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Parmelia isidiiveteris

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Parmelia isidiiveteris
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Lecanoromycetes
Order: Lecanorales
Family: Parmeliaceae
Genus: Parmelia
Species:
P. isidiiveteris
Binomial name
Parmelia isidiiveteris
Poinar, E.B.Peterson & Platt (2000)

Parmelia isidiiveteris is a fossilised species of foliose lichen in the family Parmeliaceae. It was found in Dominican amber and described as a new species in 2000. It was tentatively placed in the genus Parmelia although its true generic placement is difficult to determine with only a single specimen available for analysis.

Taxonomy

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The fossil was discovered in Dominican amber and formally described as a new species in 2000 by George Poinar Jr., Eric Peterson, and Jamie Platt. The holotype specimen (Poinar AF9-17B) is kept at the University of Oregon.[1]

Because of its resemblance to modern-day members of Parmelia, the fossil lichen has been placed provisionally in that genus, although the authors acknowledge that without sacrificing more of the single available specimen for analysis, it is impossible to assert this definitively. Although the authors noted "striking resemblance" to some members of Hypotrachyna, they chose to tentatively group the fossil taxon in Parmelia because of the mostly simple (i.e., unbranched) rhizines, a trait characteristic of that genus.[1] Some later authors have opined, however, that this taxon, and another fossil lichen described concurrently, Parmelia ambra, do not belong to the genus concept of the Parmelia as presently circumscribed, although there is agreement that the Parmeliaceae is the appropriate family.[2][3]

Based on what types of organisms are used for dating, Dominican amber dates from 15–20 million years ago (based on foraminifera fossils), to 30–45 million years (based on coccolith fossils).[1] Because lichens are scarce in the fossil record, specimens like this are often used as calibration points for molecular clock analyses to improve understanding of lichen evolution.[4][5][6]

Description

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The fossil lichen has a thallus comprising dichotomously branched lobes with a smooth, slightly convex. The lobes measure 1.0–1.35 mm wide at the internode. The upper thallus surface is shiny and greenish in colour, lacking pseudocyphellae (tiny pores). Isidia are unevenly scattered on the thallus surface. The underside of the thallus is black with dark rhizines measuring 0.3–0.7 mm long. Neither apothecia nor pycnidia are apparent on the fossil. The isidia are 300–500 μm high and 40–50 μm in diameter, and leave pits on the surface of the cortex where they have been broken off. The specimen also has light-coloured squamules (scales) similar to those found in genus Cladonia.[1]

References

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  1. ^ a b c d Poinar, G. O.; Peterson, E. B.; Platt, J. L. (2000). "Fossil Parmelia in new world amber". The Lichenologist. 32 (3): 263–269. doi:10.1006/lich.1999.0258. S2CID 86227172.
  2. ^ Beimforde, Christina; Feldberg, Kathrin; Nylinder, Stephan; Rikkinen, Jouko; Tuovila, Hanna; Dörfelt, Heinrich; Gube, Matthias; Jackson, Daniel J.; Reitner, Joachim; Seyfullah, Leyla J.; Schmidt, Alexander R. (2014). "Estimating the Phanerozoic history of the Ascomycota lineages: Combining fossil and molecular data". Molecular Phylogenetics and Evolution. 78: 386–398. doi:10.1016/j.ympev.2014.04.024. PMID 24792086.
  3. ^ Kaasalainen, Ulla; Heinrichs, Jochen; Krings, Michael; Myllys, Leena; Grabenhorst, Heinrich; Rikkinen, Jouko; Schmidt, Alexander R. (2015). Wilf, Peter (ed.). "Alectorioid morphologies in Paleogene lichens: new evidence and re-evaluation of the fossil Alectoria succini Mägdefrau". PLOS ONE. 10 (6): e0129526. Bibcode:2015PLoSO..1029526K. doi:10.1371/journal.pone.0129526. PMC 4460037. PMID 26053106.
  4. ^ Amo de Paz, Guillermo; Cubas, Paloma; Divakar, Pradeep K.; Lumbsch, H. Thorsten; Crespo, Ana (2011). "Origin and diversification of major clades in parmelioid lichens (Parmeliaceae, Ascomycota) during the Paleogene inferred by Bayesian analysis". PLOS ONE. 6 (12): e28161. Bibcode:2011PLoSO...628161A. doi:10.1371/journal.pone.0028161. PMC 3234259. PMID 22174775.
  5. ^ Prieto, María; Wedin, Mats (2013). "Dating the Diversification of the major lineages of Ascomycota (Fungi)". PLOS ONE. 8 (6): e65576. Bibcode:2013PLoSO...865576P. doi:10.1371/journal.pone.0065576. PMC 3683012. PMID 23799026.
  6. ^ Divakar, Pradeep K.; Del‐Prado, Ruth; Lumbsch, H. Thorsten; Wedin, Mats; Esslinger, Theodore L.; Leavitt, Steven D.; Crespo, Ana (2012). "Diversification of the newly recognized lichen‐forming fungal lineage Montanelia (Parmeliaceae, Ascomycota) and its relation to key geological and climatic events". American Journal of Botany. 99 (12): 2014–2026. doi:10.3732/ajb.1200258. PMID 23204485.