Graphis marusae B. Peña & Lücking
Mycobank MB 517777
Thallus corticolous, up to 5 cm diam., 50–100 µm thick, continuous; surface smooth, pale greenish grey, shiny; prothallus absent. Thallus in section with cartilaginous upper cortex, irregular algal layer and clusters of crystals. Apothecia lirelliform, flexuose, usually unbranched, prominent, lacking or with indistinct basal to lateral thalline margin, 1–5 mm long, 0.2–0.3 mm wide, 0.2–0.25 mm high; disc concealed; proper margin thick, labia for a long time entire but eventually becoming striate; thalline margin indistinct, thin, basal to almost lateral, greenish grey, the grey-black labia almost fully exposed. Excipulum entire to apically crenulate, completely carbonized, 80–120 µm wide, black; basally covered by thin thallus layer; hypothecium prosoplectenchymatous, 10–20 µm high, colourless; hymenium 100–150 µm high, colourless, clear; epithecium indistinct. Paraphyses unbranched; asci fusiform, 90–120 x 25–35 µm. Ascospores 8 per ascus, oblong, 9–13-septate, 50–70 x 10–15 µm, 4–5 times as long as wide, colourless. Secondary chemistry: no substances detected by TLC.
Because of its completely carbonized excipulum, clear hymenium, and mid-sized, transversely septate ascospores, this new species would key out under Graphis cognata Müll. Arg. with entire labia and under G. longula Kremp., G. asterizans Nyl., and G. glauconigra Vain. with striate labia (Lücking et al., 2009). The latter species agrees in the mostly entire labia which eventually become striate, but differs in the shorter lirellae with distinct, conspicuous lateral thalline margin. Graphis asterizans likewise also has a distinct thalline margin and the lirellae are stellately branched. Graphis longula differs in the soon striate labia and the distinct lateral thalline margin which also forms white lines between the labial striae. The most closely related species seems to be G. cognata, but that species has a white-grey thallus and shorter lirellae with jet-black labia and a distinct basal thalline margin.
This new species is dedicated to our mentor and colleague, María de los Angeles Herrera-Campos for her important contributions to lichenology in Mexico and especially the taxonomy of the genus Usnea.
The new species is known from the Biosphere Reserve Los Tuxtlas in Veracruz, Mexico, a relict tropical lowland rainforest. It was found on bark of Astrocaryum mexicanum and Pseudolmedia oxyphyllaria in exposed understory at 200–345 m altitude.
Type:—MEXICO. Veracruz: Municipio Catemaco, Los Tuxtlas Biosphere Reserve, Ejido Adolfo López Mateos Ecological Reserve; 18º26’N, 94º28’W, 345 m; lowland rainforest, on bark of Astrocaryum mexicanum; Apr 2009, Bárcenas Peña 1077 (holotype MEXU).
Additional specimens examined (paratypes):—None.
Sicut Graphis longula sed lirellis nudis differt.