Stigmidium congestum
≡*Pharcidia congesta Körb., Parerga Lich.: 470 (1865).
Description : Lichenicolous on discs of Lecanora carpinea, the brown, vegetative hyphae causing internal browning of the host tissues. Perithecia black, immersed to subimmersed in host tissue, globose to oblong, 40–85 × 30–80 μm, ostiole not apparent. Perithecial wall brown, 5–12 μm thick, of two cell layers. Periphyses and pseudoparaphyses present, 5–11 × 1–2.5 μm. Asci broadly cylindrical to clavate, 24–37 × 10–18 μm, 8-spored. Ascospores colourless, ellipsoidal to oblong, 1-septate, both cells equal and not constricted at septum, (11–)12–14(–16) × 2.5–4 μm. Pycnidia among perithecia, 25–50 × 20–40 μm, subglobose to oblong, brown, wall of isodiametric cells, 3–5 μm diam. Conidia bacillar, 2–3 × 0.5–1 μm.
N: S: Known also from Europe and Scandinavia (Roux & Triebel 1994; Martínez et al. 2002; Santesson et al. 2004).
?Cosmopolitan
Host : The species occurs most commonly on the apothecia and rarely on the vegetative thalli of corticolous species of Lecanora, especially L. carpinea (Triebel et al. 1991: 290; Roux & Triebel 1994: 485).
Illustrations : Roux & Triebel (1994: 467, fig. 8A, 472, fig. 12, 484, figs 20–22); Boqueras (2000: 411, fig. 68D, E).
* Stigmidium congestum is characterised by: the lichenicolous habit (apothecial discs of Lecanora carpinea); immersed perithecia and pycnidia; 1-septate ascospores, (11–)12–14(–16) × 2.5–4 μm; and bacillar conidia, 2–3 × 0.5–1 μm.
