# Orceolina

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{{Short description|Genus of lichens}}
{{Use dmy dates|date=July 2025}}
{{Use Oxford spelling|date=July 2025}}
{{Automatic taxobox
| image =
| image_caption =
| taxon = Orceolina
| authority = [Hertel](/source/Hannes_Hertel) (1970)
| type_species = ''[Orceolina kerguelensis](/source/Orceolina_kerguelensis)''
| type_species_authority = ([Tuck.](/source/Tuck.)) Hertel (1970)
| subdivision_ranks = Species
| subdivision = ''[O. antarctica](/source/Orceolina_antarctica)''<br />
''[O. kerguelensis](/source/Orceolina_kerguelensis)''
| synonyms_ref = <ref name="Species Fungorum synonymy"/>
| synonyms = *''Urceolina'' {{au|Tuck. (1875)}}
}}

'''''Orceolina''''' is a small [genus](/source/genus) of [lichen](/source/lichen)-forming [fungi](/source/fungi) in the family [Trapeliaceae](/source/Trapeliaceae).<ref name="Wijayawardene et al. 2020"/> Established in 1970 as a replacement name for an earlier genus that was already used for flowering plants, ''Orceolina'' comprises just two species that form orange to deep red [crusty](/source/crustose_lichen) patches on sun-exposed rocks. These lichens are found exclusively on the windswept [subantarctic islands](/source/subantarctic_islands) of the southern Indian Ocean, where they grow from sea level to [alpine](/source/Alpine_tundra) ridges on [basalt](/source/basalt)ic and [granitic](/source/granitic) surfaces.

==Taxonomy==

The genus ''Orceolina'' was erected by [Hannes Hertel](/source/Hannes_Hertel) in 1970 as a [replacement name](/source/replacement_name) for [Edward Tuckerman](/source/Edward_Tuckerman)'s 1875 ''Urceolina'',<ref name="Tuckerman 1875"/> which was pre-occupied by a [flowering-plant genus](/source/Urceolina). Tuckerman's original [taxon](/source/taxon), ''U.&nbsp;kerguelensis'', thus became ''Orceolina kerguelensis''. For decades the lichen had been shuffled among ''[Lecanora](/source/Lecanora)'' and ''Placodium'' until Hertel's action clarified its status as a distinct [lineage](/source/lineage_(evolution)).<ref name="Poulsen et al. 2001"/> Modern checklists place ''Orceolina'' in the family [Trapeliaceae](/source/Trapeliaceae).<ref name="CoL_CDS8Z"/>

Only two species are currently accepted: ''O.&nbsp;kerguelensis'' and ''O.&nbsp;antarctica''. Early [molecular phylogenetics](/source/molecular) analysis showed that they form a tight [clade](/source/clade) that is [sister](/source/sister_taxon) to the southern-hemisphere {{lichengloss|placodioid}} genus ''[Placopsis](/source/Placopsis)'', and together those two genera are sister to ''[Trapelia](/source/Trapelia)''. The evolutionary relationships indicate that the genus' simplified spore-bearing structure evolved by becoming reduced from a ''Trapelia''-type ancestor rather than being an [original primitive feature](/source/primitive_(phylogenetics)).<ref name="Poulsen et al. 2001"/> The species ''[Ducatina umbilicata](/source/Ducatina_umbilicata)'', described from the [Crozet](/source/Crozet_Islands) and [Kerguelen Islands](/source/Kerguelen_Islands), is closely related to ''Orceolina''; it is differentiated by its [morphology](/source/morphology_(biology)) (it has a large {{lichengloss|umbilicate}} thallus) and lack of [secondary metabolite](/source/secondary_metabolite)s.<ref name="Ertz et al. 2017"/>

==Description==

''Orceolina'' species are rock-dwelling ([saxicolous](/source/saxicolous_lichen)) [crustose lichen](/source/crustose_lichen)s whose [thalli](/source/thallus) spread as irregular orange to deep red patches. The surface is variously cracked into wart-like or lobed units, a pattern termed {{lichengloss|verrucose}}-{{lichengloss|areolate}} or {{lichengloss|effigurate}}. Each patch is dominated by a thick outer skin ({{lichengloss|cortex}}) composed of densely packed fungal threads ([hypha](/source/hypha)e) standing perpendicular to the surface; in ''O.&nbsp;kerguelensis'' the cortex may exceed 1&nbsp;mm in the centre.<ref name="Poulsen et al. 2001"/>

[Green alga](/source/Green_alga)l partners (a ''[Coccomyxa](/source/Coccomyxa)''-like {{lichengloss|photobiont}}) occupy a layer beneath the cortex, but conspicuous vertical columns of algal cells periodically pierce the cortex almost to the surface. This three-dimensional arrangement helps the symbiosis [photosynthesise](/source/photosynthesis) through the massive wall. The inner body ([medulla](/source/medulla_(lichenology))) is thin and often blends with grains of the underlying basalt or granite. No [secondary metabolite](/source/secondary_metabolite)s have been detected by [thin-layer chromatography](/source/thin-layer_chromatography).<ref name="Poulsen et al. 2001"/>

Reproduction is by plentiful urn-shaped ({{lichengloss|urceolate}}) apothecia deeply embedded in the thallus. Each fruiting cup contains asci that lack the dome-like amyloid cushions seen in many relatives; nevertheless the ascus wall [stains](/source/staining) pale blue in [iodine](/source/iodine), indicating a weakened [amyloid](/source/amyloid_(mycology)) reaction. Eight colourless, single-celled spores ([ascospore](/source/ascospore)s) measuring roughly 22–29 × 16–19&nbsp;μm are produced. Immersed pycnidia yield long, curved [asexual](/source/sexual_reproduction) spores ([conidia](/source/conidia)) about 15–25&nbsp;μm in length.<ref name="Poulsen et al. 2001"/>

==Habitat and distribution==

As a genus ''Orceolina'' is confined to the wind-lashed subantarctic islands of the southern Indian Ocean. Both species [colonise](/source/colonisation_(biology)) exposed, vegetation-free [basalt](/source/basalt)ic or [granitic rock](/source/granitic_rock)s and pebbles from near sea level to the higher alpine ridges (up to roughly 650&nbsp;m). Confirmed records come from the [Kerguelen Islands](/source/Kerguelen_Islands), [Crozet Islands](/source/Crozet_Islands), Marion and [Prince Edward Islands](/source/Prince_Edward_Islands), and [Heard Island](/source/Heard_Island). ''O.&nbsp;kerguelensis'' tends to be more common on drier, west-facing slopes, whereas ''O.&nbsp;antarctica'' often occupies slightly moister ridges, but the two can co-occur. No populations are known outside this isolated subantarctic archipelago belt, making ''Orceolina'' an example of high-latitude island [endemism](/source/endemism).<ref name="Poulsen et al. 2001"/>

==Species==

* ''[Orceolina antarctica](/source/Orceolina_antarctica)'' {{au|(Müll.Arg.) R.S.Poulsen & Søchting 2001)}}
* ''[Orceolina kerguelensis](/source/Orceolina_kerguelensis)'' {{au|(Tuck.) Hertel 1970)}}

==References==
{{Reflist|colwidth=30em|refs=

<ref name="CoL_CDS8Z">{{Catalogue of Life |id=CDS8Z |title=''Orceolina'' |access-date=9 July 2025}}</ref>

<ref name="Ertz et al. 2017">{{cite journal |last1=Ertz |first1=Damien |last2=SøChting |first2=Ulrik |last3=Gadea |first3=Alice |last4=Charrier |first4=Maryvonne |last5=Poulsen |first5=Roar S. |title=''Ducatina umbilicata'' gen. et sp. nov., a remarkable Trapeliaceae from the subantarctic islands in the Indian Ocean |journal=The Lichenologist |volume=49 |issue=2 |year=2017 |doi=10.1017/S0024282916000700 |pages=127–140 |bibcode=2017ThLic..49..127E }}</ref>

<ref name="Poulsen et al. 2001">{{cite journal |last1=Poulsen |first1=R.S. |last2=Schmitt |first2=I. |last3=Søchting |first3=U. |last4=Lumbsch |first4=H.T. |title=Molecular and morphological studies on the subantarctic genus ''Orceolina'' (Agyriaceae) |journal=The Lichenologist |volume=33 |issue=4 |year=2001 |doi=10.1006/lich.2001.0327 |pages=323–329 |bibcode=2001ThLic..33..323P }}</ref>

<ref name="Species Fungorum synonymy">{{cite web |title=Synonymy. Current Name: ''Orceolina'' Hertel, Vortr. GesGeb. Bot., ser. 2 4: 182 (1970) |url=https://www.speciesfungorum.org/Names/SynSpecies.asp?RecordID=3633 |publisher=[Species Fungorum](/source/Species_Fungorum) |access-date=9 July 2025}}</ref>

<ref name="Tuckerman 1875">{{cite journal |last=Tuckerman |first=E. |year=1875 |title=Lichens of Kerguelen's Land |journal=Bulletin of the Torrey Botanical Club |volume=6 |pages=57–59 |doi=10.2307/2477595 |jstor=2477595 |url=https://www.biodiversitylibrary.org/page/646689}}</ref>

<ref name="Wijayawardene et al. 2020">{{cite journal |display-authors=6 |last1=Wijayawardene |first1=Nalin |last2=Hyde |first2=Kevin |first3=LKT |last3=Al-Ani |first4=S |last4=Dolatabadi |last5=Stadler |first5=Marc |last6=Haelewaters |first6=Danny |last7=Tsurykau |first7=Andrei |last8=Mesic |first8=Armin |last9=Navathe |first9=Sudhir |last10=Papp |first10=Viktor |last11=Oliveira Fiuza |first11=Patrícia |last12=Vázquez |first12=Víctor |last13=Gautam |first13=Ajay |last14=Becerra |first14=Alejandra G. |last15=Ekanayaka |first15=Anusha |last16=K. C. |first16=Rajeshkumar |last17=Bezerra |first17=Jadson |last18=Matočec |first18=Neven |last19=Maharachchikumbura |first19=Sajeewa |last20=Suetrong |first20=Satinee |year=2020 |title=Outline of Fungi and fungus-like taxa |journal=Mycosphere |volume=11 |pages=1060–1456 |doi=10.5943/mycosphere/11/1/8 |doi-access=free|hdl=10481/61998 |hdl-access=free }}</ref>

}}

{{Taxonbar|from=Q7100165}}

Category:Baeomycetales
Category:Lichen genera
Category:Baeomycetales genera
Category:Taxa described in 1970
Category:Taxa named by Hannes Hertel

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Adapted from the Wikipedia article [Orceolina](https://en.wikipedia.org/wiki/Orceolina) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Orceolina?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.