José Antonio Vázquez-García

Vegetation ordination at the southern Chihuahuan Desert (San Luis Potosi, Mexico)

Cover data for 93 perennial plant species from fifty 1 ha sites, were used to ordinate desert vegetation in relation to 50 environmental variables at El Huizache Corridor. Cumulative variance recovered in the Bray and Curtis variance-regression ordination was substantial (80%). Community structure of desert plant communities at El Huizache Corridor may be influenced primarily by a combination of landscape and edaphic variables, which in turn may determine the distribution and abundance of moisture and nutrients, and perhaps promote habitat specialization and or competitive exclusion. Secondly, to a lesser extent, climate variables could be influencing community organization at small scale gradients, the longer the gradient the more relevant climatic factors become. First axis represented a landscape gradient; it was positively correlated to exposure, geology, slope angle, rocks, stoniness, iron, January mean temperature, and organic matter content; it was negatively correlated with latitude, longitude, soil depth, and potassium content. The second axis represented mainly a climatic gradient; it was positively correlated with mean precipitation of January, February, July, August, September, November, December, annual mean precipitation, Langs Index, organic matter content, and stoniness. The third axis represented an edaphic gradient; it was positively correlated with electrical conductivity, Mn, Zn and elevation, and negatively correlated with pH, nitrates, Ca, and disturbance. These findings should guide conservation efforts to maintain species diversity and endemism at this area.

A new species and a new subspecies of Salvia (Lamiaceae) from Jalisco and Michoacán, Mexico

A new species and a new subspecies of Salvia, Salvia vazquezii and Salvia vazquezii subsp. tancitaroensis, from the Jalisco-Colima border and Michoacán, Mexico, respectively, are segregated from the S. gravida complex. They are described, illustrated and compared. A key to the three taxa and a translated and expanded circumscription of S. gravida are provided.ResumenSe segregan una nueva especie y una subespecie del complejo de Salvia gravida, Salvia vazquezii y Salvia vazquezii subsp. tancitaroensis, de los límites entre Jalisco y Colima, y Michoacán, respectivamente. Se describen, ilustran y comparan. Se incluye una clave para la separación de los tres taxa y una circunscripción traducida y expandida de S. gravida.

Agave temacapulinensis (Agavaceae), a New Ditepalous Species from the Los Altos Region, Jalisco, Mexico

Abstract.  Agave temacapulinensis A. Vázquez & Cházaro (Agavaceae) is described and illustrated from Jalisco, Mexico. The new species belongs to Agave L. subg. Agave and is a member of the Ditepalae group, sensu Gentry. It is related to A. wocomahi Gentry in terms of its rosette size, solitary habit in most cases, the smooth texture of the leaves, the red-tipped dimorphic tepals, and the deep floral tube. Agave temacapulinensis differs from A. wocomahi in having light gray, glaucous rosettes (vs. dark green to glaucous green); short acuminate leaves (vs. long acuminate); crenate margins (vs. straight to undulate) with smaller marginal teeth (8–10 mm vs. 10–20 mm); larger panicles (5.5–6.5 m vs. 3–5 m) with more lateral branches (16 to 18 vs. 8 to 15); and smaller seeds (5–6 × 3–4 mm vs. 7 × 4.5–5 mm). Resumen.  Una nueva especie, Agave temacapulinensis A. Vázquez & Cházaro (Agavaceae), es descrita e ilustrada de Jalisco, Mexico. Pertenece a Agave L. subg. Agave y corresponde al grupo Ditepalae sensu Gentry. La especie está relacionada con A. wocomahi Gentry en términos de tamaño de roseta, hábito no surculoso en la mayoría de los casos, textura suave de las hojas, tépalos dimórficos con puntas rojizas y tubo floral profundo, pero difiere de ésta ultima por poseer rosetas de color glauco-gris claro (vs. verde oscuro-verde glauco); hojas cortamente acuminadas (vs. largamente acuminadas); márgenes crenados (vs. rectos a ondulados); con dientes más pequeños (8–10 mm vs. 10–20 mm); panículas más grandes (5.5–6.5 m vs. 3–5 m) con más ramas laterales (16 a 18 vs. 8 a 15); y semillas más pequeñas (5–6 × 3–4 mm vs. 7 × 4.5–5 mm).