Irish lichens

Opegrapha niveoatra

Order: Arthoniales       Family: Roccellaceae

Species: Opegrapha niveoatra

Growth type crustose.
Photos: On Laburnum. Kinsale, Co. Cork, SW Ireland.
Identification confirmed by John Douglass

Thin dull-grey to olive-brown thallus, similar to O. vulgata but with shorter lirellae, to 1mm long. Scattered or contiguous apothecia, discs becoming partly exposed, exciple +/- uneven. Spores 4-7 septate, conidia worm-like. Often sterile but pycnidia abundant. Chemical reactions negative.

Found on neutral and basic-barked trees; Ash, Sycamore and Elm. Most frequently recorded from eastern Ireland.

Similar: Opegrapha vulgata. Larger discs, conidia sickle-shaped

Opegrapha niveoatra
Opegrapha niveoatra May 2010

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