New Species of Philodendron (Araceae) in the Guianas

During recent National Geographic Society sponsored expeditions to the Guianas from January to March and August to September 2011, more than 1884 collections (including 5721 specimens) with 817 collections of Araceae were collected. Among them were four new species of Philodendron that are described below. Although some collections, particularly specimens of Philodendron subgen. Pteromischum, remain undetermined, good estimates of the total flora are now available. The Araceae for the Flora of the Guianas has 163 species with a very unequal distribution. Guyana with 78 species has the lowest number of species perhaps owing to its extensive areas of savanna, these being notoriously poor in species of Araceae. Suriname has 101 species and French Guiana has 132 species.
French Guiana is the richest in species perhaps owing to its much more extensive expanse of primary vegetation. The area has a very low population and very little agriculture since much of the population works for the government, or are on subsistence support from the French government. Some of the new species and new records for French Guiana have come from the region near the Brazilian border and are thus species not ranging into adjacent Suriname.
It is interesting to note that the Flora of the Guianas is much less species-rich than areas in the Andes. The Guianas with 163 species in an area of 179, 000 sq. miles contrasts poorly with Ecuador, for example. Ecuador has only 104,510 sq. miles but has a flora of 943 published species, making it almost 12 times richer per unit area. However, the Flora of the Guianas does have a significantly endemic flora with 23 naturally occurring genera including 4 genera endemic to the Guianas, and a total of 50% of the species in the Guianas are endemic to the Guianas. A total of 71 species (44% of the total) are endemic to eastern South America.