Mycobank MB 517794
Thallus corticolous, blackish olivaceous, ecorticate or thallus granules and apothecia pseudocorticate, gelatinous when wet, granulose to irregularly areolate, granules ca. 65–165 µm wide, effuse to later aggregated forming irregularly shaped areoles, 0.6–2.5 mm wide giving the thallus a very uneven appearance, fixed to the substrate by pale rhizohyphae. Isidia and soralia lacking. Apothecia small, 0.25–0.37 mm, subglobose, adnate with slightly constricted base to stipitate, disc at first punctiform, eventually opened, pale brownish, plane, thalline margin thin, 25–30 µm thick, soon receding. Excipulum proprium thin but distinct, composed of few interwoven hyphae, pale, basally 5 µm thick, laterally ca. 10 µm thick, apically widened and seen from above as pale ring. Hymenium clear, 110–120 µm high, KOH/IKI+ blue, paraphyses distinct, sparsely branched, apically widened. Asci broad cylindrical to obclavate, 75–80 x 12–15 µm, wall thin, not amyloid, tip not thickened. Ascospores 8/ascus, simple, ellipsoid to broad ellipsoid, hyaline, (10.5–)13–19(–20.5) x (6–)6.5–8(–9) µm. Pycnidia and pycnoconidia not seen. Ascomata developing from tangle of generative hyphae. Photobiont Nostoc in bead-like chains. Secondary chemistry: nil.
The new species is characterized by its corticolous habit and granulose to irregularly areolate growth form. The thallus is essentially ecorticate as in all species of Lempholemma but especially at the base of the thallus granules as well as towards the base of the apothecia a primitive pseudocortex (Degelius, 1954: 46, 47) may be observed. The hyphae forming this pseudocortex are quite robust whereas those attacking the photobiont are more delicate. Hitherto, no species of Lempholemma was knownto grow directly on bark. Dry or moist rock, mosses and soil being preferred substrata. Growth form varies considerably among species of Lempholemma. Whereas membanaceous to subfoliose-plicate and umbilicate, squamulose-lobate thalli are common, granulose thalli are rare . L. minutulum (Born.) Zahlbr. and Psorotichia lutophila Arnold, both pioneer species on soil, are examples of the latter. Lempholemma is a mid-sized genus of c. 40 species occurring worldwide. The genus is in the family Lichinaceae and is distinguished from all other members of the family by the presence of Nostoc photobionts. The genus Collema also contains Nostoc photobionts but differs in the presence of septate ascospores, a thickened, amyloid ascus apex, a different type of pycnidia and conidiophores and the lack of finger-like fungal haustoria invaginating the cells of the photobiont.
Referring to the substrate, which is most unusual in the genus.
So far known only from the bark of old Platanus orientalis trees in the Fassas Valley in western Crete, in the vicinity of a stream. The riverine Platanus forests are in severe decline and threatened by encroachment of developments and orange plantations.
Type:—GREECE: Crete: Fassas Valley, between Langos and Nea Roumata; 35°24'N, 23°53’E, 350 m; corticolous on Platanus orientalis; May 2004, Spribille 13286 (holotype GZU; isotype HBG).
Thallus corticola, nigrescente-olivaceus, ecorticatus, madefacte gelatinosus, granulosus vel irregulariter areolatus, granulis effusis, deinde aggregatis areolae irregulares formantes. Hyphae reticulum formantes. Apothecia thallo concolore, parva, 0.25–0.37 mm lata, adnata vel stipitata, margine thallino tenui, excipulo proprio pallido, disco pallide rufescenti, plano. Hymenium iodo caerulescens. Ascosporae octonae, simplices, ellipsoideae, (10.5–)13–19(–20.5) x (6–)6.5–8(–9) µm. Cyanobacterium symbioticum Nostoc. Pycnidia et pycnoconidia non visa.