Solange Sotuyo

A new species of Caesalpinia from the Río Balsas Depression, Mexico, and an updated taxonomic circumscription of the Caesalpinia hintonii complex (Leguminosae: Caesalpinioideae: Caesalpinieae: Poincianella Group)

Caesalpinia oyamae, a new species from the Río Balsas Depression, Mexico, is described and illustrated based on morphological evidence. It is similar toCaesalpinia hintonii, and grows in seasonally dry forests, between 500–1490 m.

Genetic diversity and structure of the endemic Caesalpinia hintonii complex (Leguminosae: Caesalpinioideae) in Mexico

Abstract.The Caesalpinia hintonii complex is formed by five endemic species (C. hintonii, C. laxa, C. macvaughii, C. melanadenia and C. epifanioi) occurring in central Mexico. This species complex is under incipient genetic divergence as by-product of local adaptations in reproductive and morphological traits to different habitats. We estimate the genetic variation and structure of populations of this species complex to assess the extent of genetic differentiation among populations and related species along its geographic distribution. Estimations of genetic diversity and structure were done based on ten enzymes and 18 loci. Mean number of alleles per locus ranged from 1.5 to 1.9. Polymorphic loci ranged from 42.1 to 68.4. Observed (Ho: range 0.191–0.275) and expected (He: range 0.205–0.317) heterozygosities in this complex were higher compared with other endemic and legume species. Nei’s genetic diversity estimates showed that most genetic variation was found within (HS = 0.325) rather than among populations (DST = 0.085). Populations of the species C. hintonii showed a considerable genetic differentiation (FST = 0.207). The results of genetic diversity and structure within and among populations are in accord with the great morphological differentiation described for this species complex.

A new species of Erythrostemon (Leguminosae, Caesalpinioideae) from the western Río Balsas Depression, Mexico

Abstract A new legume species from a seasonally dry forest of the Western Río Balsas Depression, in the states of Guerrero and Michoacán, Mexico, Erythrostemon guevarafeferii, is herein described and illustrated. The new species shows morphological affinities with Erythrostemon hintonii, from which it is distinguished in having fewer leaflets per pinna, mature leaflets disposed toward the upper half of the pinnae rachises, long inflorescences on curved slender peduncles, abundant red glands on its flowers and inflorescences, and its fruit glabrous with red stipitate glands at maturity. A taxonomic key to the Río Balsas Depression species of Erythrostemon is included.