Fissurina subcomparimuralis Common & Lücking
Mycobank MB 517773
Thallus corticolous, 1–2 cm diam., 30–50 µm thick, continuous; surface smooth, yellowish-brown to olive-brown. Thallus in section with prosoplectenchymatous upper cortex, irregular algal layer and scattered clusters of crystals. Lirellae straight to curved, unbranched to sparsely branched, erumpent, fissurine, with complete thalline margin, 1–3 mm long, 0.2–0.25 mm wide, 0.12–0.15 mm high; disc concealed; labia conspicuous but not thickened, greyish black to brown-black below corticate thalline margin; thalline margin olive-brown. Excipulum entire, brown-black, 20–40 µm wide; covered by corticate algiferous thallus including clusters of crystals; hypothecium prosoplectenchymatous, 5–10 µm high, colourless to pale yellowish; hymenium 70–90 µm high, colourless, clear; epithecium granulose, 5–10 µm high, grey-brown. Paraphyses unbranched, glabrous; periphysoids present, apically spinulose; asci fusiform, 70–80 x 15–20 µm. Ascospores 8 per ascus, ellipsoid, muriform with 5–7 x 1–3 septa, 15–25 x 6–8 µm (including 1–1.5 µm thick wall), 2.5–3 times as long as wide, with x trypethelioid septa and lumina, colourless, I–. Secondary chemistry: no substances detected by TLC.
This new species was at first identified with F. comparimuralis Staiger, until we discovered two significant differences: F. comparimuralis has I+ distinctly violet-blue ascospores and lacks spinulose periphysoids. Since we consider these characters taxonomically important, we describe the Florida material as a separate species. Fissurina subcomparimuralis grows together with the morphologically similar F. tuckermanii (see below), which is clearly set apart by the very different ascospores. The two species form part of a group of species with corticate, olive-brown thalli and carbonized, erumpent-fissurine lirellae looking like a black roof, which probably deserves generic status. The group also includes F. comparilis (Nyl.) Nyl. (ascospores 3-septate, I–), F. humilis (ascospores 3-septate, I+, paraphyses spinulose), and F. inquinata C. Knight & Mitt. (ascospores 3-septate, I–, stictic acid).
The epithet refers to the close similarity with F. comparimuralis.
Fissurina subcomparimuralis is known from several rich collections from Fakahatchee Strand Preserve State Park in Florida.
Type:—U.S.A. Florida. Collier County, Fakahatchee Strand Preserve State Park; Common 7323A (holotype MSC; isotype hb. Common).
Additional specimens examined (paratypes):—U.S.A. Florida. Collier County, Fakahatchee Strand Preserve State Park, Common 7276A, 7276J (hb. Common).
Sicut Fissurina comparimuralis sed ascosporis I– et periphysoidis spinulosis differt. Thallus corticatus. Lirellae fissurinae, 1–3 mm longae, 0.25 mm latae. Ascosporae muriformes, 15–25 x 6–8 µm, I–. Acidi lichenici desunt.