Acanthothecis

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 stain blue in iodine tests (non-amyloid) and is usually clear, while the asci are of the 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, stictic, protocetraric acid or psoromic acids, the yellow pigment lichexanthone, or the anthraquinone isohypocrellin. Morphologically the genus clusters into three informal groups. A. obscura has a dark brown excipulum and an (grainy) hymenium; the A. hololeucoides group features a grey to pale yellowish thallus with mainly smooth lirellae; and the 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, growing on the bark of living trees in primary or only lightly disturbed evergreen forests, where they tolerate both shaded and moderately exposed microhabitats. Because the genus favours intact forest canopies, several species are considered 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==