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Verrucaria macrostoma  Dufour ex DC.

Synonyms:

Family: VERRUCARIACEAE

Habitat: Ubiquitous

Description

    Thallus crustose, usually rather thick, cracked-areolate or subsquamulose, dried mud-like during dry periods, areola plane to slightly convex, 0.5-1.5 mm diam., smooth to faintly rough, dark brown to brownish when dry, olive-brown to olive-green when moist (and then, with green thallus, subsquamulose towards margin). Perithecia globular, numerous, 1 to 3 per areola, 0.3-0.5 mm diam., half immersed in thallus and half-projecting above the surfaces of the areoles, blackish. Ascospores simple, colourless, ellipsoid, 20-28 x 10-13 µm. Chemical spot tests negative. On hard calcareous rocks and, in our prospection area, mostly abundant on mortar of shaded and humid walls near the seashores. Can be confused with a close taxa, Verrucaria viridula that also grows on walls, usually dryer and with perithecia pear-shaped and smaller, deeply immersed in the thallus and less prominent. A different morph growing on damp walls with soredia and propagules at the areoles margin, can also be found: Verrucaria macrostoma f. furfuracea. See also Verrucaria nigrescens with colours drab and not turning green. N.B. A Verrucaria squamulosa Brand & van den Boom, that strongly resembles to some very squamulose morphs of Verrucaria macrostoma (see photos) but genetically distinct, have been described but, for now, we could not distinguish between them since all intermediate specimen seem possible.*







Verrucaria macrostoma L'Aber en Crozon 1
Bernard BOUFFINIER



Verrucaria macrostoma Landévennec 1
Bernard BOUFFINIER



Verrucaria macrostoma Sainte Anne la Palud 2
Bernard BOUFFINIER



Verrucaria macrostoma Sainte Anne la Palud 4
Bernard BOUFFINIER



Verrucaria macrostoma Sainte Anne la Palud 4
Bernard BOUFFINIER



Verrucaria macrostoma L'Aber en Crozon 2
Bernard BOUFFINIER



Verrucaria macrostoma L'Aber Rozan
Bernard BOUFFINIER



Verrucaria macrostoma Forme intermédiaire L'Aber Rozan
Bernard BOUFFINIER



Verrucaria macrostoma Sur mortier d'un mur Sainte Anne la Palud 1
Bernard BOUFFINIER



Verrucaria macrostoma sec Le Passage 1
Bernard BOUFFINIER



Verrucaria macrostoma Sec L'Aber en Crozon 5
Jacques HAINE



Verrucaria macrostoma Asque Bleu Coton L'Aber en Crozon 6
Jacques HAINE



Verrucaria macrostoma Asque Eau L'Aber en Crozon 7
Jacques HAINE



Verrucaria macrostoma Spores Eau L'Aber en Crozon 8
Jacques HAINE



Verrucaria macrostoma humide Le Passage 2
Bernard BOUFFINIER



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