Cyathus morelensis was described from Mexico in the state of Morelos by Gómez & Pérez-Silva (1988), with records for the Brazilian Amazon by Cruz et al. (2012), and Brazilian Atlantic rainforest in 2021 by Nascimento et al. (2021, in press). No synonyms and other scientific names are recorded or used for this species.

Cyathus morelensis is a rare species found in Amazon, Atlantic Forest (Brazil), and Mexico. As it is a species that occurs in such different environments with only four isolated records, the potential distribution of the taxon becomes a challenge, not allowing the understanding of which threats exactly affect the species in its subpopulations. The lack of this knowledge is especially worrying for Brazilian forest areas, due to negligence in the application of environmental laws, even with the increasing loss of habitat and the reduction in pluviosity caused by climate change. For these reasons, this species can be considered as Date Deficient (DD).

Cyathus morelensis is a potential rare species that was initially described for the state of Morelos, Mexico, in a region characterized by temperate forests with high rainfall throughout the year. Subsequently, collection additions were made in areas of the Amazon Forest (Manaus, Amazonas) by Cruz et al. (2012) and in an area of ​​Atlantic rainforest in Northeastern Brazil (Alagoas) by Nascimento et al. (2021, in press). Occurring in potentially balanced forest environments, with natural clearings and on plant debris that undergoes decomposition, this species is expected to occur in forest patches along with Central America, in areas of the Amazon Forest, and extend to the Brazilian coastal Atlantic Forest. However, there are no records other than those previously registered. Despite recurrent collection efforts in the Caatinga Domain located between the Amazon and the Atlantic Forest, since 2012, no other record has been located, indicating the need for greater efforts to expand and understand the species distribution data.

Based on the GBIF and Specieslink databases and associated publications, there are a total of 4 occurrence records, three of which are located in Brazil and one in Mexico, the type locality of the species. The record from Mexico is from the paper published by Gómez & Pérez-Silva (1988), with samples growing on the ground and litter. Subsequently, a new record was published for Amazon Forest (Cruz et al. 2012), with two distinct points (Adolpho Ducke Forest Reserve in this first article, and for Manacapuru), and for Alagoas (Nascimento et al. 2021), in litter and decaying wood. The species can be considered rare, but this fact may be wrong due to the lack of specialists in the group and the isolated collection points concerning the size of the phytophysiognomies. Based on the species ecology, 3 subpopulations can be delimited by forest areas or natural barriers: a subpopulation in the Amazon Forest region, a subpopulation in the northeast coastal portion of the Atlantic Forest, both separated from each other by the Caatinga domain, and the third subpopulation in Central America, separated from the Amazon subpopulation by the Andes.
Through the records of the species, it is possible to observe a pattern of 2-10 mature individuals per site, formed by fragments of mycelium that develop in small trunks or litter in the vicinity of where the peridiole was fixed during the dispersion process, and knowing it is a fungus that grows in soil, litter and decaying wood, it can be considered generations of 10 years in duration, with 3 generations in a period of 30 years.
Due to the huge differences between the phytophysiognomies where the species records were made, delimiting the potential sites of occurrence becomes a challenge and it is necessary to expand the ecological and environmental information (mainly soil and climate) that allow this species to develop, and the correct distribution for a proper assessment of conservation status. For these reasons, this species can be considered as Data Deficient (DD).

Cyathus morelensis was found growing on the ground and in the litter in temperate forest regions that have abundant rainfall throughout the year in Mexico, but with the sample collected in September. The Brazilian species were found in the Amazon and Atlantic rainforest, growing on decaying wood and only during periods with higher local rainfall, in months close to the collection period in Mexico (November in the Amazon, and between September and October in the Northeastern Atlantic Forest). Species of the genus Cyathus are organisms that need more open forest areas, either in natural forest glade or in areas along trail edges, developing in moist and soft plant debris in a more advanced process of decomposition (old plant debris which has suffered initial decomposition by other lignocellulolytic fungi for at least a week or two before). Naturally open (non-deforested) forest areas are important to ensure that the raindrops come into contact with the mature fruiting body, allowing the ejection of the peridiole (a resistant and dormant structure where the spore is produced and stored) at a distance of up to 2 meters from the location of the basidiome.

In Brazil, Cyathus morelensis can be strongly threatened by anthropic actions that reduce the vegetation of the collection areas in the Amazon and Atlantic Forest, as well as climate changes that affect the pluviosity and influence the growth of these organisms in these environments. In general, both biomes present agricultural expansion based on monoculture plantations, and agricultural activities are predominant, in addition to the incidence of fire and deforestation to form large pasture fields directly affecting the occurrence of the organism in this environment, as it directly affects its survival in these habitats. Specifically for Amazon Forest, deforestation for commercial logging and agriculture, frequent fire, and illegal mining can direct the biome to a tipping point (Joly et al., 2014; Rezende et al., 2018; Silva et al., 2020; Amigo, 2020). For the Atlantic Forest, the predatory exploration of resources, territorial occupation, an increase of fire frequency and intensity, species introduction, and ‘savannization’ are threatening Cyathus morelensis and other species (Pinto et al., 2006; Tabarelli et al., 2006; Rezende et al., 2018). In Morelos (Mexico), where the species was originally collected, there are no significant changes in vegetation cover in recent years (Global Forest Watch, 2014), but this data may not represent the potential risk in forest areas across Central America. Expanding knowledge of the species’ distribution will allow a better definition of potential risks to the three subpopulations.

Maintain priority conservation areas (or create new ones), especially in regions that are under strong anthropogenic actions in Brazil; increase control of illegal deforestation; reduction of clandestine fires, especially those used for agricultural activities, in addition to the control of monoculture plantations, especially to the two Cyathus morelensis South American subpopulations because is uncertain how endangered this species could be. The effective application of existing environmental laws in Brazil is also an action to be taken by environmental authorities and politicians.

Studies involving Cyathus biodiversity are still needed to see if the occurrence of C. morelensis is not underestimated once this species can be rare to be found in the field, in addition to the need to incorporate molecular data for further studies with the species. Additional collections in Central America, Atlantic Forest, and Amazon regions may evidence the occurrence of Cyathus morelensis elsewhere in these areas, and in sites that could potentially connect the Amazon to Atlantic Forest in the past.

No commercial or traditional use was known for the species.