[6] The first article about this species was published in 1875 by Edward Drinker Cope who wrote of the toad as a particular but unnamed variety of Bufo valliceps from eastern Costa Rica.
[13] In 2009 Pauly et al. suggested that because the recent partitioning of Bufo had made the formerly monophyletic genus paraphyletic and that the new genera were too imperfectly defined to be phylogeneticly stable, as the large number of recent (officially mandated) name changes caused by Frost in 2006 was evidencing, and that the hitherto done genetic analyses were yet too vague to properly resolve relationships, thus Incilius should be treated as a subgenus of Bufo.
A phylogenetic analysis by Mendelson based on morphology, life history, and molecular data was published 2011 which recommending sinking Cranopsis/Cranophryne, Ollotis and Crepidius/Crepidophryne back into Incilius.
[14] Mendelson et al. (2011) suggest that this species is part of an I. valliceps species group, or more specifically in what they termed the "Forest Group" subgroup, including the taxa I. aucoinae, I. cavifrons, I. campbelli, I. cristatus, I. leucomoyos, I. macrocristatus, I. spiculatus and I.
[12] There is marked sexual dimorphism, the females having more irregular dark colouration on their back and being larger, but the males having longer heads and more brawny forearms.
[12] The dorsum (back) is very warty,[4] but is covered in a smooth skin except near the shoulders and hips, which has small, low and rounded protrusions.
[12] The lateral side of the toad is bordered along the upper part with a row of light-coloured, low to medium-sized, sharp but rounded, spine-shaped warts extending from the paratoid gland to the groin.
[12] In general the colour of this toad is brown or grey, mottled with irregular splotches of dark gray or black.
[12] The ventral surface has a yellowish base,[4] while the throat and chest are black,[2][12] and the underside of the lower jaw has white spots along the edge.
There is a mottled dark brown region from the eye to the edge of the paratoid gland, which appears somewhat like a mask.
[1] McDiarmid and Savage recorded it in 2005 in meadows of the Peninsula de Osa, extending the distribution to the Pacific slopes in the far southwest of the country.
[1] In 2004 the toad was recorded in Nicaragua for first time (correctly) in the Indio Maíz Biological Reserve by Gunther Köhler and his team,[1] in 2009 it was also recorded from Río San Juan under auspices of an expedition by Köhler[4] and in 2014 it was reported in Rivas Department on the Pacific coast by a Nicaraguan team.
[12] Reproduction happens during the dry season[4][12] starting with the males calling from January to February from pools along rocky streams, or within 50 cm (20 in) of water.
[1] When the species had been less studied, earlier authors such as Bolaños & Chaves writing for the IUCN in 2004 mistakenly believed it to be endemic to Costa Rica.
It was described in 2004 as most likely not very tolerant of deforestation and siltation and pollution of its breeding habitat, but nonetheless it was downgraded to "least concern" in 2004.
[9] As of 2008 the IUCN describes it as "widespread and regularly encountered" and "common and somewhat adaptable with a presumed large population".
It is regularly seen during the breeding period,[1] and is common in wet forests at higher elevations at favoured habitats.
[12] It occurs at La Selva Biological Station, in the Monteverde Cloud Forest Reserve (if correctly identified)[1] and throughout the Maquenque National Wildlife Refuge in Costa Rica,[6] and in the Indio Maíz Biological Reserve[1][4] and Río San Juan Wildlife Refuge in Nicaragua.