Micraspidales » Micraspidaceae » Micraspis

Micraspis tetraspora

Micraspis tetraspora Graddon, Trans. Br. mycol. Soc. 83: 379. 1984. emend. Quijada, IF:106265
Apothecia up to 0.2–0.5 mm diam., black, elliptical, erumpent between fibers, margin differentiated, smooth to crenate or slightly lacerate, hymenium black to dark brownish and without covering layers above. Ectal excipulum dark brown, composed of textura epidermoidea from margin to lower flank, 21–48 µm thick, at base textura epidermoidea to textura angularis, 25–30 µm thick. Cells at margin and upper flank 3.5–6 × 1.5–3 µm, cells at base 3–7 × 1.5–4 µm, cells wall dark brown, up to 1.5 µm thick. Cortical layer of the margin outside covered by a thin refractive golden gel, up to 1 µm, mostly present in the upper flanks and margin of the receptacle. Medullary excipulum plectenchymatous, strongly differentiated from the ectal excipulum, 15–54 µm thick. Asci (33.5–)42–46(–51) × (6–)7–8(–9) µm, 4–8-spored. Ascospores (7.5–)9.5–10.5(–13.5) × (2–)3–4 µm, 1–3(–5)-septate, with groups of tiny guttules mostly at poles, conidia only formed directly from ascospores walls, 2–3 × 0.7–1.1 µm. Paraphyses cylindric, uninflated, 3–4 equidistant septa, not branched, straight or slightly sinuous, covered by a brownish thin smooth exudate, without guttules, apical cells (5–)9–13 × 1–1.5 µm, straight or slightly curved, lower cells 8.5–11.5 × 1–1.5 µm, basal cells (6–)9–12.5 × 1–1.5 µm. Asexual morph unknown.
Typus: UK, Dymock woods, Herefords, on wood of Picea sitchensis, 10 Nov. 1982, W.D. Graddon (K-M-44301, holotype).

Sexual morphs of Micraspis: N–S. Micraspis tetraspora. N1–N4. Rehydrated apothecia; O1–O3. Transverse section of the excipulum; P1–P4. Immature and mature asci with ascospores and base of the asci with croziers; Q1–Q3. Paraphyses; R1–R3. Immature and mature ascospores without conidia; S. Ascospores with conidia budding directly from walls.

Reference:

Quijada L, Tanney JB, Popov E, Johnston PR, Pfister DH. 2020. Cones, needles and wood: Micraspis (Micraspidaceae, Micraspidales fam. et ord. nov.) speciation segregates by host plant tissues. Fungal Systematics and Evolution 5, 99-111.

 

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