Amazonotrema

Amazonotrema
Scientific classification
Kingdom:	Fungi
Division:	Ascomycota
Class:	Lecanoromycetes
Order:	Graphidales
Family:	Graphidaceae
Genus:	Amazonotrema Kalb & Lücking (2009)
Species:	A. nigrum
Binomial name
Amazonotrema nigrum Kalb & Lücking (2009)

Amazonotrema is a monotypic genus of lichenised fungi in the family Graphidaceae.¹ It was circumscribed in 2009 by Klaus Kalb and Robert Lücking for the species Amazonotrema nigrum.²³ The type specimen of A. nigrum was collected from virgin rainforest along the Rio Negro in the Brazilian state of Amazonas.

The genus name is a combination of Amazon, for the Amazon basin region from which the type specimen was collected, and trema, for the systematic position of the genus within the family Graphidaceae; it falls into the "thelotremoid" group because of the structure of its fruiting bodies (apothecia).³ As of 2020, it had not been genetically sequenced, so its relationship to other genera in the family is uncertain.⁴

Amazonotrema nigrum is a crustose lichen with a smooth, grey, and somewhat glossy surface, and it grows on tree bark, stripped wood and tree fern stems.³ Unlike most plant-dwelling lichens (but like many other tropical, crustose lichens),⁵ it lives partially immersed in the bark or stems on which it grows – a strategy known as endophloeodal.³ Its apothecia, which tend to be dispersed across the lichen's surface, are steep-sided, broadly rounded at the apex, and the same colour as the thallus.⁶ The apothecia's central disc is typically black, which is what led to the scientific name nigrum. ³ It is not known to have either isidia or soralia (two lichen structures which allow vegetative reproduction).⁷

Each ascus within the apothecia contains 5–8 ascospores, which are chestnut-brown in colour and arranged in rows. The spores themselves are muriform – divided into smaller compartments by intersecting partitions known as septa.⁷

The lichen produces several secondary metabolites, including stictic acid and constictic acid.⁷