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Opegrapha niveoatra (Borrer) J. R. Laundon (redirected from: Opegrapha dubia)
Family: Graphidaceae
[Opegrapha amphotera Nyl.,  more]
Opegrapha niveoatra image
Life habit: lichenized Thallus: thin, sometimes inconspicuous, smooth, continuous to rimose, without distinct prothallus surface: white to gray or olive-brown Ascomata: 0.3-1.5 x 0.1-0.2 mm, sessile, scattered or contiguous, simple, straight, curved or stellate; disc slit-like, partly slightly widened with age, epruinose exciple: closed, K± olivaceous hymenium: 50-70 µm, I+ reddish; subhymenium: brown, (12-)15-25 µm; paraphysoids: to 1 µm wide asci: cylindric-clavate, 40-55 x 11-13 µm (Vulgata-type) ascospores: acicular to fusiform, straight or slightly curved, hyaline, (18-)20-27(-30) x 2.5-4 µm, 4-7(-8)-septate, (Vul-gata-type) Pycnidia: immersed or subimmersed conidia: curved, worm-like, 4-8 x 1-1.5 µm Spot tests: thallus K-, C-, KC-, P- Secondary metabolites: none detected. Substrate and ecology: on neutral and basic deciduous bark, in wayside and woodland situations, in areas with humid climate World distribution: Europe, North America (west coast) and northern Africa Sonoran distribution: southern California and Baja California. Notes: Opegrapha niveoatra is very close to O. vulgata which differs by longer and narrower conidia.