John D. Mitchell

To move or to evolve: contrasting patterns of intercontinental connectivity and climatic niche evolution in 'Terebinthaceae' (Anacardiaceae and Burseraceae)

Many angiosperm families are distributed pantropically, yet for any given continent little is known about which lineages are ancient residents or recent arrivals. Here we use a comprehensive sampling of the pantropical sister pair Anacardiaceae and Burseraceae to assess the relative importance of continental vicariance, long-distance dispersal and niche-conservatism in generating its distinctive pattern of diversity over time. Each family has approximately the same number of species and identical stem age, yet Anacardiaceae display a broader range of fruit morphologies and dispersal strategies and include species that can withstand freezing temperatures, whereas Burseraceae do not. We found that nuclear and chloroplast data yielded a highly supported phylogenetic reconstruction that supports current taxonomic concepts and time-calibrated biogeographic reconstructions that are broadly congruent with the fossil record. We conclude that the most recent common ancestor of these families was widespread and likely distributed in the Northern Hemisphere during the Cretaceous and that vicariance between Eastern and Western Hemispheres coincided with the initial divergence of the families. The tempo of diversification of the families is strikingly different. Anacardiaceae steadily accumulated lineages starting in the Late Cretaceous–Paleocene while the majority of Burseraceae diversification occurred in the Miocene. Multiple dispersal- and vicariance-based intercontinental colonization events are inferred for both families throughout the past 100 million years. However, Anacardiaceae have shifted climatic niches frequently during this time, while Burseraceae have experienced very few shifts between dry and wet climates and only in the tropics. Thus, we conclude that both Anacardiaceae and Burseraceae move easily but that Anacardiaceae have adapted more often, either due to more varied selective pressures or greater intrinsic lability.

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.

Poupartiopsis gen. nov. and its Context in Anacardiaceae Classification

Abstract Poupartiopsis spondiocarpus, a modest-sized tree of littoral forests of eastern Madagascar, is recognized as a distinct genus and described. Emended descriptions and circumscriptions of the recognized subfamilies Spondioideae and Anacardioideae are provided, as are separate keys to the genera of Spondioideae based on flowering and fruiting material and a table of diagnostic characters for distinguishing the genera. Molecular phylogenetic analysis and structural data including leaf architecture, floral morphology, and endocarp structure place Poupartiopsis in the Spondioideae, one of two subfamilies in Anacardiaceae.

A revision of Spondias L. (Anacardiaceae) in the Neotropics.

Abstract As part of an ongoing study of Anacardiaceae subfamily Spondioideae, the ten native and one introduced species of Spondias in the Neotropics are revised. The genus is circumscribed. Three new species, Spondias admirabilis, Spondias expeditionaria, and Spondias globosa, are described and illustrated; a key to the taxa found in the Neotropics and distribution maps are provided. The Paleotropical species and allied genera are reviewed. Diagnostic character sets include leaf architecture, habit, flower morphology, and gross fruit morphology. Notes on the ecology and economic botany of the species are provided.

Phylogenetic Split of Malagasy and African Taxa of Protorhus and Rhus (Anacardiaceae) Based on cpDNA trnL–trnF and nrDNA ETS and ITS Sequence Data

Abstract The African-Malagasy genus Protorhus and the African-Malagasy species of Rhus s.l. have been suggested to be polyphyletic, but definitive evidence has been lacking. We investigated a clade of Anacardiaceae subfamily Anacardioideae in order to clarify evolutionary relationships of the African-Malagasy members of these two genera. Phylogenetic analysis of sequence data from cpDNA trnL–trnF, and nrDNA ETS and ITS provide strong statistical support for the 1) polyphyly of Protorhus; 2) monophyly of Malagasy Protorhus species; 3) polyphyly of Rhus section Baronia (Malagasy Rhus). These results support the need for new circumscriptions of these groups. Two new combinations are proposed, Searsia erosa and Searsia pendulina.

The “tortoise’s cajá”—a new species of Spondias (Anacardiaceae) from southwestern Amazonia

Botanical exploration in southwestern Amazonia has revealed a new species, Spondias testudinis J. D. Mitch. & Daly, described and illustrated here. Its distribution appears to be restricted to the Brazilian state of Acre; Pando in Bolivia; and Huánuco and Ucayali in Peru. The sexuality of the flowers of Spondias and its implications regarding their morphology is discussed. A provisional key to the neotropical species is presented.

Oriental Lacquer. 11. Botany and Chemistry of the Active components of Poisonous Anacardiaceae

Abstract Some aspects of the botany of the family Anacardiaceae are discussed with special emphasis on the poisonous genera and species. The focus is on the well-known members of the genus Toxicodendrons, i.e., the lacquer tree, poison ivy, poison sumac, and poison oak. These genera have as their toxic, dermatitis-causing ingredients catechols with C15 and C17 aliphatic side chains of various degrees of unsaturation and a variety of compositions of the individual components. Saps with a catechols mixture of a high triene content are used as lacquer for highly desired objects of art and daily use with great beauty and considerable value. Some other members of the Anacardiaceae family which grow in South East Asia have active catechol and phenol components with slightly different chemical side chain structure.

A revision of Thyrsodium (Anacardiaceae)

Recent research for floristic treatments of the Anacardiaceae led to the discovery of three new species ofThyrsodium:T. rondonianum, T. bolivianum, andT. puberulum. Historically, the genus was confused with the burseraceous genusGaruga. Study of these genera has helped to refine our understanding of the relationships between the Anacardiaceae and Burseraceae. A revised description ofThyrsodium, a key to the species in the genus, descriptions, distribution maps, and notes on the distribution and ecology of all the species are provided.

Additions to Anacardium (Anacardiaceae). Anacardium amapaënse, a new species from French Guiana and eastern Amazonian Brazil

Anacardium amapaënse, a new species, is described and segregated fromA. parvifolium. Its leaf domatia are substantially different in morphology from the latter. Based on gross morphological characters,Anacardium amapaënse appears to be most closely allied withA. fruticosum. An emended description ofA. parvifolium, distribution maps ofA. amapaënse, A. fruticosum andA. parvifolium, and a revised key toAnacardium are included.

A new species of Tapirira (Anacardiaceae) from the Isthmus of Tehuantepec, Mexico

Tapirira chimalapana is a new species of tree common in the rain forests and lower montane forests of the Isthmus of Tehuantepec in the Mexican states of Veracruz and Oaxaca. It is most similar to the AndeanT. guianensis Aubl. subsp.subandina Barfod & Holm-Niels. but differs from this and all other congeners by having larger petals on pistillate flowers than on staminate flowers and by pubescence features. Details of field characteristics, distribution, ecology, phenology, germination, and local names and uses are included.ResumenLa nueva especieTapirira chimalapana es un árbol frecuente en la selva alta perennifolia y en las elevaciones inferiores del bosque mesófilo de montaña de la vertiente del Golfo del Istmo de Tehuantepec en los estados de Veracruz y Oaxaca, México. La especie más emparentada a ésta parece serT. guianensis Aubl. subsp.subandina Barfod & Holm-Niels.Tapirira chimalapana difiere de todas las demás especies descritas del género por el mayor tamaño de los pétalos de las flores pistiladas comparado con el de las estaminadas así como por el tipo de pubescencia. En el presente artículo se incluyen datos sobre las características de campo de la nueva especie, además de datos sobre su distribución, fenología, germinación, nombres comunes y usos locales.