Parmotrema aptrootii

Short description: Species of lichen

Parmotrema aptrootii

Scientific classification
Kingdom:  | Fungi
Division:  | Ascomycota
Class:  | Lecanoromycetes
Order:  | Lecanorales
Family:  | Parmeliaceae
Genus:  | Parmotrema
Species:  |

P. aptrootii

Binomial name
Parmotrema aptrootii

Aubel (1992)

Parmotrema aptrootii is a species of corticolous (bark-dwelling) foliose lichen in the family Parmeliaceae. Found in South America, it was described as new to science in 1992. It has a pale yellowish to greenish-grey thallus measuring up to about 10 cm (4 in). The lichen has also been recorded from Acre, Brazil, where it is commonly found on dead branches in dense shrubby campinas.

## Contents

* 1 Taxonomy
* 2 Description
* 3 Habitat and distribution
* 4 See also
* 5 References

## Taxonomy

Parmotrema aptrootii was formally described in 1992 by J. van Aubel from material collected along the Kamarang River in the Cuyuni-Mazaruni region of Guyana. The holotype (Sipman & Aptroot 18187, herbarium U) was taken from the bark of a mahogany tree about 500 m above sea level. The specific epithet honours the Dutch lichenologist André Aptroot, one of the collectors of the type. Within Parmeliaceae the species sits among a small cohort of sorediate Parmotrema taxa, but it is readily distinguished by its rather narrow, [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] lobes and by the combination of secondary metabolites detected by thin-layer chromatography. Apothecia and pycnidia have not been observed in this species.[1]

## Description

The lichen forms a closely attached ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]) foliose (leafy) thallus up to about 10 cm across. Individual lobes are 3–6 mm wide, with rounded tips and a slightly [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]], wavy outline. Along the raised [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] margins lie the soralia—small, initially dot-like patches that can elongate and coalesce. These soralia release soredia: minute, flour-like clumps of algal and fungal cells that give the margins a [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] appearance. The upper surface is pale yellowish- to greenish-grey, dull and without pale spotting ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]); near the thallus centre it becomes faintly wrinkled ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]) and may crack, sometimes showing flakes of [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] where the margins lift.[1]

Internally, the medulla is white and unpigmented. The lower surface is black in the centre but grades to dark brown towards the lobe tips; it bears sparse, simple, jet-black rhizines up to 0.4 mm long that act as tiny holdfasts. No [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] fringe the margins. Secondary chemistry is dominated by usnic acid (which lends the thallus its pale green cast) together with echinocarpic and protocetraric acids, a profile that helps separate the species from chemically similar members of the genus.[1]

## Habitat and distribution

Parmotrema aptrootii is corticolous, growing on the bark of hardwoods in warm, humid lowland forest. The type population occurs on riverside mahogany at about 500 m in the Upper Mazaruni District of western Guyana.[1] Subsequent records extend its range west and south into the Colombian Amazon (Araracuara region[2]) and to white-sand campina shrublands in Acre State, Brazil, where it is common on dead branches protruding into the canopy light. The scattered, disjunct localities all lie within the northern Amazon basin, suggesting the species favours nutrient-poor, well-lit bark substrates in tropical lowland to sub-montane settings.[3]

## See also

* List of Parmotrema species

## References

1. ↑ 1.0 1.1 1.2 1.3 Sipman, H.; Aubel, R.J.M.T. van. (1992). "New Parmeliaceae (Lichenes) from the Guianas and surroundings". Mycotaxon 44 (1): 1–12. http://www.cybertruffle.org.uk/cyberliber/59575/0044/001/0001.htm.
2. ↑ Sipman, Harrie J.M. (1997). "Additions to the lichen flora of Araracuara (Colombian Amazonia)". Caldasia 19 (1/2): 247–255.
3. ↑ Daly, Douglas C.; Silveira, Marcos; Medeiros, Herison; Castro, Wendeson; Obermüller, Flávio A. (2016). "The white-sand vegetation of Acre, Brazil". Biotropica 48 (1): 81–89. doi:10.1111/btp.12307. Bibcode: 2016Biotr..48...81D.

Wikidata ☰ Q10620700 entry

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