Platystomum compressum

Platystomum compressum (Pers.) Trevis., Bull. Soc. R. Bot. Belg. 16: 16 (1877)

Index Fungorum number: IF 144522; Facesofungi number: FoF 00815

= Lophiostoma lojkanum (Sacc.) Mussat, in Saccardo, Syll. fung. (Abellini) 15: 198 (1900)

Reference specimen: MFLU 14-0589

Saprobic on woody substrates in terrestrial habitats. Sexual morph: Ascomata 400–950 μm high, 350–950 μm diam. (x̄ = 654 × 606 μm, n = 15), solitary or gregarious, immersed, papilla erumpent through host surface, coriaceous to carbonaceous, black, globose to subglobose, ostiolate. Ostiole slit-like, central, papillate, with a reduced crest and a pore-like opening, plugged by gelatinous tissue, made up of lightly pigmented, pseudoparenchymatous cells. Peridium 50–130 μm wide (x̄ = 85 μm, n = 15), wider at the apex and thinner at the base, comprising two strata, outer layer composed of dark brown walled, flattened cells of textura prismatica, fusing and indistinguishable from the host tissues and the inner layers with 6–8 layers of brown to lightly pigmented cells of textura angularis. Hamathecium comprising 1–3 μm wide, numerous, branched, cellular pseudoparaphyses, situated between and above the asci, embedded in a gelatinous matrix. Asci 76–160 × 8–15 μm (x̄ = 126 × 13 μm, n = 15), 8-spored, bitunicate, fissitunicate, cylindric-clavate, with a long pedicel, apically rounded with an ocular chamber. Ascospores 17–32.5 × 7–9.5 μm (x̄ = 22.5 × 7.9 μm, n = 30), uniseriate, partially overlapping, hyaline when immature, becoming brown to dark brown when mature, ellipsoidal to fusiform, muriform, (4−)5–7 transversely septate, with 1–3 vertical septa, constricted at the central septum, guttulate, smooth-walled, lacking a mucilaginous sheath. Asexual morph: Undetermined.

Culture characteristics: Ascospores germinating on PDA within 18 h and producing germ tubes from several septa. Colonies on PDA growing slowly, attaining 12 mm diam. after 21 days at 25–30 °C, white at first, after 1 to 2 weeks becoming ashy-white, flat to effuse, raised in the middle, velvety, dense, surface smooth, with entire to slightly undulate edge.

Material examined: HUNGARY, Somogy, Kaposvàr in Ungarn, Lojka, 1872 (S-F7232, holotype of Lophiostoma lojkanum Rehm.); ITALY, Province of Forlì-Cesena [FC], Strada San Zeno, Galeata, on dead branch of Salix sp. (Salicaceae), 1 December 2012, Nello Camporesi IT 932 (MFLU 14-0589, HHUF 30462, reference specimen of Platystomum compressum designated here); living culture, MFLUCC 13-0343, ICMP.

GenBank:

Notes: Notes: Cesati and De Notaris (1863) transferred and accommodated Sphaeria compressa Pers. in Lophiostoma (Lophiostomataceae) based on immersed to slightly erumpent ascomata with a cylindrical papilla. Lophiostoma compressum was transferred to several different genera, but Zhang et al. (2009, 2011) placed L. compressum in Lophiostoma based on its phylogenetic placement. Platystomum was introduced by Trevisan (1877) and is typified by Platystomum compressum (Pers.) Trevis. Platystomum compressum is listed as a synonym of Lophiostoma compressum (Pers.) Ces. & De Not. in Index Fungorum (2015). However, Mugambi and Huhndorf (2009) showed in their combined phylogenetic analysis, a putatively named strains of P. compressum grouped with Pseudotrichia guatopoensis Huhndorf and Xenolophium guianense Huhndorf in a separate clade from Lophiostomataceae, which may correspond to the family Platystomaceae (Mugambi and Huhndorf 2009, Hyde et al. 2013). However, in this phylogenetic analysis, the strain (MFLUCC 13-0343) from new collection of P. compressum grouped in Lophiostomataceae with other new species of Platystomum (MFLUCC 14-0925, 15-0632, 15-0633) and the putatively named strains of L. compressum (KT 521, JCM 13125 and IFRD 2014), Lophiostoma triseptatum Peck (SMH 5287 and SMH 2591) and Lophiostoma viridarium Cooke (IFRDCC 2090) in a same subclade. We observed and illustrated the specimens attached to KT 521, JCM 13125 strains and the strains of L. triseptatum and L. viridarium in GenBank are named without attached voucher material. Therefore, it is impractical to confirm their characters. Re-collection, epitypification or a reference specimen (Ariyawansa et al. 2014b) with molecular data are essential for the type species of L. viridarium and L. triseptatum to establish their placement in Platystomum. We accept Platystomum in Lophiostomataceae as a distinct genus and introduce four new species in Platystomum based on new collections and two strains (KT 521 and JCM 13125).