Taxonomic and phylogenetic studies on dothideomycetes on monocotyledons in Thailand

Name: Rungtiwa Phookamsak

Organization : Mae Fah Luang University

keyword: Monocotyledons

LCSH: Phylogeny

Classification :.LCCS: QK495.A14

LCSH: Monocotyledons

Abstract: Dothideomycetes, one the largest, most diverse and important class of the Ascomycota, comprises 22 orders, 110 families, 1261 genera and more than 19,000 species. Dothideomycetous taxa can be distinguished from other classes due to their characteristic bitunicate asci. The relationships of Dothideomycetes are uncertain with other classes, also the subdivision of this class is very confusing with the molecular data. In the past 10 years, many authors attempted to clarify the phylogenetic relationships of Dothideomycetes. However, the taxonomic position of several taxonomic groups within Dothideomycetes remains unclear and warrant further investigations. Thailand is a tropical country with high biodiversity. Many organisms have been well-documented in Thailand, but some taxonomic groups such as invertebrates, amphibians and fungi were poorly studied. During the past 10 years, many mycologists have studied microfungi on monocotyledons in Thailand. However, these studies have only been carried out mostly in connection to applications and lack taxonomic and phylogenetic studies. In this study, Dothideomycetes are collected on monocotyledons (especially bamboo and grasses) from the north and some provinces in Northeastern Thailand. Based on morphology and phylogenetic relationships, 113 collections yielded 110 isolates and were identified to 86 species, distributed in six orders viz. Botryosphaeriales, Capnodiales, Hysteriales, Myriangiales, Pleosporales and Tubeufiales. Two new families, 12 new genera and 42 new species are introduced from this study. Additionally, Leptosphaerulina oryzae and Pallidocercospora thailandica are new combinations. Roussoella nitidula and Roussoellopsis macrospora are epitypified and a neotype of Botryosphaeria agaves is designated. The reference specimens, Psiloglonium colihuae and P. sasicola are re-described and their taxonomic placement resolved within Hysteriaceae (Hysteriales). Astrosphaeriella is a poorly known genus of Dothideomycetes which commonly occurs on bamboo, palms and stout grasses. Many studies of Astrosphaeriella were carried out based on morphological criteria, but molecular data and phylogenetic analyses are generally missing. In the study five type specimens of Astrosphaeriella were requested from herbaria worldwide to be re-examined and illustrated. In addition, collections of Astrosphaeriella were also collected in Thailand and morphologically and phylogenetically examined. Phylogenetic analyses show that Astrosphaeriella species can be distinguished in at least three families. Species of Astrosphaeriella sensu stricto with erumpent, carbonaceous ascostromata, form a strongly supported clade with the genus Pteridiospora and a new family Astrosphaeriellaceae is introduced to accommodate these taxa. Astrosphaeriella sensu lato characterized by immersed, coriaceous ascostromata, with short to long papilla and striate ascospores, form a sister clade to Tetraplosphaeriaceae. The genus Pseudoastrosphaeriella is described to accommodate these Astrosphaeriella sensu lato taxa and thus a new family Pseudoastrosphaeriellaceae is introduced to accommodate this monotypic genus. Astrosphaeriella bakeriana forms a distinct lineage basal to Aigialaceae. Therefore, the species is excluded from Astrosphaeriella and placed in a new genus Astrosphaeriellopsis, Dothideomycetes, genera incertae sedis. The third group of Astrosphaeriella sensu lato (lophiostoma-like), having immersed ascostromata with slit-like openings, has been transferred to Fissuroma and Rimora in Aigialaceae. The genus Fissuroma (Aigialaceae) is re-visited and is shown to be a species complex. Phaeosphaeriaceae is a large and important family in the order Pleosporales. Species of Phaeosphaeriaceae mostly occur on monocotyledons, but also found on dicotyledons. Phaeosphaeriaceae contains a wide range of morphological characters and only few genera have been clarified their natural placement. In this study, 14 generic type specimens of Phaeosphaeriaceae were borrowed from herbaria worldwide and are re-examined and illustrated. Fresh collections were also obtained from Thailand for examination and illustration. Multigene phylogenetic analyses of ITS, LSU, SSU, RPB2 and TEF1α sequence datasets show that 21 genera belong in Phaeosphaeriaceae viz. Amarenomyces, Ampelomyces, Chaetosphaeronema, Dematiopleospora, Entodesmium, Loratospora, Neosetophoma, Neostagonospora, Nodulosphaeria, Ophiobolus, Ophiosphaerella, Paraphoma, Parastagonospora, Phaeosphaeria, Phaeosphaeriopsis, Sclerostagonospora, Setomelanomma, Setophoma, Vrystaatia, Wojnowicia and Xenoseptoria. Genera Amarenographium, Bricookea, Dothideopsella, Eudarluca, Phaeostagonospora, Scolecosporiella and Tiarospora are included based on morphological characters. Amarenomyces is reinstated in this study. Wilmia clusters in Didymosphaeriaceae and is synonymized under the genus Letendraea. In contrast Barria, Chaetoplea, Hadrospora, Lautitia, Metameris, Mixtura and Pleoseptum are excluded from Phaeosphaeriaceae based on their morphological characters. The asexual genera Mycopappus and Xenostigmina form a clade in Melanommataceae and thus the genera are excluded from Phaeosphaeriaceae. Fenestellaceae and Schizothyriaceae are poorly known families in Dothideomycetes. Most genera of these families lack modern taxonomic descriptions, molecular data and phylogenetic investigation. Therefore, generic type and other representative specimens of genera in Fenestellaceae and Schizothyriaceae were loaned from herbaria worldwide to be re-examined, described and illustrated for a better understanding of each genus in these two families. In this study, the family Fenestellaceae is maintained until the type species is recollected and molecular phylogeny is obtained to confirm its natural placement. Lojkania is excluded from Fenestellaceae based on morphology and tentatively placed in Testudinaceae. Morphologically, five genera are accepted in Schizothyriaceae viz. Hexagonella, Lecideopsella, Mycerema, Plochmopeltis and Schizothyrium, while Kerniomyces, Metathyriella and Myriangiella are treated in Schizothyriaceae, genera incertae sedis. Chaetoplaca, Henningsiella, Hysteropeltella, Linopeltis, Neopeltella and Orthobellus are excluded from Schizothyriaceae based on morphologically distinct. Phylogenetically, Mendogia is placed in the family Myriangiaceae. However, representative species of the genera in Schizothyriaceae, including the type species, need to be recollected and sequenced to clarify the natural placement in Schizothyriaceae.

Mae Fah Luang University

Address: CHIANG RAI

Email: library@mfu.ac.th

Name: Kevin D. Hyde

Role: Advisor

Name: Ekachai Chukeatirote

Role: Co-Advisor

Created: 2016

Issued: 2017

Modified: 2020-04-27

Issued: 2017-04-11

วิทยานิพนธ์/Thesis

application/pdf

CallNumber: Thesis QK495.A14 R942t 2016

eng

DegreeName: Dotor of Philosophy

Level: Doctoral Degree

Descipline: Biosciences

Grantor: Mae Fah Luang University

©copyrights Mae Fah Luang University

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