Stigmidium pumilum
≡*Rosellinia pumila Lettau, Feddes Repert. Spec. nov. Veg. 61 (2): 150 (1958).
Description : Lichenicolous. Perithecia, black, glossy, immersed in central parts of thallus, 30–80 μm wide and 40–70 μm tall, creating a gall where perithecia are numerous and crowded; vegetative hyphae dark-brown, smooth. Perithecial wall red-brown, of irregularly polyhedral cells, 5–10 μm diam. Asci functionally bitunicate, swollen, short and wide, pedicellate, broadly rounded at the apex, with a distinct ocular chamber, 20–40 × 8–15 μm. Ascospores 1-septate at maturity, constricted at septum, with a prominent yellowish, granular oil body in each cell, (8–)9–13(–16) × 3–7 μm.
S: Canterbury (Cave Stream, Flock Hill). On limestone outcrops in grassland. Also known from Europe, Scandinavia, North America and the Canary Is (Matzer & Hafellner 1990; Cole & Hawksworth 2001; Santesson et al. 2004; Triebel & Cáceres 2004).
Cosmopolitan
Hosts : Physcia caesia, P. dubia (Matzer & Hafellner 1990; Cole & Hawksworth 2001).
Illustrations : Matzer & Hafellner (1990: 118, figs 20, 21); Cole & Hawksworth (2001: 331, fig. 8).
* Stigmidium pumilum is characterised by: the lichenicolous habit; black perithecia forming galls on host tissue (Physcia caesia); an absence of pseudoparaphyses; and colourless to pale-yellowish, 1-septate ascospores, constricted at septum, (8–)9–13(–16) × 3–7 μm.
