PLESOM
On October 9, 2022 the VPA (SEE) listed 14,632 orchids (species, notospecies and natural hybrids) in New World, 11,740 of which in South America. Of the more than 350 genera of Orchidaceae in the hemisphere, a group of six genera stands out: the PLESOM group, formed by Pleurothallis, Lepanthes, Epidendrum, Stelis, Oncidium and Masdevallia. These genera together have 5,820 spp., about 40% of all Neotropical diversity; in South America they are 4,773 spp., which is also around 40% of the local amount.
Vanilla, Habenaria, Corymborkis, Bulbophyllum, Polystachia, Calanthe, Tropidia, Liparis, Malaxis and Eulophia are the only South American genera not restricted to New World.
By country, Brazil has the 3ª greatest diversity of orchids in the world, behind its (quasi-)neighbors Colombia and Ecuador. By the way, the national family diversity in these countries is the largest for a single family in a single country ever described. Ecuador at 2,228 of its 4,289 spp. belonging to PLESOM (c. 52% of its national diversity); Colombia has 1,818 of its 4186 in PLESOM (c. 43% of national diversity). Brazil has in PLESOM only 269 spp. of its 2,734 spp., less than 10%.
Excluding the PLESOM group, we have the following national diversities: Ecuador 2,061; Colombia 2,368; Brazil 2,465. The numbers show that the very high diversity of Orchidaceae in the two Andean countries is due to an explosion of diversity in the PLESOM group; outside of it, Brazil has more diversity of Orchidaceae.
OVER GENERIC DIVERSITY
All South American Orchidaceae tribes occur in Brazil except Colllabieae (20/443), which has its only South American species in Colombia (Calanthe calanthoides (A. Rich. & Galeotti) Hamer & Garay). Brazil has 203 genera, Colombia has 230 and Ecuador 217.
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| SOUTH AMERICAN GENERA BY GROUP; FOR BRAZIL, /BR DENOTES ABSENT GENERA; [BR] DENOTES ENDEMIC GENERA. |
In the subfamilies Vanilloideae and Cipripedioideae, Brazil and Colombia have all 6 South American genera; Ecuador and Peru 5 of them (except Duckeella). In species at Brazil against Colombia, Brazil wins in Vanilloideae for 22 spp., and Colombia wins Brazil in Cipripedioideae for only one species.
In the subfamily Orchidoideae (Microchilus inc. Aspidogyne, Kreodanthus, Platythelys, Stephanothelys; Solenocentrum absent in Colombia), South America has 52 genera, Brazil and Peru have 31 each, Colombia has 30, and Ecuador has 32; national endemic genera in this subfamily occur only in Brazil (4, Espinhassoa, Thelyschista, Cotylolabium and Nothostele) and Venezuela (2, Aracamunia and Stalkya). Brazil has more Orchidioideae species than Mexico and Colombia.
Degranvillea dermaptera Datermann from French Guiana and Suriname is the only South American mycoheterotrophic orchid outside Epidendroideae.
Among Epidendroideae, the ten smaller clades (Neottieae, Sobralieae, Tropidieae, Triphoreae, Xerorchideae, Wullschaegelieae, Gastrodieae, Malaxideae, Vandeae, Collabieae) has 22 genera in South America, 21 in Colombia, 19 in Venezuela, 18 in Ecuador and 17 in Brazil.
In Epidendreae, with 70 genera in South America, Colombia has 60 genera, Ecuador 54, Venezuela 53, Peru 52, and Brazil only 51.
In Cymbidieae, South America has 145 genera; Colombia has 108, Ecuador 104, Venezuela 95, Brazil 93, and Peru 90.