genus Fosterella L.B.Sm.
Literature references:
Comments:
- On the Diversity and Biogeography of the Genus Fosterella L.B. Smith (Bromeliaceae) by Pierre L. Ibisch, Elvira Gross, Georg Rauer & Dirk Rudolph in J. Brom. Soc. 47(5):211-217. 1997
The genus Fosterella was established by L.B. Smith in 1960. However, half of today's known species had been described in other genera by the 1940s (figure 6). In the last few decades the descriptions of new species has increased significantly and there are undoubtedly more species remaining to be discovered. In his taxonomic revision of the genus, Read (in prep.) will describe five new species. Ultimately the number of Fosterella species may approach 30.
The first species discovered was the central American Fosterella micrantha, described as Pitcairnia micrantha by Lindley in 1843. The latest described species, and the ones still to be described, grow in the Central Andes or in the humid lowlands of central South America. Bolivia, in particular, is a country where new, even surprisingly spectacular species (like the red-flowered Fosterella spectabilis H. Luther 1997) can still be discovered. Bolivia is also the region where, in 1993, the authors found the new species Fosterella vasquezii:
Fosterella is a tropical genus which enters subtropical forests only in Argentina. It is marked by a disjunct distribution. An isolated partial distribution in Central America is formed by F. micrantha. All the other species are known from central South America: in the Andes from Peru (Huanucu) in the north to Argentina (Salta) in the south, and in the lowlands from Bolivia (Santa Cruz) and Brazil (Mato Grosso) to Paraguay. A clear diversity center is located in the dry to semihumid inter-Andean and foothill region of the La Paz Yungas where about 50% of the species are concentrated. A zone of high Fosterella diversity is found in an adjacent area in Southern Peru. With regard to the other genera of Bromeliaceae, Fosterella is probably unique by having its diversity center in this region.
In all other known ranges, it is not likely to find more than one or two species within a small region. Up to now the distribution in the Bolivian Andes seems to be discontinuous. It is possible that new records may fill the distributional gaps. Most of the Fosterella species are not found in very humid forests such as those that are present in the mentioned gap of the Cochabamba Yungas. Most of them occur in dry to semihumid forests like those typical for inter-Andean regions and the edge of the Chaco. The new species, F. vasquezii, seems to be one of the few species which are adapted to very humid conditions. In the South American lowlands the Fosterella species apparently depend on mountain chains and rocky slopes. Here, none of the species is found on forest floors. In the Andes, most of the species are found below 1,500 metres in elevation; F. albicans and F. schidosperma are even known from sites at altitudes around 2,000 metres.
ENDEMISM AND CONSERVATION ASPECTS
Currently more than 80% of the Fosterella species have to be considered as local endemics. A high tendency to endemism is observed within most genera of the subfamily Pitcairnioideae. The small seeds, which are not dustlike, are not suited for long-distance dispersal. So, especially those taxa which live in more or less isolated dry or semihumid forests may evolve species characterized by small ranges. The diversity center of the genus Fosterella in Bolivia is, at the same time, the center of local endemics which up to now only have been found at or nearby the type locality.
Probably none of the Fosterella species is currently endangered. Many of the local endemics live at azonal sites like rocks or the habitats that are not suffering such transformations that might prove detrimental to their existence. Furthermore, the species are not very attractive for many horticulturists, so overcollecting would not seem to be a potential threat. The new species, F. vaszquezii, grows within the National Park Noel Kempff Mercado and can be considered to be well protected.
The collections of Fosterella specimens are still very poor, so remarks on the ecology and range of the species are necessarily of a preliminary nature. Soon, large collections of Bolivian Fosterella specimens (M. Kessler, pers. com.) will help to provide more precise information for several species. However, without doubt the distribution patterns based on the known specimens permit a first assessment of the biogeography and diversity of this rather species-poor bromeliad genus. Smith & Downs (1974) were the first to illustrate the range of Fosterella. Taking into consideration new records for both known and new species, we have provided a new distribution map, which for the first time also tries to give an assessment of the diversity of the genus (figure 11).
