A Lichenological Legacy – Festschrift Thomas H

(Colour Plate 16F)
Description: Prothallus thin or indistinct, white to dark brown. Thallus effuse,
formed partly by minute areolae and partly by isidia developing directly from the
prothallus, not radiating at the margin; isidia often dominating. Areolae up to 0.06
mm wide, adnate, isodiametrical, plane to weakly convex, medium to dark green,
more or less shiny, epruinose, glabrous. Isidia abundant, cylindrical, long, 0.03–
0.05 mm wide, medium to dark green, simple to slightly branched. Upper cortex
poorly defined, 5–10 μm thick, not containing crystals. Medulla containing
crystals dissolving in K; PD–, K–. Apothecia not common (seen in the type only),
up to 1 mm diam., plane when young, later weakly to moderately convex, dark
brown, shiny, rounded, mostly simple, with a distinct, brownish black, not
pubescent margin when young, later more or less immarginate. Excipulum dark
reddish brown in inner part, paler in the rim, containing colourless crystals dissolving
in K. Hypothecium reddish brown in lower part, deeper pigmented in upper
part, containing some scattered colourless crystals dissolving in K. Epithecium
colourless. Reddish brown pigment in apothecium K+ purple. Ascospores
acicular, simple, usually with 3 pseudosepta, 27–42 ca. 1.5 μm (n = 20).
Chemistry: hyperlatolic acid (major), perlatolic acid (minor) and superlatolic acid
(minor).
Notes: The species is morphologically and anatomically similar to P. furfuracea
and the paleotropical P. dolichospora Timdal & Krog, P. foliatella Elix, P.
homosekikaica Elix, and P. methoxymicareica Elix, but differs from them all both
in chemistry and in ascospore size. In P. furfuracea, the ascospores are narrowly
ellipsoid, 7–13 2–3 μm, and the thallus contains furfuraceic acid or no lichen
substances; in P. dolichospora the spores are bacilliform, 16–25 2–3 μm, and
the thallus contains methyl furfuraceiate (major), methyl homofurfuraceiate
(major), and furfuraceic acid (minor); in P. foliatella the spores are 11–18 μm
long and the thallus does not contain lichen substances; in P. homosekikaica the
spores are narrow-ellipsoid, 7–11 2–3 μm, and the thallus contains
homosekikaic acid (major) and hyperhomosekikaic acid (major); and in P.
methoxymicareica the spores are ellipsoid, 10–14 3–5 μm, and the thallus
contains methoxymicareic acid (major) and hydroxymicareic acid (trace) (TIMDAL
& KROG 2001, ELIX 2006b, 2006c, 2008). See also P. teretiuscula for discussion.
Phyllopsora tobagensis is known from seven collections along three trails in
the Main Ridge rainforest in Tobago, collected at altitudes of about 400–520 m.
The species is corticolous or growing over corticolous bryophytes.
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