This concept previously bore the name Cycloramphus carvalhoi (Heyer 1983). Following the accidental confusion between Zachaenus carvalhoi and Cycloramphus carvalhoi due to changes made by Dubois et al. (2021), C. carvalhoi has been renamed as C. heyeri (Segalla et al. 2021).

This species is suspected to have become extinct at the type locality in the 1970s or 1980s. However, surveys in 2005 recorded it at a new site 200 km to the southwest of its type locality. The species is now known only to persist at this site, but there is ongoing decline in the quality and extent of the habitat. Its extent of occurrence (EOO) and area of occupancy (AOO) are estimated to be 4 km², and this is considered only one threat-defined location, hence it is listed as Critically Endangered.

This species was previously known only from the type locality at Alto Itatiaia, in the Parque Nacional do Itatiaia, municipality of Resende, Rio de Janeiro State (Heyer 1983). Its range was subsequently expanded in 2005 when it was recorded about 200 km to the southwest at a single site in the municipality of Campos do Jordão, in São Paulo State (Martins et al. 2007). The species has been recorded at 1,500 and 2,400 m asl. Surveys in the Serra da Mantiquiera to the northeast and southwest of Campos do Jordão have failed to record the species, despite the presence of suitable habitat. It has not been recorded again at the type locality since 1959 and is considered possibly extinct at this locality. At present the species is known to be extant at only one site, and the extent of occurrence (EOO) and area of occupancy (AOO) are given the smallest possible value of 4 km².

The species was collected at the type locality in 1951 and 1959 (Heyer 1983). It has not been seen at the type locality since that time, despite numerous surveys over the decades including surveys using eDNA methods to detect the presence of amphibian genetic material in streamwater (Lopes et al. 2020, Lyra et al. 2020, I.F. Machado pers. comm. 2021). It is considered possibly extinct at this site. 

At Campos do Jordão, the species was first recorded in 2005, then again in 2012 and 2017 during surveys using pitfall traps; the species persists at this site (I. Martins pers. comm. 2021). 

Frequent general amphibian surveys and targeted surveys for this species to areas of suitable habitat between Alto Itatiaia and Campos do Jordão since the 1980s have yet to record the species. Surveys in the Serra da Mantiqueira to the southwest of Campos do Jordão, did not record the species: neither the Dacnis project in the municipality of São Francisco Xavier 2015-2021 (M. Moroti pers. comm. 2021); nor surveys in the municipalities of Camanducaia between 2000-2021 and Monte Verde between 2017-2021 (I. Martins pers. comm. 2021).

Due to ongoing decline in the quality and extent of its habitat in the municipality of Campos do Jordão, which is thought to contain the only remaining individuals of this species, the overall population trend is inferred to be decreasing. 

The habitat from which the species was collected at the type locality is unknown. At the second more recent locality, Campos de Jordão, the species was collected in the leaf litter in closed-canopy rainforest (I. Martins pers. comm. 2021), from this it is concluded that this is one of the terrestrial Cycloramphus species of the Atlantic Forest biome. Based on the lack of streams and other waterbodies at or near this site, the species is inferred to breed by direct development (I. Martins pers. comm. 2021).

In Campos de Jordão, there is habitat loss due to expanding urban areas, and silviculture plantations. In addition, wildfires accidentally caused by hunting or other activities including the maintenance of agricultural areas, and used for the illegal expansion of agricultural land are a threat (Brazilian Red List Assessment Workshop 2021). 

Across the distribution, the emerging threat of climate change, in particular changes in precipitation and humidity and higher average temperatures (Steigerwald 2021), is projected to degrade the high-elevation forest on which this species depends (Laurance et al. 2011, Pepin et al. 2015). As species are forced to move up in elevation, dispersal may be hampered by declines in the extent, area and/or quality of suitable habitat (La Sorte and Jetz 2010). Although at present there is no known ongoing decline in the extent or quality of the habitat, this degradation and future shifts in the habitat are expected to negatively affect this species. 

The amphibian fungal pathogen, Batrachochytrium dendrobatidis (Bd) is a potential threat as it is suspected to be implicated in the declines of congeners (Brazilian Red List Assessment Workshop 2021), although this requires confirmation. No samples of this species have been tested for Bd, but the synergistic effects of both climate change and Bd cannot be ruled out as potential causes of declines in this species.

There are no records of the species being utilized.

Conservation Actions In-Place
The historical site in Rio de Janeiro is within the Parque Nacional do Itatiaia.

Conservation Actions Needed
A full evaluation of the most appropriate conservation actions is needed. Under consideration should be the protection of the site in Campos do Jordão through collaboration with local landowners, as this may be the only remaining site at which this species occurs. It may be a candidate for the establishment of a Reserva Particular do Patrimônio Natural (RPPN), which is a private conservation unit, recorded in perpetuity in the property's registration, with the objective of conserving biological diversity and can provide local landowners with compensation. In addition, the suitability of establishing a captive breeding programme to assist in the recovery of the species from its apparent decline should also be evaluated.

Research Needed
Targeted surveys for this species in the region of the Serra da Mantiqueira between the type locality and Campos do Jordão should continue. In addition to surveys back to vicinity of the latter site are needed both to monitor the species and determine whether any other subpopulations are extant. Additional work is needed to determine the causes of its apparent disappearance from the type locality and susceptibility to Bd.