Biatoropsis usnearum
Description : Basidiomata extremely variable in form, size and colour, generally subspherical and convex with a constricted base, often with lobate margins, sometimes flattened or with a concave central part, rarely effuse and covering larger areas around the branches of the host, surface smooth, rarely tuberculate, cartilaginous, pale pinkish, reddish-brown, dark-brown or black, 0.2–2.5 mm diam. Context hyphae 2–3 m wide, mostly uniform, the walls not markedly thickened, clamp connections absent; haustorial branches frequent, mother cell subspherical or sometimes elongate, 2.5–4.5 μm diam., haustorial filaments 0.5–1 μm thick, 3–7 m long. Hymenium hyaline, sometimes reddish brown in upper part and then yellow in K, thickness variable, with numerous probasidia. Basidia when mature, clavate to subcylindrical, with 1–3 transverse septa, 20–44 × 3–6.5 μm; epibasidia 2–3 μm thick, and to 85 μm long. Basidiospores subglobose to ellipsoidal, with a distinct apiculum, 4.5–8 × 4–7.5 μm. Anamorph hyphomycetous, often present, forming long branching chains of hyaline, ellipsoidal, simple conidia 3–5 × 2–3.5 μm.
N: Northland (Warkworth) to Wellington. S: Nelson to Southland. St: A: C: Widely distributed in temperate and tropical biomes and ranging from s.l. to 3600 m and known from Europe, Asia, Africa, North, Central and South America, Australia and the Falkland Is (Diederich & Christiansen 1994; Goward et al. 1994a; Esslinger & Egan 1995; Diederich 1996, 2003, 2004d; Alstrup & Cole 1998; Triebel 1999; Hafellner et al. 2002; Etayo & Osorio 2004).
Cosmopolitan
Hosts : species of Usnea.
Illustrations : Acharius (1810: tab. XIV, fig. 7A, B); Galløe (1950: 71, pls 112–115); Diederich & Christiansen (1994: 50, fig. 1A–E; 51, fig. 2A–C; 53, fig. 4A–D); Grube & de los Ríos (2001: 1118, figs 1–3; 1119, figs 4–9); Lawrey & Diederich (2003: 81, fig. 1).
* Biatoropsis usnearum is characterised by: the lichenicolous habit; the formation of pale pinkish to reddish brown, dark-brown or black, convex galls, 0.2–2.5 mm diam., often on the branch tips of the host (Usnea); auriculoid basidiomata, 20–44 μm long, with elongate epibasidia almost parallel to the basidium; basidiospores with a distinct apiculum.
