High lichen species richness in Polylepis australis forest: new records from South America and Argentina

The Polylepis australis forests in Central Argentina support a great biodiversity in a relative small area. As a result of this study focusing on the diversity and ecology of the lichen communities of these forests, we present five new species for South America: Rinodina ficta, R. malcolmii, R. obscura, Usnea glabrata, Tetramelas triphragmioides and eight taxa new for Argentina: Calicium abietinum, Erioderma leylandii subsp. leylandii, Leptogium microstictum, Phaeophyscia endococcinodes, Rinodina dolichospora, R. intermedia, Usnea cirrosa and U. flavocardia. Unidentified Usnea species, similar to U. silesiaca, were also characterized and discussed.


Introduction
Forest and shrubland patches with canopies dominated by ~28 species of the genus Polylepis occupy the uppermost forested slopes of the high mountains of tropical and subtropical South America (Fjeldså & Kessler 2004;Renison et al. 2018;Segovia et al. 2018). These Polylepis forests exhibit huge environmental differences with a latitudinal distribution of 4500 km from Venezuela to Central Argentina, elevation ranges from 900 to 5000 m above sea level and includes the world record for the highest elevation displaying tree growth, and a large range of precipitations from 100 to 3000 mm (Harden et al. 2013;Cuyckens et al. 2016;Renison et al. 2018). As a result of their isolation and a relatively stable climate throughout the Pleistocene, many Polylepis forests are inhabited by species of birds, rodents, plants and fungi with high levels of endemisms (Tarifa & Yensen 2001;Calvelo & Liberatore 2002;Fjeldsa 2002;Bellis et al. 2009;Robledo & Renison 2010;Sylvester et al. 2017;Ames-Martínez et al. 2019;Quispe-Melgar et al. 2020). The ecology and biodiversity of the heterogeneous forest types classified as 'Polylepis forests' are still poorly represented in the scientific literature with a recent review reporting 139 published studies, of which only 25 studies centered on Polylepis forest biodiversity (Renison et al. 2018).
Studies that report lichen diversity in Polylepis forests are particularly scarce. To the best of our knowledge, only two have been published. One in the context of edge effects in two Polylepis forest patches in the Andes of Colombia (Pulido Herrera & Ramos Montaño 2016) and a second regarding the effects of fires in the mountains of Central Argentina (Perazzo & Rodriguez 2019). Given the island nature of mountain highlands and the diversity of habitat types for Polylepis forests from arid regions to wet cloud forests, the lichen communities of the high mountain Polylepis forests of South America are largely unexplored and probably hide a wealth of new species to science.
According to the IUCN, 15 of the approximately 30 described Polylepis tree species are considered threatened. Hence, the forests they dominate including their endemic biota are also considered threatened (IUCN 2020). The reasons for their threatened status involve the limited distribution range of many of the Polylepis species in combination with an important human pressure on the forests. These forests are subjected to small scale, but continuous logging, burning to produce pastures for domestic livestock or land for agriculture, invasion by exotic species and are vulnerable to quick climate change (Fjeldså 2002;Fjeldså & Kessler 2004;Cingolani et al. 2008;Renison et al. 2013;Cuyckens et al. 2016). The description of the Polylepis forests vanishing biodiversity has the potential to promote awareness from conservation agencies and local people about their rich endemic biota. In particular, to date no Polylepis forest endemic species for the most studied taxa such as birds, mammals and vascular plants have been described in the southernmost forest. However, new species to science and a host of possible endemics are emerging for wood decaying fungi and lichens in this location (Robledo et al. 2003;Rodriguez et al. 2011Rodriguez et al. , 2017. The southernmost Polylepis forests are dominated by P. australis and are located in the Higher Cordoba Mountain range of Central Argentina. These forest patches represent less than 10% of the vegetation cover in this location (Cingolani et al. 2008;Renison et al. 2013). Within the wooded patches, in addition to P. australis¸ as a secondary tree species Maytenus boaria may be found, as well as the shrub species Escalonia cordobensis and Berberis buxifolia and a large number herbaceous plants, ferns and grasses. The plant diversity along with climate gradient provide a wide variety of habitats ideal for the development of very diverse lichen communities. Recently, a review of the lichen genus Pannaria in Argentina included two new records in the P. australis forests (Passo et al. 2020) and the presence of one Oropogon species was rediscovered here (Rodríguez & Filippini 2020). However, the lichen composition in P. australis forests is far from complete. The objective of this work is to describe noteworthy lichen species in Polylepis australis forests including new records for South America and Argentina.

Material and methods
Between the years 2015 and 2020 more than 1000 lichen collections were made in Polylepis australis forests from the mountains of Central Argentina (31°34′S, 64°50′W). The elevation range is 1200-2800 m above sea level (Renison et al. 2002). Mean temperatures of the coldest and warmest months are 5.0°C and 11.4°C, respectively, with no frost-free period. Mean annual precipitation is 920 mm, with 83% of the rainfall being concentrated in the warmer months, between October and April (Colladon 2002; Renison et al. 2002). The vegetation in the mountains of Central Argentina consists of a mosaic of tussock grasslands, grazing lawns, degraded grazing lawns, eroded areas with exposed rock surfaces, granite outcrops, closed and open Polylepis australis forests or shrublands (Fig. 1). The lichen collection sites were in the Condorito National Park under permit DRC 321 (Argentinian National Parks Administration) issued to the first author.
The specimens were studied morphologically under stereomicroscope using standard techniques in lichenology. The anatomical characters were studied through handmade sections mounted in water or KOH. The spore measurements are reported with their range. The percentage of cortex, medulla and axis in Usnea (%CMA) is reported as min−X−max where 'min' and 'max' are the extreme observed values and X the arithmetic mean. The lichen substances were identified by TLC (Orange et al. 2001) using A, B´, C and/or G solvents. Also K (5% KOH), C (commercial bleach), KC (K followed by C), PD and UV (fluorescence at 366 nm) were used when necessary (not needed for all species). For the specific morphological characters studied in each genus see the literature in the descriptions. All specimens are preserved in the CORD herbarium.  For a detailed description see Jørgensen & Arvidsson (2002).
Notes. This subspecies is similar to E. leylandii subsp. velligerum (Tuck) Jørg., cited for Patagonia in cold temperate Nothofagus ssp. forests, which is characterized by the presence of argopsin instead of pannarin, and a more conspicuously hirsute upper surface (Jørgensen 2001).
Notes. This rare and poorly known species is characterized by its minute foveolae on the upper surface. It is similar to L. foveolatum Nyl. that has larger foveolae and spores (Kitaura 2012).

Distribution and ecology.
It is the first record for the country and for southern South America, previously cited for USA, Mexico (Sierk 1964;Kitaura 2012), and Venezuela (Marcano et al. 1996). So far, it is only known from one specimen, growing among mosses on a shaded place. For a detailed description see Moberg (1995).
Notes. This species is easily recognizable by the presence of orange-red pigment in the medulla.
Distribution and ecology. In South America the species is known from Brazil, Chile, Colombia, Peru and Venezuela (Moberg 1993;Sipman et al. 2008). Here, it has been found growing over bryophytes on stone. Notes. The type (Pachysporaria with granular inclusions) and size of spores separate Rinodina dolichospora from the other species of Rinodina from Polylepis forests studied in this contribution.

Rinodina dolichospora
Distribution and ecology. The species has been described from Brazil (Malme 1902). It is also known from Australia (Mayrhofer et al. 1999), North America (Sheard 2010) and southern Europe (Giralt et al. 2009).
Notes. This species is separated from the other Rinodina species studied here based on the very thin thallus, the smaller Pachysporaria-type spores and their ontogeny of type B.

Distribution and ecology.
Rinodina ficta is new for South America. It is described from South Africa (Stizenberger 1890; Mayrhofer et al. 2014). It occurs also in New Zealand (Mayrhofer et al. 2007, as R. boleana) and Mediterranean Europe (Mayrhofer et al. 2014). It has been found on dead wood in well conserved Polylepis forest stands. For a detailed description see Mayrhofer et al. (2001) Diagnostic characters. Thallus light-gray-green or ochraceous to light brown (Fig. 3H), frequently with marginal lobes; apothecia sessile, broadly attached, frequent, often contiguous with dark brown to black disc (Fig. 3I); ascospores large, 20-31 × 12-15 µm, submuriform with typically more than four locules at maturity (Fig. 3J).

Distribution and ecology.
Rinodina intermedia is widely distributed in dry regions at low altitudes; known from Colombia and Ecuador in South America, the Caribbean, western North America, Macaronesia, southern Europe, and north to the Channel Islands, U.K., eastwards to the Himalaya and as far south as Kenya and the Cape Verde Islands in Africa (Mayrhofer et al. 2001, Sheard 2010. It grows on soil or terricolous bryophytes, often in crevices between rocks, rarely on horizontal stems of dead shrubs (Mayrhofer et al. 2001, Sheard 2010 (Fig. 3K-M) For a detailed description see Elix et al. (2020).
Distribution and ecology. Rinodina malcolmii is new from South America. This species has been recently discovered (Elix et al. 2020) in New Zealand. Here it grows on P. australis bark and on twigs of Maytenus boaria or Berberis buxifolia mixed with many other crustose species (Lecanora spp., Caloplaca spp.) and small fruticose Ramalina and Usnea species. For a detailed description see Mayrhofer et al. (1999).
Distribution and ecology. Rinodina obscura is new from South America. It has been described in Australia (Müller 1893) and is widely distributed in southeastern mainland Australia and Tasmania (Mayrhofer et al. 1999).
It is a rare species in P. australis forests.
Chemistry. Medula K+ yellow turning orange. TLC: usnic and norstictic acids; K-. TLC: usnic and psoromic acids. There are other chemotypes in this species , also in Argentina (unpubl. data). However, the specimens studied here belongs to the norstictic or psoromic acids chemotypes.
Notes. The recently published U. subaranea and U. subglabrata (Truong & Clerc 2016) are similar to U. glabrata. The former developed circular soralia that remain isolated, the cortex is rigid and the medullary hyphae arranged in bundles. The second species presents more conspicuous papillae and stictic acid in medulla. The characteristics observed fit well with the variation of U. glabrata described in Halonen et al. (1998)  Usnea aff. silesiaca (Fig. 4K-N) Diagnostic characters. Thallus subpendulous to shrubby, up to 10 cm long, yellowish -green, sometimes slightly pruinose (Fig. 4K); ramifications anisotomic dichotomous; trunk and basal part of main branches jet black sometimes with reddish pigment, with numerous and conspicuous annular cracks extending upwards (Fig. 4L); branches cylindrical or tapering; secondary branches not narrowed at attachment points; segments cylindrical and terete in transverse section; papillae present, verrucous, mainly on main branches; fibrils slender, frequently in a fish-bone pattern, up to 5 mm; soralia variable: initially punctiform then rounded to irregular, planar to concave, larger than half of the diameter of the branch, remaining discrete, sometimes confluent (Fig. 4M); isidiomorphs rare, generally absent on mature soralia; cortex matte to ± glossy, thick 10.7-12.9-15.2%; medulla white, compact to dense, very thin 4.4-12.3-16.2%; axis thick 39.8-49.1-61.7% (Fig. 4N).
Ecology. This species has been found growing on P. australis and rarely on M. boaria or fences.
Notes. Usnea aff. silesiaca is very similar to Usnea silesiaca (Clerc 1991(Clerc , 2006(Clerc , 2007 sharing the extended black pigment and anulate base, the CMA value and the morphology of branches and segments. Also the variation of soralia characteristics is in the range of U. silesiaca. However, the chemistry of Usnea aff. silesiaca without medullary compounds has not been observed previously in U. silesiaca and the medulla is compact to dense. Also there are specimens with a red tinge when the black pigmentation finishes in the first mm of main branches. For all these reasons, up to the moment, Usnea silesiaca cannot be confirmed in South America and more studies are needed to confirm the identity of Usnea aff. silesiaca. This species is similar to U. columbiana, a common subpendulous (to pendulous) species with an extended jet black base and thick cortex. However, U. columbiana possesses tuberculate soralia, tubercles and salazinic acid.
Notes. This species is very notable because of the pale yellow color. Cratiria lauricassiae is another common buellioid species with triseptate spores in Polylepis forests. However, the thallus is green, K+ yellow-orange, because of the presence of norstictic acid and UV-.
Chemistry. K-, C-; there are no substances detected by TLC.
Notes. The presence of isidia and the type of rhizines separate Hypotrachyna vexans from H. americana, a very common species in Polylepis forests that possesses coacervate rhizines and no isidia or soredia (Calvelo & Estrabou 1997).
Distribution and ecology. Hypotrachyna vexans has been recorded from Asia, North America and South America: Argentina, Brazil, Ecuador and Venezuela (Calvelo & Estrabou 1997;Spielmann 2006). Previously, it has been recorded from northwest Argentina as Everniastrum vexans (Calvelo & Estrabou 1997). It is rare in the Polylepis forest. For a detailed description see Galloway & Jørgensen (1995).
Distribution and ecology. The species is widespread globally, especially in temperate and subtropical regions. In Argentina, it has been cited for Buenos Aires and Patagonia (Calvelo & Liberatore 2002). Leptogium cyanescens grows on bark, rarely on stone and it is very common in Polylepis forests. For a detailed description see Galloway & Jørgensen (1995).
Distribution and ecology. The species has been previously recorded for Patagonia (Calvelo & Liberatore, 2002). It has been found on the bark of Polylepis. Leptogium phyllocarpum (Pers.) Mont., Annales des Sciences Naturelles Botanique 10: 134. 1848. (Fig. 7E) For a detailed description see Galloway & Jørgensen (1995) Diagnostic characters. Thallus subpulvinated, swelling with wet, loosely adnate, pale to dark gray; lobes oblong, anastomosing, with undulating margins; uppers surface with numerous prominent wrinkles or outgrowths; lower surface paler, also wrinkled, without hairs; apothecia submarginal to laminal, short pedicelate to sessile, with thick swelling margins. Distribution and ecology. It has been recorded in different regions of Argentina, probably a widely distributed species (Calvelo & Liberatore 2002). This species is very common on Polylepis forest and it grows on bark and stone under the canopy. For a detailed description see Adler & Calvelo (1993).
Diagnostic characters. Thallus foliose, submonophilous, more or less orbicular, centrally attached to substratum, dark brown to ochraceous; lobes wide, upper surface irregular, covered by small globose to coralloid isidia; lower surface cream-whitish, covered by fine tomentum, with broad white cyphellae; apothecia very rare, not seen.
Distribution and ecology. Usnea subelegans is widespread from Mexico to Argentina (Gerlach et al. 2017