One-hundred and sixty-three new or noteworthy lichens and allied fungi are reported from Ontario based on new collections. The lichens Lecanora atromarginata, L. gisleriana, Rhizocarpon ridescens and Sclerococcum griseisporodochium are new to North America. The reported species new to Canada are: Abrothallus bertianus, Absconditella trivialis, Agonimia opuntiella, Diploschistes gypsaceus, Ephebe solida, Heterodermia japonica, Minutoexcipula tuckerae, Peltula bolanderi, Placynthium petersii, Protothelenella sphinctrinoides, Pycnora praestabilis, Thelopsis melathelia, Toninia tecta and Verrucaria quercina. Sixty-one taxa reported new to Ontario include: Abrothallus peyritschii, A. usneae, Agonimia tristicula, Arctoparmelia subcentrifuga, Arthrorhaphis citronella, Bachmanniomyces uncialicola, Baeomyces placophyllus, Biatora printzenii, Bilimbia lobulata, Calicium lucidum, Caloplaca stillicidiorum, Cetraria nigricans, Chaenothecopsis australis, Cystocoleus ebeneus, Dactylospora lobariella, Dendriscocaulon intricatulum, Dermatocarpon schaechtelinii, Enchylium conglomeratum, Endocarpon pulvinatum, Gyrographa gyrocarpa, Henrica theleodes, Heterodermia neglecta, Homostegia piggotii, Hypotrachyna afrorevoluta, H. revoluta, Lathagrium auriforme, Lecanora appalachensis, Lecanora epibryon, Lecanora orae-frigidae, Lecidea lapicida, Lecidella wulfenii, Lempholemma radiatum, Lepraria oxybapha, Lichenoconium usneae, Lichenomphalia umbellifera, Lichenostigma elongata, Lopadium coralloideum, Ophioparma lapponica, Pertusaria bryontha, P. coriacea, P. globularis, Phylliscum demangeonii, Plectocarpon lichenum, Polycauliona stellata, Porpidia flavicunda, Pseudosagedia chlorotica, Rhizocarpon eupetraeoides, Rostania ceranisca, Sclerophora farinacea, Scytinium schraderi, Solorina bispora, Sphaerellothecium minutum, Sticta beauvoisii, S. fuliginosa, Tetramelas papillatus, Tremella cetrariicola, Umbilicaria lyngei, Usnea ceratina, Xanthomendoza fulva and Xylographa opegraphella. Details on additional rare or otherwise rarely collected species new to explored counties and districts are also provided. These include: Acarospora bullata, Ahtiana aurescens, Amygdalaria panaeola, Anaptychia crinalis, Arctoparmelia incurva, Arthonia diffusella, Baeomyces carneus, Blastenia ferruginea, Buellia badia, Calicium abietinum, Caloplaca saxicola, Cetraria aculeata, Chaenotheca stemonea, Chaenothecopsis perforata, Cliostomum griffithii, Cyphobasidium hypogymniicola, Dermatocarpon dolomiticum, Dibaeis baeomyces, Flavocetraria nivalis, Fuscopannaria leucosticta, Heppia adglutinata, Heterodermia hypoleuca, H. obscurata, Hyperphyscia syncolla, Hypogymnia vittata, Immersaria athroocarpa, Inoderma byssaceum, Lecanora epanora, Lepraria cryophila, Leproplaca chrysodeta, Leptogium rivulare, Lichenodiplis lecanorae, Lichenostigma cosmopolites, Lithothelium hyalosporum, Lobaria scrobiculata, Lobothallia alphoplaca, Lopadium disciforme, Melanelixia albertana, M. subargentifera, Melanohalea halei, M. subolivacea, Muellerella erratica, Mycoblastus alpinus, Mycoglaena myricae, Myelochroa obsessa, Ovicuculispora parmeliae, Pannaria tavaresii, Parmotrema hypotropum, P. reticulatum, P. stuppeum, Peltigera venosa, Pertusaria superiana, Phacopsis oxyspora var. oxyspora, Physcia americana, Physcia tenella, Physconia grumosa, Placidium arboreum, Polychidium muscicola, Porina scabrida, Porpidia degelii, Pseudocyphellaria holarctica, Pseudoschismatomma rufescens, Psoroma hypnorum, Punctelia appalachensis, P. stictica, Rhizocarpon eupetraeum, Rinodina pachysperma, Sarea difformis, Scytinium gelatinosum, Scytinium intermedium, Sphaerophorus fragilis, S. globosus, Stictis radiata, Synalissa ramulosa, Syzygospora physciarcearum, Teloschistes chrysophthalmus, Thyrea confusa, Toninia aromatica, Tremella everniae, Umbilicaria arctica, U. hirsuta, U. proboscidea, U. torrefacta, Usnea glabrescens and Xanthoparmelia angustiphylla.