Background: Ruehssia is the only genus of Marsdenieae occurring in the Americas, and is restricted to this region with around 150 species. Mexico and Brazil have been recognized as the principal centers of diversity of the genus. The distinctive morphology and localities of the collected plants in Veracruz and Campeche, Mexico, suggests that this is a new species. Questions: Do the collected specimens belong to a new species? What is its conservation status? Studied species: Ruehssia golfomexicana. Study site and dates: Mexico and Central America, 2024-2025. Methods: Botanical specimens were analyzed and compared with a literature review, herbarium specimens, and photographic records from iNaturalistMX. The conservation status of the new taxon was evaluated, following the International Union for Conservation of Nature Red List criteria. Results: Ruehssia golfomexicana is compared with R. propinqua, R. hiriartiana, R. veronicae, and R. zimapanica. The proposed new species differs by its glabrous leaves, numbers of inflorescences per node and the green to greenish-yellow flowers, the new taxon is categorized as Endangered. Conclusions: Ruehssia is a genus of significant diversity in Mexico, and with this new addition reaches 42 species. This diversity places it as the third most species-rich genus of Apocynaceae in Mexico.
Antecedentes: La diversidad alfa cuantifica la biodiversidad a escala local e incluye los componentes taxonómicos y filogenéticos. En la Península de Yucatán se han realizado numerosos estudios botánicos; una de las familias con mayor riqueza de especies es Asteraceae. Pregunta: ¿Los registros de herbario y la filogenia de Asteraceae podrían ayudar a identificar patrones de diversidad alfa en la Península de Yucatán? Especies estudiadas: Familia Asteraceae. Sitio de estudio: Península de Yucatán, en los estados de Campeche, Quintana Roo, Tabasco y Yucatán. Métodos: Se utilizaron registros de herbario sobre la presencia de especies en celdas de 0.5° y una filogenia calibrada basada en el marcador ITS. Se calcularon cinco índices de diversidad alfa: tres del componente taxonómico (riqueza de especies, endemismo ponderado y redundancia) y dos del componente filogenético (diversidad y endemismo filogenéticos). Resultados: Los registros de herbario de Asteraceae tuvieron un mayor esfuerzo de recolección en los años 70 y el número acumulado de especies indica que nos acercamos a un inventario satisfactorio de la familia en la Península. Se identificaron 12 sitios con alta diversidad alfa, tanto en el componente taxonómico como en el filogenético; destacan los centros de población y la Reserva de la Biosfera de Calakmul. Se identificaron 28 sitios con lagunas de información, baja riqueza de especies y redundancia. Conclusiones: Aunque la riqueza de especies de Asteraceae es menor en la región que en otras familias como Fabaceae o Poaceae, varios sitios destacan por la alta diversidad alfa de la familia en la Península de Yucatán.
Background: The tropical deciduous forest hosts high diversity of species with anatomical characteristics in their wood that are subject to marked differences in precipitation through the year. Question: Can the wood anatomical characters reveal species strategies associated with drought avoidance or tolerance mechanisms in atropical deciduous forest? Study species: Eighty-three species of woody eudicots (trees and shrubs) from tropical deciduous forest in Tonatico, State of Mexico, during 2019-2023. Methods: Methods: Samples were processed using conventional histological techniques; nine anatomical characters and wood density were evaluated through correlation and principal component analyses. Results: Principal component analysis explained 65% of the variation in the first three components. Two extreme positions are recognized; one of them mainly contains species that are shrubs with numerous (up to 209 vessels/mm2) grouped and narrow (<48 & micro;m) vessels, in contrast to those arranged in the opposite direction. Species with intermediate characteristics in the aforementioned traits are distributed between the two. Conclusions: The results suggest that there are different arrangements of anatomical attributes that show a continuum, with species oriented toward tolerance versus avoidance at opposite extremes. Wood density is also associated with species groups, with the heaviest being tolerant, corresponding mainly to shrubs of the upper part of the ravine.
Background: Common bean (Phaseolus vulgaris) is a staple food in South America and North Africa. Conventional breeding has prioritized drought tolerance, and grafting has emerged as strategy to enhance stress tolerance. Hypotheses: The grafting compatibility of P. vulgaris onto P. acutifolius influence the short-term adaptation to water deficit. Studied species: Non-grafted P. vulgaris and P. acutifolius were used for to obtain grafted plants to evaluate physiological and biochemical responses to water deficit. Study site and dates: The experiment was conducted in a greenhouse at Colegio de Postgraduados, Montecillo, Texcoco, M & eacute;xico (19 degrees 27 ' 40 '' N, 98 degrees 54 ' 19 '' Wand altitude of 2,353 m). Methods: Plants were well watered until the pod-filling stage (R8). Then, plants were divided into two groups: one continued under well watered (control), while the other group was subjected to water suspension until physiological maturity stage (R9). Stomatal conductance was measured as an indicator of short-term water deficit, and proteomic analysis was performed. Statistical analysis was conducted using ANOVA followed by Tukey's test (P <= 0.05). Results: Grafted plants mitigated the water deficit in short term by increasing stomatal conductance (gs) at 24 h and declined after 48 y 72 h of water deficit. Plants reduced the seed number but stable seed weight distribution. Proteomic analysis from phloem exudates identified GDSL esterase/lipase, which is involved in catabolic processes, lipid catabolism, and transport. Conclusions: This study provides further evidence for the role of the rootstock (P. acutifolius) affect short-term responses to water deficit.
Background: In Mexico, copals are trees of the Bursera genus, from which fragrant resins used as incense are extracted. In Chiapas, there are 17 species, but compared to the extensive documentation of copal use in central Mexico, mentions of this in the southeast are sporadic, particularly Questions: What are the species of Bursera used as copal in the Zoque communities of the Central Depression of Chiapas? What are their uses? Study site and dates: Six Zoque-origin localities in the state of Chiapas, Mexico. 2023-2024. Methods: Ethnobotanical walks and semi-structured interviews with people selected mainly at markets, religious ceremonies and rituals. Results: The following were documented: a) uses of the resin and other botanical parts as incense and medicine; b) preparation of incense; c) commercialized forms of copal; d) methods of extraction; and e) transmission of traditional knowledge. Communities of Zoque origin collect, Conclusions: The Zoque communities of Chiapas have a deep knowledge of the use of Bursera spp., mainly as incense and medicine. Although the management of the trees and the extraction of resin may seem simple compared to other regions of Mexico, it has allowed populations of these Bursera species to continue being used today, despite the intensity and frequency of their use.
