Joel Alejandro Mercado-Díaz

Sticta tainorum is a rare species of foliose lichen in the family Peltigeraceae. Found in Puerto Rico, it was formally described as a new species in 2020 by Joel Mercado‐Díaz and Robert Lücking. The type specimen was collected by the first author in Toro Negro State Forest at an elevation of 1,036 m (3,399 ft). It is only known to occur on a few trees in high-elevation forests on the eastern part of the island, near Pico Doña Juana. The specific epithet refers to the indigenous Taíno people.

Sticta riparia is a species of foliose lichen in the family Peltigeraceae. Found in Puerto Rico, it was formally described as a new species in 2020 by Joel Mercado‐Díaz and Robert Lücking. The type specimen was collected by the first author in San Cristóbal Canyon at an altitude of 465 m (1,526 ft); here it was found growing on the vertical surface of a rock by the river. Although most commonly encountered along riverbanks along the Cordillera Central, it has also been found in secondary forests. The specific epithet alludes to its riparian habitat.

Sticta parvilobata is a species of foliose lichen in the family Peltigeraceae. Found in Puerto Rico, it was formally described as a new species in 2020 by Joel Mercado‐Díaz and Robert Lücking. The type specimen was collected along a trail to Monte Guilarte in the Guilarte State Forest (Guilarte, Adjuntas), at an altitude of 1,100 m (3,600 ft). The lichen is only known to occur in high-elevation forests at this location as well as the Toro Negro State Forest. The specific epithet parvilobata refers to the usually smaller lobes in mature specimens of this species, compared to its close relative

Sticta harrisii is a species of foliose lichen in the family Peltigeraceae. Found in Puerto Rico, it was formally described as a new species in 2020 by Joel Mercado‐Díaz, Bibiana Moncada, and Robert Lücking The type specimen was collected by the first author in El Yunque National Forest. The lichen is only known to occur in high-elevation forests at this location and also in Carite State Forest, where it typically grows as an epiphyte on Heterotrichum cymosum, Cecropia schreberian, vines, ferns, and occasionally on rocks. The specific epithet harrisii honours the American lichenologist

Sticta guilartensis is a species of foliose lichen in the family Peltigeraceae. Found in Puerto Rico, it was formally described as a new species in 2020 by Joel Mercado‐Díaz and Robert Lücking. The type specimen was collected by the first author on the trail to Monte Guilarte (Guilarte, Adjuntas) at an altitude of 1,100 m (3,600 ft). It is only known to occur at this single locality, where it grows on rocks and on roots and trunks of trees, often with bryophytes, in shaded and humid habitats. The specific epithet refers to the name of the forest at the type locality, Bosque Estatal de

Sticta densiphyllidiata is a species of foliose lichen in the family Peltigeraceae. Found in Puerto Rico, it was formally described as a new species in 2020 by Joel Mercado‐Díaz and Robert Lücking. The type specimen was collected by the authors along a trail in El Yunque National Forest (Mameyes II, Río Grande), at an altitude of 909 m (2,982 ft).The lichen is common in the rainforests on the eastern part of the island, where it thrives in humid and shaded habitats. It grows on rocks but the authors note that it could also grow as an epiphyte. The specific epithet densiphyllidiata refers to

Sticta corymbosa is a species of foliose lichen in the family Peltigeraceae. Found in Puerto Rico, it was formally described as a new species in 2020 by Joel Mercado‐Díaz and Robert Lücking. The type specimen was collected by the first author in the El Yunque National Forest at the summit of Pico El Toro (Las Piedras) at an altitude of 1,048 m (3,438 ft). It is only known to occur at the type locality, where it grows as an epiphyte in humid and open to partially shaded habitats. The specific epithet refers to the corymbose (clustered) isidia found along the margins of the lobes.

Sticta borinquensis is a species of foliose lichen in the family Peltigeraceae. Found in Puerto Rico, it was formally described as a new species in 2020 by Joel Mercado‐Díaz and Robert Lücking. The type specimen was collected by the first author on the El Toro Trail leading to Pico El Toro (Guzmán Arriba Barrio, Río Grande municipality). Its centre of distribution is the high-elevation forests in the eastern part of the island, particularly in El Yunque National Forest, where it grows as an epiphyte in shaded and humid habitats. The specific epithet refers to "Borinquen", which means "Puerto

Cora yukiboa is a species of basidiolichen in the family Hygrophoraceae. Found in Puerto Rico, it was formally described as a new species in 2016 by Joel Mercado-Díaz, Bibiana Moncada, and Robert Lücking The specific epithet yukiboa refers to Yukibo, the Taíno chief of the Daguao village where the type locality is. The lichen is found in summit forests of El Toro peak in the El Yunque National Forest, at an elevation of 1,074 m (3,524 ft). Here it grows as an epiphyte on shrubs.

Clandestinotrema portoricense is a rare species of corticolous (bark-dwelling) crustose lichen in the family Graphidaceae. Found in Puerto Rico, it was described as a new species in 2014. It is characterised by its white, slightly shiny thallus that can span several centimetres in diameter, and its rounded ascomata that are immersed in the thallus. Unlike most of its genus counterparts, C. portoricense possesses septated (partitioned) spores and a carbonised (blackened) excipulum and columella, effectively distinguishing it from similar species.

Thalloloma rubromarginatum is a little-known species of corticolous (bark-dwelling) script lichen in the family Graphidaceae. This lichen stands out from its counterparts within its genus, most notably Thalloloma haemographum, due to its corticate thallus and the presence of norstictic acid. Thalloloma rubromarginatum is found in the Sierra palm forests of Puerto Rico.

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Pyrenula sanguineostiolata is a species of corticolous (bark-dwelling) crustose lichen in the family Pyrenulaceae. Found in Puerto Rico, it was formally described as a new species in 2018 by André Aptroot and Joel Alejandro Mercado Diaz.

Pyrenula sanguineomeandrata is a rare species of corticolous (bark-dwelling) crustose lichen in the family Pyrenulaceae. It was formally described as a new species in 2018 by André Aptroot and Joel Alejandro Mercado Diaz. This distinctive lichen forms a thin, yellowish-brown crust on tree bark with a characteristic net-like pattern of dark red pigmentation across its surface. It is known only from wet mountain forests in Puerto Rico at around 850 metres elevation, where it grows in the Maricao State Forest.

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Ocellularia vulcanisorediata is a rare species of corticolous (bark-dwelling) lichen in the family Graphidaceae. Described as a new species in 2014, it is only known to occur in Puerto Rico.

Ocellularia portoricensis is a rare species of corticolous (bark-dwelling) crustose lichen in the family Graphidaceae. It was discovered in Puerto Rico, where it grows on tree trunks within shadowy understories of specific forests. This organism is distinct from other related lichens by its unique characteristics such as a white medulla and relatively larger, brown-tinted ascospores.

Compositrema isidiofarinosum is a species of corticolous (bark-dwelling) crustose lichen in the family Graphidaceae. This lichen was discovered in Puerto Rico. It flourishes in the shaded understory of the palo Colorado forest in El Yunque National Forest, clinging to the trunks of unidentified trees.

Compositrema borinquense is a species of corticolous (bark-dwelling) crustose lichen in the family Graphidaceae. It is found in northeastern Puerto Rico, where it grows on the trunks of trees in the palo Colorado forest of El Yunque National Forest. This lichen differs from others in the genus Compositrema, most notably from its closest relative, C. thailandicum, due to its distinctive, irregularly radiating columella–a central shaft of fungal hyphae in the ascoma.

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Acanthotrema alboisidiatum is a species of corticolous (bark-dwelling) crustose lichen in the family Graphidaceae. Described as a new species in 2014, it is primarily distinguished by its striking white isidia that contrast with its light olive-green thallus. The lichen was recognized as a new species despite the absence of ascomata and ascospores, usually crucial for taxonomic identification. Its DNA sequence data confirms its place in the Acanthotrema genus but distinguishes it from other known members of this genus. The species grows up to a diameter of 5 cm (2 in) and bears short, white

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