Henk van der Werff

Pucara (Amaryllidaceae) Reduced to Synonymy with Stenomesson on the Basis of Nuclear and Plastid DNA Spacer Sequences, and a New Related Species of Stenomesson

Abstract Pucara leucantha is transferred to Stenomesson as Stenomesson leucanthum based on the phylogenetic position of Pucara resolved by nuclear and plastid DNA sequences. An allied species, Stenomesson chloranthum, is described from the Departments of Amazonas and Cajamarca in Peru, but at lower elevations. Both of these species release their pollen in tetrads, unique within Amaryllidaceae, and have tri-lobed stigmas, unique within Stenomesson.

Molecular phylogeny of the moonseed family (Menispermaceae): implications for morphological diversification

We used the chloroplast gene ndhF to reconstruct the phylogeny of the moonseed family (Menispermaceae), a morphologically diverse and poorly known cosmopolitan family of dioecious, primarily climbing plants. This study includes a worldwide sample of DNA sequences for 88 species representing 49 of the 70 genera of all eight traditionally recognized tribes. Phylogenetic relationships were estimated, and the Shimodaira-Hasegawa test was used to compare the likelihood of alternative phylogenetic hypotheses and to evaluate the monophyly of tribes currently in use. The monospecific Indo-Malesian Tinomiscium is sister to the remaining members of the family, within which are two major clades. Within these two clades, well-supported clades correspond to four of the eight traditionally recognized tribes, while others, such as Menispermeae, are polyphyletic. Mapping of major morphological characters on the phylogeny indicates that the crescent-shaped seed is derived from a straight seed, the tree habit has arisen multiple times, endosperm has been lost many times, but unicarpellate flowers evolved only once. Morphological synapomorphies for Menispermaceae include the presence of a condyle, a large embryo, and druplets. The phylogeny provides for the first time a detailed molecular-based assessment of relationships in Menispermaceae and clarifies our understanding of morphological diversification within the family.

MOLECULAR PHYLOGENETIC ANALYSIS OF THE PERSEA GROUP (LAURACEAE) AND ITS BIOGEOGRAPHIC IMPLICATIONS ON THE EVOLUTION OF TROPICAL AND SUBTROPICAL AMPHI-PACIFIC DISJUNCTIONS

UNLABELLED PREMISE OF THE STUDY The Persea group (Lauraceae) has a tropical and subtropical amphi-pacific disjunct distribution with most of its members, and it includes two Macaronesian species. The relationships within the group are still controversial, and its intercontinental disjunction has not been investigated with extensive sampling and precise time dating. • METHODS ITS and LEAFY intron II sequences of 78 Persea group species and nine other Lauraceae species were analyzed with maximum parsimony and Bayesian inference. Divergence time estimation employed Bayesian Markov chain Monte Carlo method under a relaxed clock. • KEY RESULTS Several traditional genera or subgenera within the Persea group form well-supported monophyletic groups except Alseodaphne and Dehaasia. The divergence time of the Persea group is estimated as ∼55.3 (95% higher posterior densities [HPD] 41.4-69.9) million years ago (mya). Two major divergences within the Persea group are estimated as ∼51.9 (95% HPD 38.9-63.9) mya and ∼48.5 (95% HPD 35.9-59.9) mya. • CONCLUSIONS Persea can be retained as a genus by the inclusion of Apollonias barbujana and exclusion a few species that do not fit into the established subgenera. A major revision is recommended for the delimitation between Alseodaphne, Dehaasia, and Nothaphoebe. We suggest that the Persea group originated from the Perseeae-Laureae radiation in early Eocene Laurasia. Its amphi-pacific disjunction results from the disruption of boreotropical flora by climatic cooling during the mid- to late Eocene. The American-Macaronesian disjunction may be explained by the long-distance dispersal.

A Synopsis of Ocotea (Lauraceae) in Central America and Southern Mexico

Ocotea is the largest genus of Lauraceae in Mesoamerica (Central America and Southern Mexico, i.e., the area between the Isthmus of Tehuantepec in Mexico and the Panamanian-Colombian border) with 102 species recognized. The most recent treatment of Mesoamerican Ocotea was published by Carolyn Allen in 1945. It included 33 species and is now seriously outdated. A synopsis of the genus as it is currently known from Mesoamerica is presented here, consisting of a key to species, synonymy, type information, some brief notes on characters useful in their identification, and distribution by country and altitude.

Species number, area and habitat diversity in the Galapagos Islands

The Galapagos vascular plant species are divided into two groups, showing preferences for dry and wet habitats. This division is based on the results of a phytosociological study and is not influenced by such factors as island area, elevation, climate or soil types. The different distribution patterns of the dry and wet species are discussed and it is concluded that habitat diversity offers a better explanation for species numbers and distribution patterns than do island size and isolation. Claims that a dynamic MacArthur-Wilson type equilibrium has been reached for vascular plants in the Galapagos archipelago seem premature.

A Revision of the Genus Pleurothyrium (Lauraceae)

Pleurothyrium, a genus of Lauraceae mostly consisting of trees, ranges from Guatemala to Bolivia and possibly Southern Brazil. The genus is best represented in Peru, Ecuador, and Colombia and mostly occurs at low elevations. In this revision 39 species are included in Pleurothyrium, of which 19 are described as new. Taxonomic history, characters, and phylogenetic classification are discussed. Data on phenology, habitat preference, and altitudinal range are presented when available

A REVISION OF MEZILAURUS (LAURACEAE)

The neotropical genus Mezilaurus (Lauraceae), which consists of 18 species and is best represented in the drainage area of the Amazon, is revised. Clinostemon, a genus of two species recently separated

Amazon plant diversity revealed by a taxonomically verified species list

Significance Large floristic datasets that purportedly represent the diversity and composition of the Amazon tree flora are being widely used to draw conclusions about the patterns and evolution of Amazon plant diversity, but these datasets are fundamentally flawed in both their methodology and the resulting content. We have assembled a comprehensive dataset of Amazonian seed plant species from published sources that includes falsifiable data based on voucher specimens identified by taxonomic specialists. This growing list should serve as a basis for addressing the long-standing debate on the number of plant species in the Amazon, as well as for downstream ecological and evolutionary analyses aimed at understanding the origin and function of the exceptional biodiversity of the vast Amazonian forests. Recent debates on the number of plant species in the vast lowland rain forests of the Amazon have been based largely on model estimates, neglecting published checklists based on verified voucher data. Here we collate taxonomically verified checklists to present a list of seed plant species from lowland Amazon rain forests. Our list comprises 14,003 species, of which 6,727 are trees. These figures are similar to estimates derived from nonparametric ecological models, but they contrast strongly with predictions of much higher tree diversity derived from parametric models. Based on the known proportion of tree species in neotropical lowland rain forest communities as measured in complete plot censuses, and on overall estimates of seed plant diversity in Brazil and in the neotropics in general, it is more likely that tree diversity in the Amazon is closer to the lower estimates derived from nonparametric models. Much remains unknown about Amazonian plant diversity, but this taxonomically verified dataset provides a valid starting point for macroecological and evolutionary studies aimed at understanding the origin, evolution, and ecology of the exceptional biodiversity of Amazonian forests.

A synopsis of Persea (Lauraceae) in Central America

During preparation of a treatment of Persea for the Flora Mesoamericana three new species were recognized. A description of these species (Persea albiramea van der Werff, P. brevipetiolata van der Werff, and P. laevifolia van der Werff) is presented, as well as a key to all the known species in the Flora Mesoamericana region including brief notes giving synonyms, distribution, and noteworthy features for these species.

Origins and evolution of cinnamon and camphor: a phylogenetic and historical biogeographical analysis of the Cinnamomum group (Lauraceae)

Tropical and subtropical amphi-Pacific disjunction is among the most fascinating distribution patterns, but received little attention. Here we use the fossil-rich Cinnamomum group, a primarily tropical and subtropical Asian lineage with some species distributed in Neotropics, Australasia and Africa to shed light upon this disjunction pattern. Phylogenetic and biogeographic analyses were carried out using sequences of three nuclear loci from 94 Cinnamomum group and 13 outgroup samples. Results show that although there are three clades within a monophyletic Cinnamomum group, Cinnamomum and previously recognized subdivisions within this genus were all rejected as natural groups. The Cinnamomum group appears to have originated in the widespread boreotropical paleoflora of Laurasia during the early Eocene (ca. 55Ma). The formation and breakup of the boreotropics seems to have then played a key role in the formation of intercontinental disjunctions within the Cinnamomum group. The first cooling interval (50-48Ma) in the late early Eocene resulted in a floristic discontinuity between Eurasia and North America causing the tropical and subtropical amphi-Pacific disjunction. The second cooling interval in the mid-Eocene (42-38Ma) resulted in the fragmentation of the boreotropics within Eurasia, leading to an African-Asian disjunction. Multiple dispersal events from North into South America occurred from the early Eocene to late Miocene and a single migration event from Asia into Australia appears to have occurred in the early Miocene.