Dermatocarpon Linkolae

''Dermatocarpon'' is a genus of lichens in the family Verrucariaceae. Members of the genus are commonly called stippleback lichens because they have fruiting structures called perithecia that are flask-shaped structures embedded in the nonfruiting body (thallus), with a hole in the top to release spores, causing an appearance of being covered with small black dots.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, Its species are told apart chiefly by spore size, the colour and texture of the lower surface, and whether the gives a bloom.

Description

''Dermatocarpon'' lichens form grey-brown sheets that range from minute overlapping scales () to broad, leaf-like lobes ( thalli). Each thallus is anchored by one or several stout holdfasts that act like suction pads; the lower surface otherwise lacks the root-like rhizines common in many rock-dwelling lichens, although a few species develop wart-like or hair-like nodules that can be mistaken for rhizines. Both upper and lower faces possess a true —a layer of tightly packed fungal cells. On the upper side these cells are arranged in a tissue and often contain brown pigment near the surface. An overlying film of dead, compressed cells (the ) is usually thin; when its cells collapse and trap air the surface appears dusted with a pale bloom (), but in many species the layer remains compact and the thallus looks plain. Beneath the cortex lies a loose medulla of filamentous hyphae. The lower cortex mirrors the upper one in construction but its outermost cells are smaller, thicker-walled and usually pigmented brown.

The photosynthetic partner is almost always the from the green algal genus ''Diplosphaera'' (class Trebouxiophyceae), specifically ''D. chodatii'' in most studied material; rarer reports of ''Myrmecia biatorellae'' and '' Protococcus dermatocarponis'' suggest some flexibility. Algal cells occupy a distinct band just under the upper cortex, leaving the medulla fungus-only. Sexual reproduction takes place in flask-shaped fruiting bodies (perithecioid ascomata) that are sunk into the thallus surface so that only their tiny pores are visible. Each perithecium lacks the dark protective cap () seen in many relatives; its wall is colourless except for a ring of pigment around the pore. Short sterile threads ( and ) line the neck canal, but the longer filaments (paraphyses) found in many lichens are absent. The jelly that embeds the spore sacs stains weakly with iodine: it turns red in standard strength and blue when highly diluted, a behaviour known as hemiamyloidy.

Each club-shaped ascus contains eight smooth, colourless ascospores that are single-celled and ellipsoidal; they lie irregularly rather than in neat rows. Asexual reproduction is handled by immersed pycnidia scattered across the surface; these produce rod-shaped conidia. Chemical spot tests and thin-layer chromatography have failed to detect acetone-soluble secondary metabolites, though some species show a distinctive iodine-positive (red) reaction in the hyphal walls, indicating a polysaccharide rather than an aromatic lichen product.

Ecology

''Dermatocarpon'' typically colonises siliceous or calcareous rock in moist settings—river margins, seepage faces and shaded cliffs.

Species

*'' Dermatocarpon americanum''
*'' Dermatocarpon arenosaxi'' – United States
*'' Dermatocarpon arnoldianum''
*'' Dermatocarpon atrogranulosum'' – Canada
*'' Dermatocarpon bachmannii''
*'' Dermatocarpon deminuens''
*'' Dermatocarpon dolomiticum'' – United States
*'' Dermatocarpon intestiniforme''
*'' Dermatocarpon leptophyllodes''
*'' Dermatocarpon leptophyllum''
*'' Dermatocarpon linkolae''
*'' Dermatocarpon lorenzianum''
*'' Dermatocarpon luridum''
*'' Dermatocarpon meiophyllizum''
*'' Dermatocarpon moulinsii''
*''Dermatocarpon miniatum''
*'' Dermatocarpon muhlenbergii''
*'' Dermatocarpon multifolium'' – United States
*'' Dermatocarpon polyphyllizum''
*'' Dermatocarpon reticulatum''
*'' Dermatocarpon rivulorum''
*'' Dermatocarpon schaechtelinii''
*'' Dermatocarpon taminium''
*'' Dermatocarpon tenue''
*'' Dermatocarpon tomentulosum'' – USA; Bahamas
*'' Dermatocarpon vellereum''

References

Gallery

Image:Dermatocarpon luridum.jpg, '' Dermatocarpon luridum''
Image:Dermatocarpon_miniatum.jpg, ''Dermatocarpon miniatum''

{{Taxonbar, from=Q10469480

Verrucariales
Eurotiomycetes genera
Lichen genera
Taxa described in 1824
Taxa named by Franz Gerhard Eschweiler