Graphis itatiaiensis Nelsen, Lücking & Spielmann
MycoBank MB 517776
Thallus corticolous, up to 7 cm diam., 30–70 µm thick, continuous; surface smooth to uneven-verrucose, greenish grey, with scattered isidioid outgrowths; isidoid outgrowths globose to irregular, 0.05–0.1 mm diam. Thallus in section with cartilaginous upper cortex, irregular algal layer and large clusters of crystals; photobiont trentepohlioid. Apothecia lirelliform, flexuose, stellately branched and aggregate into pseudostromatic clusters, prominent to sessile, with thick, almost complete thalline margin leaving only the uppermost part of the labia exposed, 1–3 mm long, 0.3–0.5 mm wide, 0.25–0.35 mm high; disc concealed; proper margin thick, labia entire, grey-black; thalline margin thick, covering the labia except for the uppermost part, white-grey and contrasting with the darker surrounding thallus. Excipulum completely carbonized, 50–100 µm wide, black; laterally covered by algiferous thallus lacking crystals; hypothecium prosoplectenchymatous, 10–15 µm high, colourless to pale yellowish; hymenium 150–200 µm high, colourless, clear; epithecium granulose, 10–15 µm high, olive brown. Paraphyses unbranched; asci fusiform to clavate, 130–180 x 30–40 µm. Ascospores 2–4 per ascus, oblong to cylindrical, 15–25-septate, 100–150 x 14–17 µm, 7–9 times as long as wide, colourless, with thin gelatinous caps at both ends. Secondary chemistry: no substances detected by TLC.
Graphis is a large genus with over 300 species found primarily on tree bark in semi-open to open conditions in midelevation sites, such as lower montane rainforests (Lücking et al., 2008; Lücking, 2009; Lücking et al., 2009). The genus is typically characterized by a white-grey, corticate thallus, with erumpent-prominent lirellae, a partly to fully carbonized excipulum, a hymenium mostly lacking inspersion and transversely septate to muriform ascospores reacting I+ violet-blue (Staiger, 2002; Lücking et al., 2008; Lücking, 2009). G. itatiaiaensis is distinguished from G. rhizocola (Fée) Lücking & Chaves by its coarsely isidiate thallus and stellately branched lirellae. G. itatiaiaensis differs from G. isidiata (Hale) Lücking in that the new species has elongate, stellately branched lirellae and septate rather than muriform ascospores. G. itatiaiaensis differs from G. patwardhanii C. R. Kulk, another isidiate species with stellately branched lirellae, in having prominent-sessile lirellae covered with thallus, slightly larger ascospores with a greater number of septa per ascospore, a completely carbonized excipulum, and labia lacking striations.
The epithet refers to the type locality.
The new species is known from a few collections in lower montane Atlantic rainforest in southeastern Brazil.
Type:—BRAZIL: Minas Gerais: Parque Nacional do Itatiaia, Estrada das Prateleiras; 22°22’S, 44°44’W; Jul 2009, Nelsen 4185 (holotype SP; isotype F).
Additional specimens examined (paratypes):—BRAZIL: Minas Gerais: Parque Nacional do Itatiaia, Estrada das Prateleiras; Nelsen 4186 (F).
Sicut Graphis rhizocola sed thallo isidioso et lirellis astroideis aggregatis differt.