Castilla elastica Sess

This taxon can be found in the Chocó-Darién moist forests ecoregion, one of the most species rich lowland areas on Earth, with exceptional abundance and endemism over a broad range of taxa including plants, birds, amphibians and arthropods. The biological distinctiveness is exceptional, with considerable biodiversity.

There are three principal geomorphologic types in the ecoregion: alluvial plains of recent origin, low mountains formed by the relatively recent dissection of sediments from the Tertiary and Pleistocene periods, and the complexes in mountain areas consisting of mesozoic rocks. The high precipitation and the topography mean that the ecoregion includes a complex of great hydrographic basins, the most important being those of the Atrato, Baudó, and San Juan Rivers and the Micay and Patía Rivers in the south. The force of the water in many of these rivers form deep gorges cutting through the mountains, creating spectacular rapids and waterfalls in the mountains. At lower elevations, large rivers become very wide and with many meanders. Given the high precipitation in the region, it is not surprising that the soils are severely leached and poor in nutrients. Most of the ecoregion has typical laterite soils with reddish clay, although the soils are younger and less leached in some areas, especially close to the base of the Andes and in the floodplains of the major rivers. Of particular botanical interest are the white clay soils in the region of Bajo Calima in Colombia, which are associated with the gigantic sclerophyllous leafed and unusually large fruited vegetation.

Depending on the altitudinal gradient, soil water content and the effect of the sea, there are various types of vegetation that make up the ecoregion. In broad terms, in the northern part of the ecoregion, the lowland rainforests correlate to the Brosimun utilis alliance, including communities dominated by the deciduous Cuipo tree (Cavanillesia platanifolia), the Espavé wild cashew (Anacardium excelsum), the Panamanian rubber tree (Castilla elastica), Brosimum guianense, Bombacopsis spp., Ceiba pentandra, Dipteryx panamensis, and others. In the undergrowth Mabea occidentalis, Clidemia spp., Conostegia spp. and Miconia spp. are abundant. In zones that are occasionally flooded, the Cativo (Prioria copaifera) flourishes as well. In the southern part of the ecoregion, these rainforests have multiple strata, with two layers of trees, lianas, and epiphytes with vigorous growth rates. The number of deciduous plants increases in the north and south, where there is a dry season, particularly near the coast. The forests at higher altitudes, starting at 600 meters, have communities with the following species: Guamos (Inga spp.), Billia columbiana, Brosimum sp., Sorocea spp., Jacaranda hesperia, Pourouma chocoana, Guatteria ferruginea, Cecropia spp., Elaegia utilis, and Brunellia spp.

There are at least 127 species of amphibians in the Choco-Darien, including the following endemic anuran species: Isla Bonita robber frog (Craugastor crassidigitus); Kokoe poison frog (Phyllobates aurotaenia NT), found on western slopes of the Cordillera Occidental , along the Ra­o San Juan drainage south to the Ra­o Raposo; Golden poison frog (Phyllobates terribilis EN); La Brea poison frog (Oophaga occultator); Andagoya robber frog (Pristimantis roseus); Antioquia beaked toad (Rhinella tenrec); Atrato glass frog (Hyalinobatrachium aureoguttatum); Blue-bellied poison arrow frog (Ranitomeya minuta); Colombian egg frog (Ctenophryne minor), known only to the in the upper Ra­o Saija drainage; Condoto stubfoot toad (Atelopus spurrelli VU); Flecked leaf frog (Phyllomedusa psilopygion); LeDanubio robber frog (Strabomantis zygodactylus). An endemic salamander present in the Choco-Darien is the Finca Chibigui salamander (Bolitoglossa medemi VU).

Some other non-endemic anurans found here are: Anatipes robber frog (Strabomantis anatipes); Banded horned treefrog (Hemiphractus fasciatus); Black-legged poison frog (Phyllobates bicolor NT); Horned marsupial frog (Gastrotheca cornuta EN), known for having the largest amphibian eggs in the world; El Tambo stubfoot toad (Atelopus longibrachius EN); Elegant stubfoot toad (Atelopus elegans CR). Endemic caecilians in the ecoregion include the Andagoya caecilian (Caecilia perdita).

There are a number of reptilian taxa within the ecoregion, including: Adorned graceful brown snake (Rhadinaea decorata); the endemic Black centipede snake (Tantilla nigra); Boulenger's least gecko (Sphaerodactylus scapularis VU); the endemic Iridescent ground snake (Atractus iridescens); the endemic Cauca coral snake (Micrurus multiscutatus); the endemic Colombian coral snake (Micrurus spurelli); the endemic Dark ground snake (Atractus melas); the endemic Colombian mud turtle (Atractus melas VU); and the endemic Echternacht's ameiva (Ameiva anomala).

There are 577 species of birds recorded; Tyrannidae is listed as the most diverse avian family, presenting 28 genera and 60 species within the ecoregion. The Choco-Daroemis is a center of avian endemism of the Neotropics; moreover, according to Stattersfield, this ecoregion spans two Endemic Bird Areas, one in Central America and one in South America.

Between these two Endemic Bird Areas there are over sixty restricted range species, including the Chocó tinamou (Crypturellus kerriae VU), Chestnut-mantled Oropendola (Psarocolius cassini EN), Viridian dacnis (Dacnis viguieri), Crested ant-tanager (Habia cristata), Lita woodpecker (Piculus litea), and Plumbeous forest-falcon (Micrastur plumbeus EN). Also to be noted is the presence of the Harpy eagle (Harpia harpyja), the Black and white crowned eagle (Spizastur melanoleucus), taxa increasingly rare in many areas of the Neotropics, and possibly the Speckled antshrike (Xenornis setifrons EN) although one has not been recorded in Colombia since the 1940s.

The region is rich in mammalian taxa, but the larger animals have received inadequate research. These include the Bush dog (Speothos venaticus NT); Chocó tamarin (Saguinus geoffroyi EN), the Baird's Tapir (Tapirus bairdii EN), the Giant anteater (Myrmecophaga tridactyla VU), the Brown-headed spider monkey (Ateles fuscipens CR), the Puma (Puma concolor VU), the Ocelot (Leopardus pardalis LC), and the jaguar (Panthera onca NT).