Schismatomma
Type : Schismatomma pericleum (Ach.) Branth. & Rostr. [Lichen pericleus Ach.]
Description : Thallus crustose, endo- or epiphloeodal, homoiomerous, coherent, but when epiphloeodal usually incoherent, compact, smooth or finely wrinkled, epruinose, white to grey-white or brownish grey, 0.05–0.2 mm thick, calcium oxalate generally present, ecorticate, sometimes sorediate, never isidiate. Photobiont green, Trentepohlia. Ascomata apothecia, numerous, pluricarpocentral, discothecial, solitary, elongate, irregular or circular, sessile, not constricted at base, 0.15–0.5(–1.3) mm diam.; disc exposed, convex to ±plane, rarely concave, pruinose, rarely epruinose. Thalline margin present but usually poorly developed. Proper exciple parathecial (soon grading into the thalline margin plectenchyma), usually thicker in upper part, rarely inconspicuous, brown to dark-brown, rarely pale, plectenchyma of loosely interwoven hyphae, pruina usually present. Hypothecium dark-brown, rarely pale-brown or colourless, extending down to substratum. Hamathecia of paraphysoids, unbranched to sparsely branched, inconspicuously septate or septate with cells to 10 μm long. Hymenium colourless; epithecium brown, hyphal tips 2–4 μm diam., verrucose, brown. Asci bitunicate, clavate, 50–80 × 10–15 μm; ocular chamber with nasse and ring structure; ectotunica thin; endotunica thin but noticeably thicker towards apex, hemiamyloid in upper parts and apical ring, the remainder I−. Ascospores fusiform or acicular-fusiform, smooth, 3-septate, not constricted at septa, colourless. Conidiomata pycnidia, solitary, immersed or subsessile, black or brown, c. 0.05–0.15 mm diam. Microconidia bacillar, rarely filiform, curved, simple or 1-septate, colourless.
Schismatomma, included in the family Roccellaceae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005), is a genus of c. 8 species (Tehler 1993a, 1993c, 1994a, 2002; Kirk et al. 2001). Schismatomma s. lat. (e.g. Zahlbruckner 1922–24: 547–566, 1931–32: 231–232; Galloway 1985a: 520–522) was shown to be paraphyletic, and from it Tehler (1993a) segregated the genera Byssophoropsis (Vain.) Tehler [=Sagenidiopsis R.W.Rogers & Hafellner] and Syncesia Taylor, and described Sigridea Tehler, which he subsequently monographed (Tehler 1993d). Schismatomma s. str. is recognised by a combination of several characters: (1) a thin, sometimes endophloeodal and incoherently organised, usually whitish thallus containing calcium oxalate; (2) small (c. 0.5 mm diam.) often elongated discothecia; (3) a poorly developed thalline margin; (4) a parathecium (if present) of plectenchyma with either or both intricately and anticlinally arranged hyphae; (5) a carbonised hypothecium; (6) fusiform or acicular-fusiform, 3-septate ascospores; (7) bacillar microconidia' (8) a chemistry of roccellic acid; and (9) a corticolous substratum preference (it does not occur on rocks). One species is known from New Zealand. In the Flora treatment (Galloway 1985a: 520–522), Schismatomma atratum (Stirt.) Zahlbr. is now referred to Bactrospora, and S. tumidulum (C.Knight & Mitt.) Zahlbr. is a later synonym of Chiodecton colensoi.
