{{Short description|Genus of lichens}} {{Use dmy dates|date=June 2025}} {{Use Oxford spelling|date=June 2025}} {{Automatic taxobox | image = Gabura fasciculare 11361947.jpg | image_caption = ''Gabura fascicularis'' from New Zealand | taxon = Gabura | authority = Adans. (1763) | type_species = ''Gabura fascicularis'' | type_species_authority = (L.) P.M.Jørg. (2014) | subdivision_ranks = Species | subdivision = ''G. borbonica''<br /> ''G. fascicularis''<br /> ''G. insignis'' }}

'''''Gabura''''' is a small genus of lichen-forming fungi in the family Arctomiaceae. These lichens form low-growing patches that range from thin, crust-like films to small, crumpled cushions, appearing dark olive-green to almost black when dry but swelling like a sponge and becoming softer when wet. They partner with blue-green algae called ''Nostoc'' and grow on tree bark or soil, often among mosses, reproducing through tiny disc-shaped fruiting bodies that contain long, multi-celled ascospores.

==Taxonomy==

Although it was originally circumscribed in 1763 by French botanist Michel Adanson, the name was nomen rejiciendum–it was "suppressed" against the conserved name ''Collema'', and for a long time considered a synonym of ''Arctomia''.<ref name="Index Fungorum: Gabura"/> In 2014, Per Magnus Jørgensen proposed to use the name ''Gabura'' for what was then known as ''Collema fasciculare''.<ref name="Jørgensen 2014"/> The name was formally resurrected for use in 2020. ''Gabura'' has three species transferred from the genus ''Arctomia'' following molecular phylogenetic analysis.<ref name="Magain et al. 2020"/>

==Description==

''Gabura'' forms low-growing thalli that range from a thin, crust-like film firmly attached to the substrate to small, crumpled cushions whose margins break into indistinct {{lichengloss|lobes}}. When dry the surface is a dark olive-green to almost black; in many species it absorbs water like a sponge, swelling noticeably and taking on a softer texture. A true {{lichengloss|cortex}}—the protective outer skin seen in many lichens—is poorly developed or absent, so the underlying tissues show through. Some taxa produce powdery patches called soralia, whose yellow- to brown-tinged {{lichengloss|granules}} contain both partners of the lichen symbiosis and serve as ready-made propagules for dispersal.<ref name="Cannon et al. 2025"/>

Embedded among the fungal threads are clusters of the cyanobacterium ''Nostoc''; its orangey-green cells, measuring 5–7&nbsp;micrometres across, sit within a clear jelly that helps the thallus retain moisture. Sexual reproduction, where it occurs, takes place in minute disc-shaped fruit bodies (apothecia) that arise directly from the lobes and remain almost stalkless. These {{lichengloss|discs}} lack a distinct rim of thallus tissue and may be flat or gently domed. Inside, slender branched filaments (paraphyses) stand amongst the asci; their tips broaden and darken to brown. Each ascus is of the ''Trapelia'' type: it has a thickened apex (the {{lichengloss|tholus}}) that remains colourless in iodine, while the surrounding gelatinous sheath stains blue, and it normally contains eight long, spindle-shaped ascospores divided by multiple cross-walls (septa).<ref name="Cannon et al. 2025"/>

Asexual reproduction is achieved through flask-shaped pycnidia sunk in the thallus; these release tiny, rod-shaped conidia. Chemical screening with thin-layer chromatography has so far revealed no secondary metabolites, making the genus unreactive with standard chemical spot test. The combination of a swelling, dark thallus with optional soralia, cyanobacterial photobiont, ''Trapelia''-type asci and multiseptate spores distinguishes ''Gabura'' from superficially similar gelatinous crusts in the same habitats.<ref name="Cannon et al. 2025"/>

==Habitat, distribution, and ecology==

Species of ''Gabura'' have a scattered but wide distribution, spanning oceanic and humid temperate regions in both hemispheres. ''Gabura fascicularis'' is recorded from oceanic and sub-oceanic parts of Europe, with reports extending into North Africa and Asia, and it is also known from the Southern Hemisphere (including Australasia); in molecular sampling, collections identified as ''G.&nbsp;fascicularis'' fell into geographically disjunct European and Southern Hemisphere lineages.<ref name="ITALIC"/><ref name="Lichens of Wales"/><ref name="Kantvilas 1990"/><ref name="Magain et al. 2020"/> ''Gabura insignis'' is best known from the Pacific Northwest of North America and has confirmed occurrences in Ireland and Scotland, with additional reports from Ecuador and Japan; related early-diverging lineages occur in Madagascar, Réunion and South Africa, and much of the group's genetic diversity is centred in the south-western Indian Ocean.<ref name="McCune & Geiser 2023"/><ref name="Magain et al. 2020"/><ref name="Jørgensen & Palice 2016"/><ref name="原田浩 2022"/> The third species, ''G.&nbsp;borbonica'', is widespread on Réunion in the Mascarene Islands.<ref name="Magain & Sérusiaux 2012"/>

Across the genus, ''Gabura'' lichens are usually epiphytic on woody substrates such as bark, twigs and trunks, and they are most often recorded in persistently humid, shaded settings. In Europe, ''G.&nbsp;fascicularis'' occurs mainly on the bark of old broad-leaved trees such as elm (''Ulmus'') and ash (''Fraxinus''), sometimes over mosses on bark or rock and occasionally among mosses on calcareous rock outcrops; in Australasia it inhabits very wet, shaded microhabitats on the lower parts of trees in humid forests.<ref name="Lichens of Wales"/><ref name="Kantvilas 1990"/> In the Pacific Northwest, ''G.&nbsp;insignis'' grows on twigs of conifers, hardwoods and shrubs in coastal forests and has also been found on stabilised dunes and headlands; the type was collected near sea level (about 10&nbsp;m elevation) on an alder (''Alnus'') trunk, while British Isles records are from trees in parkland settings.<ref name="McCune & Geiser 2023"/><ref name="Magain et al. 2020"/> On Réunion, ''G.&nbsp;borbonica'' occurs in mountain forest and thicket habitats, including disturbed secondary thickets with ''Eucalyptus'' plantations, where it has been recorded on ''Eucalyptus'' and ''Acacia heterophylla'' trunks and on the main stems of ''Erica'' thickets.<ref name="Magain & Sérusiaux 2012"/> In Britain and Ireland, members of the genus have also been recorded growing on soil (terricolous) and amongst mosses.<ref name="Cannon et al. 2025"/>

''Gabura'' species are cyanolichens with ''Nostoc'' as their photobiont, and differences in reproductive strategy have ecological consequences. ''Gabura fascicularis'' can produce apothecia on the thallus surface, whereas members of the ''G.&nbsp;insignis'' complex are sorediate and may lack known sexual fruiting bodies in parts of their range; European thalli can be minute (about 2–5&nbsp;mm across) and easily overlooked in surveys.<ref name="Cannon et al. 2025"/><ref name="Magain et al. 2020"/> ''Gabura borbonica'' produces {{lichengloss|goniocysts}} at lobe margins that break down into a soredioid fringe.<ref name="Magain & Sérusiaux 2012"/> At least some species appear sensitive to the continuity and quality of their substrates: in Britain, ''G.&nbsp;fascicularis'' has declined alongside the loss of mature host trees and other pressures such as acid rain, and it is treated as near threatened there.<ref name="Lichens of Wales"/><ref name="ITALIC"/>

==Species== *''Gabura borbonica'' {{small|(Magain & Sérus.) Magain & Sérus. (2020)}} *''Gabura fascicularis'' {{small|(L.) P.M.Jørg. (2014)}} *''Gabura insignis'' {{small|(P.M.Jørg. & Tønsberg) Magain & Sérus. (2020)}}

==References== {{Reflist|refs=

<ref name="Cannon et al. 2025">{{cite book |last1=Cannon |first1=P. |last2=Coppins |first2=B. |last3=Sanderson |first3=N. |last4=Simkin |first4=J. |year=2025 |title=Arctomiales: Arctomiaceae, including ''Arctomia'', ''Gabura'' and ''Gregorella'' |series=Revisions of British and Irish Lichens |volume=56 |pages=2–3 |url=https://britishlichensociety.org.uk/sites/default/files/Arctomiales.pdf}}{{Open access}}</ref>

<ref name="Index Fungorum: Gabura">{{cite web |title=Record Details: ''Gabura'' Adans., Fam. Pl. 2: 6 (1763) |url=http://www.indexfungorum.org/names/NamesRecord.asp?RecordID=2023 |publisher=Index Fungorum |access-date=17 April 2022}}</ref>

<ref name="ITALIC">{{cite web |last1=Nimis |first1=P.L. |last2=Martellos |first2=M. |first3=S. |last3=Conti |title=''Gabura fascicularis'' (L.) P.M. Jørg. |website=ITALIC 8.0 |date=4 December 2001 |url=https://italic.units.it/index.php?procedure=taxonpage&num=1008 |access-date=25 August 2025}}</ref>

<ref name="Jørgensen 2014">{{cite journal |last=Jørgensen |first=Per M. |title=Taxonomy and nomenclature of ''Collema fasciculare'' (L.) G. H. Weber |journal=The Lichenologist |volume=46 |issue=4 |year=2014 |doi=10.1017/s0024282914000140 |pages=594}}</ref>

<ref name="Jørgensen & Palice 2016">{{cite journal |last1=Jørgensen |first1=Per M. |last2=Palice |first2=Zdeněk |title=''Leptogium insigne'' new to Ecuador, with notes on its generic position |journal=Evansia |volume=33 |issue=1 |year=2016 |doi=10.1639/0747-9859-33.1.14 |pages=14–17}}</ref>

<ref name="Kantvilas 1990">{{cite journal |last=Kantvilas |first=Gintaras |title=Notes on the lichen flora of New South Wales 1. New records |journal=Telopea |volume=4 |issue=1 |year=1990 |doi=10.7751/telopea19904914 |doi-access=free |pages=19–31}}</ref>

<ref name="Lichens of Wales">{{cite web |title=''Collema fasciculare'' |website=Lichens of Wales |publisher=British Lichen Society |url=https://wales-lichens.org.uk/species-account/collema-fasciculare |access-date=25 August 2025}}</ref>

<ref name="Magain & Sérusiaux 2012">{{cite journal |last1=Magain |first1=Nicolas |last2=Sérusiaux |first2=Emmanuël |title=A further new species in the lichen genus ''Arctomia'': ''A. borbonica'' from Reunion (Mascarene archipelago) |journal=MycoKeys |issue=4 |year=2012 |doi=10.3897/mycokeys.4.2809 |pages=9–21|doi-access=free }}</ref>

<ref name="Magain et al. 2020">{{cite journal |last1=Magain |first1=Nicolas |last2=Spribille |first2=Toby |last3=DiMeglio |first3=Joseph |last4=Nelson |first4=Peter R. |last5=Miadlikowska |first5=Jolanta |last6=Sérusiaux |first6=Emmanuël |title=Phylogenetic evidence for an expanded circumscription of ''Gabura'' (Arctomiaceae) |journal=The Lichenologist |volume=52 |issue=1 |year=2020 |doi=10.1017/s0024282919000471 |pages=3–15}}</ref>

<ref name="McCune & Geiser 2023">{{cite book |authorlink=Bruce McCune |last1=McCune |first1=Bruce |last2=Geiser |first2=Linda |year=2023 |title=Macrolichens of the Pacific Northwest |edition=3 |publisher=Oregon State University Press |location=Corvallis |isbn=978-0-87071-251-7 |page=187}}</ref>

<ref name="原田浩 2022">{{cite journal |last=原田浩 |year=2022 |title=日本新産属のラン藻地衣, ''Gabura insignis'' シワキノリ (Arctomiaceae タカネノリ科) |trans-title=''Gabura insignis'' (lichenized Ascomycota, Arctomiaceae), a new genus to Japan |journal=Lichenology: A journal devoted to all research fields of lichenology |volume=20 |issue=1 |pages=25–27 |language=ja}}</ref>

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Category:Baeomycetales Category:Baeomycetales genera Category:Lichen genera Category:Taxa described in 1763 Category:Taxa named by Michel Adanson