Niebla disrupta

Niebla disrupta is a fruticose lichen that has been recognized to occur largely in coastal areas of California. The geographical range of N. disrupta partially overlaps with N. homalea in the Channel Islands and on Isla Guadalupe in Baja California and on the mainland from San Luis Obispo to Mendocino Cos. It is notably absent south of Morro Bay. The type locality is not specifically known; however, the type specimen compares most closely to specimens from coastal Marin County, while the collector and collection date are also unknown. The type would appear to be a fragment of a specimen from perhaps the Museum of Natural History in Paris

Niebla disrupta is morphologically similar to N. homalea from which it is distinguished by having sekikaic acid and not divaricatic acid. Despite their similar morphology, chemistry, and geographical distribution, they are not sibling species. DNA phylogeny studies by Spjut et al. (2020) and Jorna et al. (Authorea. Apr 2021) reveal that species of Niebla producing sekikaic acid form a separate clade; however, sekikaic acid specimens have not been reportedly collected in California for the DNA studies.

Niebla disrupta may be recognized morphologically by the terminal whip-like, often sharply pointed branchlets, usually with undeveloped apothecia, while mature apothecia develop nearer the base of thallus. The whip-like branches often change direction where apothecia initiate. Niebla homalea, in contrast, has mostly ribbon like branches with apothecia maturing nearer apex, usually elevated on a short broad flat lobe. Both species may occur together as evident from herbarium collections.

Variants assigned to this species include specimens collected by Charis Bratt 5182 from Santa Barbara Island and by Reifner 86-25 (Fig. 8.4 in Spjut 1996) from Morro Bay, and possibly a Stephen Sharnoff photo titled “Niebla homalea 4” reportedly taken on Santa Rosa Island. These 'disruptoid' nieblas, which share the terminal whip like branches with subterminal apothecia, are similar to N. suffnessii that differs by the more rounded branches in x-section with a thinner cortex; however, they appear to belong to a separate undescribed southern California species complex that includes variants of N. cornea, N. dissecta, N. laminaria, and possibly N. lobulata; the latter has not been recognized from California.

The two Niebla disrupta variant specimens mentioned above have an irregular network of cortical ridges between branch margins; the branches appearing 3–4 angled in cross section as seen in N. dissecta, a species recognized by a broader than tall thallus and terminal wide-spreading branchlets arising from dilated branches. The apothecia are larger and positioned more on the face of the branch rather than perpendicular to an expanded margin of the branch. They are referred to N. disrupta by the thallus appearing taller than wide, and by the terminal whip-like branches as just noted. This variation may be a product of geographical (evolutionary) differentiation of N. disrupta south of Monterrey Co. that involved genetic exchange with variants of N. cornea occurring further south and on Santa Barbara Island, N. laminaria at Pt. Loma, and N. aff. lobulata in the Santa Monica Mts.

A related sekikaic acid species, Niebla fimbriata, has spindle-shaped branchlets that are relatively straight in a wind-swept appearance along one or both margins of an aching branch, analogous to “scorpiod cyme (seund) type of inflorescence in angiosperms.

The sekikaic-acid species considered most similar to N. disrupta are Niebla cornea and N. dissecta. They are distinguished in the following table, diagnostic characters in bold type.

Character	*N. disrupta*	*N. cornea*	*N. dissecta*

Branching general	Anisotomic.	Anisotomic.	Anisotomic.
Terminal bifurcate branches	Usually not evident.	Bifurcate and rabbit-like ear-lobes, or trifurcate with unequal lobes, or often expanded with digitate-like segments	Common, antler-like, often 3-pointer in one division, 2-pointer on other, more flattened and digitate in type
Branch shape lengthwise	Sublinear.	Scoop-like to ribbon-like	Sublinear with expanded lobes, especially near apex.
Branch shape cross-section	Elliptic or 3–4 angled in one variant	Elliptic.	Prismatic, or ±4-angled.
Branches twist	Frequent between base and apex.	Irregularly twisted or not twisted, often irregularly contorted.	Frequent between base and apex.
Branch margin	Usually well-defined, acute.	Rounded to acute, sometimes thickened.	Variable.
Cortex	Glassy, transversely cracked at various intervals.	Mostly smooth, irregularly transversely cracked or reticulate ridged	Dull, transversely cracked and reticulate ribbed with tertiary longitudinal sinuous ridges between the margins.
Apothecia	Subterminal undeveloped apothecia on long whip-like branches, mature apothecia often on lower short lateral branches, oriented perpendicular to branch margins, shorter branches often at nearly right angles.	Terminal in small loose aggregates, often in 4's on short lobes of an expanded branch, or sessile and in plane with the main branch.	Generally most developed near base of thallus, sessile, submarginal.

Marin Co., Pt. Reyes, CA, L. E. Rose, 16 Jul 1952 TLC: Sekikaic acid & triterpenes, 3 Sep 1993	Marin Co., Pt. Reyes, CA V. Ahmadjian, 20 May 1966 TLC: Sekikaic acid & triterpenes, 1 Sep 1993	Tomales Bay, near Marshall, CA Cooke & Cooke, 16 Jul 1942 TLC: Sekikaic acid & triterpenes, 3 Sep 1993
Pt. San Pedro, San Mateo Co., CA Herre & Doty 3332, 22 May 1942 (L75743, L74403, COLO)	Marin Co., Willow Camp, CA H. E. Parks 2733, 25 Apr 1925 TLC: Sekikaic acid & triterpenes, 3 Sep 1993	Niebla disrupta, Lectotype
	Niebla disrupta Santa Barbara Island Bratt 5182, Jan 1987.