Barbara Whitlock

The Caribbean biodiversity hotspot has both high plant diversity and endemism, yet the origins of this unique flora have not been well explored. Here, we use a phylogenetic approach with the American genus Ayenia (sensu stricto) to test hypotheses on the origins, number, and timing of its Caribbean lineages. We conduct time-calibrated phylogenetic and biogeographic analyses using DNA sequences of three chloroplast markers from ca. 70 % of the species diversity of Ayenia, including representatives from all sections of the genus and from all regions in the Americas. Contrary to existing hypotheses, we conclude that Ayenia diverged from neotropical Byttneria in South America 21.7 Ma in the early Miocene, as global climates were warming. Early diverging species of Ayenia are from mesic communities, characterized by an arborescent habit, larger leaves, and multiaperturate foliar nectaries. The majority of species of Ayenia resolve themselves into two major clades; within each, we find parallel migrations north, into North America and the Caribbean. Caribbean lineages of Ayenia thus arose at least twice, with one colonization dating to 6.2 Ma in the late Miocene, and a second to 2.8 Ma in the late Pliocene, with evidence of at least one dispersal back to mainland North America. Given the distributions of species and the divergence times we recovered, we reject over-land dispersal as a viable route into the Caribbean islands for Ayenia. While the monophyly of Ayenia continues to be supported, two of its three sections are non-monophyletic. In light of our results, we also suggest an updated sectional classification of the genus.

Crop wild relatives (CWRs) of cultivated species may provide a source of genetic variation that can contribute to improving product quantity and quality. To adequately use these potential resources, it is useful to understand how CWRs are related to the cultivated species and to each other to determine how key crop traits have evolved and discover potentially usable genetic information. The chocolate industry is expanding and yet is under threat from a variety of causes, including pathogens and climate change. Theobroma cacao L. (Malvaceae), the source of chocolate, is a representative of the tribe Theobromateae that consists of four genera and c. 40 species that began to diversify over 25 million years ago. The great diversity within the tribe suggests that its representatives could exhibit advantageous agronomic traits. In this study, we present the most taxonomically comprehensive phylogeny of Theobromateae to date. DNA sequence data from WRKY genes were assembled into a matrix that included 56 morphological characters and analyzed using a Bayesian approach. The inclusion of a morphological data set increased resolution and support for some branches of the phylogenetic tree. The evolutionary trajectory of selected morphological characters was reconstructed onto the phylogeny. This phylogeny provides a framework for the study of morphological and physiological trait evolution, which can facilitate the search for agronomically relevant traits.

Premise: Imaging technologies that capture three-dimensional (3D) variation in floral morphology at micro- and nano-resolutions are increasingly accessible. In herkogamous flowers, such as those of Theobroma cacao, structural barriers between anthers and stigmas represent bottlenecks that restrict pollinator size and access to reproductive organs. To study the unresolved pollination biology of cacao, we present a novel application of micro-computed tomography (micro-CT) using floral dimensions to quantify pollinator functional size limits.Methods: We generated micro-CT data sets from field-collected flowers and museum specimens of potential pollinators. To compare floral variation, we used 3D Slicer to place landmarks on the surface models and performed a geometric morphometric (GMM) analysis using geomorph R. We identified the petal side door (an opening between the petal hoods and filament) as the main bottleneck for pollinator access. We compared its mean dimensions with proposed pollinators to identify viable candidates.Results: We identified three levels of likelihood for putative pollinators based on the number of morphological (body) dimensions that fit through the petal side door. We also found floral reward microstructures whose presence and location were previously unclear.Discussion: Using micro-CT and GMM to study the 3D pollination biology of cacao provides new evidence for predicting unknown pollinators. Incorporating geometry and floral rewards will strengthen plant-pollinator trait matching models for cacao and other species.

Abstract Background and Aims Byttneria is one of the few climbing genera in Malvaceae. Some Byttneria are known for their lobed stems. We explore the development of these stems, how they have evolved within the group and their relevance in the evolution of the climbing growth form in Malvaceae. Methods We combine developmental anatomical work with phylogenetic comparative methods. We use Byttneria divaricata and B. filipes as models in the anatomical work, a review of herbarium vouchers, and the most recent phylogeny of Byttneria and allies to elucidate how these stems evolved within the clade under maximum-likelihood and Bayesian approaches. We use Pagel94 tests to analyse the correlated evolution of lobed stems and prickles. Key Results Each lobe coincides with one of the five vascular bundles. By augmented activity of the fascicular cambium in the lobes coupled with reduced activity of the interfascicular cambium in the interlobes, secondary growth increases the lobulation already present during primary growth. Within Byttneria and allies, lobed young stems appeared at least three times, once in Ayenia and twice in the paraphyletic Byttneria. Lobed adult stems were conserved in Byttneria s.s., where lobed adult stems in combination with prickles were shown to have evolved as a climbing mechanism within the group; prickles were lost once within Byttneria s.s., in a shrubby subclade. Byttneria Clade 2 comprises climbers with twining cylindrical adult stems and no prickles, which constitutes a different climbing mechanism in the group. Conclusions We provide evidence of one of the few cambial variants known whose secondary body reflects the primary body vasculature and show that lobed adult stems and prickles in Byttneria could be used in the new delimitation of genera in the group. Lobed stems independently appeared in climbing Grewia, suggesting a convergence favouring the climbing growth form.

Species of Gordonia s.l. are characterized by having seeds with prominent flattened apical wings. However, recent molecular phylogenetic studies show that this concept of Gordonia is not monophyletic, with species occurring in two tribes of Theaceae. We examine seed coat micromophology of 14 species of Gordonia s.l., including representatives from all proposed lineages, and ten species from six genera from all three tribes of Theaceae. We observed that seeds from Gordonieae, including two species of Gordonia s.l., have irregularly protruding groups of cells on the seed coat that appear to be unique in the family. Seeds of Theeae, including all remaining species of Gordonia s.l., lack protruding cells and include testa cells that are isodiametric to elongate. Seeds of Stewartieae lack protrusions and elongate testa cells, and often have sculpting visible below the seed coat. Seeds of Gordonia s.l. from Gordonieae appear significantly smaller than species placed in Theeae. These results may help to infer relationships of fossilized seeds previously identified as Gordonia.

Seringia J.Gay and Keraudrenia J.Gay are widely spread in Australia, and one species occurs in Madagascar. Revision of these closely related genera suggested that neither genus is monophyletic on the basis of morphological or preliminary molecular data. As a result, Keraudrenia is subsumed into Seringia. There are now 20 species of Seringia, including the currently accepted type species Seringia platyphylla J.Gay (=Seringia arborescens (W.T.Aiton) Druce). Five new species S. adenogyna C.F.Wilkins, S. cacaobrunnea C.F.Wilkins, S. elliptica C.F.Wilkins, S. undulata C.F.Wilkins and S. saxatilis C.F.Wilkins are described. Four species of Keraudrenia initially described as Seringia and recognised as the latter by F. J. H. von Mueller are reinstated (S. adenolasia F.Muell., S. corollata Steetz, S. lanceolata Steetz, S. nephrosperma F.Muell.). Five previous combinations of Keraudrenia and Seringia as Seringia are recognised (S. hermanniifolia (J.Gay) F.Muell., S. hillii (Benth.) F.Muell., S. hookeriana (Walp.) F.Muell., S. integrifolia (Steud.) F.Muell., S. velutina (Steetz) F.Muell.) and five new combinations are made (S. collina (Domin) C.F.Wilkins & Whitlock, S. denticulata (C.T.White) C.F.Wilkins & Whitlock, S. exastia (C.F.Wilkins) C.F.Wilkins & Whitlock, S. katatona (C.F.Wilkins) C.F.Wilkins & Whitlock, S. macrantha (Baill.) C.F.Wilkins & Whitlock. Keraudrenia collina var. multiflora Domin is placed in synonymy under S. nephrosperma F.Muell. Keraudrenia corollata var. denticulata C.T.White is recognised as a distinct species, S. denticulata (C.T.White) C.F.Wilkins & Whitlock. Anatomical studies, taxonomic descriptions, distribution maps, illustrations and identification keys are presented for Seringia, and an identification key to genera of the tribe Lasiopetaleae is provided.

A new genus, Androcalva C.F.Wilkins & Whitlock, is here described and includes 22 species previously described as Commersonia, four species formerly described as Rulingia and seven new species, including A. aphrix C.F.Wilkins, A. perlaria C.F.Wilkins, A. bivillosa C.F.Wilkins, A. adenothalia C.F.Wilkins, A. fragifolia C.F.Wilkins, A. incilis C.F.Wilkins and A. lachna C.F.Wilkins. Rulingia pauciflora Turcz. is here placed in synonymy with C. gaudichaudii J.Gay as A. gaudichaudii. Recognition of Androcalva is supported by the results of a previous molecular phylogenetic analysis demonstrating that neither Rulingia nor Commersonia as previously circumscribed is monophyletic. Species of Androcalva share characters of extrorse anther dehiscence and glabrous central staminodes. In contrast, species in the redefined Commersonia have anthers with sublatrorse dehiscence and hairy central staminodes. Taxonomic descriptions, a key, distribution maps, conservation status and illustrations are presented.

A taxonomic revision and DNA sequence analysis of all species previously attributed to Rulingia R.Br. and Commersonia J.R.Forst. & G.Forst. resulted in two major groupings, referred to a redefined Commersonia and a new genus (Androcalva C.F.Wilkins & Whitlock 2011). In total, 25 species are now recognised within Commersonia, including the type species of Rulingia, and 14 species previously included in Rulingia and 10 in Commersonia. Three of these are described as new (C. apella C.F.Wilkins, C. erythrogyna C.F.Wilkins and C. gilva C.F.Wilkins). A new subspecies, C. magniflora subsp. oblongifolia C.F.Wilkins, is recognised and C. bartramia (L.) Merr. var. tahitensis Dorr is raised to species level as C. tahitensis (Dorr) C.F.Wilkins & Whitlock. Two new combinations are made, Rulingia platycalyx Benth. and R. parviflora Endl. as C. parviflora (Endl.) C.F.Wilkins & Whitlock; and R. cistifolia Steetz and R. rugosa Steetz as C. rugosa (Steetz) F.Muell. The redefined Commersonia is monophyletic and characterised by anthers with sublatrorse dehiscence and mainly hairy staminodes, compared with extrorse dehiscence and glabrous staminodes as seen in Androcalva.