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The Marcgraviaceae of Colombian Amazonia: Preliminary study on its diversity, distribution and phytogeography
Abstract
The Marcgraviaceae is a small-sized neotropical family with 8 genera and perhaps 110 species mainly distributed in Colombian Amazonia, Costa Rica, Panama and Andean Colombian and Peruvian montane rain forests. Five genera and 27 species were recorded from Colombian Amazonia, where the most diverse genus was Marcgravia (13 species), followed by Souroubea (6 species), Marcgraviastrum (4 species), Norantea and Ruyscliia with 2 species each. Based on a phenetic biogeographical classification, comparisons of diversity, distribution, affinity, and endemism among different Neotropical regions are provided. Although the knowledge of the Marcgraviaceae is still incomplete, some features with regard to their diversity and distribution in the Neotropic begin to emerge: 1. The Marcgraviaceae are more diverse in Western Amazonia, particularly Colombian Amazonia, than other areas (e.g., southern Mexico and southern Brazil); 2. Narrow endemic species appears to be low (ca. 24%); 3. Fifty percent of the Marcgraviaceae have a restricted distribution to a phytogeographical Region level; 4. The distribution of the numerous wide-ranging species are more or less patchy; 5. This family showed its highest endemism in northwestern of South America (Peru and Colombia); 6. The geologic history of the Andes has played an important role in the distribution and evolution of the Marcgraviaceae. For instance, most of the species diversity of several genera tends to be concentrated in Central America (Norantea), the Colombian Andean Region (Marcgraviastrum), or Western Amazonia (Marcgravia), and these areas correspond to areas of different geologic age. The Marcgraviaceae seems to have originated in South America and thus probably migrated to Central America.
... With ca. 60 species, Marcgravia is the most diverse genus of this family, distributed mainly in lowland and montane rain forests of Amazonia, parts of the Andean cordillera, the Guyanas, several islands of the Antillean arc and Mesoamerica (Gentry, 1993;Giraldo-Caaeas, 1999;Dressler, 2001). Little is known about the pollination and seed dispersal ecology. ...
We recorded nectarivorous and frugivorous visitors of Marcgravia longifolia (Marcgraviaceae) at the Estación Biológica Quebrada Blanco in the northeastern Peruvian Amazonia. M. longifolia belongs to the subgenus Plagiothalamium, with downward facing flowers. A glossophagine bat, probably Anoura caudifer, was identified as a potential pollinator. Three primate species - Saguinus fuscicollis, Saguinus mystax and Callicebus cupreus - were recorded as potential seed dispersers. This is the first documentation of primate seed dispersal of a species from the family Marcgraviaceae.
A new species of Schwartzia, S. parrae, is described and illustrated. The new species is known only from the Andean Central Cordillera of Colombia (Departamento de Antioquia). A key for the Colombian species of Schwartzia is provided.
A taxonomie study of the South American species of the genus Schwartzia is presented. Aspects related to the classification, nomenclature, and generic affinities are discussed. Keys to the five genera of the Norantea-Complex and the 14 South American species of Schwartzia are given, as well as descriptions of the species, synonymy, geographical distribution, and morphological and ecological observations. Countries with the greatest number and diversity of Schwartzia species are Colombia with six species (four endemics), followed by Brazil (four species, all endemics), Ecuador (three species, one endemic), Peru (two species, one endemic), and Bolivia and Venezuela with one species each one.
Four species are recognized, and the first records for the Central Corillera of Colombia are presented. Two new species, P. ochroleuca and P. roldanii, are described, illustrated and their relationships, ecology and geographical distribution discussed.
A new species, Marcgravia punctifolia, is described and illustrated. It occurs in the tepui region of the Guiana Shield and is distinguished from all other taxa of the genus by the combination of abaxially punctate leaves, leaf shape, and apparently cauliflorous inflorescences.
Previous paleobotanical studies on Tertiary floras from northern Latin America have documented that the lowland tropical rain forest and associated communities underwent significant change in their range and composition during the past 60 Ma. New data from pollen and spore assemblages allow refinement in the nature of these changes in three different geographic regions of the neotropics. At the northern limit in central Mexico through northern Central America, changing climates, particularly fluctuating temperatures, are revealed as a principal force driving vegetation dynamics. In southern Central America (including the proto-Antilles), climatic change had less effect on the vegetation. Rather, there was extensive volcanism and profound, rapid alterations in physiography. In the Amazon Basin there were limited topographic changes and moderate climatic effects. A primary forcing mechanism was fluctuating water tables induced by sea-level changes. It is speculated that these separate histories may have elicited a reordering in the myriad of factors constituting the speciation process and, therefore, provided different mechanisms for achieving biodiversity. An awareness of these separate physiographic provinces with distinct environmental histories may be useful in 1) accounting for geographically correlated genotypic and phenotypic features within a genus; 2) understanding factors that shaped the origin and diversification of individual taxa, and 3) refining scenarios to explain diversity in various parts of the neotropics.