William Wayt Thomas

William Wayt Thomas
New York Botanical Garden · Institute of Systematic Botant

PhD

About

148
Publications
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3,207
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Publications

Publications (148)
Article
A taxonomic revision of the species currently circumscribed in Tarenaya Raf. (Cleomaceae) is presented here. Tarenaya comprises 38 species distributed from Mexico to Argentina (except for Chile) and the West Indies, and with one species disjunct in Central Africa. We present a new combination, 14 lectotypifications, and two neotypifications, and de...
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The present study aims to improve the knowledge of Simaroubaceae in the Reserva Ducke, Manaus, Amazonas. It is based on morphological analysis of herbaria collections and field expeditions. The family is represented in that area by six species belonging to four genera: Homalolepis (1 sp.), Picrolemma (1 sp.), Simaba (3 spp., including a new one des...
Article
The name Cleome heptaphylla was published by Linnaeus in the second edition of Species plantarum and is still untypified. Analysis of the protologue and the associated pre‐Linnaean names indicated the absence of original material that could serve for lectotypification. A specimen from Miller’s herbarium at BM is designated as its neotype. The neoty...
Article
Background and aims: Eriocaulaceae exhibit a great variety of floral traits associated with insect (e.g., nectariferous structures) and wind pollination (unisexual flowers, exposed sexual organs, and small pollen grains), as well as 'selfing syndrome' (small flowers, short distance between stigma and anthers, and temporal overlap of male and femal...
Article
Floral colors and odors are evolutionary strategies used by plants to attract pollinating animals and may be absent in mostly anemophilous groups, such as Cyperaceae. However, considering that insects are floral visitors of some Rhynchospora species, the objective of this study was to characterize the floral traits and the pollination systems withi...
Article
An unusual tree was collected in the Manu National Park in Peru in 1973 and although recollected many times, remained unidentified for decades. Preliminary molecular analysis indicated that it belonged to the Picramniaceae, even though the vegetative features were discordant. Using the nuclear marker ITS and the chloroplast marker rbcL, sequences w...
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The recovery of tree species composition after disturbance depends on dispersal either from nearby forests or from surviving individuals within the disturbed area. Understanding the influence of proximity to mature forests on species composition of regenerating secondary forests can help in predicting the trajectory of recovery from anthropogenic d...
Article
New combinations for Cryptangium verticillatum and for Lagenocarpus tristis are proposed here. Three neotypes and three lectotypes for names actually belonging to the genus Cryptangium, and seven lectotypes for names belonging to Lagenocarpus are designated here.
Article
Ambophily (wind and insect pollination) has been reported for some genera of the typically wind‐pollinated family Cyperaceae, including the genus Rhynchospora. The significance of wind and insect pollination can vary, depending on local microclimatic conditions. Rhynchospora cephalotes is an ambophilous species that can grow under different environ...
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Cyperaceae (sedges) are the third largest monocot family and are of considerable economic and ecological importance. Sedges represent an ideal model family to study evolutionary biology because of their species richness, global distribution, large discrepancies in lineage diversity, broad range of ecological preferences, and adaptations including m...
Article
Cryptangieae is a monophyletic tribe, as asserted in a recent molecular hypothesis, but there are questions about the circumscription and relationships of its genera. We enlarged the sampling of the tribe diversity, including about 80% of known species, and provide new analyses using single and combined matrices from two chloroplast (rbcL and trnL-...
Article
Rhynchospora is one of the most species-rich genera of Cyperaceae, comprising c. 400 species in 28 sections. Rhyncospora section Tenues is one of the largest sections and one of the most problematic. Because it is morphologically similar to sections Laevinuces, Luzuliformes and Spermodontes, the characters traditionally used to distinguish section...
Article
The family Cleomaceae is represented in the Neotropics by nine native lineages, with some of them currently recognized as distinct genera and others in need of clear delimitation. We present here a new phylogenetic hypothesis for the New World Cleomaceae with a more comprehensive sampling, including samples of 62 species with emphasis on Tarenaya a...
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Seed arrival is a limiting factor for the regeneration of diverse tropical forests and may be an important mechanism that drives patterns of tree species’ distribution. Here we quantify spatial and seasonal variation in seed rain of secondary forests in southern Bahia, Brazil. We also examine whether secondary forest age enhances seed dispersal and...
Article
Usually considered anemophilous, grasses (Poaceae) have been the subject of few studies that recorded insects visiting their flowers. Such visitors, with wind, could act as pollen vectors in a possible ambophilous system. Since colour and scent are floral cues attracting pollinating insects, we aimed to provide the first insights into how these cue...
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Tarenaya longicarpa, commonly known as “mussambe,ˆ ” is a new species from South America. Iltis previously recognized it as a subspecies of Cleome spinosa Jacq. but never published the name. Molecular phylogenetic studies have confirmed this taxon as a distinct lineage from T. spinosa. In addition, the results of a revision of Tarenaya, now underwa...
Article
Tropical forests are converted at an alarming rate for agricultural use and pastureland, but also regrow naturally through secondary succession. For successful forest restoration, it is essential to understand the mechanisms of secondary succession. These mechanisms may vary across forest types, but analyses across broad spatial scales are lacking....
Article
Rhynchospora seccoi, a new species of Rhynchospora sect. Tenues (Cyperaceae) is herein described and illustrated. This new species from Serra dos Carajás (Pará State, Brazil) is morphologically similar to R. tenuis and R. riparia, but differs by being annual and having often cauline leaves, a synflorescence comprising 1 terminal and 2–3 axillary pa...
Article
Phylogenetic hypotheses and morphological characterizations of genera in the Abildgaardieae have suggested that current generic circumscriptions are not monophyletic. We here provide an updated phylogenetic hypothesis of the Abildgaardieae using nrDNA ITS sequences that continues to support the derivation of Nemum from within the Bulbostylis lineag...
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Old-growth tropical forests harbor an immense diversity of tree species but are rapidly being cleared, while secondary forests that regrow on abandoned agricultural lands increase in extent. We assess how tree species richness and composition recover during secondary succession across gradients in environmental conditions and anthropogenic disturba...
Article
The taxonomic identity of Rhynchospora panduranganii and R. corymbosa (Cyperaceae) is resolved based on a detailed study of both herbarium specimens and living collections. We provide distinguishing characters of both species, along with photographs for easy identification.
Article
Rhynchospora Vahl (1805:229) is the richest genus of Cyperaceae in southern Brazil (66 spp., Flora do Brasil 2020). Most species grow in open areas such as meadows and grasslands but some occur in forests or along forest edges. As part of a taxonomic and phylogenetic study of the related sections Luzuliformes Kük. (1950:183) and Tenues Kük. (1950:1...
Presentation
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Kükenthal included Rhynchospora sections Laevinuces Kük., Luzuliformes Kük., Spermodontes Kük., and Tenues Kük. in the Psilocarya group of subgenus Rhynchospora. Existing molecular studies have included only a few of the 41 species in these four sections and indicate that they are sister to a group that includes sections Psilocarya and Dichromena....
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Homalolepis Turcz. is a neotropical, monophyletic genus, recently reestablished as a segregate from Simaba Aubl., based on molecular and morphological grounds. As here defined, Homalolepis comprises 28 species, mainly distributed in tropical South America, with one species extending to Central America. Most species occur within the Cerrado and Atla...
Cover Page
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Cover page of Phytotaxa 366. 2018
Article
As recognized traditionally and until recently, Simaba ferruginea A.St.-Hil. sensu Engler was a polymorphic taxon with a disjunct distribution on dry formations of central and northeastern Brazil, and the northernmost region of Colombia and adjacent Venezuela. A detailed morphological survey of this complex based on fieldwork and herbarium specimen...
Cover Page
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Homalolepis ferruginea (A.St.-Hil.) Devecchi & Pirani
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Habitat loss and fragmentation in the Atlantic forest of northeastern Brazil has been extremely extensive since colonial period leaving only small and isolated forests. Phytosociological studies are important because help to understand the vegetation structure and allow to verify what is the conservation level of habitats. In this study, we evaluat...
Article
We endorse the tribal status of Cryptangieae and discuss its most probable sister-group based on phylogenetic analyses using rbcL, trnL-trnL-trnF and ITS sequences. Cryptangieae were poorly sampled in previous molecular phylogenies of Cyperaceae: only three of about 50 species were sampled and all of them are currently included in the genus Lagenoc...
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Tarenaya clade includes 37 species based on phylogenetic relationships and on the stipular spine synapomorphy, however only 10 species thought to belong to the genus have had names established in Tarenaya. Besides the two new species are being described, we present 25 new combinations for the species and refine the typification of 13 species. Ten l...
Article
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In typically anemophilous families, there are species, such as Rhynchospora ciliata (Cyperaceae), in which both wind and insects have been registered as pollen vectors (ambophily). However, the contribution of each vector to pollination of ambophilous species can change under different environmental conditions. Therefore, this study aimed to determ...
Article
We describe and illustrate two new species of Homalolepis Turcz. (Simaroubaceae), a genus recently reinstated based on molecular evidence indicating that Simaba Aubl. as currently circumscribed is not monophyletic. Both species are dwarf, geoxylic subshrubs with restricted distribution in the Brazilian savanna (cerrado). Homalolepis planaltina is s...
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Karyotype evolution in species with non-localised centromeres (holocentric chromosomes) is usually very dynamic and associated with recurrent fission and fusion (also termed agmatoploidy/symploidy) events. In Rhynchospora (Cyperaceae), one of the most species-rich sedge genera, all analysed species have holocentric chromosomes and their numbers ran...
Article
A new species of Rhynchospora section Tenues, from western Bahia, Brazil, is described, illustrated, and compared to related species.
Article
Generic circumscriptions in the mostly pantropical family Simaroubaceae are somewhat controversial. Simaba is the largest genus, currently defined as exclusively neotropical, with around 25 species of trees and shrubs, but both its limits and infrageneric classification have been a matter of discussion and divergence. Traditionally, species of the...
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During the revision of the genus Bulbostylis for Brazil four new species were found, which are proposed here. Bulbostylis amazonica, B. decidua, B. minensis and B. wanderleyana are fully described, illustrated, and compared to other South American species.
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Tribe Rhynchosporeae (ca. 386 spp.; Cyperaceae) has high levels of endemicity (≥ 44%) in tropical and subtropical American savannas and can provide insights into the diversifi cation of their biotas. Wind pollination, occupation of a savanna habitat, and a C3 photosynthetic pathway are common in the tribe, but showy (presumably insect- pollinated)...
Article
Although Cyperaceae are considered anemophilous, some species exhibit features that are attractive to pollinators, such as the white UV-reflecting involucral bracts of Rhynchospora ciliata. But how effective are these conspicuous adaptations? To address this question, we tested the hypothesis that species such as R. ciliata are visited by greater n...
Article
Two species of Scleria section Hypoporum from the state of Espírito Santo, Brazil, are described, illustrated, mapped, and compared to two similar species, S. virgata and S. variegata. While most species of sect. Hypoporum are small and narrowleaved, these two species are robust.
Article
Aim: Using a comprehensive floristic database (2616 species, 36,004 occurrence records from 128 unique localities), we model species turnover along the central region of the Atlantic Forest hotspot to (1) test whether local rivers, particularly the Rio Doce, are associated with marked biogeographical breaks, and (2) investigate how regional composi...
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In this paper we describe and illustrate a new species of Simaba from the sandy coastal plains in northeastern Brazil, and discuss the controversial limits of the three sections proposed in the genus by Englerian classification. Simaba arenaria has a restricted distribution: it is known only from two small, somewhat disturbed areas, in restinga veg...
Article
As part of The New York Botanical Garden’s 125th anniversary, a summary of floristic research by NYBG staff is presented. The first 50 years of the Garden were extremely productive and resulted in floras covering most of the United States and Canada. The focus of research at the Garden shifted to the Neotropics and diversified, especially in northe...
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We submitted tree species occurrence and geoclimatic data from 59 sites in a river basin in the Atlantic Forest of southeastern Brazil to ordination, ANOVA, and cluster analyses with the goals of investigating the causes of phytogeographic patterns and determining whether the six recognized subregions represent distinct floristic units. We found th...
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An updated inventory of Brazilian seed plants is presented and offers important insights into the country’s biodiversity. This work started in 2010, with the publication of the Plants and Fungi Catalogue, and has been updated since by more than 430 specialists working online. Brazil is home to 32,086 native Angiosperms and 23 native Gymnosperms, sh...
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Habitat fragmentation may lead to spatial genetic structuring of plant populations, but the magnitude of this effect differs among species. In this study, the effects of fragmentation on spatial genetic structure of Manilkara maxima , an ecologically important tree species endemic to the Atlantic forest of southern Bahia, Brazil, were examined. To...
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Background: Understanding floristic and geographic patterns in one of the most biodiverse regions in the world – the Atlantic forest of eastern Bahia, Brazil – can identify the drivers of diversity in tropical forests and provide useful information for biological conservation. Aims: To understand the role of both climate and geographical location o...
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Carex (Cyperaceae), with an estimated 2000 species, nearly cosmopolitan distribution and broad range of habitats, is one of the largest angiosperm genera and the largest in the temperate zone. In this article, we provide argument and evidence for a broader circumscription of Carex to add all species currently classified in Cymophyllus (monotypic),...
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Pleurostachys Brongn. is a Neotropical genus of Cyperaceae closely related to Rhynchospora Vahl. It is found in the Atlantic and Amazon Forests from northern South America to southern Brazil and most of the species grow in the humid and shady understory. Fourteen species are confirmed, 11 of them are endemic to the Brazilian Atlantic Forest and six...
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(Hypolytrum (Cyperaceae): taxonomic and nomenclatural notes, geographical distribution and conservation status of Neotropical species.) Hypolytrum (Mapanioideae) is a medium-size and Pantropical genus of Cyperaceae, closely related to Mapania, Principina, and Scirpodendron. In the Neotropics, it is found from southern Mexico to southern Brazil wher...
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Fragmentation threatens biodiversity globally. Manilkara maxima (Sapotaceae) is listed by the IUCN as threatened and is an economically and ecologically important tree species endemic to the Atlantic forest of southern Bahia, Brazil, a biodiversity hotspot. The objectives of this study were to examine the effect of fragment size on density and gene...
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One of the greatest challenges in achieving the goals of the World Flora Online (WFO) will be to make available the huge amount of botanical information that is not yet available digitally. The New York Botanical Garden is using the Flora Neotropica monograph series as a model for digitization. We describe our efforts at digitizing Flora Neotropica...
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Here, we report the diversity of trees and lianas in two fragments of coastal Atlantic forest in the Brazilian state of Sergipe. We found a total of 314 trees in 86 species and 37 families in in the Trapsa forest, and 147 trees in 44 species and 28 families in the Junco forest. The diversity of lianas was similar between sites, with 16 species (10...
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This article is part of a series of taxonomic monographs of families occurring on fragments of Atlantic Forest from Usina São José, Igarassu, Pernambuco. It presents treatments of Picramniaceae (Picramniales) and of two families of Sapindales: Rutaceae and Simaroubaceae. Field trips were conducted between the years of 2007 and 2013. Local herbarium...
Conference Paper
Fragmentation threatens biodiversity globally. Manilkara maxima (Sapotaceae) is an IUCN threatened, economically and ecologically important tree species endemic to the Atlantic forest of southern Bahia, Brazil, a biodiversity hotspot. The objectives in this study were to report the population genetics and examine the effect of fragment size on dens...
Article
Pleurostachys arcuata is described as a new species endemic to the Atlantic forest of Brazil. It is illustrated and is compared to other species of Pleurostachys. It has the large achenes of P. macrantha but has small, axillary synflorescences similar to those of P. gaudichaudii.
Conference Paper
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Using flow cytometry, we analyzed genome size (2C, nuclear DNA amount) and genomic base composition (GC content) in more than 600 taxa of Cyperaceae + Juncaceae + Thurniaceae covering representatively all main lineages of this Cyperid clade. Compared to representatives of the other 13 families in Poales, the evolution of the holokinetic chromosome...
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Monographs are fundamental for progress in systematic botany. They are the vehicles for circumscribing and naming taxa, determining distributions and ecology, assessing relationships for formal classification, and interpreting long-term and short-term dimensions of the evolutionary process. Despite their importance, fewer monographs are now being p...
Article
Monographs are fundamental for progress in systematic botany. They are the vehicles for circumscribing and naming taxa, determining distributions and ecology, assessing relationships for formal classification, and interpreting long–term and short–term dimensions of the evolutionary process. Despite their importance, fewer monographs are now being p...