A Synopsis of the Genera Skyttea, Llimoniella and - Lichens of ...

448 THE LICHENOLOGIST Vol. 32
J
FIG. 6. Skyttea tavaresae (Tavares 1419). A, ascoma on Pyrrhospora thallus; B, excipular hairs.
Scales: A=100|im; B = 5nm.
but just below the subhymenium reddish brown, K+ pale purplish or violet,
N - , 15-20 um thick; excipular hairs dark greyish brown, K+ bright aeruginose
green, N+ dark reddish brown, straight, wall apically not thickened,
with irregular, pigmented ring-like structures (see Fig. 6), c. 30-48 x 2-5-
3 um. Subhymenium hyaline to yellowish, c. 10 um thick. Hymenium 30-60 urn
thick. Epihymenium hyaline. Paraphyses filiform, simple, septate, 1-5 um thick,
apically slightly thicker. Asci subcylindrical, wall apically thicker, 8-spored,
c. 43-50 x 5-8 um. Ascospores hyaline, elongate ellipsoid, O(-l)-septate,
biguttulate, (8-)9-12(-13) x 2-5-3 um.
Host. On the thallus of Pyrrhospora cf. quernea.
Distribution. Known from two localities in the USA (California).
Observations. This species is mainly characterized by the unusual dark
greyish brown exciple, which is K+ bright aeruginose green and N+ dark
reddish brown (basally with an additional, reddish brown, K+ purplish or
violet pigment), by the long concolorous excipular hairs (hairs are pale
greenish or hyaline in most other Skyttea species) and the long, but narrow,
biguttulate ascospores. The differences with S. carboneae and 5. nitschkei are
given in the identification key. The species is named after I. I. Tavares who
collected the first specimen of this species and who made it available for study.
We studied a specimen of a similar, but distinct species, growing on
Pertusaria cf. santamonicae [USA, California, Santa Barbara Co., Santa Rosa
Island, pass along the main road just SE of Black Mountain, 33°58'45"N,
120°4'30"W, i 1994, T. H. Nash III 32.615 (ASU)]. The ascospores are
8-5-10-5(-ll-5) x 3-3-5 um, the ascomata 150-250(-300) um in diam., the
hairs reach at least 50 um and the exciple contains the dark red, K+
B