Acanthothecis Sarcographoides

''Acanthothecis'' is a genus of lichen-forming fungi in the family Graphidaceae. The genus was circumscription (taxonomy), circumscribed by Frederick Edward Clements in 1909. These lichens form pale grey-brown to olive-green crustose lichen, crusts on tree bark and are characterized by elongated, pencil-like slits containing spores, with distinctive tiny spines on internal filaments that help distinguish them from similar genera. The genus includes about 50 species found primarily in tropical and subtropical forests worldwide, where they grow on living tree bark and serve as bioindicator, indicators of relatively undisturbed woodland environments.

Description

''Acanthothecis'' forms a pale grey-brown to olive-green crust (thallus) that may lack a skin () or bear a thin one, and often contains scattered crystals that give a slightly texture. Its fruit bodies are —elongated, pencil-like slits—ranging from immersed to sitting on the surface; their lips are usually well developed and can be smooth or faintly striate. The rim that encircles each lirella () is generally colourless rather than the charcoal-black seen in many relatives, and it houses minute filaments ( and paraphyses) whose tips are armed with tiny spines—an unusual diagnostic trait in the family. Inside, the hymenium (spore-bearing layer) does not staining, stain blue in iodine tests (non-amyloid (mycology), amyloid) and is usually clear, while the ascus, asci are of the ''Graphis (lichen), Graphis''-type and release two to eight hyaline ascospores that are —divided by thin inner walls that give each compartment a lens-shaped outline—and typically show no iodine reaction (I–).

Secondary metabolites vary between species and may include norstictic acid, norstictic, stictic acid, stictic, protocetraric acid, protocetraric acid or psoromic acids, the yellow pigment lichexanthone, or the anthraquinone isohypocrellin.

Morphology (biology), Morphologically the genus clusters into three informal groups. ''Acanthothecis obscura, A. obscura'' has a dark brown excipulum and an (grainy) hymenium; the ''Acanthothecis hololeucoides, A. hololeucoides'' group features a grey to pale yellowish thallus with mainly smooth lirellae; and the ''Acanthothecis subclavulifera, A. subclavulifera'' group shows an olive thallus with conspicuously striate lips. The combination of spinulose filaments, predominantly non- rim, and I– spores separates ''Acanthothecis'' from superficially similar genera such as ''Anomalographis'', ''Anomomorpha'', ''Fissurina'', ''Gymnographopsis'' and ''Hemithecium'', all of which lack one or more of these features.

Ecology

''Acanthothecis'' occurs across the humid to seasonally dry tropics and subtropics worldwide. They are predominantly corticolous lichen, corticolous, growing on the bark of living trees in primary or only lightly disturbance (ecology), disturbed evergreen forests, where they tolerate both shaded and moderately exposed microhabitats. Because the genus favours intact forest canopy (botany), canopies, several species are considered bioindicator, indicators of relatively undisturbed woodland and may decline with intensive logging or land conversion.

Species

, Species Fungorum (in the Catalogue of Life) accepts 56 species of ''Acanthothecis''.

*''Acanthothecis abaphoides''
*''Acanthothecis adjuncta''
*''Acanthothecis africana''
*''Acanthothecis aggregata'' – Brazil
*''Acanthothecis alba'' – Mexico
*''Acanthothecis aquilonia'' – Australia
*''Acanthothecis archeri'' – India
*''Acanthothecis asprocarpa''
*''Acanthothecis aurantiaca''
*''Acanthothecis aurantiacodiscus''
*''Acanthothecis bicellularis'' – Brazil
*''Acanthothecis bicellulata'' – Brazil
*''Acanthothecis borealis'' – Australia
*''Acanthothecis celata'' – India
*''Acanthothecis coccinea'' – India
*''Acanthothecis collateralis'' – India
*''Acanthothecis dialeuca''
*''Acanthothecis dialeucoides'' – Thailand
*''Acanthothecis farinosa'' – Brazil
*''Acanthothecis floridana'' – United States
*''Acanthothecis floridensis'' – United States
*''Acanthothecis fontana'' – United States
*''Acanthothecis gracilis''
*''Acanthothecis gyridia''
*''Acanthothecis kalbii''
*''Acanthothecis latispora'' – Brazil
*''Acanthothecis leucopepla''
*''Acanthothecis leucoxanthoides'' – United States
*''Acanthothecis maritima'' – Panama
*''Acanthothecis megalospora'' – Brazil
*''Acanthothecis mosquitensis''
*''Acanthothecis multiseptata'' – Brazil
*''Acanthothecis nivalis'' – India
*''Acanthothecis norstictica'' – Brazil
*''Acanthothecis oryzoides'' – Brazil
*''Acanthothecis pachygraphoides''
*''Acanthothecis paucispora'' – United States
*''Acanthothecis peplophora''
*''Acanthothecis poitaeoides''
*''Acanthothecis pruinocarpa''
*''Acanthothecis rimosa'' – Brazil
*''Acanthothecis rosea''
*''Acanthothecis roseola'' – Brazil
*''Acanthothecis salazinica'' – Panama
*''Acanthothecis sarcographoides'' – Brazil
*''Acanthothecis saxicola'' – Brazil
*''Acanthothecis socotrana''
*''Acanthothecis subabaphoides'' – Brazil
*''Acanthothecis subaggregans''
*''Acanthothecis subclavulifera''
*''Acanthothecis subconsocians'' – India
*''Acanthothecis subfarinosa'' – Brazil
*''Acanthothecis submuriformis'' – Brazil
*''Acanthothecis tetraphora''
*''Acanthothecis verrucosa'' – Vietnam
*''Acanthothecis virgulicola'' – Tasmania
*''Acanthothecis yokdonensis'' – Vietnam

Former species;
''A. salazinica'' = ''Acanthothecis yokdonensis''

References

{{Taxonbar, from=Q4672057

Acanthothecis,
Lichen genera
Graphidales genera
Taxa named by Frederic Clements
Taxa described in 1909