Niebla podetiaforma
Niebla podetiaforma is a fruticose lichen that grows frequently on small stones in fog regions along the Pacific Coast of Baja California from San Vicente Canyon to Morro Santo Domingo. The epithet, podetiaforma is in reference to a primary inflated branch of the thallus that resembles a podetium, a common feature in the lichen genus Cladonia.
Distinguishing features
Niebla podetiaforma is distinguished by the thallus divided into small tufts of yellowish-green, tubular-inflated, branches not more than 5 cm high, the branches usually less than 20 in number, erect to spreading and curved, occasionally divided into similar branches, or more often fringed along the upper side with shorter branches or lobes that bear apothecia, and by containing the lichen substance divaricatic acid, with triterpenes, and with yellow pigments concentrated at the base. The cortex is relatively thin, 25–50 μm thick, covering a fistulose medulla. Similar species are Niebla turgida, which differs by the bushy growth with long tapered branches, Niebla undulata, distinguished by the recessed cortical surface between the cortical ridges, Niebla rugosa that differs by the ladder-like transverse cortical ridges between branch margins, and Niebla contorta that is recognized by the terminal rounded lobes thickened along margins, usually with submarginal apothecia; all contain divaricatic acid and less inflated branches. A sekikaic acid-containing species, Niebla siphonoloba, often recognized by the simple branches with a closely reticulate cortex similar to a honeycomb, occasionally has less conspicuous reticulate ridging that may be confused with N. podetiaforma; this form is more easily distinguished by its secondary lichen metabolite.Niebla podetiaforma is a common lichen of coastal pebble lichen communities in the Northern Vizcaíno Desert of Baja California. It often occurs on leeward slopes, and on mesas more inland from the coast than other species of Niebla. This adaptation undoubtedly is related to the thin cortex and hollow medulla, which probably account for bloated appearance of the branches. Rare thalli have a flattened appearance as if someone had stepped on them, but can be identified N. podetiaforma by the fine reticulate pattern of cortical ridges. Divaricatic-acid species of Niebla are generally distinguished by cortical features, in contrast to branching patterns in salazinic acid-containing species, and apothecial developmental patterns in sekikaic acid-containing species, with exceptions that require application of other morphological characters.