Contribución taxonómica y molecular al estudio de la myxobiota nival ibérica

Abstract

Myxomycetes are an order of protozoa (Amoebozoa) that have been studied by mycologists since their discovery. This is due to the similarity of their fructifications with those of fungi. There is an ecological group of Myxomycetes, the so-called nivicolous Myxomycetes, that fruits at the edge of melting snow during spring and summer. This doctoral thesis includes three different study approaches regarding these organisms. Firstly, it is a taxonomic contribution to the knowledge of nivicolous Myxomycetes in the Iberian Peninsula, including definitions, comments, and macro- and micrographs of each species studied. The second part is a compendium of their distribution in the study area, where old and new records are included. Finally, the third part consists of a deep molecular study of the genus Lamproderma, focused on the species with maculated peridium. The hypotheses for the molecular work were that maculated Lamproderma were not a monophyletic group and that the species Lamproderma macrosporum was not a species on its own. Materials and methods: A total number of 1153 specimens of nivicolous Myxomycetes have been studied. They have been deposited in the herbarium of the University of Alcalá. One semipermanent slide has been made for each specimen, using ethanol and Hoyer’s medium, as well as tweezers and entomology needles. Scanning electron microscopy (SEM) preparations have also been made for the detailed study of sporal ornamentation, performing the critical point technique and metallization of the samples. Photographs of all species have been taken to illustrate their descriptions. For the species distribution study, a total of 25 papers where nivicolous Myxomycetes appear have been reviewed. Then, one map per species has been developed, including the old and the new records. Regarding the molecular study, Lamproderma specimens have been gathered from different herbaria and collecting areas, including nivicolous and non-nivicolous species, as well as species with maculated and non-maculated peridium. The number of readable sequences was 328 for the molecular marker SSU, and 190 for EF-1α. Conclusions: Among the 1153 samples studied, 57 nivicolous and 13 non-nivicolous species have been identified. A detailed description of the nivicolous ones has been made, and a plate for each of them has been created. Concerning the nivicolous Myxomycetes, five species and one variety new to science have been published, in addition to six new non-nivicolous species. The number of new records of nivicolous Myxomycetes for the next territories are – Spain (3), Pyrenees of Huesca (9), Pyrenees (4), sierra de Ayllón (2), Sierra Nevada (15), and Sistema Central (9). Molecularly it has been found that maculated Lamproderma do not create a monophyletic group and that Lamproderma macrosporum is, indeed, an independent species. Additionally, it has been confirmed that there are 7 species of maculated Lamproderma, and the trees obtained have supported the theories about the polyphyly of the nivicolous lifestyle, as well as the possibility of endemicity in Myxomycetes.