Hypoxylon lilloi Sir, Lambert & Kuhnert, sp. nov.
Mycobank number: MB 814982, Facesoffungi number: FoF 02034, Figs. 2, 3 and 4
Etymology – In honor of Dr. Miguel Lillo, a pioneer biologist in Tucuman province (Argentina).
Holotype – ARGENTINA, Salta, Depto. Anta, Parque Nacional El Rey, 30 April 2014, Sir & Hladki 739 (LIL, extype culture STMA 14142)
Differs from Hypoxylon vogesiacum by livid purple stromatal pigments in 10 % KOH, as well as in having an amyloid apical apparatus and smaller ascospores.

Sexual morph Stromata effused-pulvinate, 14 – 30 mm long × 5 – 26 mm broad × 1 mm thick; plane or with inconspicuous perithecial mounds; surface Purplish Gray (128) or Vinaceous Grey (116); pruinose; brown to dark red granules immediately beneath surface and between perithecia; with KOH-extractable pigments Livid Purple (81), the tissue below the perithecial layer inconspicuous, black, 0.2 – 0.5 mm thick. Perithecia obovoid to lanceolate-tubular 0.5 – 0.8 mm high × 0.2 – 0.3 mm diam; ostiolar openings lower than the stromatal surface, umbilicate with white area surrounding ostioles. Paraphyses 2 – 4 μm wide at base, tapering above asci. Asci 8-spored, cylindrical, 92 – 134.5 μm total length, the spore-bearing parts 56 – 46 μm long × 5 – 6.5 μm broad, the stipes 40 –82.5 μm long; with amyloid, discoid apical apparatus 0.7 – 0.9 μm high × 1.9 – 2.3μm broad. Ascospores brown to dark brown, unicellular, ellipsoid-inequilateral, with narrowly rounded ends, slightly curved, 7.4 – 8.9 (9.7) × 3.2 – 4.2 μm (n = 60, Me = 8.3 × 3.8 μm); with straight germ slit sporelength on convex side; perispore dehiscent in KOH; with inconspicuous coil-like ornamentation by light microscopy, revealing reticulate ornamentation by SEM (5000×); epispore smooth. Asexual morph In culture, Conidiophores with virgariella-like branching pattern, usually borne on aerial hyphae, hyaline, smooth. Conidiogenous cells hyaline, smooth, 10 – 27 × 1 – 2.5 μm. Conidia 4 – 5 × 1.5 – 2.5 μm, ellipsoid, hyaline, smooth-walled.

Culture – Colonies on OA covering Petri dish in 2 week, at first whitish, becoming Olivaceous Grey (121) to Dull Green (70), felty, zonate, with entire margin; reverse Apricot (42), later turning Dark Green (21) in places. Sporulating regions scattered over entire surface of colony.

Secondary metabolites – Stromata of this species contain two unknown major metabolites in its stromatal extracts.

Additional material examined – ARGENTINA, Jujuy Province, Depto. Santa Bárbara, Reserva provincial Las Lancitas, 13 May 2012, Sir & Hladki 278 (LIL); Salta, Depto. Anta, Parque Nacional El Rey, 30 April 2014, Sir & Hladki 744 (LIL, culture STMA 14143).

Notes – Hypoxylon lilloi, which was found in the course of a study on Xylariaceae of the Argentine cloud forest BLas Yungas^ (Sir et al. 2016) might be confused with H. vogesiacum (Pers. ex Curr.) Sacc. due to their similar purplish gray or vinaceous grey stromatal surfaces. However, H. lilloi differs in having livid purple KOH-extractable pigments, smaller ascospores and in lacking a dotted band in the centre of the ascospores. This new taxon resembles the group of species with purplish KOH-extractable pigments, such as H. lienhwacheense Y.M. Ju&J.D. Rogers,H. lividicolor Y.M. Ju & J.D. Rogers, H. lividipigmentum F. San Martín et al. and H. texcalense F. San Martín et al. Those can be easily differentiated from H. lilloi by the colour of the stromatal surface and granules. In addition H. lienhwacheense has smaller ascospores (6 – 7.5 × 3 – 3.5 μm vs. 7.4 – 9.7 × 3.6 – 4.6 μm) and a smooth perispore. Hypoxylon lividicolour differs in having longer perithecia (0.5 – 1.3 × 0.2 – 0.4 mm vs. 0.5 – 0.8 × 0.2 – 0.3 mm), larger ascospores (11 – 12.5 × 4.5 – 5 μm vs. 7.4 – 9.7 × 3.6 – 4.6 μm) and sporothrix-like conidiogenous structures and H. lividipigmentum can be differentiated by its larger ascospores (10 – 15 × 4.5 – 6 μm vs. 8.5 – 10 × 4 – 4.5 μm) and nodulisporium-like conidiogenous structures. In comparison with H. texcalense, the latter has also much larger ascospores (17 – 24 × 6.5 – 9.5 μm vs. 7.4 –9.7 × 3.6 – 4.6 μm), and lack ascal apical rings and nodulisporium-like conidiogenous structures.

The type of secondary metabolites produced in the stromata seems to be a unique feature of the species, because they were not detected in more than 1000 studied specimens. Only BNT could be identified, which is common in hypoxyloid genera of the Xylariaceae.

In the phylogenetic reconstruction based on β-tubulin gene sequences (Fig. 1), H. lilloi forms a separated clade. The latter is located between the H. fragiforme clade and H. lenormandii clade. Besides huge morphological differences of those species compared to H. lilloi, they can be easily distinguished by their orange KOH-extractable pigments due to the production of azaphilones such as the mitorubrins (H. cinnabarinum Henn.) Y.M. Ju & J.D. Rogers, H. fragiforme (Pers.) J. Kickx f., H. jecorinum Berk. & Ravenel, H. rickii Y.M. Ju & J.D. Rogers) and the lenormandins (H. lenormandii Berk.& M.A. Curtis; cf. Kuhnert et al. 2016).

Fig. 1 Phylogenetic relationships among Hypoxylon lilloi and related Xylariaceae as inferred from β-tubulin gene sequences. Likelihood (ML) bootstrap support values above 50 %, from 1000 RAxML replicates are assigned to the tree topology of the most likely tree found by RAxML. The tree is rooted to Creosphaeria sassafras. Species names are followed by strain numbers. Ex-type strains are highlighted in bold and new isolates are in blue.

Fig. 2 Hypoxylon lilloi (holotype) a Stromatal habit b Close-up view of stromatal surface with white area surrounding umbilicate ostioles (black arrow) c Bown granules beneath surface and between perithecia (white arrow) d Asci e extractable pigments in 10 % KOH f Section through stroma showing perithecia and dark red granules (white arrow) g Apical ring bluing in melzer’s iodine reagent (black arrow) h Ascospores showing germ slit (white arrow) i Ascospores showing perispore dehiscent in KOH (black arrow) j Perispore showing inconspicuous ornamentation k, l Ascospores showing reticulate ornamentation on perispore under SEM. Scale bars: a = 5 mm, b, c and f = 0.5 mm, d = 20 μm, g, h, i and j = 10 μm, k=2 μm, l=200 nm.

Fig. 3 Hypoxylon lilloi (extype) Culture of on OA after 3 weeks a top view b reverse c, d Conidiophores with virgariellalike branching patterns e Conidia. Scale bars: c – e = 5 μm)

Fig. 4 in addition to some other yet unknown minor metabolites, besides binaphthalene tetrol (BNT).