''Punctelia negata'' is a little-known species of

foliose lichen Foliose lichen is one of the morphological classes of lichens, which are complex organisms that arise from the symbiotic relationship between fungi and a photosynthetic partner, typically algae. This partnership allows lichen to live in diverse ...

in the family

Parmeliaceae The Parmeliaceae is a large and diverse family of Lecanoromycetes. With over 2700 species in 71 genera, it is the largest family of lichen-forming fungi. The most speciose genera in the family are the well-known groups: '' Xanthoparmelia'' ( 822 ...

. It is found in South America.

Taxonomy

The lichen was described as a new species by Finnish lichenologist William Nylander in 1872. Giving a brief diagnosis in a footnote, he distinguished it from the similar species '' P. rudecta'' and '' P. borreri'' by its longer

ascospore An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or s ...

s and

conidia A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an asexual, non-motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also called mitospores due to the ...

, and its more wrinkled amphithecia (the inner layer of the perithecium next to the

hymenium The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in others some ...

). The original specimens were collected by Alexander Lindig in "Nova Granata" (i.e. Republic of New Granada specifically

Bogotá Bogotá (, also , , ), officially Bogotá, Distrito Capital, abbreviated Bogotá, D.C., and formerly known as Santa Fe de Bogotá (; ) during the Spanish period and between 1991 and 2000, is the capital city of Colombia, and one of the larges ...

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

), at an altitude of . In 1982, Norwegian botanist Hildur Krog transferred the taxon to the newly circumscribed ''

Punctelia ''Punctelia'' is a genus of foliose lichens belonging to the large family Parmeliaceae. The genus, which contains about 50 species, was segregated from genus ''Parmelia'' in 1982. Characteristics that define ''Punctelia'' include the presence of ...

'', a segregate genus from ''Parmelia'' created to contain species with rounded

pseudocyphella Pseudocyphellae (singular ''pseudocyphella'') are structures in lichens that appear as tiny pores on the outer surface (the cortex of the lichen. They are caused when there is a break in the cortex of the lichen, and the medullary hyphae extend t ...

e. The lichen is poorly known, and has been rarely collected since its original description. Specimens reportedly collected from

Rio Grande do Sul Rio Grande do Sul (, , ; "Great River of the South") is a Federative units of Brazil, state in the South Region, Brazil, southern region of Brazil. It is the Federative_units_of_Brazil#List, fifth-most-populous state and the List of Brazilian st ...

and from Paraná in 1999 and 2001 were examined later and determined to have been misidentified, representing instead the species '' Punctelia borrerina''. Consequently, the only verified material of ''Punctelia negata'' is the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

and isotypes collected from the type locality in Colombia.

Description

Major characteristics of ''Punctelia negata'' include the presence of small lobes (lobules) on the upper

thallus Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms wer ...

surface, a pale brown lower thallus surface, long threadlike (filiform)

s measuring 19–23

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

long, and a medulla that reacts C− in a

lichen spot test A spot test in lichenology is a spot analysis used to help identify lichens. It is performed by placing a drop of a chemical on different parts of the lichen and noting the colour change (or lack thereof) associated with application of the chemical ...

. A

high-pressure liquid chromatography High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to pa ...

analysis of the type specimen revealed several secondary chemicals, including

constipatic acid Constipatic acid is a fatty acid found in several lichen species. It was isolated, identified, and named by Douglas Chester and John Alan Elix in a 1979 publication. The compound was extracted from the Australian leafy lichen called '' Xanthop ...

and protoconstipatic acid as major products, and dehydroconstipatic acid, protodehydroconstipatic acid, atranorin, and chloroatranorin as minor products.

References

{{Taxonbar, from=Q10646754 negata Lichen species Lichens of Colombia Lichens described in 1872 Taxa named by William Nylander (botanist)