Niebla isidiaescens

©The World Botanical Associates Web Page
Prepared by Richard W. Spjut
October 2005, Sep 2012, Jan 2015

Niebla and Vermilacinia (Ramalinaceae) from California and Baja California.  
Spjut, R.W., 1996. ISSN 0833-1475, 208 pp.  
Sida, Botanical Miscellany 14. Botanical Research Institute of Texas, Inc.


Mesa Camacho,
Spjut 11263, Apr 1990

Vizcaíno Peninsula,
Sierra Hornitos,
 Spjut 9691, May 1986

Mesa Camacho,
Spjut 11282, Apr 1990

Type of Niebla isidiaescens (Marsh 6142, ASU) at CNAL. Downloaded here under fair use for the educational purpose to show the mixed collection of species. Lectotype needs to be designated. All the pale orange thalli are Vermilacinia paleoderma. Pale green is N. isidiaescens. Loose branches with a similar color and shiny cortex are probably Niebla contorta. Below shows arrows pointing to examples of the mixed species.


     Niebla isidiaescens was recognized by Spjut long before his publication appeared (Spjut 1996), to occur only in Baja California under an unpublished name based on specimens he first collected from the Vizcaíno Peninsula in May 1986. These were annotated and deposited at the United States National Herbarium (US). At that time isidiate species in the genus Niebla were hardly known. Nash et al. (Marsh & Nash 1994; Bowler et al. 1994) subsequently found the species based on collections by Janet Marsh in Dec 1990 on the Vizcaíno Peninsula. Additionally, Bowler et al. (1994) and Bower & Marsh 2004) reported the species to occur in southern California Santa Monica Mountains and in the Channel Islands, whereas Spjut (1996) did not cite specimens from California. The only isidiate species he had seen from California was Vermilacinia acicularis, and the isidiate-sorediate Niebla sorediata.   Specimens obtained by Spjut of  isidiate species of Niebla were reported to occur from the Magdalena Desert Region in Baja California Sur north to Mesa Camacho, half way up the northern peninsula. 

       In view of the apparent rush by Bowler et al. (1994) to publish Niebla isidiaescens, among other species, they noted that  lichen metabolites were not determined for all specimens they cited, which included  collections by Janet Marsh from Cedros Island. Moreover,  the methodology for identifying lichen substances for those cited (Bowler et al. 1994)  was not described. In considering that various collaborators from different institutions were involved, the methods and interpretations in identification of the secondary metabolites probably vary, while it may be further noted that Bowler himself was not evidently involved in the Niebla field work and determinations (since 1972), judging from the collections cited.

     Spjut (1996), who conducted TLC of all specimens he studied of Niebla and Vermilacinia,   had distinguished a morphologically similar isidiate species Niebla usneoides by its lichen substance of sekikaic acid (with triterpenes), in contrast to the occurrence of divaricatic acid N. isidiaescens.  The two species generally do not occur together, which may suggests that the differences in their secondary metabolites are genetic, especially since they reproduce only asexually (isidia).  Nevertheless, the geographically distinct  chemotypes may be considered “races” (Rundel 1978) or “strains” (Krog & Řsthagen 1980), instead of different species as may be recognized for other genera (Kalb & Elix 2014). For example, Rundel (1978) indicated that each of three chemical races of Ramalina usnea (1. sekikaic acid with homosekikaic acid, 2. divaricatic acid, 3, no detectable metabolites) exhibit a broad pattern of morphological diversity and “that this variability in morphology is the result of differing evolutionary selection pressures over the range of the species.”  This view emphasizes morphological characters for defining species.

     Bowler and Marsh (2004) treated Niebla usneoides as a synonym of N. isidiaescens, because they viewed the sekikaic acid chemotype as a “sekikaic acid race” (Bowler et al. 1994).  Additionally, they considered N. sorediata, an isidiate-sorediate species found on Isla Guadalupe and in the Channel Islands, too uncommon to be formally recognized as a species, while also concluding that it must be an odd isolated morph of N. homalea.  This decision was further justified by analogy to ground and bush forms of Seirophora californica.  The same reasoning was applied to another rare isidiate species known only from Isla Guadalupe, N. isidiosa.  Although some lichenologists may view N. isidiaescens and N. usneoides as sibling species, or species pairs independently derived from fertile N. flagelliforma (divaricatic acid) and N. suffnessii (sekikaic acid), respectively, they may also be cryptic species (Crespo & Ortega 2009).

     Differences in lichen metabolites in similar morphological species may represent different species  only if practical to determine such as by chemical spot tests. Thin-layer chromatography (TLC) is generally not considered practical for routine identifications.  However,  chemical spot tests have limitations (Lumbsch & Leavitt 2011) as evident from the inconsistent treatment of N. homaleoides as a synonym of N. homalea (Bowler & Marsh 2004) when TLC reveals a satellite compound in N. homaleoides that indicates a close relationship to species that contain salazinic acid (Spjut 1996). 

     Also, the use of chemical characters (secondary lichen substances) in taxonomy for distinguishing lichen species is controversial; for example, divaricatic acid and sekikaic acid have similar chemical structures for which a biogenetic relationship seems evident when the thalli with the different chemotypes are morphologically indistinguishable and not geographically or ecologically separated as reported for species in the related genus Ramalina (Culberson & Elix 1989; Krog & Řsthagen 1980).  On the other hand, both morphological and chemical data may not be adequate to fully delimit lichen species (Lumbsch & Leavitt. 2011; Stenroos et al. 2002).  Thus, there are a lot more lichen species than meets the eye.

     Bowler et al. (1994) specified  Marsh 6142 as “type” but did not clearly indicate  whether the type material contained divaricatic acid or sekikaic acid.  All the isosyntypes cited from the type locality (Marsh 6128, 6130, 6139, 6155) were reported to contain divaricatic acid. Although Spjut (1996) had reportedly seen the "type,"  this was only briefly during a visit to ASU that unexpectedly involved reviewing other specimens, leaving little time to photograph and study all the relevant type material. The specimens are here referred to as syntypes because the "type" (Marsh 6142, ASU) is a mixture of mostly two species among evidently a single gathering of approximately 20 specimens, all included in a standard herbarium packet labeled holotype (Consortium of the North American Lichen Herbaria (CNALH), which by default would be a holotype if it represented by a single specimen or a gathering of one taxon. Judging from the morphology, the type collection includes Niebla contorta (branch fragments), N. isidiaescens (~10 specimens), and Vermilacinia paleoderma (~8 specimens). 

     The original publication of Niebla isidiaescens included a photo of the species—a “representative specimen”,  Riefner 92-61 (IRVC), also cited separately (syntype) to have been collected from Conejo Mountain, Los Angeles County.  It is not a clear image but the compact appearance of the thallus appears similar to Vermilacinia ceruchoides. An image on Wikipedia identified N. isidiaescens  reportedly taken of a thallus growing on Conejo Mountain is most likely Vermilacinia acicularis.  As indicated above, the methodology in chemical determination of the lichen metabolites by the various collaborators was not described, and considering the misidentifications of the triterpene zeorin with the diterpene (-)-16 α-hydroxykaurane, and the depside 3,5 methyl-dichlorolecanorate with an unknown terpene, the entire taxonomic treatment of Niebla by Bowler et al. (1994) is questionable.

     The International Code of Botanical Nomenclature  under Art. 8 defines a type as a single specimen (Art. 8.1) that can also be a gathering, disregarding admixtures (Art. 8.2), while  typification  is “the one specimen or illustration…used by the author, or designated by the author as the nomenclatural type” (Art. 9.1), and  valid publication can be met by reference to the entire gathering…even if it consists of two or more specimens as defined in Art. 8. (Art. 37.2).  There is a contradiction in the ICBN in the semantics of defining a single specimen as also consisting of more than one specimen as along as it represents a single gathering.   Nevertheless, it might appear that Niebla isidiaescens is validly published; however, under Art. 45.1 “a name published on or after 1 January 1973 for which the various conditions for valid publication are not simultaneously fulfilled is not validly published unless a full and direct reference (Art. 33.3) is given to the places where these requirements were previously fulfilled.”  A lectotype still needs to be identified and designated among the syntypes, from which isolectotypes should also be designated.

Additional References.

Crespo, A. & S. P. Ortega. 2009. Cryptic species and species pairs in lichens: A discussion on the relationship between molecular phylogenies and morphological characters. Anales del Jardín Botánico de Madrid 66: 71–80.

Culberson, C. F. and J. A. Elix. 1989. Lichen substances. In: Methods in plant biochemistry. Vol. 1. Plant Phenolics. P. M. Dey & J. B. Harborne, eds. Academic Press, Lond and San Diego.

Kalb, K. and J. A. Elix. 1995. The lichen genus ''Physcidio''. In: Studies in lichenology with emphasis on chemotaxonomy, geography and phytochemistry Festschrift Ch. Leuckert Eds: Knoph, J.-G., Schriifer, K. & Sipman, H. J. M. - Bibliotheca Lichenologica 57:265 -296. J. Cramer in der Gebriider Borntraeger Verlagsbuchhandlung, Berlin-Stuttgd.

Lumbsch, H. T. & S. D. Leavitt. 2011. Goodbye morphology? A paradigm shift in the delimitation of species in lichenized fungi. Fungal Diversity 50: 59–72.

Rundel, P. W. 1978. Evolutionary relationships in the Ramalina usnea complex/ Lichenologist 10: 141–156.

Stenroos, S.,  J. Hyvo, L, Myllys A Thell and T. Ahti. 2002. Phylogeny of the genus Cladonia (Cladoniaceae, Ascomycetes) Inferred from molecular, morphological, and chemical data. Cladistics 18, 237–278,