Mucoharknessia cortaderiae Crous, R.M. Sánchez & Bianchin., 2015

Crous, Pedro W., Müller, Michael M., Sánchez, Romina M., Giordano, Lucrecia, Bianchinotti, M. Virginia, Anderson, Freda E. & Groenewald, Johannes Z., 2015, Resolving Tiarosporella spp. allied to Botryosphaeriaceae and Phacidiaceae, Phytotaxa 202 (2), pp. 73-93 : 86-87

Mucoharknessia cortaderiae Crous, R.M. Sánchez & Bianchin. , sp. nov. MycoBank MB811255; Fig. 6

Etymology:— After the genus Cortaderia on which the fungus was first found.

Conidiomata immersed, separate or aggregated, pycnidial, unilocular, globose to subglobose, blackish on leaves, 110–315 μm high, 250–350 μm diam. Ostiole subepidermal, circular to subcircular, opening onto the abaxial side of leaves by means of a longitudinal split in epidermis; lacking furfuraceous tissue that surrounds ostiolar openings in Harknessia s.str. Peridium arranged in two layers, the external stromatic, with brown cells of textura angularis, 35–45 μm thick; the internal conformed by flattened, hyaline cells, 10–15 μm thick. Conidiophores reduced to conidiogenous cells, lining the conidiomatal cavity. Conidiogenous cells lageniform to subcylindrical, smooth, covered in mucus, hyaline, 7–18 μm long, 3–6 μm diam at the base, 2–4 μm diam at the apex; proliferating several times percurrently at apex, with flared collarette visible. Conidia oval to ellipsoidal, appendaged, thick-walled, smooth to finely verruculose, lacking striations, brown, (18–)21–27(–39) × (9–)11–12(–17) μm; apical appendage extracellular (Type B, sensu Nag Raj 1993), mucilaginous, irregular, smooth, hyaline, 3–5 μm long, best seen with India ink; basal appendage tubular, thin walled, smooth, hyaline, 1–5 μm long, 3–5 μm diam, often collapsing. Microconidia not seen.

Cultural characteristics:— Colonies covering the dish in 2 wk, with sparse aerial mycelium, and even feathery margins; surface on MEA and PDA olivaceous grey, reverse iron grey.

Specimen examined:— ARGENTINA. Buenos Aires Province, Punta Alta, 38°47’27,6”S 62°6’48,6”W, on leaves of Cortaderia selloana (Schult. & Schult. f.) Asch. & Graebn. ( Poaceae ), 29 Mar. 2011, F.E. Anderson (holotype BBB, (MVB 1502), isotype CBS H-21853, culture ex-isotype CBS 131032 = CPC 19974, CPC 22208, 22209).

Additional specimens examined:— all on leaves of Cortaderia selloana ; ARGENTINA. Buenos Aires Province: La Paz, S35°21’32.5” W59°19’57.2”, 30 May 2011, F. E. Anderson, C10 ; Miramar , S38°13’12” W57°42’51”, 18 Jul. 2011, L. Gallego, C14-1 ; Monte Hermoso , S38°59’9.5” W61°7’42.9, 24 Apr. 2011, F. E. Anderson, C7 ; Tandil , S37°18’17.5” W59°8’4.9”, 23 Apr. 2011, L. Gallego, C8-1 , Tandil, S37°18’17.5” W59°8’4.9”, 18 Jul. 2011, L. Gallego, C8-3 .

Notes:— Conidiomata interveinal, associated with elongated, pale brown to yellowish or orange-brown necrotic leaf blade sections, most likely as a secondary invader, which proved to be rather uncommonly encountered. With its unilocular conidiomata, and pigmented, appendaged conidia, it is somewhat reminiscent of Harknessia ( Crous et al. 2012) and Macrophomina ( Sarr et al. 2014) . Phylogenetically however, it proved to be allied to genera in the Tiarosporella complex in the Botryosphaeriaceae ( Fig. 1 ), which was quite unexpected.

Figures

FIGURE 1. The first of 1000 equally most parsimonious trees (TL = 367; CI = 0.638; RI = 0.928; RC = 0.591) resulting from a parsimony analysis of the LSU (28S) sequence alignment. The bootstrap support values are indicated at the nodes (parsimony bootstrap / distance with HKY85 model bootstrap; only values>74%) and the scale bar represents the number of changes. Thickened branches reflect those branches present in the strict consensus tree. Orders are indicated in darker blue and orange blocks and family names

FIGURE 6. Mucoharknessia cortaderiae (CPC 19974). A. Conidiomata on leaf blade of Cortaderia selloana. B. Aggregated conidiomata forming on PDA. C. Vertical section through a pycnidium, showing wall anatomy. D–G. Conidiogenous cells giving rise to conidia (note collarettes, F, G). H. Appendaged conidia with arrows indicating apical mucoid caps. I, J. Brown, finely verruculose, ellipsoid conidia. Scale bars:A, B = 300 μm, all others = 10 μm.