Arturo Castro-Castro

Richness, geographic distribution patterns, and areas of endemism of selected angiosperm groups in Mexico: Species richness and endemism patterns in Mexico

Mexico is a megadiverse country. Presently, 22u2009126 species of angiosperms have been registered within its territory and 11u2009001 are considered to be endemic. However, their geographical distributions are far from homogeneous. In addition, Mexico is the center of diversification of several groups. Our analysis focused on such groups. The aims were to identify areas of species richness and endemism. A data matrix with 766 species and 25u2009579 geographical records was analyzed. It included Calochortus (Liliaceae); Bletia (Orchidaceae); Tigridieae (Iridaceae); Amaryllidaceae; Poliantheae, Echeandia (Asparagaceae); Crassulaceae; Hylocereus (Cactaceae); Solanum, Lycianthes and Physalinae (Solanaceae); Salvia section Membranaceae (Lamiaceae); and Cosmos and Dahlia (Asteraceae). Using Geographic Information Systems, we determined richness and distribution based on: (i) Mexican political divisions, (ii) biogeographical regions and provinces, (iii) a grid of 0.5u2009×u20090.5°u2009cells, and (iv) elevation. The areas of endemism were estimated using the endemicity analysis. The highest number of taxa and endemic plants were concentrated within the Transmexican Volcanic Belt in the Mexican Transition Zone. This mountain range has been recognized as a province on the basis of geologic, tectonic, geomorphologic, physiographic and biogeographic criteria. It is a 1000u2009km long volcanic arc that extends east to west through Central Mexico and is variably from 80 to 230u2009km wide, between 17°30′ to 20°25′N and 96°20′ to 105°20′W. Our results represent a local deviation from the global richness latitudinal gradient of angiosperm species.

Polianthes quilae (Poliantheae, Agavaceae), a New and Endemic Species to Western Mexico

Abstract n The floristic inventory of the Sierra de Quila Natural Reserve, in western Mexico, resulted in the discovery of Polianthes quilae (Polianthes subgen. Bravoa). The novelty is related to P. cernua and P. geminiflora var. clivicola but is distinguished by the erect lanceolate leaves, glauous inflorescence with 4–21 floral nodes, 0.9–2.1 cm long pedicels, tubular-ventricose and bicolorous perigone with ascending lobes, and filament insertion site 3–5 mm above ovary apex. Data on geographic distribution and ecology, phenology, and conservation status are presented. Lastly, a key to all species of Polianthes is provided. Resumen n El inventario florístico del Área de Protección de la Flora y la Fauna Sierra de Quila, en el occidente de México, resultó en el descubrimiento de Polianthes quilae (Polianthes subgénero Bravoa). El nuevo taxón se relaciona con P. cernua y P. geminiflora var. clivicola pero se distingue por sus hojas erectas y lanceoladas, inflorescencias glaucas con 4–21 nudos florales, pedicelos de 0.9–2.1 cm de longitud, perigonio tubular-ventricoso y bicolor con los lóbulos ascendentes y por la inserción de los filamentos 3–5 mm por arriba del ápice del ovario. Se aportan datos sobre la distribución geográfica, hábitat, fenología y estado de conservación del taxón nuevo. También, se provee una clave para la identificación de las especies de Polianthes.