-65 million years old, an age that predates the current Hawaiian Islands by about 20 million years. Evidence that Hillebrandia sandwicensis has survived on the Hawaiian Archipelago by island hopping from older, now denuded islands to younger, more mountainous islands is presented. Various scenarios for the origin of ancestor to Hillebrandia are considered. The geographic origin of source populations unfortunately remains obscure; however, we suggest a boreotropic or a Malesian-Pacific origin is most likely. Hillebrandia represents the first example in the well-studied Hawaiian flora of a relict genus.