Bulbilla applanata is a lichenicolous fungi known from South America. It was described based on the formation of bulbils (sclerotia-like sterile structures) and neither basidiomata or conidiomata were observed. There are very few records available for this species, but its population size is projected to be above 18000 individuals and a significant population decline is not expected. Therefore, it is assessed as Least Concern (LC).

B. applanata is the only species in the Bulbilla genus, described in 2014 based on molecular data (Diederich et al., 2014). It is synonymous with Adamflakia applanata, a name introduced subsequently to account for nomenclature rules but that has since been considered illegitimate (He et al. 2019).

So far known from South America, in Ecuador (Provinces of Loja, Tungurahua and Zamora-Chinchipe), Bolivia (Yungas montane forest) and Chile (Los Lagos, Valdivia) (Diederich et al., 2014).

B. applanata has only been documented from 6 sites (Bolivia: 1, Chile: 1, Ecuador: 4). However, given its recent description, distribution, large number of hosts and minute and inconspicuous structures (only up to 400µm in diameter), the total number of sites is expected to be much larger. Therefore, following guidelines by Dahlberg and Mueller (2011), total population size is expected to be around 18000 individuals, applying a large multiplier for unknown sites (x1000) and assuming 1 mature individual exists per patch (individual lichens), and at least 3 patches per site.

A significant total population decline is also not expected, given the wide host breadth and relatively large distribution.

B. applanata is a lichenicolous species that parasitises thalli or apothecia of Peltigerales lichens (e.g. Lobariella crenulata, Peltigera sp., Pseudocyphellaria faveolata and Sticta sp.). It is known exclusively from bulbils and neither basidiomata or conidiomata were observed. Diederich et al. (2014) also hypothesise that this may be a strictly lichenicolous species, and possibly a virulent parasite for hosts.
Often found in montane forests, including the Yungas montane forest (alt. 1550 m) in Bolivia, a primary montane forest (alt.1945 m) and a cloud forest (alt. 2400–3800 m) in Ecuador, but also in a forest dominated by Nothofagus dombeyi (alt. 920–980 m) in Chile. In some cases, parasitised lichens were found growing on Nothofagus sp., Hieronyma asperifolia or were epiphytic. (Diederich et al. 2014)

No threats have been identified for this species.

No specific conservation actions are needed for this species.

Further records and research into the ecology of this species are needed to help establish distribution limits and determine population size.