Architrypethelium barrerae sp . nov . from a cloud forest in Veracruz , Mexico

A new species of corticolous microlichen, Architrypethelium barrerae, is described from the cloud forest in the ecological park ‘El Haya’ in Xalapa, Veracruz, Mexico. It is characterized by two-spored asci, cortex UV+ yellow, and an internal K+ pigment in its pseudostromata. Photographs of macroand microscopic structures are presented. Key words—tropical lichens, Trypetheliales, Trypetheliaceae Introduction Cloud forests contain the highest vascular plant diversity in Mexico (Rzedowski 1996). Despite the rich documentation of the vascular flora there, lichen diversity from these, as with other tropical regions in Mexico, is poorly known. Although some monographs and synopses have improved our understanding of tropical lichens for some genera (e.g., Ahti 2000, Kurokawa 1962, Lücking 2008), overall little is known about the entire tropical lichen flora. New species have been described from tropical regions (e.g., CórdovaChávez & al. 2014, Guzmán-Guillermo & al. 2019, Hodkinson & al. 2014) at a rather fast rate considering the paucity of specimens from such regions. This highlights the potential for a great number of overlooked species yet to be described. Tropical Mexican lichens such as Trypetheliaceae are very poorly known, and few reports have been published. This family comprises 16 mostly corticolous genera with perithecioid ascomata, with or without stromatic tissues, and 750 ... Guzmán-Guillermo & Llarena Hernández sometimes with xanthones and anthraquinones (Aptroot & Lücking 2016). Within this family, Architrypethelium Aptroot contains perithecioid crustose lichens similar to Astrothelium Eschw., but with large (>100 μm), brown, often 3-septate ascospores (Aptroot 1991). To date, this genus includes eight accepted species, of which six are known to occur in the neotropics (Aptroot & al. 2008, Aptroot & Lücking 2016, Flakus & al. 2016, Lücking & al. 2016), one is paleotropical (Luangsuphabool & al. 2018), and one has a pantropical distribution (Aptroot & Lücking 2016). As part of a larger project, a survey was carried out to collect microlichens in the megadiverse region in the center of Veracruz, a state of Mexico. We collected corticolous microlichens in tropical vegetation, such as the cloud forest in the ecological park ‘El Haya’ in Xalapa city. One result of our efforts was the discovery of a previously unknown Architrypethelium, which we propose as the new species A. barrerae. Materials & methods The material studied is preserved in the mycology collections in the herbarium of Universidad Veracruzana, Xalapa, Veracruz, Mexico (XALU) and the herbarium of Escuela Nacional de Ciencias Biológicas, Mexico City, Mexico (ENCB). Specimens were collected in El Haya ecological park in Xalapa, Veracruz, México, located at 19.5181°N 96.9436°W and 1300 m a.s.l. Terminology is based on Aptroot & al. (2008) and Aptroot & Lücking (2016), and morphological analysis was conducted by conventional lichenological techniques following Brodo & al. (2001). Sections for anatomical examination were made by hand under a Zeiss Stemi Dv4 stereoscope and microscopical measurements were taken in Lugol’s solution using a Zeiss Primo Star microscope. Thin layer chromatography (TLC) was performed using solvent C following conventional chromatography techniques described in Elix (2014). Spot tests used were C (NaClO) and K (KOH 5%). To test hymenium amyloidity, sections of ascomata were mounted with I (Lugol’s solution) and resultant coloration was observed.


Introduction
Cloud forests contain the highest vascular plant diversity in Mexico (Rzedowski 1996). Despite the rich documentation of the vascular flora there, lichen diversity from these, as with other tropical regions in Mexico, is poorly known. Although some monographs and synopses have improved our understanding of tropical lichens for some genera (e.g., Ahti 2000, Kurokawa 1962, Lücking 2008, overall little is known about the entire tropical lichen flora. New species have been described from tropical regions (e.g., Córdova-Chávez & al. 2014, Guzmán-Guillermo & al. 2019, Hodkinson & al. 2014) at a rather fast rate considering the paucity of specimens from such regions. This highlights the potential for a great number of overlooked species yet to be described.
Tropical Mexican lichens such as Trypetheliaceae are very poorly known, and few reports have been published. This family comprises 16 mostly corticolous genera with perithecioid ascomata, with or without stromatic tissues, and sometimes with xanthones and anthraquinones . Within this family, Architrypethelium Aptroot contains perithecioid crustose lichens similar to Astrothelium Eschw., but with large (>100 µm), brown, often 3-septate ascospores (Aptroot 1991). To date, this genus includes eight accepted species, of which six are known to occur in the neotropics (Aptroot & al. 2008, Flakus & al. 2016, one is paleotropical (Luangsuphabool & al. 2018), and one has a pantropical distribution .
As part of a larger project, a survey was carried out to collect microlichens in the megadiverse region in the center of Veracruz, a state of Mexico. We collected corticolous microlichens in tropical vegetation, such as the cloud forest in the ecological park 'El Haya' in Xalapa city. One result of our efforts was the discovery of a previously unknown Architrypethelium, which we propose as the new species A. barrerae.

Materials & methods
The material studied is preserved in the mycology collections in the herbarium of Universidad Veracruzana, Xalapa, Veracruz, Mexico (XALU) and the herbarium of Escuela Nacional de Ciencias Biológicas, Mexico City, Mexico (ENCB). Specimens were collected in El Haya ecological park in Xalapa, Veracruz, México, located at 19.5181°N 96.9436°W and 1300 m a.s.l. Terminology is based on Aptroot & al. (2008) and , and morphological analysis was conducted by conventional lichenological techniques following Brodo & al. (2001). Sections for anatomical examination were made by hand under a Zeiss Stemi Dv4 stereoscope and microscopical measurements were taken in Lugol's solution using a Zeiss Primo Star microscope. Thin layer chromatography (TLC) was performed using solvent C following conventional chromatography techniques described in Elix (2014). Spot tests used were C (NaClO) and K (KOH 5%). To test hymenium amyloidity, sections of ascomata were mounted with I (Lugol's solution) and resultant coloration was observed. Guzm  Thallus corticate, green to yellowish, smooth to uneven. Ascomata trypethelioid, with apical ostioles, 0·7-1·2 mm diam., erumpent to prominent, covered by thallus except for the ostiolar area. Ascomata internally with a yellow pigment. Wall fully carbonized and K+ olive green, apical and lateral portions thick, base thin and touching the substrate. Hamathecium not inspersed. Asci cylindrical, longer than 300 µm. Ascospores two per ascus, 160-200 × 50-75 µm, oblong-ellipsoid, triple-septate, outer lumina much smaller than inner lumina, lumina rounded in the corners, brown when free from the ascomata.
Ecology & distribution-Corticolous in open areas, in cloud forest at 1300 m a.s.l. Sometimes covered with moss. Known only from the type locality in the El Haya ecological park in Xalapa city, Veracruz, Mexico.
Comments-Architrypethelium barrerae is morphologically similar to the other Architrypethelium species but contains lichexanthone in its cortex. Within the genus, only A. hyalinum Aptroot is known to have this chemistry, but its spores are shorter (160-200 × 30-50 µm) and its asci are 4-8-spored . Another characteristic only found in A. barrerae is the pseudostromata with a conspicuous internal yellow pigment which is K+ yellow to dark red.