Males measure 32.99-34.8 mm in SVL and the single female specimen measured 41.04 mm in SVL. Head is flat dorsally. Snout is short; in dorsal view it is acute and in profile it projects. Canthus rostralis is well-defined. External nostrils are very slightly prominent; they are lateral, oval, postero-laterally directed, and located closer to the tip of the snout than to the eyes. Inter-narial region is slightly concave. Loreal region is concave. Tympanum, tympanic ring, and columella auris pharyngea ostia are all absent. Prominent supratympanic fold is present. Choanae are oval and small. Spatulate tongue without apparent notch, free in the posterior third. Parotoid glands are only slightly evident. Forearms are robust. Fingers have rounded tips. Hands have vestigial webbing. Palmar surfaces with abundant low tubercles. Hind limbs are short. Knees, ankles and tarsus are without folds. Feet are moderately webbed,with fingers I, II, and V fully webbed, III with 1 ½ phalanges free and IV with 2 ½ phalanges free. The outer metatarsal tubercle is rounded and raised while the internal metatarsal tubercle is flat and round. Small and irregular low tubercles are abundant on the plantar surface. Head and trunk are thick and smooth with some warts on trunk. Forelegs and hind legs are covered with small warts, ventral surfaces are granular. Large warts on flank.Males have paired vocal slits and have more robust forearms than females.Males also have rather bulky nuptial excrescences on the pollices, consisting of a patch of keratinized fine spinules covering the dorsal surface of finger I (Ardila-Robayo and Ruiz-Carranza 1998).
In life, the dorsum is pea green with scattered black spots, freckles and/or black. Flanks are cream and black (in Colombian specimens) or yellowish-cream with a thick black reticulation (in Ecuadorian females). The venter is creamy white with small black spots that are elongated in shape and irregular size, and may be individual or coalescent (in Colombian specimens), or orange and black (in Ecuadorian specimens). Palms and soles are yellow. Iris greenish yellow with thick black circular line, parallel to the pupil (in Colombian specimens), or dark brown with yellow edging on the pupil (in Ecuadorian specimens) (Ardila-Robayo and Ruiz-Carranza 1998; Coloma et al. 2010).
Color in 70% ethanol: dorsum is medium gray with black blotches. All yellow coloration becomes cream.
Described by Ardila-Robayo and Ruiz-Carranza (1998).
The genus Atelopus, with 113 described and putative species, appears to be the most threatened clade of amphibians (La Marca et al. 2005). Chytridiomycosis is thought to be a primary factor in the decline and disappearance of species in this genus (La Marca et al. 2005). At least 30 Atelopus species appear to be extinct, having been missing from all known localities for at least 8 years (La Marca et al. 2005). Only 52 of the surviving species have sufficient data with which to evaluate population trends; of these, 81% (42 of 52) have population sizes that have been reduced by at least half (La Marca et al. 2005). Higher-elevation species (those living at least 1000 m asl) have been hit the worst, with 75% (21 of 28) having disappeared entirely (La Marca et al. 2005). Most Atelopus species are local endemics and are restricted to very limited areas along mid- to high-elevation streams (generally 1500-3000 m asl, though the maximum vertical range is from sea level to permanent snow; Lötters 2007), a habitat preference frequently associated with the co-occurrence of chytridiomycosis (La Marca et al. 2005). At least 26 species are known only from a single population inhabiting a narrow altitudinal range (La Marca et al. 2005). Due to their restricted ranges, they are thought to have limited ability to adapt to warming climatic conditions (Lötters 2007).
- Stuart, S., Hoffmann, M., Chanson, J., Cox, N., Berridge, R., Ramani, P., and Young, B. (eds) (2008). Threatened Amphibians of the World. Lynx Edicions, IUCN, and Conservation International, Barcelona, Spain; Gland, Switzerland; and Arlington, Virginia, USA.
- Ardila-Robayo, M. C. (2005). ''Atelopus angelito.'' Ranas Arlequines. Rueda-Almonacid, J. V., Rodríguez-Mahecha, J. V., Lötters, S., La Marca, E., Kahn, T. R., and Angulo, A., eds., Conservación Internacional. Panamericana Formas e Impresos S. A., Bogotá, Colombia.
- Ardila-Robayo, M. C. and Ruiz-Carranza, P. M. (1998). ''Una nueva especie de Atelopus A. M. C. Dumeril & Bibron 1841 (Amphibia: Bufonidae) de la Cordillera Central Colombiana.'' Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 22(83), 281-285.
- Coloma, L.A., Duellman, W.E., Almendáriz, A., Ron, S.R., Terán-Valdez, A., and Guayasamin, J.M. (2010). ''Five new (extinct?) species of Atelopus (Anura: Bufonidae) from Andean Colombia, Ecuador, and Peru.'' Zootaxa, 2574, 1-54.
- La Marca, E., Lötters, S., Puschendorf, R., Ibáñez, R., Rueda-Almonacid, J. V., Schulte, R., Marty, C., Castro, F., Manzanilla-Puppo, J., García-Pérez, J. E., Bolaños, F., Chaves, G., Pounds, J. A., Toral, E., and Young, B. E. (2005). ''Catastrophic population declines and extinctions in neotropical harlequin frogs (Bufonidae: Atelopus).'' Biotropica, 37(2), 190-201.
- Lötters, S. (2007). ''The fate of the Harlequin Toads help through a synchronous multi-disciplinary approach and the IUCN Amphibian Conservation Action Plan.'' Zoosystematics and Evolution, 83( Supplement 1), 69-73.
- Merino-Viteri, A. (2001). ''Análisis de posibles causas de las disminuciones de poblaciones de anfibios en los Andes del Ecuador.'' Tesis de Licenciatura, Quito, Ecuador, Pontificia Universidad Católica del Ecuador,
- Yánez-Muñoz, M. and Altamirano B., M. (2005). ''Atelopus sp. 14.'' Ranas Arlequines. Rueda-Almonacid, J.V., Rodríguez-Mahecha, J. V., LaMarca, E., Lötters, S., Kahn, T., and Angulo, A., eds., Conservación Internacional. Panamericana Formas e Impresos S. A., Bogotá.