Polymeridium is a genus of lichen-forming fungi in the family Trypetheliaceae. Species in the genus are corticolous (bark-dwelling) and typically occur in tropical areas.
Astrothelium bullatothallinum is a species of corticolous (bark-dwelling) lichen in the family Trypetheliaceae. Found in Venezuela, it was formally described as a new species in 2019 by lichenologists André Aptroot and Harrie Sipman. The type specimen was collected by Sipman along the Carapo River at an altitude of 800 m (2,600 ft). The lichen has a smooth, yellowish orange thallus that is more or less shiny and covers areas up to 15 cm (6 in) in diameter. It has roughly spherical ascomata, measuring 0.3–0.5 mm in diameter, which aggregate on the thallus surface in lines or in irregular groups. The ascospores are hyaline with three septa and measure 20–25 by 6–9 μm. The specific epithet bullatothallinum refers to the bullate thallus.
Astrothelium septemseptatum is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae. Formally described as a new species in 2016 by Dutch lichenologist André Aptroot, it is found in Guyana and Venezuela, where it grows on trees in savanna and rainforest. The type specimen was collected by Harrie Sipman about 3 km (1.9 mi) south of Kuyuwini Landing at an altitude of 230 m (750 ft); there, it was found growing on smooth tree bark. The lichen has a smooth and somewhat shiny, pale yellowish-grey thallus with a cortex and a thin black prothallus line. It covers areas of up to 9 cm (3.5 in) in diameter. The presence of the lichen does not induce the formation of galls in its host plant. Both the thallus and the pseudostroma contain lichexanthone, a lichen product that causes these structures to fluoresce yellow when lit with a long-wavelength UV light. The combination of characteristics of the lichen that distinguish it from others in Astrothelium are the presence of lichexanthone in thallus and ascomata, and the ascospores, which are divided by from 7 to 9 septa and have dimensions of 50–55 by 12–17 μm.
Astrothelium philippinense is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae. Found in the Philippines, it was formally described as a new species in 2016 by lichenologists André Aptroot and Felix Schumm. The type specimen was collected from Mount Talinis at an altitude between 1,100 and 1,600 m ; there, it was found in a rainforest growing on smooth tree bark. The lichen has a smooth and shiny, pale ochraceous-green thallus with a cortex and a thin brown to black prothallus line. It covers areas of up to 7 cm (2.8 in) in diameter. The presence of the lichen induces galls in the host plant, leading to the formation of numerous wart-like structures about 1–2 mm wide. No lichen products were detected in collected samples of the lichen using thin-layer chromatography. The combination of characteristics of the lichen that distinguish it from others in Astrothelium are the bullate, gall-like thallus; and the ascomata that are immersed in large thallus verrucae that are covered by thallus. The ascospores of A. philippinense number four per ascus. They are hyaline, ellipsoid, and muriform, with dimensions of 125–170 by 30–35 μm.
Astrothelium pseudannulare is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae. Found in Ecuador, it was formally described as a new species in 2016 by Dutch lichenologists André Aptroot and Javier Etayo. The type specimen was collected from the Podocarpus National Park at an altitude of 3,000 m (9,800 ft); there, it was found in a montane forest growing on smooth tree bark. The lichen has a smooth and shiny, olive-green thallus comprising patches of cortex that break through the host bark, covering areas about 1.0 to 3.5 mm in diameter. No lichen products were detected from collected samples of the lichen using thin-layer chromatography. The combination of characteristics of the lichen that distinguish it from others in Astrothelium are the rough thallus; the distribution of the ascomata, which ranges from solitary to irregularly confluent; and the form of the ascomata, which ranges from prominent to sessile. The ascospores are hyaline, spindle-shaped (fusiform), and have three septa; they measure 62–80 by 20–25 μm. The species epithet pseudannulare alludes to its resemblance to Astrothelium annulare, another species with large 3-septate spores.
Astrothelium pseudoferrugineum is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae. Found in Indonesia, it was formally described as a new species in 2016 by Dutch lichenologist André Aptroot. The type specimen was collected in 1937 by Pieter Groenhart on Jombang (Java); there, it was found in a disturbed rainforest growing on smooth tree bark. The lichen has a smooth and somewhat shiny to glossy, bright orange thallus with a cortex but without a prothallus. The orange crust is about 0.1 mm thick and covers areas of up to 3 cm (1.2 in) in diameter. The use of thin-layer chromatography shows the lichen contains an orange anthraquinone, possibly parietin. The main characteristics of the lichen that distinguish it from others in Astrothelium are its immersed to erumpent, whitish pseudostromata. It is named for its similarity to Astrothelium ferrugineum, from which it differs in its glossier thallus and larger ascospores.
Polymeridium rhodopruinosum is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae. Found in Puerto Rico, it was formally described as a new species in 2016 by Dutch lichenologist André Aptroot. The type specimen was collected by the author from Vereda Los Viveros in the Maricao State Forest (Maricao) at an altitude of 850 m (2,790 ft); there, it was found in a sclerophyllous forest growing on tree bark. The lichen has a white thallus lacking a cortex. The only lichen product detected from collected specimens using thin-layer chromatography was an anthraquinone compound. The combination of characteristics of the lichen that distinguish it from others in Polymeridium are the ascomata with external, red pruina that turn dark blood red with a K+ spot test; and the dimensions of its ascospores.
Astrothelium bivelum is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae. Found in Brazil, it was formally described as a new species in 2016 by lichenologists André Aptroot and Marcela Cáceres. The type specimen was collected by the authors in the Parque Natural Municipal de Porto Velho, in a primary rainforest. The lichen has a smooth and somewhat shiny, ochraceous-green thallus with a 0.4 cm-wide rough and irregular prothallus; the thallus covers areas of up to 3 cm (1.2 in) in diameter. The presence of the lichen does not induce the formation of galls in the host. The ascomata are pear-shaped (pyriform), measure 0.5–0.7 mm in diameter, typically aggregate in groups of two to six, and are usually immersed in the bark tissue. The characteristics that distinguish it from other members of Astrothelium include the diffusely pseudostromatic, erumpent ascomata that are covered by thallus and have an external pink pigment, with each containing a single group of fused ascomata; and the 5-septate ascospores. A. bivelum is one of the few Astrothelium-like species with 5-septate ascospores that does not contain lichexanthone.
Architrypethelium hyalinum is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae. Found in Costa Rica and Brazil, it was formally described as a new species in 2008 by lichenologist André Aptroot. The type specimen was collected by Harrie Sipman from the Las Cruces Biological Station in Puntarenas. The lichen has a smooth to uneven, olive-green thallus. Its ascomata occur solitarily, have an apical ostiole, and measure 0.7–1.5 mm in diameter. Ascospores number 4 to 8 per ascus, have an oblong to ellipsoid shape with 3 septa, and measure 100–150 by 30–50 μm. These spores are among the largest of the 3-septate lichens in the Trypetheliaceae. Both the thallus and ascomata contain lichexanthone, a lichen product that causes these structures to glow yellow when lit with a long-wavelength UV light; A. hyalinum is the only species in genus Architrypethelium that contains lichexanthone.
Polymeridium xanthoexcentricum is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae. It is found in southwestern Bolivia.
Polymeridium albidoreagens is a species of corticolous (bark-dwelling) lichen in the family Trypetheliaceae. Found in Brazil, it was formally described as a new species in 2013 by lichenologists André Aptroot, Aline Anjos Menezes, and Marcela Cáceres. The type specimen was collected in Rondônia's Porto Velho, Parque Natural Municipal, at an altitude of 100 m (330 ft); other specimens have been reported from Ceará in the Chapada do Araripe. This lichen species is similar to Polymeridium albidum but is characterized by its UV+ (yellow) thallus. The ecorticate, whitish-grey thallus features spherical, erumpent, solitary ascomata with diameters ranging from 0.2 to 0.4 mm and an apical ostiole. The hamathecium is not inspersed, and the ascospores number 8 per ascus, contain 3 septa, and measure 20–23 by 6–8 μm without ornamentation. The lichen's chemistry includes the presence of lichexanthone.
Polymeridium albidovarians is a species of corticolous (bark-dwelling) lichen in the family Trypetheliaceae. The lichen was first discovered in Indonesia on the island of Java, specifically at the Kawi-complex, Tjemarakandang, at an altitude of 2,700 m (8,900 ft). This species closely resembles Polymeridium albidum, but is differentiated by its UV+ (yellow) thallus and inspersedhamathecium. The yellowish-white, ecorticate thallus features spherical, erumpent, solitary ascomata measuring 0.2–0.4 mm in diameter, with an apical ostiole. The hamathecium is inspersed with oil droplets, and the ascospores number eight per ascus, contain three septa, and measure 20–23 by 6–8 μm without ornamentation. The lichen's chemistry is characterized by the presence of lichexanthone.
Polymeridium catapastoides is a species of corticolous (bark-dwelling) lichen in the family Trypetheliaceae. It has a widespread distribution, with occurrences reported in Australia, Malaysia, Thailand, Indonesia, Papua New Guinea, and Brazil. The lichen was formally described as a new species in 2013 by Dutch lichenologist André Aptroot. Resembling Polymeridium catapastum, P. catapastoides can be differentiated by its non-fluorescent thallus under ultraviolet light (UV–). The type specimen was collected in Cape Tribulation, Queensland (Australia), north of Daintree, growing on tree bark.
Polymeridium costaricense is a species of corticolous (bark-dwelling) lichen in the family Trypetheliaceae. Found in Costa Rica and Brazil, it was formally described as a new species in 2013 by Dutch lichenologist André Aptroot. The lichen bears a resemblance to Polymeridium chioneum but is differentiated by its non-fluorescent thallus under ultraviolet light (UV–). The type specimen of P. costaricense was collected in Palo Verde National Park, Guanacaste, Costa Rica, along the trail to Rio Tempisque, growing on tree bark. The type specimen of P. costaricense was initially reported and illustrated as P. chioneum by Aptroot and colleagues in 2008. Additional specimens have been examined from Chapada do Araraipe, Ceará, Brazil.
Polymeridium inspersum is a species of corticolous (bark-dwelling) lichen in the family Trypetheliaceae. Found in pantropical regions, it was formally described as a new species in 2013 by Dutch lichenologist André Aptroot. This lichen closely resembles Polymeridium subcinereum but is differentiated by its inspersedhamathecium. The type specimen of P. inspersum was collected by the author in Kuranda, Queensland, along the Jumrum Creek track, growing on a twig.
Polymeridium multiforme is a species of corticolous (bark-dwelling) lichen in the family Trypetheliaceae. It is found in the Neotropics, with specimens recorded from Brazil, Guyana, and Venezuela. The lichen was described by Dutch lichenologist André Aptroot in 2013. This lichen closely resembles Polymeridium quinqueseptatum, but its thallus is whitish-grey and fluoresces yellow under ultraviolet light. Additionally, the hamathecium of P. multiforme is not interspersed with oil droplets. The type specimen was collected in Guyana, at the base of Makarapan Mountain, on the bark of a Myrsinaceae tree.
Polymeridium multiseptatum is a species of corticolous (bark-dwelling) lichen in the family Trypetheliaceae. Found in Brazil, it was described by lichenologists André Aptroot, Aline Anjos Menezes, and Marcela Cáceres in 2013. The thallus of P. multiseptatum is ecorticate and whitish-grey in color, with the distinctive feature of fluorescing yellow under ultraviolet light. This lichen closely resembles Polymeridium quinqueseptatum, with the primary distinguishing characteristic being the UV+ (yellow) thallus. The ascomata are 0.2–0.4 mm in diameter, featuring a solitary, spherical centrum that is erumpent. The ostiole is apical, and the hamathecium is interspersed with oil droplets, with filaments profusely anastomosing. There are eight ascospores per ascus, which are iodine-negative, 4–7-septate, and measure 18–28 by 5–7 μm. The ascospores are not ornamented, and the wall is not thickened. The lichen's chemistry reveals the presence of lichexanthone. The type specimens were collected in Chapada do Araripe, Ceará, at an altitude of 800 m (2,600 ft), where it was found growing on tree bark.
Polymeridium neuwirthii is a species of corticolous (bark-dwelling) lichen in the family Trypetheliaceae. Found in Venezuela, it was formally described as a new species in 2014 by Dutch lichenologist André Aptroot. This ecorticate lichen has a pinkish-grey thallus that does not fluoresce under ultraviolet light. P. neuwirthii is similar to Polymeridium quinqueseptatum but can be differentiated by its hamatheciuminspersed with large oil droplets and consistently 7-septate, rough ascospores. The ascomata are 0.4–0.6 mm in diameter, with a spherical centrum that is erumpent and solitary. The ostiole is apical, and the hamathecium contains large oil droplets. There are eight ascospores per ascus, which are iodine-negative, 7-septate, and measure 30–33 by 9–10 μm. The ascospore wall is roughly ornamented. No chemical substances have been detected in this lichen. The type specimen was collected in Puerto Ayacucho, Venezuela, on a twig of a shrub. The species is named in honour of the collector of the type and only specimen, Gerhard Neuwirth.
Polymeridium submuriforme is a species of corticolous (bark-dwelling) lichen in the family Trypetheliaceae. It occurs in the Philippines. This ecorticate lichen is characterized by its pinkish-grey thallus, which does not fluoresce under ultraviolet light. P. submuriforme is similar to Polymeridium cinereonigricans but can be distinguished by its much smaller ascospores and inspersedhamathecium. The ascomata measure 0.3–0.6 mm in diameter, with a solitary, spherical centrum that is erumpent. As the ascomata age, the wall expands up to 0.2 mm sideways. The ostiole is apical, and the hamathecium is inspersed. The ascospores number 6–8 per ascus, iodine-negative, somewhat muriform, and measure 18–20 by 6–7.5 μm. These ascospores are not ornamented and are surrounded by a 1–2 μm wide gelatinous sheath. No chemical substances have been detected in this lichen. The type specimen was collected from Leyte on tree bark.
Polymeridium tribulationis is a species of corticolous (bark-dwelling) lichen in the family Trypetheliaceae. Found in Australia, it was formally described as a new species in 2013 by Dutch lichenologist André Aptroot. This ecorticate lichen is characterized by its yellowish-white thallus, which does not fluoresce under ultraviolet light. P. tribulationis closely resembles Polymeridium sulphurescens, but can be distinguished by its hamathecium, which is inspersed with oil droplets. The ascomata, measuring 0.4–0.6 mm in diameter, have a spherical centrum that is mostly covered by the thallus. The ostiole is apical and usually surrounded by a ring. The ascospores number eight per ascus, are iodine-negative, have three septa, and measure 20–24 by 7–10 μm without ornamentation. No chemical substances have been detected in the lichen. The type specimen was collected by Mason Hale from Cape Tribulation, Queensland, on tree bark.
