[2] The center of the ecoregion is in the extreme south of Venezuela, and covers part of the Parima Tapirapecó National Park.

[1] Until recently the lowland plains of the region were covered in lakes and seas, which deposited layers of sediment.

Humiriaceae, Rapateaceae, Tepuianthaceae, Theaceae and Xyridaceae are common families that do not belong to the Amazon flora.

The dominant trees of the low palm forests are Mauritia flexuosa, Mauritiella aculeata, and dense groups of Euterpe catinga, Iriartea setigera, and Socratea exorrhiza.

[4] The 40 metres (130 ft) terra firme forest holds Lecointea amazonica, Clathrotropis glaucophylla, Peltogyne venosa, and species in the Ocotea, Nectandra, Licania, Trichilia, Guarea, Toulicia, Erisma, and Ruizterania genera.

The tall canopy forests also hold trees of the Oenocarpus, Socratea, Leopoldinia, and Bactris genera.

There is a high level of endemism of flora including the genera Duckeanthus, Heteropetalum, Pseudephedranthus, Urospathella, Aquiaria, Angostylis, Astrococcus, and Chonocentrum.

[4] In the Rio Negro basin the many blackwater streams and small rivers flood a large area of igapó forest for 5–6 months each year.

[4] There are 194 species of mammals, including a few endemic species such as golden-backed uakari (Cacajao melanocephalus), black bearded saki (Chiropotes satanas), Tschudi's slender opossum (Marmosops impavidus), least big-eared bat (Neonycteris pusilla), Guianan spear-nosed bat (Phyllostomus latifolius), Eldorado broad-nosed bat (Platyrrhinus aurarius), Venezuelan fish-eating rat (Neusticomys venezuelae), MacConnell's climbing mouse (Rhipidomys macconnelli), the guinea pig Cavia guianae and Simon's spiny rat (Proechimys simonsi).

Common species include South American tapir (Tapirus terrestris), collared peccary (Pecari tajacu), pale-throated sloth (Bradypus tridactylus), long-tailed weasel (Mustela frenata), short-eared dog (Atelocynus microtis), bush dog (Speothos venaticus) and three species of small cats of the Leopardus genus.

They include the endemic grey-legged tinamou (Crypturellus duidae), crestless curassow (Mitu tomentosum), double-striped thick-knee (Burhinus bistriatus), oilbird (Steatornis caripensis), tawny-tufted toucanet (Selenidera nattereri), Orinoco piculet (Picumnus pumilus), Yapacana antbird (Myrmeciza disjuncta), gray-bellied antbird (Myrmeciza pelzelni), spot-tailed nightjar (Hydropsalis maculicaudus), azure-naped jay (Cyanocorax heilprini), and white-naped seedeater (Dolospingus fringilloides).