Parmotrema reticulatum (Taylor) M. Choisy

    Thallus foliose, loosely attached to the substratum, to 15 cm across, lobes 5-15 mm wide, tips rounded and crenulate; upper surface grey-glaucous, pale grey, minutely reticulated, reticulations suggesting minute cracks on old and dry specimen, swollen and capitate soralia at lobe margins, cilia almost absent or then very short and black; lower surface dark brown to black with simple rhizines extending up to the margin. Apothecia very scarce, markedly sessile and almost shortly stipitate, 5-8 mm diam., disc brownish, exciple sorediate.  Ascospores simple, ellipsoid, 13-19 x 8-10 µm. Cortex: C-, KC-, K+ yellow (red after a few minutes and cortex lysis and medulla reaction), Pd+/- yellow ; medulla: C-, KC+ yellow > red, K+ yellow > red, Pd+ red-orange, UV-. Oceanic trends, rather common on tree trunks and also on mossy rocks. Not to be confused with Parmotrema perlatum of which soredia distribution suggests pearl necklace, without rhizine at lobe margins, without reticulum on the lobe upper surface and K+ yellow, nor with Parmotrema arnoldii, which is Pd- and with long black cilia towards lobe margins. N.B. Parmotrema pseudoreticulatum was described in 1974. It differs by its lobe margins, thicker and less upturned, devoid of rhizines, and by the less conspicuous and less developed reticulum on lobe upper surface sometimes maculate or dotted. Intermediate specimen may be found.*