The term ‘siphuloid’ is introduced for a suite of distinct lichen genera with a superficially similar foliose to fruticose morphology, notably Siphula, Siphulella, Siphulopsis, Parasiphula and Knightiellastrum. Three new species are described: Parasiphula squamosa Kantvilas (from Tasmania and New Zealand), characterized by a whitish grey, squamulose or minutely foliose thallus lacking lichen substances or containing traces of atranorin; Siphula capensis Kantvilas (from southern Africa), containing baeomycesic and squamatic acids, and characterized by robust, broadly flattened, rounded lobes with thickened apices; and S. crittendenii (from the Caribbean but with an outlying collection from Queensland, Australia), an epiphytic species containing thamnolic acid, with fragile, flattened lobes mostly to 10 mm long and 1−5 mm wide, with ragged or much-divided apices. Salient features of the species of Parasiphula are summarized and a first key for this genus is presented. Infrageneric problems in Siphula are also discussed briefly.

The genus Arthothelium A. Massal. in Tasmania comprises ten species. Five of these are described as new: A. bacidinum Kantvilas, a saxicolous, littoral species with subglobose apothecia, non-macrocephalic ascospores, 25−40 × 11−19 μm, and containing the pigment Endoaurantiacum-gold which yields a K+ red reaction; A. insolitum Kantvilas, lichenicolous in rainforest and characterized by subglobose apothecia, very large, non-macrocephalic ascospores, 50−80 × 22−40 μm, and containing the pigment Interveniens-brown which reacts K+ olive green; A. macounioides Kantvilas, corticolous in wet forest and characterized by sessile, convex apothecia, macrocephalic ascospores, 29−42 × 11−18 μm, and containing the pigment Endoaurantiacum-gold; A. magenteum Kantvilas, a common wet forest epiphyte with applanate apothecia, non-macrocephalic ascospores, 25−55 × 11−22 μm, and containing a unique maroon-red, K+ pink pigment; and A. subtectum Kantvilas, a saxicolous species with convex apothecia, macrocephalic ascospores, 22−36 × 9−14 μm, and containing Endoaurantiacum-gold. The New Zealand species A. endoaurantiacum Makhija & Patw. and A. suffusum (C. Knight) Müll. Arg., and the Australian A. velatium Müll. Arg. are recorded for Tasmania for the first time. The names A. obtusulum (Nyl.) Müll. Arg., A. pellucidum (C. Knight) Müll. Arg. and A. polycarpum Müll. Arg. are considered synonyms of the widespread A. ampliatum (C. Knight & Mitten) Müll. Arg. Arthothelium ferax Müll. Arg. is a synonym of A. interveniens (Nyl.) Zahlbr. and A. subspectabile Vĕzda & Kantvilas is a synonym of A. suffusum. The sole record of A. macrothecum (Fée) A. Massal. from Tasmania is found to be based on a misidentification. A key to the species is provided. The importance of apothecial pigments, apothecial morphology and ascospore septation is discussed, and three pigments are characterized by their appearance in water and other standard media.

The new genus Australidea Kantvilas, Wedin & M. Svensson is described to accommodate Lecidea canorufescens Kremp., a widespread lichen in temperate Australasia. It is characterized by a crustose thallus with a green photobiont, reddish brown, biatorine apothecia with an internally hyaline, cupulate proper exciple constructed of branched and anastomosing hyphae, mainly simple paraphyses, 8-spored, Porpidia-type asci and simple, hyaline, non-halonate ascospores. A phylogenetic analysis places the new genus in the family Malmideaceae. Lecidea canorufescens Kremp., L. glandulosa C. Knight, L. immarginata R. Br. ex Cromb. and L. intervertens Nyl. are lectotypified. These names, plus L. dacrydii Müll. Arg. and L. eucheila Zahlbr., are all synonyms of Australidea canorufescens (Kremp.) Kantvilas, Wedin & M. Svensson comb. nov. Several genera superficially similar to Australidea, including Malcolmiella Vĕzda, Malmidea Kalb et al. and Myochroidea Printzen et al., are compared. A comprehensive anatomical and morphological description of the genus Malcolmiella, recorded for Tasmania for the first time, is also provided. The new combination M. interversa (Nyl.) Kantvilas, Wedin & M. Svensson is introduced and the names M. cinereovirens Vĕzda and M. cinereovirens var. isidiata Vĕzda are reduced to synonyms. The systematic position of this genus remains unclear, although phylogenetic analysis suggests its affinities lie with a group of genera that includes Bryobilimbia Fryday et al., Romjularia Timdal and Clauzadea Hafellner & Bellem.

Caloplaca tephromelae Kantvilas, Suija & Motiej., a lichenicolous species growing on saxicolous thalli of species of Tephromela, is described from Tasmania. The new species is characterized by lecanorine to zeorine apothecia with a whitish grey thalline margin devoid of anthraquinone pigments, a non-inspersed hymenium, paraphyses without oil vacuoles and ascospores 10–14 × 5–8 μm, with a septum 5–8 μm thick. It is compared with selected taxa of Caloplaca s. lat. that share these salient features. Molecular data support the distinctiveness of the new species but do not suggest any obvious close relatives.

The lichen genus Lecanactis Körb. in Tasmania comprises six species: L. abietina (Ach.) Körb., which is widespread and pan-temperate; L. latispora Egea & Torrente and L. neozelandica Egea & Torrente, both shared with New Zealand and with the former recorded here from the Auckland Islands for the first time; L. mollis (Stirt.) Frisch & Ertz, shared with Victoria and New Zealand; L. aff. dilleniana (Ach.) Körb., a European species recorded provisionally for Tasmania on the basis of several sterile collections; L. scopulicola Kantvilas, which is described here as new to science and apparently a Tasmanian endemic. This new taxon occurs in rocky underhangs and is characterized by a thick, leprose thallus containing schizopeltic acid, and 3-septate ascospores, 19–30 × 4.5–6 μm. Short descriptions and a discussion of distribution and ecology are given for all species. A key for all 11 Australian species of the genus is provided, including L. subfarinosa (C. Knight) Hellb. and L. tibelliana Egea & Torrente, which are recorded for Australia for the first time, and L. platygraphoides (Müll.Arg.) Zahlbr., a first record for New South Wales. Lecanactis spermatospora Egea & Torrente and L. sulphurea Egea & Torrente are also included.

Two Tasmanian species of the genus Cresponea are treated: C. graemeannae Kantvilas sp. nov., characterized by a very thin, saxicolous thallus, apothecia with a thick, radially fissured margin, thinly pruinose disc, hypothecium inspersed with oil droplets, and 5–9-septate ascospores, 25–40 × 6–8 μm; and C. subpremnea (Kantvilas & Vĕzda) Kantvilas comb. nov. The latter has ascospores 30–58 × 4.5–7 μm, which distinguish it from the related C. plurilocularis (Nyl.) Egea & Torrente (ascospores 27–45 × 6–8 μm). The taxa are illustrated, discussed and compared. Cresponea litoralis Elix, based on an Australian type, is considered a synonym of Bactrospora myriadea (Fée) Egea & Torrente. A key to the species of Cresponea reported from Australia is presented.

The circumscription of the lichenized ascomycete genus Icmadophila Trevis. in the family Icmadophilaceae Triebel was investigated. Sequences of the internal transcribed spacer (ITS) region and large subunit of nuclear ribosomal DNA (nuLSU) were generated for the five Icmadophila species and additional members of Icmadophilaceae from the genera Dibaeis, Endocena, Knightiella, Siphula, Siphulella and Thamnolia. Phylogenetic analyses indicate that three Icmadophila species are closely related: the type, I. ericetorum (L.) Zahlbr., which is widespread in Eurasia and North America, I. aversa (Nyl.) Rambold & Hertel from Central and South America, and I. japonica (Zahlbr.) Rambold & Hertel, which is restricted to Far East Russia and Japan. The genus Knightiella Müll. Arg. is reinstated to accommodate I. splachnirima (Hook.f. & Taylor) D. J. Galloway emend. L. Ludw., which occurs in New Zealand and Australia. Two further species of Knightiella, K. eucalypti (Kantvilas) Kantvilas and K. queenslandica Kantvilas, are found to be unrelated to K. splachnirima, and are accommodated in two newly described genera, Knightiellastrum and Siphulopsis respectively. Knightiellastrum L. Ludw. & Kantvilas is characterized by a squamulose, erhizinate, whitish to pale grey thallus with a green, coccoid photobiont and by containing thamnolic acid. Siphulopsis Kantvilas & A. R. Nilsen is similarly characterized by an erhizinate, whitish to pale grey thallus, with a green, coccoid photobiont and containing thamnolic acid, but is instead fruticose. This study reveals considerable diversity within Australasian Icmadophilaceae; ongoing work in the Southern Hemisphere and tropical regions may reveal additional species in this family and clarify the relationships of these newly described genera.

The new combination Ocellomma rediuntum (Stizenb. ex Hasse) Kantvilas, Gueidan & Tehler is proposed, supported by morphological, anatomical and molecular data. Hitherto known only from the Californian coast, this species is here recorded for Kangaroo Island (South Australia), Victoria and Tasmania. It is described and illustrated from Australian collections. The ecology of the species and its remarkable distribution are discussed.

Thirty-five species of Micarea are recorded for Tasmania. Ten are described as new to science: M. ceracea Coppins & Kantvilas (also known from Victoria and New South Wales), characterized by a thallus containing perlatolic and didymic acids, pallid apothecia and 3(–4)-septate ascospores, 10–21 × 3·5–6 µm; M. cinereopallida Coppins & Kantvilas (also known from Chile), with a granular to coralloid, goniocyst-like thallus containing superlatolic acid, pallid to piebald apothecia and (0–)1-septate ascospores, 8–15 × 2·5–5 µm; M. micromelaena Kantvilas & Coppins, similar to the widespread M. melaena but with markedly smaller, 0–1-septate ascospores, 8–12·5 × 2·5–4 µm; M. oreina Kantvilas & Coppins, characterized by a thallus of globose areoles containing gyrophoric acid, black, subglobose apothecia, and 1-septate ascospores, 11–16·5 × 4·5–6·5 µm; M. pallida Coppins & Kantvilas, similar to M. ceracea but distinguished by the presence of porphyrilic acid and relatively small, 3-septate ascospores, 9·5–15 × 2·5–4 µm; M. prasinastra Coppins & Kantvilas (also known from New Zealand), a member of the M. prasina group with a finely granular-sorediose thallus containing gyrophoric acid, unpigmented apothecia and (0–)1-septate ascospores, 7–11·5 × 1·8–3·5 µm; M. rubiginosa Coppins & Kantvilas (also known from Chile), likewise allied to M. prasina but with apothecia containing Rubella-orange pigment and ascospores 0–1-septate, 9·5–17 × 3·5–5·5 µm; M. sandyana Kantvilas, related to M. ternaria (Nyl.) Vĕzda but differing by smaller ascospores, 7–13·5 × 3·5–6 µm; M. saxicola Coppins & Kantvilas, characterized by a relatively thick, grey-brown, areolate thallus, convex, black apothecia and 0(–1)-septate ascospores, 7–18 × 4·5–7 µm; and M. tubaeformis Coppins & Kantvilas, related to M. flagellispora and with filiform ascospores, 45–100 × 1–2 µm, but differing by containing 2′-O-methylperlatolic acid and having funnel-shaped pycnidia. Ten species of Micarea are reported for Tasmania for the first time: M. almbornii Coppins, M. argopsinosa P. M. McCarthy & Elix, M. byssacea (Th. Fr.) Czarnota et al., M. contexta Hedl., M. farinosa Coppins & Aptroot, M. humilis P. M. McCarthy & Elix, M. incrassata Hedl., M. myriocarpa V. Wirth & Vězda ex Coppins, M. nowakii Czarnota & Coppins and M. pseudocoppinsii Brand et al. Also recorded for the first time for Victoria are M. alabastrites (Nyl.) Coppins and M. cinerea (Schaer.) Hedl. A key to Micarea-like lichens in Tasmania, which includes Micarea itself as well as Brianaria, Psilolechia and Leimonis, is presented. Leimonis erratica (Körb.) R. C. Harris & Lendemer and Brianaria tuberculata (Sommerf.) S. Ekman & M. Svensson are recorded for Tasmania for the first time.

An identification key to the 39 species of Menegazzia recorded for Australia and its offshore islands (including Tasmania) is presented. Distribution patterns are discussed and summarized. Mainland Australia supports 19 species, with seven endemics, and shares 12 species with Tasmania, six with New Zealand and one with South America. The new species, Menegazzia williamsii Kantvilas from New South Wales, is described and is characterized by an inflated, fragile, esorediate thallus containing stictic acid but lacking isopigmentosin, 2-spored asci and an inspersed epihymenium. In addition, M. hypernota Bjerke, formerly known only from New Zealand, is recorded from Tasmania for the first time.

Sixteen species of lichenicolous fungi are documented from Siphula-like lichens. Two new genera based on new species are introduced. Amylogalla Suija, Motiej. & Kantvilas, characterized by I+ blue, K/I+ violet vegetative hyphae and ascomatal wall, immersed, cleistohymenial, yellowish to orange ascomata, unitunicate, non-amyloid, 8-spored asci and hyaline, ellipsoid, aseptate ascospores, is described from Parasiphula in Tasmania. Saania Zhurb., characterized by superficial, stromatic, multilocular ascomata, non-amyloid hymenial gel, persistent periphysoids, bitunicate, non-amyloid, 4(–8)-spored asci and narrowly obovate to ellipsoid, 1(–3)-septate, initially hyaline and smooth-walled, later sometimes brown and verruculose ascospores, is described from Siphula in South Africa. Four additional species are described as new: two from Siphula (Cercidospora santessonii Motiej., Zhurb., Suija & Kantvilas and Stigmidium kashiwadanii Zhurb.) and two from Parasiphula (Endococcus hafellnerianus Motiej., Suija & Kantvilas and Pyrenidium macrosporum Motiej., Zhurb., Suija & Kantvilas). Additional hosts and/or expanded geographical ranges are reported for Aabaarnia siphulicola, Epigloea soleiformis, Plectocarpon gayanum and Pyrenidium actinellum. The Southern Hemisphere is the centre of species richness for siphulicolous fungi, with 12 species restricted to this region. Taxa recorded for the Northern Hemisphere are Sphaerellothecium siphulae (arctic and boreal) and the subcosmopolitan Epigloea soleiformis and Pyrenidium actinellum, both of which are also known from various lichen hosts. The distribution of siphulicolous fungi strongly underpins the current generic classification of Siphula-like lichens, with five species being confined exclusively to Parasiphula and nine to Siphula. A key to the taxa occurring on Siphula and Parasiphula is provided.

Descriptions, illustrations, discussion and an identification key are presented for six saxicolous and terricolous species of the lichen genus Bacidia De Not. occurring in temperate Australia and Tasmania. Three species are described as new to science: B. lithophila Kantvilas from northern Tasmania, characterized by having only brown apothecial pigments and 3–5-septate, acicular ascospores, 23–35×1·5–2·0 µm; B. littoralis Kantvilas from Tasmania, South Australia (Kangaroo Island) and New South Wales, characterized by green and brown apothecial pigments and acicular, 3–7-septate ascospores, 24–48×2·0–3·5 µm; and B. maccarthyi Kantvilas from New South Wales, with pruinose apothecia and long, filiform, 17–25-septate ascospores, 65–115×2·5–4·0 µm. Three further species are reported for the region for the first time: B. bagliettoana (A. Massal. & de Not.) Jatta (Tasmania), B. curvispora Coppins & Fryday (Tasmania) and B. scopulicola (Nyl.) A. L. Sm. (Tasmania, Victoria).

Five new species of Rimularia, all endemic to Tasmania, are described, discussed and illustrated: Four species are saxicolous: R. albotessellata Kantvilas (containing pannarin): R. aspicilioides Kantvilas (containing 2′-O–methylperlatolic acid and with apothecia with a thalline margin); R. circumgrisea Kantvilas (containing norstictic acid, and with ascospores 8·5–14·0×5·0–6·5 µm); and R. coppinsiana Kantvilas (containing bourgeanic acid and with ascospores 10–19×7–12 µm). The corticolous R. asteriphila Kantvilas lacks lichen substances, contains Sedifolia-grey pigment and has ascospores 10–15×7–10 µm. The widespread R. psephota (Tuck.) Hertel & Rambold, with which several of the new taxa are compared, is also described, based on Tasmanian collections. Several chemical compounds, including bourgeanic acid, pannarin and 2′–O–methylperlatolic acid, are recorded for the genus for the first time. A key to the 12 species currently recorded for Tasmania is presented.

Three new species of Menegazzia are described and illustrated, and their relationships and affinities to other species in the genus discussed. Menegazziabjerkeana Kantvilas is an isidiate species from the coastal ranges of New South Wales; M. brattii Kantvilas is an eight-spored species related to the widespread M. pertransita (Müll. Arg.) R. Sant., and is endemic to Kerguelen Island; and M. gallowayi Kantvilas is an eight-spored species from South Island, New Zealand. Menegazzia sanguinascens (Räsänen) R. Sant. is recorded from Kerguelen for the first time.

The new species Lecanora coppinsiarum Kantvilas is described, based on collections from Tasmania. It is characterized by an entirely sorediate thallus containing atranorin only, and the anatomy of its biatorine apothecia, its Lecanora-type asci and small, hyaline, simple ascospores suggest a relationship to L. symmicta (Ach.) Ach. The South American species L. subviridis de la Rosa & Messuti is recorded for the first time for Tasmania.

With 30 species, Tasmania is a major area of species diversity in the genus Menegazzia. Seven of these are new to science: M. abscondita Kantvilas, known from Tasmania and New Zealand, and M. athrotaxidis Kantvilas, M. hypogymnioides Kantvilas, M. petraea Kantvilas, M. ramulicola Kantvilas, M. subtestacea Kantvilas and M. tarkinea Kantvilas, all endemic to Tasmania. An identification key, descriptions based exclusively on Tasmanian collections, and detailed discussion of distribution, ecology, chemical composition and inter-species relationships are provided. All literature records of Menegazzia species pertaining to Tasmania are accounted for. New synonyms include: Menegazzia prototypica P. James and Parmelia pertusa var. coskinodes F. Wilson [synonyms of M. myriotrema (Müll. Arg.) R. Sant.], M. fertilis P. James [a synonym of M. platytrema (Müll. Arg.) R. Sant.] and Parmelia pertusa var. montana F. Wilson (a synonym of M. subtestacea). Incorrectly recorded species that should be deleted from the Tasmanian census include M. castanea P. James & D. J. Galloway (present on Macquarie Island) and M. testacea P. James & D. J. Galloway (endemic to New Zealand). The South American species, M. sanguinascens (Räs.) R. Sant., is recorded in Australasia (Tasmania) for the first time, whereas the widespread south-eastern Australian M. norstictica P. James is recorded for Western Australia. Salient features of the genus are discussed, including morphology, anatomy and chemistry. The biogeography of the genus is explored briefly. Twelve species (40%) are endemic to Tasmania, a level of endemism unmatched by any other species-rich genus on the island. Twelve species are shared with mainland Australia, eleven are shared with New Zealand, and only four species are shared with southern South America, all of which are sorediate, suggesting they are products of long-distance dispersal.

The new genus, Cameronia Kantvilas, is described and illustrated. It is characterized by a crustose thallus, a chlorococcalean photobiont, deeply immersed perithecioid ascomata, four-spored asci with an intensely hemiamyloid outer wall and non-amyloid, well-developed tholus, and hyaline, muriform ascospores. The taxonomic position of the new genus is uncertain although a relationship with the Ostropomycetidae is likely. Two species, both endemic to the highlands of Tasmania, are described: C. pertusarioides Kantvilas, which is one of the most common lichens on dolerite in alpine Tasmania, and C. tecta Kantvilas, which is confined to metamorphosed sediments.