Diversity and Molecular Phylogenetic Analyses of Parmelioid Lichens (Parmeliaceae, Ascomycota) In Kenya
Muigai, Kirika Paul
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Lichens are symbiotic associations of fungi and algae or cyanobacteria.They are ecologically important as bioindicators for air pollution, forest age and health, and as sources of food, shelter and nesting materials for animals. Man has historically used them for dyes, medicines, poisons and in the manufacture of perfumes and antibiotics. Globally there are an estimated 28,000 species of lichens. Parmeliaceae is the largest family with over 2800 species in about 80 genera. Parmelioid clade is the largest group comprising 75% of the total number of species in the family. About 180 species of parmelioid lichens distributed in 19 genera are known for Kenya. The advent of molecular tools has shown that, the morphological and chemical characters traditionally used to delimit taxa in lichens underestimate diversity. Application of molecular data has therefore become a prerequisite while making taxonomic evaluations in this group. Molecular DNA sequence data were used to evaluate the phylogenetic relationships and to re-asses traditional phenotype-based taxon delimitation in Bulborrhizina, Bulbothrix, Canoparmelia, Hypotrachyna, Parmelinella, Relicina and Relicinopsis. Seventy seven samples were collected from 5 floral regions in Kenya and duplicates deposited in EA, F and MAF herbaria. Genomic DNA were extracted from newly collected samples and the ITS, nuLSU and mtSSU regions of rDNA sequenced using Sanger sequencing approach. To infer phylogenetic relationships, 6 datasets of concatenated ITS, nuLSU and mtSSU comprising 746 DNA sequences were analyzed using ML and BI methods. Three species, Bulbothrix kenyana, Hypotrachyna himalayana and Parmelinella schimperiana were described as new to science, and taxonomic re-evaluation of 22 taxa carried out. Eight new combinations were proposed: Bulbothrix sublaevigatoides, Parmotrema epileucum, P. zimbabwense, Relicina dahlii, R. intertexta, R. malaccensis, R. rahengensis and R. stevensiae. The monotypic genus Bulborrhizina had not been studied previously using molecular data and its phylogenetic position hitherto unknown. DNA sequences of Bulborrhizina africana were analyzed with 95 other samples of parmelioid lichens. In the resultant phylogenetic tree, B. africana clustered with Bulbothrix, in the Parmelina clade. Species boundaries in Bulbothrix isidiza and B. tabacina, two pantropical and asexually reproducing species were re-examined using mutilocus dataset of Bulbothrix specimens from E. Africa, Asia and S. America. Five species-level lineages in Bulbothrix isidiza s.lat. and three in B. tabacina s.lat were recovered. Alternative hypothesis testing using SH and ELW tests significantly rejected monophyly of B. isidiza and B. tabacina, respectively. In the phylogenetic analysis of Canoparmelia s.lat. the genus was recovered as polyphyletic with three divergent lineages, two formed a sister group relationship with Parmotrema. Consequently they were included in Parmotrema and recognized at subgeneric level as Parmotrema subgenus Africanae and Crespoa, the former described as new. Genetic diversity of the pantropical sorediate species Hypotrachyna sorocheila was assessed with the resultant phylogeny forming two distinct species-level lineages.The pantropical species Parmelinella wallichiana s.lat. was assessed, samples of P. wallichiana were recovered in four well-supported clades. Evolutionary relationships of Relicina and Relicinopsis were elucidated; Relicina was recovered nested with Relicinopsis. However, based on differences in conidia, Relicinopsis is accepted at a subgenus rank as Relicina subgen. Relicinopsis. The use of DNA sequence data in understanding true diversity and biogeography in Parmeliaceae is underscored. A wider taxon sampling is recommended for the lineages that remain undescribed in this study.