Thelotrema

Thelotrema is a genus of lichen-forming fungi in the family Graphidaceae, the family to which all taxa in the former Thelotremataceae now belong.

Members of the genus Thelotrema are commonly called barnacle lichens.

Description
Thelotrema lichens have a thallus with colours ranging from white to yellow-grey or light olive. The texture of the thallus can be smooth, uneven, or, with the presence of either an surface or a loosely to rarely dense  to  cortex. The and medulla frequently contain clusters of calcium oxalate crystals.

The apothecia can be immersed or sessile and appear rounded or angular-rounded. The is partially covered by remnants of the, while the margin can be entire, undulate, or fissured, displaying a distinct double margin. The is absent in this genus. The excipulum is paraplectenchymatous,, and varies in colour from colourless to brown. It has distinct, and the are unbranched.

Thelotrema are transversely septate to, fusiform-ellipsoid to oblong-cylindrical, and feature thin to thick septa with angular to rounded. The outer wall of the spores is often thick, and the spores may be colourless or brown. They can display weak to strong violet-blue amyloid reactions. The secondary chemistry of Thelotrema lichens generally includes stictic acid or norstictic acid or closely related compounds, with hypoprotocetraric acid appearing rarely.

Species
, Species Fungorum (in the Catalogue of Life) accepts 165 species of Thelotrema.


 * Thelotrema adjectum
 * Thelotrema africanum
 * Thelotrema ahtii
 * Thelotrema albidopallens
 * Thelotrema allosporoides
 * Thelotrema amabilis
 * Thelotrema amazonicum
 * Thelotrema armellense
 * Thelotrema attenuatum
 * Thelotrema australiense
 * Thelotrema berendsohnii
 * Thelotrema berkeleyanum
 * Thelotrema bicuspidatum
 * Thelotrema biliranum
 * Thelotrema byssoideum
 * Thelotrema californicum
 * Thelotrema cameroonense
 * Thelotrema canarense
 * Thelotrema canescens
 * Thelotrema capense
 * Thelotrema capetribulense
 * Thelotrema catastictum
 * Thelotrema cinerellum
 * Thelotrema cinereovirens
 * Thelotrema colobicum
 * Thelotrema conferendum
 * Thelotrema confertum
 * Thelotrema configuratum
 * Thelotrema crassisporum
 * Thelotrema crateriforme
 * Thelotrema crespoae
 * Thelotrema cubanum
 * Thelotrema cyphelloides
 * Thelotrema defectum
 * Thelotrema defossum
 * Thelotrema demersum
 * Thelotrema demissum
 * Thelotrema depressum
 * Thelotrema dignitosum
 * Thelotrema dislaceratum
 * Thelotrema dissultum
 * Thelotrema dominicanum
 * Thelotrema elmeri
 * Thelotrema endoxanthum
 * Thelotrema eungellaense
 * Thelotrema euphorbiae
 * Thelotrema expansum
 * Thelotrema exsertum
 * Thelotrema farinaceum
 * Thelotrema fijiense
 * Thelotrema fissiporum
 * Thelotrema flavescens
 * Thelotrema floridense
 * Thelotrema formosanum
 * Thelotrema foveolare
 * Thelotrema fuscosubtile
 * Thelotrema galactizans
 * Thelotrema gallowayanum
 * Thelotrema gomezianum
 * Thelotrema granatum
 * Thelotrema grossimarginatum
 * Thelotrema harmandii
 * Thelotrema hawaiiense
 * Thelotrema heladivense
 * Thelotrema hnatiukii
 * Thelotrema hypomelaenum
 * Thelotrema hypoprotocetraricum
 * Thelotrema indicum
 * Thelotrema infundibulare
 * Thelotrema inscalpens
 * Thelotrema inspersoporinaceum
 * Thelotrema integrellum
 * Thelotrema isidiophorum
 * Thelotrema isidiosum
 * Thelotrema jugale
 * Thelotrema kalakkadense
 * Thelotrema kalarense
 * Thelotrema kamatii
 * Thelotrema kinabaluense
 * Thelotrema lacteum
 * Thelotrema laurisilvae
 * Thelotrema lecanodeum
 * Thelotrema lepademersum
 * Thelotrema lepadinum
 * Thelotrema leprocarpoides
 * Thelotrema leucocarpum
 * Thelotrema leucocheilum
 * Thelotrema lirellizans
 * Thelotrema lueckingii
 * Thelotrema macrosporum
 * Thelotrema manosporum
 * Thelotrema marginatum
 * Thelotrema megasporum
 * Thelotrema meridense
 * Thelotrema minarum
 * Thelotrema minisporum
 * Thelotrema mongkolsukii
 * Thelotrema monospermum
 * Thelotrema monosporum
 * Thelotrema murinum
 * Thelotrema nipponicum
 * Thelotrema nostalgicum
 * Thelotrema occlusum
 * Thelotrema oleosum
 * Thelotrema osornense
 * Thelotrema paludosum
 * Thelotrema papillosum
 * Thelotrema parvisporum
 * Thelotrema parvizebrinum
 * Thelotrema patwardhanii
 * Thelotrema pauperculum
 * Thelotrema perriei
 * Thelotrema philippinum
 * Thelotrema phliuense
 * Thelotrema pidurutalagalum
 * Thelotrema piluliferum
 * Thelotrema poeltii
 * Thelotrema polythecium
 * Thelotrema porinoides
 * Thelotrema profundum
 * Thelotrema pruinosum
 * Thelotrema pseudosimilans
 * Thelotrema pseudosubtile
 * Thelotrema quitoense
 * Thelotrema reunionis
 * Thelotrema rhamni-purshianae
 * Thelotrema rhododiscum
 * Thelotrema rhodothecium
 * Thelotrema rockii
 * Thelotrema rugatulum
 * Thelotrema samaranum
 * Thelotrema saxicola
 * Thelotrema scabrosum
 * Thelotrema sendaiense
 * Thelotrema similans
 * Thelotrema simplex
 * Thelotrema sitianum
 * Thelotrema stenosporum
 * Thelotrema stromatiferum
 * Thelotrema subadjectum
 * Thelotrema subexpallescens
 * Thelotrema subgeminum
 * Thelotrema subgranulosum
 * Thelotrema subhiatum
 * Thelotrema submyriocarpum
 * Thelotrema suboccultum
 * Thelotrema subsphaerosporum
 * Thelotrema subweberi
 * Thelotrema suecicum
 * Thelotrema tetrasporum
 * Thelotrema thesaurum
 * Thelotrema triseptatum
 * Thelotrema tristanense
 * Thelotrema trypethelioides
 * Thelotrema umbonatum
 * Thelotrema umbratum
 * Thelotrema velatum
 * Thelotrema verrucorugosum
 * Thelotrema verruculosum
 * Thelotrema weberi
 * Thelotrema wilsoniorum
 * Thelotrema zenkeri
 * Thelotrema zimbabwense