Hilda Flores-Olvera

Comparative stem anatomy of Mirabilis (Nyctaginaceae)

Mirabilis, a primarily American genus of 50–60 species almost restricted to the New World, is the most diverse within Nyctaginaceae. It not only has the greatest number of species, but also many life forms, with annual herbaceous, suffrutescent and shrubby species and with prostrate, decumbent to erect stems that are sometimes clambering. Stem anatomy has been studied only for M. jalapa, and its characteristics extrapolated to the entire genus. In this study we evaluated the taxonomic significance of stem anatomical characters from 24 species of Mirabilis, as well as their potential relation to habit evolution. Qualitative and quantitative characters of transverse and longitudinal sections were evaluated using light and scanning electron microscopy. Stem anatomy varies in several features. The phloem is arranged in short tangential spreading bands or in large tangential bands forming semi-complete rings; the conjunctive tissue is fibrous, with thin-walled sclereids and fibres, or parenchymatous; the vessels are solitary or grouped in radial multiples or clusters; the xylem fibres are very thin-walled or thin- to thick-walled with simple to minutely bordered pits; most species are raylessness; the pith has parenchyma or thin-walled sclereids or brachysclereids. The distribution of anatomical characters in Mirabilis does not correspond with the current infrageneric classification. We suggest that some stem anatomical characters are correlated with habit and that the vascular cylinder and pith characters are related to an increase in mechanical strength. This study provides new information and novel characters about the stem anatomy not only of Mirabilis, but of the family.

Correlation of the Late Eocene–Early Oligocene Izúcar de Matamoros Evaporites (Cuayuca Formation) in Mexico Based on Parsimony Analysis of Endemicity

Abstract Based on the lithology of the Izucar de Matamoros (IzM) sections, and the occurrence of index taxa such as Armeria, Cicatricosisporites dorogensis, Corsinipollenites, Eucommia, Momipites coryloides, Momipites tenuipolus, Mutisiapollis, and Ranuculacidites operculatus, a correlation between the IzM sections and the Cuayuca Formation stratotypes is proposed. The IzM sections are Late Eocene–Early Oligocene, and they are part of the evaporitic member (Mcy) of the Cuayuca Formation. These new data are consistent with the paleoenvironmental interpretations proposed for the formation. It was probably deposited under local xeric conditions in a semiarid climate that allowed the development of grassland (Gramineae with Amaranthaceae–Chenopodiaceae and Ephedra) and a thorn shrub community with Acacia, other Leguminosae, Linum, and Plumbaginaceae. The neighboring communities were probably tropical deciduous forests, low tropical deciduous forest, thorn forest, and chaparral. There were also regional temperate vegetations such as a Picea–Pinus forest, and a cloud forest community. Using parsimony analysis of endemicity, a biogeographic method, a palynofloristic relationship between the Cuayuca Formation and the Pie de Vaca Formation (Late Eocene–Early Oligocene) is proposed. Both formations are within the Balsas Group, and are correlated with San Gregorio Formation (Oligocene) of southern Baja California.

From cacti to carnivores: Improved phylotranscriptomic sampling and hierarchical homology inference provide further insight into the evolution of Caryophyllales

PREMISE OF THE STUDY The Caryophyllales contain ~12,500 species and are known for their cosmopolitan distribution, convergence of trait evolution, and extreme adaptations. Some relationships within the Caryophyllales, like those of many large plant clades, remain unclear, and phylogenetic studies often recover alternative hypotheses. We explore the utility of broad and dense transcriptome sampling across the order for resolving evolutionary relationships in Caryophyllales. METHODS We generated 84 transcriptomes and combined these with 224 publicly available transcriptomes to perform a phylogenomic analysis of Caryophyllales. To overcome the computational challenge of ortholog detection in such a large data set, we developed an approach for clustering gene families that allowed us to analyze >300 transcriptomes and genomes. We then inferred the species relationships using multiple methods and performed gene-tree conflict analyses. KEY RESULTS Our phylogenetic analyses resolved many clades with strong support, but also showed significant gene-tree discordance. This discordance is not only a common feature of phylogenomic studies, but also represents an opportunity to understand processes that have structured phylogenies. We also found taxon sampling influences species-tree inference, highlighting the importance of more focused studies with additional taxon sampling. CONCLUSIONS Transcriptomes are useful both for species-tree inference and for uncovering evolutionary complexity within lineages. Through analyses of gene-tree conflict and multiple methods of species-tree inference, we demonstrate that phylogenomic data can provide unparalleled insight into the evolutionary history of Caryophyllales. We also discuss a method for overcoming computational challenges associated with homolog clustering in large data sets.

Floristic Diversity of Halophytic Plants of Mexico

Along the Mexican coasts of the Pacific, the Atlantic and the Caribbean, diverse plant communities affected by seawater and breeze, support salt tolerant species here considered as halophilic. Moreover, the intercontinental semiarid and arid regions, and the Transmexican Volcanic Belt are characterized by ecosystems such as endorheic basins, with species also living in salty soils. In the Chihuahuan Desert saline and saline-gypseous soils occur, supporting gypsohalophilic plants. After many years of search in literature, herbaria and fieldwork, we can provide a floristic list of 647 species of angiosperms growing in these harsh environments. In absence of a summary on the halophyte flora of Mexico we deliver a list of angiosperms distributed in saline or saline-gypseous habitats. Those species living also in other soil types are considered as non restrictive to distinguish them from those living only in these environments (restricted). The floristic diversity include endemic species of several lineages, but specially of Poaceae, Asteraceae, Euphorbiaceae, Chenopodiaceae, Amaranthaceae, Boraginaceae, Fabaceae, Cyperaceae, Brasicaceae and Cactaceae.

Suaeda pulvinata (Chenopodiaceae), a new species from saline lakes of central Mexico

Abstract Alvarado Reyes E. & Flores-Olvera H.: Suaeda pulvinata (Chenopodiaceae), a new species from saline lakes of central Mexico. — Willdenowia 43: 309–314. December 2013. — ISSN 0511-9618;

Two New Mexican Endemic Species of Iresine (Amaranthaceae)

Abstract Iresine rzedowskii Zumaya, Flores Olv. & Borsch and I. valdesii Zumaya, Flores Olv. & Borsch are described, illustrated, and compared to morphologically similar species. In addition, pollen SEM micrographs and distribution maps are provided for the new species. Iresine rzedowskii is a shrub with long clambering stems, the younger ones reddish with conspicuous lenticels and the older ones with suberose cortex. It is the only species of Iresine that has pollen grains with a foveolate tectum. Iresine valdesii is also a shrub but with stiff erect branching and small, perennial coriaceous leaves. The synflorescences of staminate plants are solitary, very small, usually once-branched thyreoid structures while those of pistillate plants are very different, with paracladia appearing terminal on most branches and erect, up to 13 cm long, and two to three times branched. Both species are restricted to Mexico. Iresine rzedowskii ranges from northwestern Chihuahua to northern Oaxaca, while I. valdesii is endemic to central and southeastern Puebla.

Two new species of Iresine (Amaranthaceae: Gomphrenoideae) from Mexico supported by morphological and molecular characters

Abstract: Two well-defined new species of Iresine from Mexico are described based on character data covering vegetative and floral morphology, pollen, and sequences of plastid matK-trnK, trnL-F and rpl16 as well as nuclear ITS. We provide morphological and molecular descriptions, as well as a discussion on diagnostic characters and taxonomic affinities. Both species are distributed in cloud forests; I. borschii is known only from two collections in Veracruz, whereas I. sousae has been collected several times in Oaxaca and Chiapas. Both species are illustrated from herbarium specimens to facilitate their recognition. New field collections and observations are needed to improve our knowledge on the habitat and conservation status of these new species. Citation: Flores-Olvera H., Zumaya S. & Borsch T. 2016: Two new species of Iresine (Amaranthaceae: Gomphrenoideae) from Mexico supported by morphological and molecular characters. — Willdenowia 46: 165–174. doi: http://dx.doi.org/10.3372/wi.46.46113 Version of record first published online on 6 April 2016 ahead of inclusion in April 2016 issue.