Stephen F. Nelsen

Allographa itatiaiensis is a little-known species of lichen-forming fungus in the family Graphidaceae. Originally described in 2011 as a member of the genus Graphis, it was later transferred to Allographa in 2018 during a major reorganization of script lichen genera. The species forms thin, greenish-grey crusts on tree bark, distinguished by small spherical outgrowths and star-shaped clusters of slender, branching fruiting bodies. It is known only from humid Atlantic Forest environments in southeastern Brazil, where it grows on tree bark in shaded, moist conditions.

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Heiomasia is a genus of corticolous (bark-dwelling), crustose lichens in the family Graphidaceae. It has five species.

Haematomma staigeriae is a species of corticolous (bark-dwelling) lichen in the family Haematommataceae. Found in Costa Rica, it was formally described as a new species in 2006 by Matthew Nelsen, Robert Lücking, and Loengrin Umaña. The type specimen was collected by the second author from the Talamanca Ridge in the Pacific La Amistad Conservation Area (Puntarenas) at an elevation between 1,600 and 1,800 m (5,200 and 5,900 ft). Here, in a montane rainforest area with secondary vegetation dominated by Cecropia, the species was found growing on the lower trunks of trees. It is only known from

Haematomma nicoyense is a species of corticolous (bark-dwelling) lichen in the family Haematommataceae. Found in Costa Rica, it was formally described as a new species in 2006 by Matthew Nelsen, Robert Lücking, and José Luis Chaves. The type specimen was collected from the Monte Alto Forest Reserve in the Nicoya Peninsula at an elevation between 750 and 900 m (2,460 and 2,950 ft). Here, in lowland to lower montane moist forests, the species was found growing on the lower trunks of exposed trees and on fence posts. The specific epithet refers to the type locality. The lichen has a

Diorygma antillarum is a species of corticolous (bark-dwelling), crustose lichen in the family Graphidaceae. It is common and widespread in the Neotropical realm, primarily found on trees in the shady understory and in slightly illuminated habitats of lowland to montane rainforests. It produces norstictic acid and salazinic acid.

Multiclavula ichthyiformis is a rare terricolous (ground-dwelling) basidiolichen in the family Hygrophoraceae. The lichen produces small, flesh-coloured fruit bodies with flattened, fishtail-shaped tops that grow directly from the soil surface and bear spherical spores on their undersurface. Endemic to a high-elevation bog in Costa Rica, it was discovered in 2007 during a biodiversity survey and remains known only from this single mountain location.

Marcelaria benguelensis is a tropical species of corticolous (bark-dwelling) and crustose lichen in the family Trypetheliaceae. It is found in continental southeast Asia.

Marcelaria is a genus of crustose lichens in the family Trypetheliaceae. It has three species. These lichens grow as crusty patches on tree bark and are recognised by their bright orange, yellow, or red colouring. They produce distinctive flask-shaped fruiting bodies that are vividly pigmented and sit directly on the lichen's surface. The genus is found mainly in tropical regions of Asia, Africa, and the Americas.

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Dictyonema aeruginosulum is a species of basidiolichen in the family Hygrophoraceae. Characteristics of the lichen include its distinctive finger-like projections and blue-green hue. It is distinguishable from its closest relatives by its unique morphology and the absence of clamp connections in its structure. Dictyonema aeruginosulum is an epiphyte, forming thick mats on tree trunks within rainforest regions. The species was first identified in Costa Rica's Tenorio Volcano National Park, and it has only been recorded from this location.

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