Micraspidales » Micraspidaceae » Micraspis

Micraspis strobilina

Micraspis strobilina Dennis, Kew Bull. 25: 362. 1971. emend. Quijada & Tanney, IF:317612
Synonym: Sporonema diamandidis Minter, Trans. & Proc. Bot. Soc. Edinb. 43: 183. 1980.
Apothecia up to 0.6 mm diam, receptacle black, round to irregular ellipsoid, erumpent, covering layer opening one (rarely more) longitudinal or lateral slit, hymenium gray. Ectal excipulum dark brown, composed of textura epidermoidea from margin to lower flank, 11–66 µm thick, at base textura epidermoidea to textura angularis, 12–39 µm thick. Cells at margin and upper flank (3.5–)4.5–6(–8.5) × (1.5–)2–2.5(–3.5) µm, cells at base (2.5–)3–4.5(–6) × 1.5–2(–2.5) µm, cell walls dark brown, up to 1.5 µm thick. Cortical layer of the receptacle covered by a refractive golden gel up to 5 µm thick. Medullary excipulum light brownish, of textura angularis to plectenchymatous tissues, 45–65 µm thick. Asci (57.5–)61.5–76(–87.5) × (7.5–)8.5–10(–10.5) µm, 8-spored. Ascospores (6.7–)10.4–12.3(–14.5) × (2.7–)3.4–3.9(–4.8) µm, 1–3-septate, scattered tiny guttules mostly present in immature ascospores, germinating at both poles and producing cylindrical or sub-cylindrical conidia (3.7–6.1 × 0.9–1.7 µm) directly from the ascospore walls or germ tubes. Paraphyses cylindrical uninflated or slightly clavate, 3–5 equidistant septa, sometimes apical cells shorter, simple or dichotomously branched in the apical or lower cells, slightly sinuous, without exudates or guttules, apical cells 4–9.5 × 1.5–2.5 µm, lower cells 6.5–16 × 1.5–2 µm, basal cells 10–16 × 1–1.5 µm. Conidiomata pycnidioid, immersed in substrate, subcuticular or sometimes partly subepidermal, scattered, up to 1 mm diam, black, shining, outline +/- circular, pulvinate, convoluted locules, inostiolate, covering layer opening by a single longitudinal slit or several radial slits. Covering layer ca. 20 µm thick, textura epidermoidea, composed of dark brown to black, septate, thick-walled, irregular hyphae agglutinated to form a compact integument that is firmly attached to the host cuticle above and sometimes containing degraded epidermal cells. Conidiophores simple or branched, aseptate or septate, subcylindrical and tapering towards apex, hyaline, smooth, frequently reduced to conidiogenous cells, in palisade lining all inner surfaces of conidioma, arising from a layer composed of hyaline to subhyaline textura angularis. Conidiogenous cells enteroblastic, phialidic, integrated or discrete, indeterminate, subcylindrical and tapering towards apex to ampulliform, widest +/- at middle, hyaline, smooth, aperture minute, collarette inconspicuous, 7–9(–12) × 1.5–2(–2.5) µm. Conidia bacillar to allantoid, apex and base obtuse, aseptate, hyaline, thin-walled, eguttulate, (3–)4–6(–8) × 1.5–2 µm.
Typus: UK, Isle of Mull, Lonch Bàa, on cones of Pinus sylvestris, 7 Aug. 1968, R.W.G. Dennis (K-M-31759, holotype).
Additional material examined: Russia, Leningrad Oblast, Vyborg District, Berezovye Ostrova Natural Sanctuary, Severny Berezovy Isl., on decaying cones of Pinus sylvestris, 19 Jul. 2005, E.S. Popov (LE 236400).

Sexual morphs of Micraspis:  H–M. Micraspis strobilina. H1–H3, Rehydrated apothecia; I Transverse section of the excipulum; J1–J4, Immature and mature asci with ascospores and base of the asci with croziers; K1, K2. Paraphyses; L1–L4. Immature and mature ascospores without conidia; M1–M3. Germinated ascospores and conidia produced from the germ tube; M4. Free conidia.

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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