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Environmental heterogeneity of Belize and southern Mexico savannahs as well as their geographical location suggest that these plant communities share floristic elements, making them conducive to a phytogeographical analysis. The aim of this study was to analyse the floristic affinities of nine savannahs of Belize and southern Mexico and to explain the similarities and differences amongst them. A binary data matrix containing 915 species was built based on the authors' own collections and on nine floristic lists already published. A second data matrix, consisting of 113 species representing trees, was also used since most literature on neotropical savannahs has focused on this life form. In addition, the ten most species-rich families as well as the characteristic species present in more than five savannahs were analysed. Floristic similarities were calculated using the Jaccard index. Dendrograms obtained in both types of analysis showed clusters with low similarity values, corresponding to geographic locations formed by the savannahs of Belize-Tabasco and the Yucatan Peninsula. The floristic affinities of the savannahs may be explained in terms of heterogeneity in climate and physiography. The Yucatan Peninsula and Belize-Tabasco groups have differences in climate type and the amount of rainfall. In addition, the Yucatan Peninsula savannahs are established at the bottom of karstic valleys, while the Belize and Tabasco savannahs develop on extensive flatlands. The savannahs of Oaxaca have the same climate type and amount of rainfall as those of the Yucatan Peninsula but they are distributed along peaks and the slopes of shale hills. Fabaceae and Poaceae mainly dominated the local floras with 121 and 116 species each; remarkably, Melastomataceae was absent in the Yucatan Peninsula and Oaxaca. Nine species occurred in five to seven savannahs, confirming that they are widespread in both Belize and southern Mexico, and the Neotropics. Geographic location and floristic affinities of the nine savannahs support, to some extent, three different biogeographic provinces. [ABSTRACT FROM AUTHOR]

In the arid and semiarid region of Mexico, data on three native grasses growing in diverse ecological environments--Muhlenbergia peruviana (P. Beauv.) Steud., in temperate forests; Bouteloua gracilis (Kunth) Lag. ex Griffiths, in grasslands; Muhlenbergia porteri Scribn. ex Beal, in xeric regions; and one introduced nonnative species, Melinis repens (Willd.) Zizka (Zizka rose Natal grass)--were used in our essay analyzing their potential distribution, based on climatic factors. We took presence-only data applied to the Bioclim algorithm included in the Diva-GIS program. Using database bioclimatic WorldClim-Global Climate Data allowed us to make predictions of the distribution, and to determine the climatic characteristics that each species needs to grow. It generated a potential distribution of the four species under study, concluding that this method can be applied to other grass species from this geographic area in order to improve: a) knowledge of the actual distribution of species in their natural environment, b) knowledge related to biodiversity, and c) to create an indicator to support decisions related to conservation and management of grasses in Mexico. We concluded that possibly climatic requirements prevent the expansion of the introduced species (Zizka rose, Natal grass). [ABSTRACT FROM AUTHOR]

New localities of geographic distribution for two grasses of Mexico are presented. Muhlenbergia filiculmis Vasey, a species known only in the West of United States is registered for the first time in Mexico. So is the distribution of Distichlis eludens (Soderstr. & H.F. Decker) H.L. Bell & Columbus, is expanded into a regional level, since it has been recently collected in Zacatecas, Mexico. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A historical perspective on the use and production of species of Dactylopius (Hemipetera: Dactylopiidae) and Opuntia (Cactaceae: Opuntioidae), information on their origin, diversity and distribution in Mexico are reviewed, and aspects of their conservation are discussed. The use and exploitation of both genera are part of Mexican cultures since prehistory. Opuntia species were among the main components of human diet during preagricultural times. Cochineal was used and probably cultivated at least from the Tenth century. During the colonial period, cochineal generated significant benefits to the Spaniard colonizers and Mexico was the world's first producer of insects and dyes until the mid Nineteenth century. Currently, Mexico is the main producer of Opuntia cladodes and prickly pear, but cochineal cultivation is marginal and only maintained in traditional indigenous systems. Mexico is one of the main areas of diversity of Opuntia, having 83-104 out of nearly 200 species worldwide. More than 50 species are used mainly as food, fodder and medicine and 20 species are cultivated with different degrees of domestication. The genus Dactylopius includes nine species, with five of them naturally occurring in Mexico. Only D. coccus has been cultivated and domesticated but other wild species have been used throughout history. Arid and semiarid areas of Mexico are among the most important reservoirs of biological diversity for both genera, particularly for D. coccus. Specific measures for protection of such biodiversity and generic resources are required. Strategies for in situ conservation combined with re-established use and cochineal production may enhance conservation policies. [ABSTRACT FROM AUTHOR]

A morphological description of the genus Mimophytum greenm. (Boraginaceae) is provided, as well as a dichotomous key to the species and ecological and distributional information. The genus is endemic to the Sierra Madre Oriental of Mexico. morphological descriptions for the two species are provided. One of them, M. benitomartinezii, is proposed as new to science. It differs from M. omphalodoides in that the stems are rhizomatous-stoloniferous, the upper leaf surfaces are glabrous, the leaf blades possess 3 basal nerves, the inlorescence is an ebracteate, scorpioid cyme, the pedicels are shorter, and the fruits have glochids forming a ring around the edges. [ABSTRACT FROM AUTHOR]

The Neovolcanic Belt is a physical and ecologic barrier that has affected plant distribution patterns in central Mexico. It has been proposed that the barrier effect is incomplete due to openings that connect valleys across the Belt and permit floristic interchange. To substantiate the presence of floristic corridors, moss collections were made in the Chalco and Toluca areas and in the valleys of the state of Morelos. About 3594 samples representing 330 species and varieties from 2700 m or below were studied. The tropical species were selected and used as markers to determine possible floristic interchanges. Although the number of species shared between valleys on either side of the Belt indicates that its topographic discontinuities may have permitted it, the time of the interchange of tropical taxa cannot be established. The alpine species may have reached the corridors in the Pleistocene along with species from other elevations. [ABSTRACT FROM AUTHOR]

The nomenclatural statuses of Tillandsia parryi Baker and T. sueae Ehlers are clarified, and 72 suesilliae is described as new. Data relative to the distribution, ecology and phenology of the studied taxa are provided. [ABSTRACT FROM AUTHOR]

As currently defined, the 24 species of Schoenocaulon occur in three disjunct areas: north central Florida (one species, S. dubium), southern Peru (portion of the range of S. officinale), and the region from southeastern New Mexico-Texas south to Venezuela; the 20 species endemic to Mexico are geographically restricted. Species delimitations, often based on tepal morphology, have been problematic. Our analyses of ITS sequence data for all 27 species and infraspecific taxa support recognition of two new species and recircumscription and placement of elements of the polyphyletic S. ghieshreghtii and S. mortonii complexes. For taxa with adequate sampling, our data also indicate 11-12 cladospecies and 3-6 metaspecies according to the apomorphic species concept. The resolved phylogeny, correlated with geography and morphology, allows insight into biogeographical diversification and the evolution of some unusual morphological characters within the genus, such as nectary differentiation and tepal margin type. [ABSTRACT FROM AUTHOR]

We report, for the first time, the presence of Nierembergia angustifolia in the state of Jalisco, Mexico. The distinctive characteristics of this species and an update of its known geographical distribution are discussed. [ABSTRACT FROM AUTHOR]

A phytosociological study of 59 relevés was carried out at Laguna Quila, National Park Lagunas de Zempoala, México, using the Zürich-Montpellier approach. Eleven communities were identified and described. A distinction was made between a submerged and a helophytic hydroseral vegetation. A pronounced humidity gradient was identified in a north-south direction, and also a continuous desiccation was observed. A vegetation map scale 1:1900 is included. 21 families of vascular plants including 41 species and 33 genera have been identified. Families best represented include Cyperaceae with seven species and Ranunculaceae with four species. Phytogeographical analysis on the generic level revealed that the temperate component reached 65%, the cosmopolitan 30% and the tropical 5%. The species of Laguna Quila have a wide distribution in Mexican hydroseries and elsewhere in temperate America. Aquatic and semi-aquatic communities are vanishing rapidly in Mexico, and it is important to understand the dynamics for adequate management of this natural resource. In order to protect this lake it is recommended to control the water extraction of the laguna, to exclude cattle and other activities who can affect indirectly Laguna Quila. [ABSTRACT FROM AUTHOR]

Two species of Valeriana of apparently very restricted distribution are described as new. V. emmanuelii, collected in two localities of the southern extreme of the municipality of Morelia, Michoacán, is related to V. retrorsa Fern. and to V. densiflora Benth. V. zamoranensis belongs to the series Ceratophyllae and is only known from the highest part of Cerro Zamorano; it seems to be related to V. zapotecana Barrie and to V. otomiana Barrie. [ABSTRACT FROM AUTHOR]

We report, for the first time, the presence of five species of Solanum for the Bajío and neighboring regions flora. Solanum brachistotrichum, S. hintonii, S. jamesii y S. morelliforme are grouped in Solanum section Petota while S. triquetum is part of Solanum section Dulcamara. We highlight the distinctive characteristics of each species and update their known geographical distribution. Finally, we present a drawing of S. triquetrum. [ABSTRACT FROM AUTHOR]

This paper presents a complete list of hermatypic coral species, analyzes the biodiversity levels and describes the biogeographic patterns of the group in the Mexican Pacific. The coral fauna of the MexicanPacific consists of 23 species, which makes this region one of the highest in terms of specific richness within the tropical eastern Pacific. In general, the species are grouped in faunistic units that correspond to the traditional zoogeographic provinces recognized in the region. There is no evidence of effective biogeographic barriers throughout the Mexican Pacific region. Local extinction events, likely caused by the narrow distribution of some species, and perhaps due to the type and frequency of transpacific colonizations, modify the normalprocesses of community succession, causing the Mexican Pacific to bea highly dynamic zone in terms of its coral fauna. [ABSTRACT FROM AUTHOR]

The phenologies of trees with temperate and tropical historical phytogeographical affinities were recorded during 60 months (1990-- 1994)in a lower montane forest (1300 m a.s.l.) in Veracruz, Mexico. The objective was to determine phenological patterns and their relation toclimate for both deciduous and broadleaved-evergreen species. Leaf fall, leaf flush, flowering, and fruiting were recorded for 107 individuals belonging to twelve deciduous and twelve broadleaved-evergreen species. Phenological stages were scaled from 0 to 4 (referring to the proportion of each tree in a phenophase), and averaged monthly as aphenological index. Phenological periodicity was analysed as a nonmetric time-series using measures of predictability, constancy, and contingency. The climate is mild with a dry-cool season (November-- March), a dry-warm season (April--May), and a wet-warm season (June--October). Foliar phenological patterns differed between deciduous and evergreen species. Deciduous species dropped leaves during the dry-cool season and leaf drop was negatively correlated with minimum temperature; leaf flushing occurred during the dry-cool and dry-warm seasons and was positively correlated with maximum temperature. In general, broadleaved--evergreen species continually dropped and flushed leaves throughout the year. Flowering and fruiting patterns did not differ between leaf habits. Mean flowering peaks occurred between February andMay, but each individual species had a different annual peak. Fruiting occurred in the dry-warm and wet-warm seasons. Three species were distinct in their fruiting phenologies, Styrax and Meliosma exhibitedsupra-annual patterns, and Hedyosmum fruited most of the year. For several species, fruiting and minimum temperature were positively correlated. Factors other than abiotic ones (e.g. biotic interactions andphylogenetic relationships) may be involved in the phenological patterns observed and they should be investigated. [ABSTRACT FROM AUTHOR]