Stigmatodiscus oculatus – Sociedad Ibérica de Micología

Stigmatodiscus oculatus Voglmayr & Pintos, Mycol. Progress 17(10): 1193. 2018.

MycoBank MB827488

AUTHORS: Pintos A. & Voglmayr H.

Taxonomic classification

phy Ascomycota

sbp Pezizomycotina

cls Dothideomycetes

sbc

ord Stigmatodiscales

fam Stigmatodiscaceae

gen Stigmatodiscus

sp Stigmatodiscus oculatus

Description

Ascomata hysteriform, scattered to gregarious, corticolous, erumpent through the periderm, commonly arranged in parallel to the branch axis, in face view (160–)280–510(–880) μm long, (110–)180–300(–380) μm wide ( n=96), with sides consisting of usually two, rarely three black lips (peridium) not inmutual contact, with a slit-like to almost circular central opening exposing the blackish elongated to broadly oval disc. Bark tissues not visibly altered, no black line visible in bark or wood. Peridium coriaceous, pseudoparenchymatous, dark brown to black, up to 120 μm thick at the apex, 38–55 μm thick at the sides, almost absent to 20 μm thick at the base, composed of small angular to rounded cells 3–10 μm diam. Hamathecium composed of hyaline, septate, filiform branched paraphyses 1.7–2.5 μm wide, embedded in tough hymenial gel, simple, not anastomosing, 82–123 μm long, longer than asci, swollen at their apices up to 5.5 μm and incrusted with dark brown granules forming an epithecium, neither staining blue in Lugol nor in Melzer’s reagent after pre-treatment with 3% KOH. Asci 72–84(–90)×(29–)35– 49μm(n=10),bitunicate, clavate to pyriform, almost sessile, with a distinct apical chamber, thick-walled, typically containing 8 irregularly bi- to triseriate ascospores, very stable, fissitunicate dehiscence not observed. Ascospores (25.5–)27.5–31(–33)×(9.5–)10.5–12.0(–12.5) μm, l/w=(2.3–)2.5–2.7(–2.9)(n=63), brown, asymmetric, broadly fusiform, straight, first 1-septate, developing 2 additional distosepta and becoming 3-septate with age, strongly constricted at the primary septum, weakly at secondary septa secondary septa with large pores, each hemispore surrounded by a separate gelatinous sheath quickly dissolving in water, upper hemispore slightly broader, with broadly rounded ends; wall finely verruculose, brown, the contents granular, often with a large and several smaller guttules per cell.