New records of Hypoxylon (Ascomycota, Hypoxylaceae) for the Argentine Yungas

Hypoxylon aeruginosum var. aeruginosum, H. fendleri and H. undulatum collected in the subtropical montane forest from northwest Argentina are reported for the first time for the Southern Cone. We describe and analyze their teleomorph and anamorph, and provide photographs and drawings of the most relevant structures. Moreover, a key to Hypoxylon species so far known from Argentina is given.


INTRODUCTION
Hypoxylon Bull. is the largest and most complex genus of the family Hypoxylaceae (Wendt et al., 2018). The genus includes species with unipartite hemispherical to effused-pulvinate stromata with colored surface and homogeneous waxy to fibrous tissue bellow perithecial layer; and a nodulisporium-like anamorph, but with variations in the branching patterns of the conidiophores (Daranagama et al., 2018;Ju & Rogers, 1996;Wendt et al., 2018). Their stromata release diverse pigments in contact with KOH solution. These pigments are secondary metabolites deposited as colored granules below the stromatal surface and surrounding the perithecia, which frequently can possess species-specific chemical entities useful to discriminate Hypoxylon species (Hellwig et al., 2005;Kuhnert et al., 2014ab;Stadler et al., 2008).
Members of the genus are recognized as saprobes or as facultative parasites when found on wood, but can also be isolated as part of the en-dophytic community in most of the forest trees (Kuhnert et al., 2014a). The majority of species has been reported from warmer climates especially the Tropics. This however could be the result of less extensive sampling in subtropical or temperate areas of the world .
Since the beginning of the century, several surveys on the xylariaceous diversity have been carried out in the Argentine Yungas, the southernmost subtropical montane forest of the Neotropics (Hladki, 2007;Kuhnert et al., 2015Kuhnert et al., , 2017Sir et al., 2012abc, 2013Sir et al., 2012abc, , 2015Sir et al., 2012abc, , 2016ab, 2018Sir & Hladki, 2014). These mycological trips showed that the genus Hypoxylon is a remarkable, yet poorly documented component of the mycobiota of this ecosystem (Sir et al., 2012a). Hladki & Romero (2009ab) and Catania & Romero (2010) published the first reports of Hypoxylon species from the Argentine northwest, recording less than ten species. In one of our previous studies, we already increased the knowledge about the diversity of the genus (Sir et al., 2016). In this context we proposed three new species: H. calileguense Sir, Kuhnert, Hladki & A.I. Romero, H. lilloi Sir, Lamb. & Kuhnert and H. spegazzinianum Sir, Kuhnert, Hladki & A.I. Romero; and recognized  Here we report, three new species records of Hypoxylon for the Southern Cone of South America, collected in the Argentine Yungas. Also, we provide an emended taxonomic key for Hypoxylon species known from Argentina.

MATERIALS AND METHODS
Fungal collections were obtained between 2011 and 2015 at the Parque Nacional Calilegua and Reserva Provincial Las Lancitas from Jujuy province, Reserva provincial de Flora y Fauna Acambuco and Parque Nacional el Rey from Salta province, and Parque Sierra de San Javier from Tucuman province.
The materials were studied and isolated according to Sir et al. (2016). The color of stromata and extractable pigments are described following the color chart of Rayner (1970). The perispore was analysed under field-emission scanning electron microscope (SEM-Zeiss, Supra 55vp) in the Centro Integral de Microscopía Electrónica (CIME, CONICET-UNT). The reference collections were deposited in the LIL herbarium. Additional specimens examined were obtained from LIP and K herbaria (acronyms are from Index Herbariorum, http://sciweb.nybg.org/ science2/IndexHerbariorum.asp). The author names of the fungal species were taken from Index Fungorum (http://www.indexfungorum. org/).  . This taxon is distinct from other Hypoxylon by its blue effused-pulvinate stromata and nearly equilateral ascospores which measure less than 11.5 µm (Ju & Rogers, 1996). The anamorph of this species is characterized and illustrated for first time herein.

Taxonomic part
In our collection a part of the specimen was found on top of another Hypoxylon sp. This phenomenon was also observed by Laessøe et al. (2010), who suggested a fungicolous life style.   Ju & Rogers (1996). Secondary metabolites: mitorubrin, mitorubrinol, mitorubrinol acetate, orsellinic acid and BNT (Stadler et al., 2008).  ; this is the first record of the species for a subtropical area of South America. The taxon can be identified by its vinaceous stromatal surface, orange granules, orange extractable pigments, ascospores with sigmoid germ slit and nodulisporium-like anamorph (Ju & Rogers, 1996). The characteristics of the cultures obtained from Argentinean material were in accordance with previous descriptions for species (Ju & Rogers, 1996). Laessøe, Mycol. Mem. 20: 199 (1996 . This species is characterized by having effused-pulvinate stromata, fuscous surface with strongly exposed perithecial mounds, ostioles with a raised disc and by lacking apparent

Key to species of Hypoxylon in Argentina
KOH-extractable pigments (Ju & Rogers, 1996). The cultures obtained from Argentine material show the same features described for the ex-type culture of this species. Medina et al. (2017) reported one specimen for Argentina found on Ocotea porphyria (Griseb.) van der Werff (Lauraceae) as H. cf. undulatum. It differs principally from the specimens here described by having orange extractable pigments.