Rambellisea a new genus of biotic marine fungi

Abstract

The oceans cover more than 70% of the surface of our planet hosting a substantial proportion of Earth’s biodiversity and a large amount of unknown biological and chemical diversity. Today, the sea represents a limitless resource of unexploited substrata and new microorganisms of great potential interest for scientific discovery and technological innovation. Despite the recent improvements in marine mycology, several taxonomical and ecological issues still need to be addressed. Among them, the main topics are: a deeper knowledge of fungal diversity and a formal description of new taxa. It is worth noting that biodiversity conservation, in situ and ex situ, is one of the main actions to contrast global change. In this study a new genus, Rambellisea, along with two new species, R. halocynthiae and R. gigliensis, was proposed to accommodate 15 strains of Lulworthiales, which were isolated from the marine tunicate Halocynthia papillosa (Central Tyrrhenian Sea). The strains exhibit only mycelia sterilia, despite the fact that multiple experiments were conducted to promote their reproduction, and they can only be taxonomically assigned using molecular techniques. This approach, while fundamentally different from traditional taxonomy, is now widely accepted in the scientific community. In recent years, several new species and genera have emerged in the absence of sexual or asexual structures. The multi-locus phylogenetic analysis, based on nrITS1-nr5.8S-nrITS2, nrLSU, and nrSSU regions, provided strong evidences supporting the establishment of these new taxa. The phylogenetic analysis, carried out using both the Maximum Likelihood and the Bayesian Inference methods, clearly demonstrates that Rambellisea represents a distinct clade within the Lulworthiales order. Furthermore, the two newly described species were placed into separate, well-supported subclades. This study represents the first documented isolation of Lulworthiales species from animal hosts, expanding the ecological understanding of these fungi. The genus was named in honour of the important Italian mycologist Prof. Angelo Rambelli (1932-2014). He was the first dean of the Tuscia University's faculty of Biological Sciences, as well as the founder and first head of the Tuscia University's Botanical Garden, which now bears his name.