Molecular Phylogeny, Character Evolution, and Biogeography of Hydrangea Section Cornidia, Hydrangeaceae.

Background: Hydrangea section Cornidia consists of 26 currently accepted species and a yet undefined number of new species and erroneously synonymized taxa. This clade consists of (sub)tropical lianas occurring from northern Mexico to southern Chile and Argentina, and one species from Southeast Asia. Currently, no molecular phylogenetic hypothesis is available that includes more than a few species of this section. Hence, a resolved and well-sampled molecular phylogenetic hypothesis may help to enforce taxonomic decisions. In this study, we present a phylogenetic framework based on sequences from two low copy nuclear genes from a comprehensive taxon sampling of H. section Cornidia and a selection of outgroups. Our phylogenetic reconstructions prove the non-monophyly of the traditionally recognized subsections Monosegia and Polysegia and their corresponding series, Speciosae and Aphananthae, and Synstyleae and Chorystyleae, respectively. Three morphologically defined species were recovered with high support as monophyletic, namely, Hydrangea panamensis, Hydrangea serratifolia, and Hydrangea tarapotensis. However, statistical support for some shallow nodes did not allow to refute, with high support, the monophyly of several of the herein recognized species for which more than one individual could be analyzed. Based on the obtained phylogenetic framework, we reconstructed the evolution of selected reproductive characters. Hydrangea section Cornidia is the only genus section for which dioecism has been extensively documented. Our character reconstruction of sexual dimorphism shows that dioecism is the ancestral state in this section and that this was reversed to monoecy in Hydrangea seemannii and Hydrangea integrifolia. Character reconstruction for the enlarged marginal flowers recovered their presence as the ancestral character state in H. section Cornidia, although at least three internal lineages independently lost them; thus, losses were reconstructed to be more likely than gain. With respect to the flower color, more species exhibit white than red flowers, and white is reconstructed as the ancestral state. Cornidia also shows an unusual disjunct geographic distribution between Asia and Central Mesoamerica-South America, as it is not present in the USA and Canada. The origin of Cornidia is reconstructed to be the New World with higher probability, and the presence of one species in Asia is likely due to long-distance dispersal.

Disentangling Species Delineation and Guiding Conservation of Endangered Magnolias in Veracruz, Mexico.

The Mexican state of Veracruz has suffered very high deforestation rates in the last few decades, and despite the establishment of protected areas and conservation projects, primary forest is now mainly persisting in mostly small, scattered, fragmented remnants. New species of Magnolia section Talauma in this state have been described with little to no reference to the already existing ones, potentially resulting in over-splitting, obscuring their taxonomic delineation and conservation status, and consequently conservation programs. To study the conservation units and their genetic diversity, we here employ 15 microsatellite markers on a highly representative sampling of 254 individuals of what are presumed to be five Magnolia species. The results support at least three species and maximum five main conservation units. We propose downgrading the latter to four, given morphological, ecological, demographical, and geographical considerations. Two out of the three sympatrically occurring species in the rainforest in the Los Tuxtlas volcanic area have weak genetic evidence to be considered separate species. Similarly, the individuals in the Sierra de Zongolica in central Veracruz, who bear a very high morphological and genetic similarity to Magnolia mexicana, have weak genetic evidence to be recognised as a separate species. Nonetheless, the individuals could be identified as Magnolia decastroi based on morphology, and further research including the full range of this species is recommended.

Towards Conservation of the Remarkably High Number of Daisy Trees (Asteraceae) in Mexico.

Mexico is floristically the fourth most species-rich country in the world, and Asteraceae is the most diverse vascular plant family in this country. The species exhibits a wide range of growth forms, but the tree-like habit, appropriately named daisy trees, is heavily underestimated, even though slightly different tree definitions are handled. Very little is known about their precise species number or conservation status in Mexico, so we update here the list of known Mexican daisy tree species, summarize their very diverse uses, present a general panorama of their present and future distribution, and discuss their conservation status. A bibliographic review and herbarium study were carried out, carefully curated taxonomical ocurrence maps were prepared for each species, and a climatic suitability modelling approach was used to characterise the spatial patterns of Mexican Asteraceae trees. With 149 daisy tree species, the country ranks second at a global level; within the country, their greatest diversity is found in central and western Mexico. A decrease in diversity is estimated in areas that currently host the highest species richness, whereas the hotspot regions are estimated to show an increase in species diversity, so climate change is not a threat to all Mexican daisy tree species.

On Hydrangea peruviana, an endangered species from Ecuador, and Hydrangea oerstedii, very common in Costa Rica and Panama, and seven threatened Central and South American Hydrangeas, which have been confounded with these.

Hydrangea section Cornidia, currently consisting of 19 accepted taxa, occurs from Mexico to Chile and Argentina, with one species in southeast Asia. Its representatives are root-climbing lianas which may grow up to 60 m high in the tree canopy of temperate to (sub)tropical forests. Our extensive field work throughout its distribution area, study of herbarium specimens and ongoing molecular studies have resulted in the discovery of species new to science, as well as new insights into the circumscription of many taxa. We here present amended descriptions for seven Hydrangea species of Central and South America and discuss the taxonomical situation of two Colombian Hydrangeas, including an identification key, illustrations, and distribution maps. Field work was carried out in Costa Rica, Panama, Ecuador and Peru, including exploration in areas where the genus had not been collected before. These specimens and observations were complemented with the study of specimens of 41 herbaria of North, Central and South America, as well as Europe. Detailed morphological studies of all species were carried out, based on living plants in their natural habitat, as well as on dried specimens from our own collections and all available herbarium material. Type material was studied in detail for all species concerned. Based on an extensive number of morphological characters, combined with distribution patterns, phenological differences and ecological preferences, including molecular data in most cases, Hydrangea peruviana and H. oerstedii are clearly distinct taxa, as well as the other seven species mentioned here, which had been synonymized with either of these two species. The present study results in the recognition of 26 species in section Cornidia and exemplifies the urgent need for profound taxonomic studies in plants, as in many families we do not dispose of well-circumscribed units for conservation to mitigate the already occurring unprecedented loss of biodiversity.

ResumenHydrangea sección Cornidia, que actualmente consiste en 19 taxones aceptados, se distribuye desde México hasta Chile y Argentina, con una especie en el sureste asiático. Sus representantes son lianas trepadoras que pueden crecer hasta 60 m de altura en la copa de los árboles de los bosques templados a (sub)tropicales. Nuestro extenso trabajo de campo en toda su área de distribución, la revisión de especímenes de herbario y los estudios moleculares en curso han dado como resultado el descubrimiento de especies nuevas para la ciencia, así como conocimiento nuevo sobre la circunscripción de muchos taxones. Aquí presentamos descripciones enmendadas para siete especies de Hydrangea de Centro y Suramérica y discutimos la situación taxonómica de dos Hydrangeas colombianas, incluyendo una clave de identificación, ilustraciones y mapas de distribución. El trabajo de campo se llevó a cabo en Costa Rica, Panamá, Ecuador y Perú, incluída la exploración en áreas donde el género no había sido recolectado antes. Estos especímenes y observaciones se complementaron con el estudio de especímenes de 41 herbarios de Norte, Centro y Suramérica, así como de Europa. Se llevaron a cabo estudios morfológicos detallados de todas las especies, basados ​​en plantas vivas en su hábitat natural, así como en muestras secas de nuestras propias colecciones y todo el material de herbario disponible. El material tipo se estudió en detalle para todas las especies en cuestión. En base a una gran cantidad de caracteres morfológicos, combinados con patrones de distribución, diferencias fenológicas y preferencias ecológicas, incluyendo datos moleculares en la mayoría de los casos, Hydrangea peruviana y H. oerstedii son taxones claramente distintos, así como las otras siete especies mencionadas aquí, que habían sido sinonimizadas con cualquiera de estas dos especies. El presente estudio resulta en el reconocimiento de 26 especies en la sección Cornidia y ejemplifica la necesidad urgente de estudios taxonómicos profundos en plantas, ya que en muchas familias no disponemos de unidades de conservación bien circunscritas para mitigar la pérdida de biodiversidad sin precedentes.