Irish lichens

Opegrapha niveoatra

Order: Arthoniales       Family: Opegraphaceae

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, but thalli are often sterile. Spores are 4-7(-8) septate, 20-30 x 2.5-4 Ám. Pycnidia are abundant, the conidia short, curved and worm-like. Micrograph below. 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

Micrograph
Opegrapha niveoatra
Opegrapha niveoatra May 2010

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