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Species delimitation in Cactaceae is a challenging task due to the proliferation of species and subspecies names. Echinocereus pulchellus occurs across a wide geographical range in Mexico and presents numerous polymorphisms. The species complex has been considered to comprise five subspecies. In the present work, we analyze morphological variation across the E. pulchellus complex to establish the taxonomic limits of the complex, to delimit taxa within it, and to determine whether morphological variation is associated with climate variables. Multivariate analyses of 50 morphological characters were conducting in a sample of ten populations representing all five of the previously recognized subspecies of the E. pulchellus complex. The results support the recognition of four distinct species, one of which contains two subspecies, and necessitate three new combinations: Echinocereus acanthosetus, E. sharpii, and E. weinbergii subsp. venustus. Six vegetative and two floral characters define the morphological limits between taxa. Correlation with climate variables was detected in the populations of E. weinbergii.

Swietenia macrophylla is an economically important tree species propagated by seeds that lose their viability in a short time, making seed germination a key stage for the species recruitment. The objective of this study was to determine the cardinal temperatures and thermal time for seed germination of S. macrophylla, and its potential distribution under different climate change scenarios. Seeds were placed in germination chambers at constant temperatures from 5 to 45 °C and their thermal responses modelled using a thermal time approach. In addition, the potential biogeographic distribution was projected according to the Community Climate System Model version 4 (CCSM4). Germination rate reached its maximum at 37.3 ± 1.3 °C (To), seed germination decreased to near zero at 52.7 ± 2.2 °C (ceiling temperature, Tc) and at 12.8 ± 2.4 °C (base temperature, Tb). The suboptimal thermal time θ150 needed for 50% germination was ca. 190 °Cd, which in the current scenario is accumulated in 20 days. The CCSM4 model estimates an increase of the potential distribution of the species of 12.3 to 18.3% compared to the current scenario. The temperature had an important effect on the physiological processes of the seeds. With the increase in temperature, the thermal needs for germination are completed in less time, so the species will not be affected in its distribution. Although the distribution of the species may not be affected, it is crucial to generate sustainable management strategies to ensure its long-term conservation.

Thermal time models are useful to determine the thermal and temporal requirements for seed germination. This information may be used as a criterion for species distribution in projected scenarios of climate change, especially in threatened species like red cedar. The objectives of this work were to determine the cardinal temperatures and thermal time for seeds of Cedrela odorata and to predict the effect of increasing temperature in two scenarios of climate change. Seeds were placed in germination chambers at constant temperatures ranging from 5 &plusmn, 2 to 45 &plusmn, 2 &deg, C. Germination rate was analyzed in order to calculate cardinal temperatures and thermal time. The time required for germination of 50% of population was estimated for the current climate, as well as under the A2 and B2 scenarios for the year 2050. The results showed that base, optimal and maximal temperatures were &minus, 0.5 &plusmn, 0.09, 38 &plusmn, 1.6 and 53.3 &plusmn, 2.1 &deg, C, respectively. Thermal time (&theta, 1(50)) was 132.74 &plusmn, 2.60 &deg, Cd, which in the current climate scenario accumulates after 5.5 days. Under the A2 scenario using the English model, this time is shortened to 4.5 days, while under scenario B2, the time is only 10 hours shorter than the current scenario. Under the German model, the accumulation of thermal time occurs 10 and 6.5 hours sooner than in the current climate under the A2 and B2 models, respectively. The seeds showed a wide range of temperatures for germination, and according to the climate change scenarios, the thermal time accumulates over a shorter period, accelerating the germination of seeds in the understory. This is the first report of a threshold model for C. odorata, one of the most important forest species in tropical environments.

International audience; Quercus magnoliifolia and Q. resinosa are two Mexican white oak species that have been taxonomically reported to exhibit morphological similarities and possible hybridization. The objective of this study was to compare the variation in Q. magnoliifolia and Q. resinosa throughout their distribution range to identify the degree of species differentiation using morphological, ecological and genetic tools. Morphological analysis showed differentiation in leaf shape between the species corresponding to the taxonomical identification of Q. magnoliifolia and Q. resinosa in almost all cases, but intermediate individuals were identified in the middle of the species ranges. Comparison of ecological niche models for Q. magnoliifolia and Q. resinosa showed non-equivalent ecological niches, high climatic niche differences and low to moderate spatial and environmental niche overlap, mainly along the Trans-Mexican Volcanic Belt where morphologically intermediate individuals between species were more frequently located, suggesting recent hybridization by secondary contact. In contrast, we found low but significant genetic differentiation between Q. magnoliifolia and Q. resinosa and lower interspecific than intraspecific genetic differentiation, and Bayesian clustering analysis (K = 2) failed to assign each species to a unique genotype, suggesting shared ancestral variation as the cause of genetic similarity between species due to recent divergence. In conclusion, although neutral molecular markers do not distinguish the species Q. magnoliifolia and Q. resinosa, we found morphological and ecological differentiation between these oaks that provide preliminary evidence for divergent selection.

Pines are the most popular species for reforestation in Mexico, however reforestation programs have little success due to a high mortality of pine seedlings. Shifts in the distribution range due to climate change has been predicted for many species specially at their distribution borders. Understanding the thermal limits of germination and early seedling growth at the leading edge population in current and future climates could enable the development of suitable propagation practices and conservation strategies. Seeds of Pinus douglasiana and Pinus maximinoi, from their northern distribution range in a temperate sub humid region, were germinated and seedlings were grown across a range of temperatures from 10 to 35 °C. A cardinal temperature model was then employed to obtain the thermal coefficients for seed germination, seedling growth and survival. Projected temperature increase by 2090 according to IPCC scenarios RCP 2.6 and RCP 8.5 were used to predict the germination and early establishment behaviour of both species. Thermal requirements were similar between species and in different developmental stages showing base temperatures of 9.4−10 °C for germination, 9.8 °C for root growth, 9.6 °C for shoot appearance and 8.4 °C for shoot growth; and thermal time requirements of 65−69 °C d for germination, 107 °C d for root growth, 103−107 °C d for shoot appearance and 140−141 °Cd for shoot growth. However, seedling survival was higher at 20 and 25 °C. Different sensitivities to low temperatures for germination and seedling establishment could be factors that drive ecological divergence between these species and explain their altitudinal tolerances. As timing of germination and seedling growth are expected to be accelerated under climate change scenarios, seedling establishment and survival in both species could be altered .

Recruitment from seeds is among the most vulnerable stage for plants as global temperatures change. While germination is the means by which the vast majority of the world's flora regenerate naturally, a framework for accurately predicting which species are at greatest risk of germination failure during environmental perturbation is lacking. Taking a physiological approach, we assess how one family, the Cactaceae, may respond to global temperature change based on the thermal buffering capacity of the germination phenotype. We selected 55 cactus species from the Americas, all geo-referenced seed collections, reflecting the broad environmental envelope of the family across 70° of latitude and 3700 m of altitude. We then generated empirical data of the thermal germination response from which we estimated the minimum (Tb), optimum (To) and ceiling (Tc) temperature for germination and the thermal time (θ50) for each species based on the linearity of germination rate with temperature. Species with the highest Tb and lowest Tc germinated fastest, and the interspecific sensitivity of the germination rate to temperature, as assessed through θ50, varied tenfold. A left-skewed asymmetry in the germination rate with temperature was relatively common but the unimodal pattern typical of crop species failed for nearly half of the species due to insensitivity to temperature change at To. For 32 fully characterized species, seed thermal parameters correlated strongly with the mean temperature of the wettest quarter of the seed collection sites. By projecting the mean temperature of the wettest quarter under two climate change scenarios, we predict under the least conservative scenario (+3.7°C) that 25% of cactus species will have reduced germination performance, whilst the remainder will have an efficiency gain, by the end of the 21st century. Fil: Seal, Charlotte E.. Royal Botanic Gardens; Reino Unido Fil: Daws, Matthew I.. Royal Botanic Gardens; Reino Unido Fil: Flores, Joel. Instituto Potosino de Investigación Científica y Tecnológica; México Fil: Ortega Baes, Francisco Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentina. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Escuela de Agronomía. Laboratorio de Investigaciones Botánicas; Argentina Fil: Galindez, Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Salta. Estación Experimental Agropecuaria Salta; Argentina Fil: León Lobos, Pedro. Instituto de Investigaciones Agropecuaria; Chile Fil: Sandoval, Ana. Instituto de Investigaciones Agropecuaria; Chile Fil: Ceroni Stuva, Aldo. Universidad Nacional Agraria La Molina; Perú Fil: Ramírez Bullón, Natali. Universidad Nacional Agraria La Molina; Perú Fil: Dávila-Aranda, Patricia. Universidad Nacional Autónoma de México; México Fil: Ordoñez Salanueva, Cesar A.. Universidad Nacional Autónoma de México; México Fil: Yáñez Espinosa, Laura. Universidad Autónoma de San Luis Potosí; México Fil: Ulian, Tiziana. Royal Botanic Gardens; Reino Unido Fil: Amosso, Cecilia. Università di Padova; Italia Fil: Zubani, Lino. Università di Padova; Italia Fil: Torres Bilbao, Alberto. Empresa Nacional para la Protección de la Flora y la Fauna; Cuba Fil: Pritchard, Hugh W.. Royal Botanic Gardens; Reino Unido

Analysis of DNA sequence data was used to clarify the circumscription and relationships of the small Mexican genus Asanthus. Results from non-coding regions, including the nuclear ITS and the chloroplast psbA-trnH spacer showed that Asanthus is clearly monophyletic and distinct from Steviopsis and Brickellia, two genera with which it is sometimes lumped, as well as from the closely related Brickelliastrum and Carminatia. The DNA sequence data also agree with morphological observations in showing that Asanthus is composed of three species, A. thyrsiflorus from the Sierra Madre Oriental and A. squamulosus and A. solidaginifolius from the Sierra Madre Occidental. Samples from the southern Sierra Madre Occidental that have been identified as A. thyrsiflorus are suggested by the presence of an additive pattern of polymorphisms in the nuclear ITS region to be of interspecific hybrid origin between A. thyrsiflorus and A. solidaginifolius, which is consistent with reports of their morphological intergrad...

In this chapter, the importance of ex situ conservation is discussed to safeguard plant genetic resources on relationship to its ethnobotanical relevance. It also highlights the importance of preserving the germplasm of species that are closely associated to human being. The diverse forms and intensities of human–plant relationship lead to the accumulation of traditional knowledge and the modification of the characteristics of plant populations as a result of human manipulation. When the germplasm of plant populations that are important to human being is protected, the information associated to this relationship is also protected, so that the conservation of biological diversity of useful plant species favors the protection of cultural diversity associated to its plant use. The urgency to conserve and protect the Mexican germplasm is associated to the fast and dramatic change of habitats that the country is facing.

Background: Over half of the world's primary forest and a quarter of the world's plant species are found in Latin America. As a result of the limited protected areas and significant degradation of terrestrial ecosystems, seed banks provide an efficient component of integrated plant conservation strategies, chiefly due to their relatively low cost and massive storage capacity for genetic resources. Aims: We analyse the role that ex situ seed banks play in the conservation and reintroduction of threatened species, and in supporting ecological restoration programmes in the region. Methods: An analysis of the second National Reports on the state of the World's Plant Genetic Resources for Food and Agriculture showed that most countries in the region had the capacity for seed conservation. Using three case studies from seed conservation programmes in Mexico, Brazilian Amazonia and Chile, together with the global Millennium Seed Bank Partnership, we review the status and potential of these initiatives for conser...

The genus Zeugites P. Browne encompasses ten species of neotropical grasses. To infer the phylogenetic relationships of the species, parsimony analyses of morphological data and DNA sequences from a nuclear region (ITS) and two non-coding plastid regions (the trnL intron and the trnL-trnF intergenic spacer) were undertaken for each data set separately and in combination. The combined analysis is presented as our preferred phylogenetic hypothesis because of its better resolution and higher support for the clades. Zeugites is monophyletic only if Calderonella sylvatica is included in it. Our analyses recover two major clades within Zeugites: Clade I, formed by Zeugites pittieri, Zeugites latifolia, Zeugites sylvatica (Calderonella sylvatica), Zeugites sagittata, and Zeugites capillaris; and Clade II, including Zeugites hackelii, Zeugites smilacifolia, Zeugites munroana, Zeugites pringlei, Zeugites mexicana, and Zeugites americana. The monospecific genus Pohlidium is strongly supported as sister of Zeugites (including Calderonella) but it is maintained as a different genus due to noticeable differences in spikelet and inflorescence morphology.

El objetivo del presente trabajo fue elaborar un inventario florístico de la vegetación original y secundaria de la selva baja caducifolia (SBC) sobre sustratos rocosos o corrientes de lava volcánica que han sido escasamente estudiados y se encuentran en buen estado de conservación, en el centro del estado de Veracruz. A través de transectos en un gradiente altitudinal de 400 a 900 m, se muestrearon áreas de 1,000 m2 para la vegetación primaria y secundaria a cada 100 m de altitud, donde se recolectaron las especies presentes. Se encontraron 104 familias con 394 géneros y 666 especies y subespecies de plantas vasculares. Las especies y subespecies presentaron los siguientes grupos de forma de crecimiento: 88 árboles, 126 arbustos, 342 hierbas, 80 bejucos y 30 epífitas. Del total de las especies registradas, entre las familias más ricas en especies destacan Fabaceae, Asteraceae, Poaceae y Euphorbiaceae. Fue notable la presencia de un componente suculento en la flora de la SBC, conformada por 204 especies y subespecies, los cuales correspondieron a 30.4% del total para estos taxa vasculares registrados en la zona de estudio. La mayor riqueza de especies suculentas se presentó en las familias más diversas, tales como Euphorbiaceae, Orchidaceae, Cactaceae y Bromeliaceae. En conclusión, se puede decir que la SBC del sustrato rocoso es muy rica en especies de la flora vascular, destacando el estrato herbáceo como el más diverso en ambas comunidades vegetales.

En este trabajo se documenta el papel y potencial de los recursos vegetales de Zapotitlán Salinas, Puebla, una comunidad de origen popoloca, ubicada en la porción más árida del Valle de Tehuacán-Cuicatlán. En total, se encontraron 298 especies divididas en 82 familias, y se presenta información etnobotánica de 288 especies pertenecientes a 219 géneros y 79 familias, cuyos usos se ubican en 19 categorías. De ellas, 164 prosperan en las distintas comunidades vegetales naturales de la zona y en algunas de las áreas transformadas, mientras que 124 se encuentran de manera exclusiva en los huertos. Las familias con mayor número de especies útiles fueron Poaceae (35 spp.), Cactaceae (24 spp.) y Asteraceae (23 spp.). En cuanto a las formas de vida, la mayor parte (162 spp.) son las herbáceas, seguida de los arbustos (86 spp.) y los árboles (41 spp.). El trabajo incluye información acerca de la disponibilidad espacial y temporal de las especies útiles, así como también de la importancia relativa de las de mayor interés para la población local, como son las combustibles, las medicinales, las alimenticias y las forrajeras.

Como un aporte al conocimiento de la flora del estado de Oaxaca, México, se realizó una revisión de las gramíneas existentes en dicho estado. Se examinaron especímenes depositados en los principales herbarios nacionales, así como también colectas de ejemplares provenientes de trabajo de campo reciente en la zona. Para la recopilación y organización de la información se elaboró una base de datos. Los resultados obtenidos muestran un total de 141 géneros y 528 especies de esta familia, incluyendo las cultivadas e introducidas, lo que equivale aproximadamente a 68.60% de los géneros y 46.76% de las especies presentes en el país. La distribución por subfamilias está representada de la siguiente manera: Centothecoideae (2 géneros y 5 especies); Arundinoideae (3 géneros y 21 especies); Bambusoideae (16 géneros y 35 especies); Pooideae (34 géneros y 76 especies); Chloridoideae (30 géneros y 141 especies); Panicoideae (56 géneros y 250 especies). Se incluye la lista de todas las especies de gramíneas registradas para el estado de Oaxaca.

The Poaceae family includes approximately 700 genera and 10 000 species, and Mexico is considered one of its most important centers of diversity and endemism. A total of 256 taxa (including 16 subspecific taxonomic units), belonging to 65 genera, are endemic to Mexico. Some of them are close relatives of important crops, while others are used in different ways all over the country. The aim of this paper is to discuss the distribution patterns at state level of the Mexican endemic species of Poaceae. Using cluster strategies, the states are classified according to their floristic similarities. Later, hotspots of endemism are identified, in order to discuss their role in conservation strategies. To evaluate the importance of each state in the conservation of the Mexican endemic Poaceae, two iterative complementarity methods were also used. Our results show that the largest concentration of endemic taxa occurs in a few states, such as Jalisco, Mexico, Michoacan, Durango, Oaxaca, Veracruz, San Luis Potosi, Chiapas, Chihuahua, Puebla, and Coahuila. The results also show that there are some patterns in the relationship to its endemism that seem to reflect important diversification trends in the family. Accordingly, 31% of the grass genera of Mexico have at least one endemic species, and 16.7% of the genera have only one endemic species. In contrast, six genera contribute 47.2% of the total number of grass endemics in Mexico. The Chloridoideae contributes 42.9% of the total grass endemic species of Mexico, whereas the Panicoideae includes 24.6%, and the Pooideae 19.8%. Thus, these three subfamilies contribute about 87% of the species endemism. On the basis of the habitat and distribution patterns of these subfamilies, two main areas of endemicity can be identified. The first area is located in warm habitats, whereas the second is related to temperate and high regions. The cluster analyses indicate the occurrence of four state groups whose phytogeographical explanation is discussed on the basis of a floristic regionalization of Mexico. The results also indicate the need to establish a relatively high number of sites and states for the conservation of 256 endemic taxa. The elevated number of sites required to conserve the Mexican endemic Poaceae is mainly due to the fact that many taxa have a restricted distribution pattern. On the basis of the patterns obtained, a few proposals are presented for undertaking the establishment of conservation priorities of these taxa.

Dada la utilidad taxonómica que presentan los caracteres de la epidermis de la lema y la escasez de información pertinente para el género Cathestecum, se examinan, describen y comparan estas características con aquellas presentadas por géneros afines de la subtribu Boutelouinae, con el fin de dilucidar sobre los posibles rasgos con valor taxonómico. Los resultados más significativos muestran la presencia de papilas en C. tamaulipense, C. erectum y C. brevifolium var. sonorense, la ausencia de aguijones y células de corcho en C. brevifolium y la ausencia de cuerpos de sílice en todas las especies de Cathestecum. Los géneros afines Buchloë, Soderstromia, Griffithsochloa, Pentarrhaphis y Bouteloua, representados en su mayoría por una sola especie, excepto Bouteloua y Pentarrhaphis, presentan abundantes papilas (no observadas en Bouteloua eludens ni en Griffithsochloa multifida) y células de corcho. Los cuerpos de sílice sólo se observaron en Buchloë dactyloides. Se concluye que algunas características micromorfológicas estudiadas pueden considerarse de valor taxonómico para separar las especies de Cathestecum, así como establecer, junto con otras fuentes de evidencia morfológicas, relaciones entre los taxa de la subtribu Boutelouinae.

An instrumental method based on a chemometric model of the medium region of the infrared (MIR) was developed to analyse total sugar content and the proportions of glucose, fructose and sucrose. In order to construct the model, a set of 127 standard aqueous solutions of different sugars in the concentration range 0–20% (w/v) were prepared and analysed in the interval 4900–700 cm−1. The MIR was transformed by normalisation, correction of baseline using the second derivative, and suppression of the signals of water and carbon dioxide. The region between 1150 and 950 cm−1 showed the highest correlation between signal and concentration. The correlation coefficient for total sugar content was 0.956, whilst those for glucose, fructose and sucrose were 0.982, 0.972 and 0.992, respectively. The method was validated using a set of 28 samples of nectar which had been assayed by chromatographic and refractometric methods. The method shows potential utility for the prediction of nectar sugar components. Copyright © 2003 John Wiley & Sons, Ltd.

The Military Macaw (Ara militaris) is a globally threatened species with a fragmented distribution, and assessing the genetics of populations could help identify conservation units. Nine microsatel...

The genus Capsicum consists of approximately 30 species of which C. annuum, C. chinense, C. frutescens, C. baccatum and C. pubescens are domesticated. Although Capsicum has been studied from the taxonomic and evolutionary point of view, using morphological, cytological and molecular characters, there are still sorne problems related to the taxonomic delimitation of the genus and its species, the nomenclature of the wild and cultivated forms, and the treatment of infraspecific variation. In order to determine the generic and specific taxonomic limits and to establish their phylogenetic and evolutionary relationships, it is necessary to undertake these studies among all the taxa of the genus Capsicum. C. annuum, C. chinense, and C. frutescens are taxa that form a taxonomic complex that can be barely differentiated and at the present it is impossible to determine whether they belong to the same or different species. The center of origin of the genus Capsicum is in South America, in the region that comprises Bolivia, northern Argentina, and central and southern Brazil. The biogeographic and archeobotanical studies indicate that during the dispersion of Capsicum along the American Continent, some of the species were domesticated independently in different places: C. annuum in Mexico; C. frutescens in Costa Rica, and possibly also in Mexico; C: chinense in the Amazonas lowlands; C. baccaturn in Bolivia, and C. pubescens in the Andes. In Mexico, C. annuwn has been cultivated throughout all the country; C. frutescens in the central and south eastern regions; C. chinense in the Yucatan Peninsula, and C. pubescens in the high lands of the central states. In addition, there are C. ciliatum and C. lanceolatum, two species that have never been used by man. Genetic and ecological studies on wild populations are very important for the use and conservation of this genetic resource.

"Quercus undata Trel. (Fagaceae, Quercus, Section Quercus) has a complex taxonomic and nomenclatural history. Intensive sampling of oaks at the type locality of Q. undata Trel. in Durango, Mexico and evaluation of herbarium specimens and plants in the field indicate that Q. undata represents variation in Quercus chihuahuensis Trel. in white oak communities where introgressive hybridization among Q. chihuahuensis, Q. grisea Liebm., and a third white oak, Q. arizonica Sarg. made species identification difficult. Endlich¿s type specimen of Q. undata, as designated by Trelease, was apparently destroyed in bombing raids on Berlin during World War II, and we propose herein as lectotype the Trelease illustration of the type. An epitype is also designated in support of the lectotype, given that some features cannot be critically observed on the illustration. The long peduncles of the specimen illustrated by Trelease indicate a close relation to Q. chihuahuensis."

Seed germination triggered by light exposure (positive photoblastism) has been determined in quantitative studies for numerous plant families and species. For Cactaceae, positive photoblastism is thought to be associated with life form and seed mass, but this association has never been evaluated. To explore hypotheses on associations between seed mass, seed dispersal, seed dormancy, life form, taxa and plant height with Relative Light Germination (RLG) in Cactaceae, we evaluated the effect of light on seed germination of 136 taxa. The taxa studied are native to several countries: México, Chile, Argentina, Brazil, Perú, USA, and Venezuela. Seed traits contrasted with RLG were life form, seed mass, seed dispersal, seed dormancy, adult plant height and taxon. We found some differences between RLG among taxa; Cacteae, Pachycereeae and Trichocereeae had higher RLG than Notocacteae. RLG was lower for seeds from taller than for shorter taxa, and lower for taxa with heavier seeds than for taxa with lighter seeds. Dispersal syndrome groups varied with RLG. RLG did not differ between cylindrical and globose taxa. Trends found here were in agreement with expectations for small-seeded species to have a light requirement to germinate more often than large-seeded species. This is the first time that cactus height is related to photoblastism. It is possible that seeds from tall plants are larger and thus have the capacity to produce taller seedlings than those from small plants, and that seedlings from large seeds with more resources have the ability to emerge from greater soil depths than those from small seeds. Fil: Flores, J.. Instituto Potosino de Investigación Científica y Tecnológica; México Fil: Jurado, E.. Universidad Autónoma de Nuevo León; México Fil: Chapa Vargas, L.. Instituto Potosino de Investigación Científica y Tecnológica; México Fil: Ceroni Stuva, A.. Universidad Nacional Agraria La Molina; Perú Fil: Dávila Aranda, P.. Universidad Nacional Autónoma de México; México Fil: Galindez, Guadalupe. Instituto Nacional de Tecnología Agropecuaria. Centro Nacional de Investigaciones Agropecuarias. Centro de Investigación de Recursos Naturales. Instituto de Recursos Biológicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Gurvich, Diego Ezequiel. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: León Lobos, P.. Instituto de Investigaciones Agropecuarias; Chile Fil: Ordóñez, C.. Universidad Nacional Autónoma de México; México Fil: Ortega Baes, Francisco Pablo. Universidad Nacional de Salta. Facultad de Cs.naturales. Escuela de Agronomia. Laboratorio de Investigaciones Botanicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentina Fil: Ramírez Bullón, N.. Universidad Nacional Agraria La Molina; Perú Fil: Sandoval, A.. Instituto de Investigaciones Agropecuarias; Chile Fil: Seal, C. E.. Royal Botanic Gardens; Reino Unido Fil: Ullian, T.. Royal Botanic Gardens; Reino Unido Fil: Pritchard, H. W.. Royal Botanic Gardens; Reino Unido

The Tehuacan-Cuicatlan biosphere reserve (BRTC) is rich in mammalian diversity, but geographical distribution information is absent or insufficient for most species. Consequently, previous efforts to model the ecological niche and potential distribution of mammals have been hampered. The main purpose of this study was to examine the patterns of mammalian diversity in BRTC using a climatic domains classification. Biological datasets composed of geographically referenced localities commonly are raw input during analyses of geographical distributions of species, but in countries like Mexico datasets frequently are incomplete and biased. The recent availability of interpolators and geographic information systems make possible the enhancement of environmental datasets and open the possibility to use climatic parameters to explain biological patterns. In this study we generated a climatic domain classification for the Tehuacan-Cuicatlan valley and its surrounding areas of influence. With this approach, climatic domains were used as biodiversity surrogates, and we justified the overlapping of environmental data with the biological dataset (species, longitude, latitude, and elevation) to evaluate and complement the available mammal diversity information within BRTC.

"El pochote (Ceiba aesculifolia subsp parvifolia) es una especie arbórea silvestre cuyas semillas se consumen y comercializan por las comunidades del Valle de Tehuacán, Puebla. Pero esta actividad se ha reducido debido a la presencia de árboles con proliferación de flores, pudrición y deformación de frutos, que son reconocidos como pochotes macho. Ésto causa pérdidas económicas importantes para los pobladores que dependen de este recurso natural. Por tanto, los objetivos de este trabajo fueron identificar al agente causal relacionado con este síndrome y establecer los factores climáticos y de manejo que determinan su incidencia y distribución en la región. La revisión del interior de los frutos reveló la destrucción de semillas por la abundancia de esporas de color café-rojizo de un hongo, que no produjo micelio ni esporas en cultivos axénicos. La comparación y alineamiento de las secuencias de los productos de la PCR de la región ITS1- ITS2 del gen rADN 18S obtenidos del ADN de las esporas aisladas de los frutos de pochote macho, con secuencias disponibles en el Genbank, mostró una identidad nucleotídica de 87 a 75% con los géneros Crinipellis y Moniliophthora. Así, es posible que las esporas encontradas en los frutos del pochote macho pertenezcan a una especie de estos hongos. Se determinó que la distribución e incidencia del pochote macho, están relacionadas directamentecon el grado de uso por los habitantes locales y no por los factores climáticos evaluados."

We examined the effects of climate change on the future conservation and distribution patterns of the cloud forests in eastern Mexico, by using as a species model to Fagus grandifolia Ehr. var. mexicana (Martinez) Little which is mainly located in this vegetation type, at the Sierra Madre Oriental. This species was selected because it is restricted to the cloud forest, where it is a dominant element and has not been considered for protection in any national or international law. It is probably threatened due to the fact that it plays an important social role as a source of food and furnishing. We used a floristic database and a bioclimatic modeling approach including 19 climatic parameters, in order to obtain the current potential distribution pattern of the species. Currently, its potential distribution pattern shows that it is distributed in six different Mexican Priority Regions for Conservation. In addition, we also selected a future climate scenario, on the basis of some climate changes predictions already proposed. The scenario proposed is characterized by +2 °C and −20% rainfall in the region. Under this predicted climatic condition, we found a drastic distribution contraction of the species, in which most of the remaining populations will inhabit restricted areas located outside the boundaries of the surrounding reserves. Consequently, our results highlight the importance of considering the effects of possible future climate changes on the selection of conservation areas and the urgency to conserve some remaining patches of existing cloud forests. Accordingly, we believe that our bioclimatic modeling approach represents a useful tool to undertake decisions concerning the definition of protected areas, once the current potential distribution pattern of some selected species is known.

Como un aporte al conocimiento de la flora del estado de Oaxaca, México, se realizó una revisión de las gramíneas existentes en dicho estado. Se examinaron especímenes depositados en los principales herbarios nacionales, así como también colectas de ejemplares provenientes de trabajo de campo reciente en la zona. Para la recopilación y organización de la información se elaboró una base de datos. Los resultados obtenidos muestran un total de 141 géneros y 528 especies de esta familia, incluyendo las cultivadas e introducidas, lo que equivale aproximadamente a 68.60% de los géneros y 46.76% de las especies presentes en el país. La distribución por subfamilias está representada de la siguiente manera: Centothecoideae (2 géneros y 5 especies); Arundinoideae (3 géneros y 21 especies); Bambusoideae (16 géneros y 35 especies); Pooideae (34 géneros y 76 especies); Chloridoideae (30 géneros y 141 especies); Panicoideae (56 géneros y 250 especies). Se incluye la lista de todas las especies de gramíneas registradas para el estado de Oaxaca.

Dada la utilidad taxonómica que presentan los caracteres de la epidermis de la lema y la escasez de información pertinente para el género Cathestecum, se examinan, describen y comparan estas características con aquellas presentadas por géneros afines de la subtribu Boutelouinae, con el fin de dilucidar sobre los posibles rasgos con valor taxonómico. Los resultados más significativos muestran la presencia de papilas en C. tamaulipense, C. erectum y C. brevifolium var. sonorense, la ausencia de aguijones y células de corcho en C. brevifolium y la ausencia de cuerpos de sílice en todas las especies de Cathestecum. Los géneros afines Buchloë, Soderstromia, Griffithsochloa, Pentarrhaphis y Bouteloua, representados en su mayoría por una sola especie, excepto Bouteloua y Pentarrhaphis, presentan abundantes papilas (no observadas en Bouteloua eludens ni en Griffithsochloa multifida) y células de corcho. Los cuerpos de sílice sólo se observaron en Buchloë dactyloides. Se concluye que algunas características micromorfológicas estudiadas pueden considerarse de valor taxonómico para separar las especies de Cathestecum, así como establecer, junto con otras fuentes de evidencia morfológicas, relaciones entre los taxa de la subtribu Boutelouinae.

Por medio de un análisis filogenético utilizando cladogramas, se plantea una hipótesis preliminar sobre las relaciones filogenéticas entre el género Sorghastrum y géneros afines, así como las relaciones existentes entre las especies de este género. Además, con base en el análisis filogenético, así como patrones de distribución actuales y pasados, se hacen algunas consideraciones biogeográficas y se propone una hipótesis de trabajo explicando el posible lugar de origen del género.

Endemism values are not equivalent among the Mexican Musci, Poaceae, and Asteraceae. The number of endemic species varies from one group to the next in various types of vegetation or geographical areas, perhaps in response to age, peculiarities of their life cycle, dispersal ability, and individual response to selective pleasures. In Mexico, the three major plant groups include 2373 endemic taxa among which 86 are mosses, 257 are grasses, and 2030 are composites. Cluster analysis of a similarity matrix shows relationships between neighboring states and among geographically related state groups. Along the Neovolcanic Belt there are areas of endemism in western and central Mexico, but the relationship between state pairs does not always have a geographical basis. From the standpoint of the number of endemic species per unit area, Distrito Federal is the richest area in Mexico.

A population ofSchisandra glabra (Schisandraceae) found in the cloud forest of northeastern Hidaglo state, Mexico, represents a new family for the Mexican flora and the first record for the species outside of the southeastern United States. Morphological comparisons of foliar and floral characteristics of this population with southeastern U.S. specimens reveal the material in both countries to be similar in morphology and apparently conspecific.Schisandra glabra is the only species of the family on the American continent. We speculate that the disjunct distribution of the Mexican population is the result of the gradual contraction of an otherwise wider distribution in connection with climatological changes associated with the Tertiary. The species is described and illustrated to familiarize students interested in the Mexican flora with the species and family.

A new species, Nanarepenta juxtla- huacensis, from the state of Oaxaca, Mexico, is de- scribed. Its habit and diagnostic characters are il- lustrated, and its relationships are discussed. This species is closely related to N. guerrerensis. It is distinguished from that species by having pistillate inflorescences shorter than the leaves, oblong and smooth capsules, as well as by having tectate-per- forate and punctuate pollen grains.

Se elaboró una lista de taxa endémicos de la flora vascular de Veracruz. Se registraron 94 géneros de 56 familias que contienen 131 especies y 10 taxa subespecíficos con distribución restringida a los límites del estado. Las familias con el mayor número de unidades endémicas fueron Orchidaceae (11), Myrtaceae (10), Bromeliaceae (9), Poaceae (8), Begoniaceae (7), Zamiaceae (5) y Polypodiaceae (5). Los tipos de vegetación que presentaron la mayor diversidad de endemismo, son el bosque tropical perennifolio (52), el bosque mesófilo de montaña (43), el bosque tropical caducifolio (23), el bosque de Quercus (20), el bosque de coníferas (16), el bosque de galería (15) y el bosque tropical subcaducifolio (11).