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Niebla siphonoloba
was first recognized from a population of mixed species of Niebla on the Vizcaíno
Peninsula near Arroyo San Andrés, all of which were found to contain sekikaic
acid; included were N. lobulata, N. suffnessii and N. usneoides. Niebla
siphonoloba
was distinguished by its mostly simple basal lobes and subterminal scattered
apothecia, N. lobulata had more flattened branches with lobulate to
broadly lobed margins, N. suffnessii was much more branched with numerous
long whip-like branchlets, and N. usneoides was easily recognized by its
abundant isidia. A community of Niebla species almost exclusively
dominated by sekikaic-acid thalli such as found here is rare, while partial
segregation of chemotypes by habitat type have been found near Punta Canoas
(Spjut 1996) and
also reported for volcanic slopes near Bahía de San Quintín (Rundel et al.
1972), and by Sipman from collections near El Tomatal (Willdenowia 19:
543–555, 1990). The sekikaic-acid species may tolerate more xeric environments as
they have been found more frequently on porous (volcanic) rocks and on other
rocks in inland
localities at the limits of the fog, whereas divaricatic-acid species have been
noted to be more common nearer the ocean (Spjut 1996).
Niebla siphonoloba
has been collected from scattered locations along the Pacific Coast as far north as
the Channel Islands, usually in association with other species that contain sekikaic acid, but
it can be locally dominant on mesas. It was found growing with N. lobulata and N.
marinii at Morro Santo Domingo, N. podetiaforma, N. lobulata,
and N. flabellata along Bahía Santa María, N. suffnessii, N.
lobulata, and N. usneoides on Mesa Camacho, and N. josecuervoi
at Bahía de San Quintín. The close association with other species
containing sekikaic acid may indicate selection (or tolerance) for more xeric microenvironments, in contrast to divaricatic-acid species generally found nearer the
ocean, or on oceanic slopes in line with advectional fog (Spjut 1996). On
Santa Cruz Island, N. siphonoloba appears to occur with N. fimbriata
where they can be difficult to distinguish from one another.
Another Niebla on Mesa Camacho, N. sinuata, which is also shown under
N. suffnessii, is recognized by the wavy cortical ridges.
Specimens from Baja
California that have aged in the herbarium often develop a slight whitish
deposit along the cortical ridges. This is helpful for separating
it from N. lobulata, which lacks the whitish ridges, and with which it
often grows intermixed. Incidentally, N. siphonoloba provides the
sharpest photographs of the species in the genus, which I believe is related to
differences in chemistry as light is reflected or refracted from specimen to the
camera lens.
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