Leandro L. Giacomin

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.

Three new species of Solanum (Brevantherum Clade) endemic to the Brazilian Atlantic Forest

Abstract Three new Brazilian species of the Brevantherum clade of Solanum (Solanaceae) are described, all closely related to the poorly known Solanum inornatum Witasek. Solanum bradei Giacomin & Stehmann, sp. nov., and Solanum kriegeri Giacomin & Stehmann, sp. nov., differ from S. inornatum in having very small deltate calyx lobes that are not accrescent in fruit. Solanum bradei is a shrub up to 1.8 m with generally pedunculate inflorescences and tiny translucent fruits, whereas Solanum kriegeri is a dwarf glabrescent plant growing on sandy soils in cloud forests, with larger fruits and sessile to subsessile inflorescence. Solanum friburgense Giacomin & Stehmann, sp. nov., has linear calyx lobes like S. inornatum, and is characterized by its 2-foliate sympodia and leaf pubescence, with trichomes concentrated on leaf veins. The species here described and illustrated are restricted to the mountain ranges of Mantiqueira and Serra do Mar in the Atlantic forests of southeastern Brazil and are all of considerable conservation concern.

New species, additions and a key to the Brazilian species of the Geminata clade of Solanum L. (Solanaceae) in Brazil

Abstract Two additions and four new species are described from Brazil for the large Geminata clade (Solanum: Solanaceae) bringing the total diversity in the group to 149 species, with 44 of these occurring in Brazil. New species are described from Brazil: Solanum amorimii S.Knapp & Giacomin, sp. nov. from Bahia and adjacent Minas Gerais states, Solanum filirhachis Giacomin & Stehmann, sp. nov. from Espirito Santo, Solanum psilophyllum Stehmann & Giacomin, sp. nov. from Minas Gerais and Solanum verticillatum S.Knapp & Stehmann, sp. nov. from São Paulo, Rio de Janeiro and Minas Gerais. Modern character-rich descriptions and lectotypifications are provided for Solanum apiahyense Witasek and Solanum lacteum Vell. All are illustrated, mapped and assessed for conservation status. We also provide a brief analysis of the diversity and endemism of the Geminata clade in Brazil and a key to all 44 Brazilian species.

A Revision of Solanum Section Gonatotrichum

Abstract Solanum section Gonatotrichum (Solanaceae) includes eight species native to North, Central, and South America. Plants of this section are herbs to woody shrubs that lack spines, are pubescent with simple or stellate hairs, and have berries that swell due to increased turgor pressure and explosively dehisce to disperse the seeds. Section Gonatotrichum is closely related to section Brevantherum, from which it differs by the presence of explosive fruit dehiscence and simple hairs in all taxa except S. lignescens, which has stellate pubescence. The morphology, taxonomic history, nomenclature, ecology, distribution, and reproductive biology of Solanum section Gonatotrichum are reviewed. A dichotomous key is provided for the species of the section.

Markea atlantica (Solanaceae): a New Species of Tribe Juanulloeae Disjunct from its Core Distribution

Abstract Markea atlantica (Juanulloeae, Solanaceae), an endemic species of the Brazilian Atlantic Rain Forest, is described and illustrated. It is characterized by its hemiepiphytic habit with stems climbing by adventitious roots, few flowers (1–3) arranged in subsessile and condensed cymes, bell-shaped yellow-greenish corollas with purple stripes in the inner surface, and stamens reaching the upper part of the corolla tube. The geographic distribution of the new species is also distinctive. While the other species of the genus are mainly found in the equatorial Amazonian region, M. atlantica is restricted to the coastal Atlantic forests of Brazil. Such a disjunction seems to reflect past connections between Amazonian and Brazilian Atlantic forests. A key for the Brazilian species of Markea is presented.

A new heterandrous species of Solanum section Gonatotrichum Bitter (Solanaceae) from Bahia, Brazil.

Abstract A new species of Solanum from Brazil is described. Solanum evolvuloides Giacomin & Stehmann, sp. nov. belongs to section Gonatotrichum, a small group assigned to the Brevantherum Clade of the genus Solanum. It resembles Solanum turneroides Chodat, sharing with it heterandry, and Solanum parcistrigosum Bitter, with which it shares a similar habit and pubescence. Despite these similarities, the species can be recognized by its ovate-elliptic to cordiform leaf shape and more membranaceous leaf texture than the other species in the section, and stem, inflorescence axes, and calyx vestiture mainly composed of glandular hairs. Solanum evolvuloides is known to occur only in southeastern of Bahia state, Brazil, and in a preliminary assessment of the IUCN criteria can be considered a threatened species. Resumo Uma nova espécie de Solanum é descrita para o Brasil. Solanum evolvuloides Giacomin & Stehmann, sp. nov. é componente da seção Gonatotrichum, um pequeno grupo associado ao Clado Brevantherum. A espécie é similar a Solanum turneroides, com a qual compartilha a heterandria, e Solanum parcistrigosum, que por sua vez apresenta um hábito e indumento foliar semelhante. Apesar da similaridade, a espécie pode ser facilmente reconhecida pela forma da folha ovada-elíptica a cordiforme e pela texura mais membranácea que as outras espécies da seção, além do indumento do caule, eixo da inflorescência e cálice, constituído em sua maioria por tricomas glandulares pedicelados. Solanum evolvuloides tem sua distribuição conhecida somente para o sudeste do estado da Bahia, Brasil, e é indicada como uma espécie ameaçada de extinção.