Ophioglossum nudicaule (Ophioglossaceae) y Paspalum serpentinum (Poaceae), dos nuevos registros para la península de Yucatán, México

Antecedentes y Objetivos: Las sabanas de la península de Yucatán han sido objeto de estudio en la última década para conocer su diversidad, estructura y los patrones fitogeográficos de sus componentes vegetales. Entre las sabanas existentes en el sur de Yucatán hay una localmente conocida como Chacho Lugo que ha sido escenario de trabajo de campo extenso y su flora es bien conocida. Producto de las exploraciones recientes en el sitio se han documentado nuevos registros de angiospermas y helechos para las sabanas de Yucatán. El objetivo de este estudio es dar a conocer las novedades que este sitio aporta a la flora peninsular. Métodos: Durante los años 2016 a 2019 se realizaron expediciones a la sabana Chacho Lugo, se colectaron ejemplares botánicos y se depositaron en el herbario UADY. Los especímenes se identificaron con la ayuda de literatura y mediante la comparación con material de herbario y ejemplares digitalizados en alta resolución disponibles en páginas electrónicas. Resultados clave: Después de la identificación de los especímenes y la revisión de su distribución se registran por primera vez Ophioglossum nudicaule y Paspalum serpentinum para las sabanas de la península de Yucatán. Conclusiones: Los nuevos registros incrementan la diversidad de Pteridofitas en 17 familias, 34 géneros y 67 especies, y a 24 las especies de Paspalum en la península de Yucatán.Background and Aims: The savannas of the Yucatán Peninsula have been studied in the last decade to know their plant diversity, structure and phytogeographical patterns of its plant components. Among the extant savannas in the south of Yucatán, one locally named Chacho Lugo has been scenario of extensive field work and its flora is well known. Recent expeditions to the site have documented new records of monocots and ferns for the Yucatán savannas. The objective of this study is to present the novelties that the site adds to the peninsular flora. Methods: During 2016 to 2019, expeditions were made to the savanna Chacho Lugo, botanical specimens were collected and deposited in the UADY herbarium. The specimens were identified using specialized literature and by comparison with herbarium material and high-resolution scanned specimens available on electronic pages. Key results: Following the identification of the specimens and the review of their distribution, Ophioglossum nudicaule and Paspalum serpentinum are registered for the first time for the savannas of the Yucatán Peninsula. Conclusions: These reports increment the diversity of Pteridophytes to 17 families, 34 genera and 67 species, and to 24 species of Paspalum in the Yucatán peninsula

FLORA VASCULAR DE LAS SABANAS DE XMABÉN, HOPELCHÉN, CAMPECHE, MÉXICO

n the Yucatan peninsula, savannas are distributed as small enclaves clearly delimited bytropical forest tree. Savanna flora is of a greatbotanical interest, because it is determinedby soil conditions. The aim of this study wastoidentify and describe the flora and ways oflife of two sheets in Xmaben, Campeche. As aresult 127 species belonging to 97 genera and41 families were recorded. Poaceae, Fabaceae,Cyperaceae, Malvaceae and Convolvulaceaehad the largest number of genera and species.The richest genera were Paspalum (six), Cyperus (five), Eleocharis (four), Echinodorus,Ipomoea, Mimosa and Panicum (three each).The herbaceous plant life form was the bestrepresented with 94 species (74.01%). TheJaccard similarity index was 0.157, since thetwo savannas share only 19 species out of 127.The absence of introduced plants in the sites isa strong indicator of its natural origin.En la península de Yucatán, las sabanas constituyen elementos característicos del paisaje,se localizan en depresiones topográficasrodeadas por mesetas de desarrollo cársticocon vegetación arbórea tropical. Estos enclaves son de gran interés botánico por lacomposición de su flora que está determinadapor condiciones ecológicas particulares. Elpresente estudio tuvo como objetivo reconocer y describir la flora y las formas de vidade dos sabanas de Xmabén, Campeche. Losresultados permiten reconocer 127 especies,que pertenecen a 97 géneros y 41 familias.Las familias con mayor número de génerosy especies fueron Poaceae, Fabaceae, Cyperaceae, Malvaceae y Convolvulaceae. Losgéneros con mayor riqueza fueron Paspalum(seis), Cyperus (cinco), Eleocharis (cuatro),Echinodorus, Ipomoea, Mimosa y Panicum(tres cada uno). La forma de vida mejorrepresentada es la herbácea con 94 especies(74.01%). El índice de similitud de Jaccardfue de 0.157, lo que demuestra una marcadadiferencia entre la flora de los sitios estudiados, ya que de las 127 especies registradassólo 19 se comparten. La ausencia de plantasintroducidas en los sitios es un fuerte indicador de su origen natural

The Role of Alien Species on Plant-Floral Visitor Network Structure in Invaded Communities

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The interactions between pairs of native and alien plants via shared use of pollinators have been widely studied. Community level studies however, are necessary in order to fully understand the factors and mechanisms that facilitate successful plant invasion, but these are still scarce. Specifically, few community level studies have considered how differences in invasion level (alien flower abundance), and degree of floral trait similarity between native and invasive species, mediate effects on native plant-pollinator communities. Here, we evaluated the role of alien species on overall plant-floral visitor network structure, and on species-level network parameters, across nine invaded coastal communities distributed along 205 km in Yucatán, México that vary in alien species richness and flower abundance. We further assessed the potential the role of alien plant species on plant-floral visitor network structure and robustness via computational simulation of native and invasive plant extinction scenarios. We did not find significant differences between native and alien species in their functional floral phenotypes or in their visitation rate and pollinator community composition in these invaded sites. Variation in the proportion of alien plant species and flower abundance across sites did not influence plant-pollinator network structure. Species-level network parameters (i.e., normalized degree and nestedness contribution) did not differ between native and alien species. Furthermore, our simulation analyses revealed that alien species are functionally equivalent to native species and contribute equally to network structure and robustness. Overall, our results suggest that high levels of floral trait similarity and pollinator use overlap may help facilitate the integration of alien species into native plant-pollinator networks. As a result, alien species may also play a similar role than that of natives in the structure and stability of native plant and pollinator communities in the studied coastal sand dune ecosystem

Análisis estadístico de la variación morfológica en el complejo Gymnopodium floribundum (Polygonaceae): definición de tres subespecies

Background and Aims: Morphological variability in Gymnopodium floribundum along its distribution area has been the source of taxonomic and nomenclatural inconsistencies, sometimes recognizing up to three species and two varieties. In this paper we present morphometric analyses of variation in 224 specimens of G. floribundum in order to determine the existence of morphological patterns that correspond to geographically structured phenotypic diversity.Methods: The data matrix consisted of 224 specimens and 32 characters, 21 were quantitative and 11 qualitative. A dendrogram was estimated with UPGMA’s algorithm and the Gower´s coefficient. The 21 quantitative characters were subjected to principal components analysis. With the groups identified in the dendrogram, we performed a PERMANOVA using all quantitative characters. Canonical Variate Analyses of leaf shape and perianth segment shape of all specimens were executed.Key results: The results of multivariate analyses suggest the existence of three phenetic groups, which mostly correspond to three geographic regions: Belize, the Pacific Coastal Plain and the Yucatán Peninsula. These groups are distinguished by the presence or absence of indument on leaf blade, ochrea and petiole, the distances between the floral fascicles, and the length and width of the external and internal segments of the perianth. Two of the geographic groups correspond to infraspecific taxa previously recognized by Standley and Steyermark. Our distances and shape morphometric analyses uncover a third group from the southern Pacific region which presents novel characters.Conclusions: Based on these results we raise the rank of two varieties G. floribundum var. antigonoides and G. floribundum var. floribundumto subspecies, and propose to recognize a new third subspecies: Gymnopodium floribundum subsp. chiapensis.Antecedentes y Objetivos: La variabilidad morfológica en Gymnopodium floribundum a lo largo de su área de distribución ha sido la fuente de inconsistencias taxonómicas y nomenclaturales, a veces reconociendo hasta tres especies y dos variedades. En este trabajo se presentan análisis morfométricos de variación en 224 especímenes de G. floribundum para determinar la existencia de patrones morfológicos que correspondan a una diversidad fenotípica geográficamente estructurada.Métodos: La matriz de datos consistió en 224 especímenes y 32 caracteres, 21 fueron cuantitativos y 11 cualitativos. El dendrograma obtenido se construyó usando el algoritmo UPGMA y el coeficiente de Gower. Los 21 caracteres cuantitativos se sometieron a un análisis de componentes principales. Con los grupos identificados en el dendograma se realizaron ánalisis PERMANOVA utilizando caracteres cuantitativos. Se hicieron Análisis de Variación Canónica de la forma de la hoja y de la forma del segmento del perianto con todos los especímenes.Resultados clave: Los resultados de los análisis multivariados sugieren la existencia de tres grupos fenéticos que en su mayoría corresponden a tres regiones geográficas: Belice, Costa del Pacífico y Península de Yucatán. Estos grupos se distinguen por la presencia o ausencia de indumento en la lámina de la hoja, ócrea y pecíolo, las distancias entre los fascículos florales y la longitud y anchura de los segmentos externos e internos del perianto. Dos de los grupos geográficos corresponden a taxones infraespecíficos previamente reconocidos por Standley y Steyermark. Los análisis morfométricos efectuados de distancias y formas descubren un tercer grupo de la región del Pacífico sur que presenta caracteres novedosos.Conclusiones: Con base en estos resultados se eleva el rango de las variedades G. floribundum var. antigonoides y G. floribundum var. floribundum a subespecies, y se propone reconocer una nueva tercera subespecie: Gymnopodium floribundum subsp. chiapensis

Diversidad y origen geográfico del recurso vegetal en los huertos familiares de Quintana Roo, México

El huerto familiar (HF) es un sistema agrícola que funciona como fuente de recursos naturales y sitio para el manejo y conservación de especies vegetales nativas e introducidas. Un ejemplo de su importancia se presenta en el área maya de la península de Yucatán, México. La conquista española es un aspecto fundamental en el desarrollo y evolución del HF, evento que favoreció la introducción de especies vegetales, lo que contribuyó a enriquecer y diversificar la flora del HF de la región. Actualmente, esta introducción es un proceso favorecido por la globalización comercial, fenómeno que ha generado cambios en el HF debido al abandono de las actividades del campo y a la búsqueda de recursos económicos fuera de éste. En la península de Yucatán se observa con mayor claridad en el estado de Quintana Roo, en donde el desarrollo socioeconómico ha favorecido que muchos campesinos mayas emigren de sus comunidades para buscar trabajo en las zonas turísticas. Para conocer el estado actual del recurso vegetal, se estudió la diversidad y origen geográfico de las especies vegetales presentes en el HF de Quintana Roo. Se caracterizaron 120 HF en tres regiones del estado: norte, maya y sur. Se registraron 449 especies correspondientes a 93 familias y 329 géneros. La familia mejor representada fue la Fabaceae con el 9.35% y el género mejor representado fueCitruscon el 2.0%. La región con mayor diversidad fue el norte (H’= 5,684). Las especies introducidas fueron principalmente de origen americano (65,8%). Recientemente, la globalización ha favorecido la introducción de especies de origen asiático, como el nim (Azadirachta indica) y el rambután (Nephelium lappaceum). Esto muestra la importancia de este fenómeno en la riqueza y diversidad actual de los huertos familiares de Quintana Roo

ANTIPROTOZOAL ACTIVITY OF EXTRACTS OF ELAEODENDRON TRICHOTOMUM (CELASTRACEAE)

Background: Chagas disease, amebiasis, giardiasis and trichomoniasis represent a serious health problem in Latin America. The drugs employed to treat these illnesses produce important side effects and resistant strains have appeared. The present study was aimed to evaluate the antiprotozoal activity of leaves, stem bark and root bark of Elaeodendron trichotomum, a celastraceus, that is used in Mexico as an anti-infective in febrile-type diseases. Materials and methods: Dichloromethane and methanol extracts of leaves, bark and roots of Elaeodendron trichotomum were tested against Entamoeba histolytica, Giardia lamblia, Trichomonas vaginalis, and Trypanosoma cruzi. A quantitative HPLC analysis of pristimerin and tingenone was performed. Results: The dichloromethane extract of roots was active against E. histolytica, G. lamblia, T. vaginalis, and T. cruzi, at IC50’s of 0.80, 0.44, 0.46, and 2.68 μg/mL, respectively. The HPLC analysis revealed the presence of tingenone (3.84%) and pristimerin (0.14%). Conclusions: The dichloromethane extract of the roots bark showed significant activity against all screened protozoa

Biogeography and cladistic relationships of Psittacanthus (Loranthaceae)

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Floristic affinities of the lowland savannahs of Belize and southern Mexico

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

Persicaria barbata (L.) H. Hara and Persicaria glabra (Willd.) M. Gómez (Polygonaceae): two newly recorded species from the Yucatan Peninsula and Mexico

Two species of Persicaria (L.) Mill. are reported for the first time in the Neotropics. Persicaria glabra (Willd.) M. Gómez is reported for the first time as part of the flora of the Yucatan Peninsula, Mexico, and Persicaria barbata (L.) H. Hara is newly recorded from Mexico and the Americas. We present morphological descriptions of these two species along with figures, a distribution map, and a dichotomous key for the identification of the six species of Persicaria from the Yucatan Peninsula

Conjugative Transfer of p42a from Rhizobium etli CFN42, Which Is Required for Mobilization of the Symbiotic Plasmid, Is Regulated by Quorum Sensing

Rhizobium etli CFN42 contains six plasmids. Only one of them, p42a, is self-conjugative at high frequency. This plasmid is strictly required for mobilization of the symbiotic plasmid (pSym). To study the transfer mechanism of p42a, a self-transmissible cosmid clone containing its transfer region was isolated. Its sequence showed that most of the tra genes are highly similar to genes of Agrobacterium tumefaciens pTiC58 and other related plasmids. Four putative regulatory genes were identified; three of these (traI, traR, and cinR) belong to the LuxR-LuxI family. Mutagenesis of these genes confirmed their requirement for p42a transfer. We found that the conjugative transfer of p42a is dependent on quorum sensing, and consequently pSym transfer also was found to be similarly regulated, establishing a complex link between environmental conditions and pSym transfer. Although R. etli has been shown to produce different N-acyl-homoserine lactones, only one of them, a 3-oxo-C(8)-homoserine lactone encoded by the traI gene described here, was involved in transfer. Mutagenesis of the fourth regulatory gene, traM, had no effect on transfer. Analysis of transcriptional fusions of the regulatory genes to a reporter gene suggests a complex regulation scheme for p42a conjugative transfer. Conjugal transfer gene expression was found to be directly upregulated by TraR and the 3-oxo-C(8)-homoserine lactone synthesized by TraI. The traI gene was autoregulated by these elements and positively regulated by CinR, while cinR expression required traI. Finally, we did not detect expression of traM, indicating that in p42a TraM may be expressed so weakly that it cannot inhibit conjugal transfer, leading to the unrepressed transfer of p42a