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When: 2008-06-08

Collection location: Plateau above Echo Cliffs, Coconino Co., Arizona, USA [Click for map]

Who: Jason Hollinger (jason)

Specimen available

Notes:
crust lichen, on exposed sandstone
THALLUS: areolate to subsquamulose, areoles mostly 0.5-1.0 mm, surface smooth and dark brown, basally pinched and developing lateral and some lower cortex, cortex composed of tightly-packed round cells with brown pigment caps, covered with thin hyaline layer of dead cells (POL+ white), K- or lower cortex K+ weak red-violet
MEDULLA: white
ALGAE: green, in a continuous dense layer just below well-defined cortex, K-
APOTHECIA: perithecia, almost completely immersed, visible as barely-raised black pimples, subglobose, exciple pale brown and uniform, involucrellum black and clasping exciple on top third to half, periphyses mostly dissolving, hymenial gel K/I+ blue, asci K/I- and broadly clavate
SPORES: 8 per ascus, biseriate, elliptical, smooth outside but with texture and usually one large bubble inside, (13)17+/-1.5(19) x (8.4)11+/-2.5(15) µm (Q=(1.1)1.5+/-0.3(2.1)) (N=11), K/I+ golden to red-brown

I’m positive of the genus, since there are no other crustose perithecioid genera with K/I+ hymenium and black involucrella, and 8-spored asci. V. macrostoma is very close, but spores are too small, and no Verrucaria mentions the K+ reaction of the lower cortex.

Images

magnification 30x
magnification 10x
perithecial section, in water, at 100x
perithecial section, in water, at 100x
perithecial section, in KOH, at 100x
perithecial section, in K/I, at 100x
perithecial section, in water, at 400x
spores, in K/I, at 1000x

Proposed Names

58% (1)
Used references: Nash’s Sonoran Flora
Based on microscopic features

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= Observer’s choice
= Current consensus

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