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Muellerella lichenicola (Sommerf. ex Fr.) D. Hawksw.
Family: Verrucariaceae
[Arthopyrenia cookei (Linds.) Arnold,  more]
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Life habit: lichenicolous Perithecia: globose to pyriform, immersed or rarely becoming sessile, (70-)100-125(-150) µm in diam. wall: brown, mainly 3-5 cell layers thick, upper part sometimes thickened, lower part grayish brown, olivaceous or brownish yellow periphyses: present, 1-2.5 µm in diam., up to 15 µm long asci: clavate to broadly clavate, 50-65 x 14-20 µm, more than 64-spored ascospores: pale brown to grayish brown or olivaceous brown, (0-)1-septate, ovoid to broadly ellipsoid, (4.5-)5-6(-7) x (2-)2.5-3(-3.5) µm, slightly aciculate, smooth, thin-walled Pycnidia: immersed, c. 50 µm in diam. conidiogenous cells: 4.5-5.5 x 3 µm conidia: hyaline, 3-3.5 x 1-1.5 µm. Hosts: apothecia and more rarely thalli of lichens, especially Teloschistaceae and Physciaceae; host lichens often on bark or calciferous rocks World distribution: worldwide; in extratropical regions, mainly at lower elevations Sonoran distribution: thus far known only from the Channel Islands of California and central Arizona.