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United States Department of Agriculture

Agricultural Research Service

Research Project: Systematics and Diagnostics of Emerging and Quarantine-Significant Plant Pathogenic Fungi

Location: Systematic Mycology and Microbiology

Title: Phylogeny and taxonomic revision of Thelonectria discophora (Ascomycota, Hypocreales, Nectriaceae) species complex

Authors
item Salgado-Salazar, Catalina -
item Vacant, Rl,
item Samuels, Gary -
item Hirooka, Yuuri -
item Sanchez, Romina -
item Chaverri, Priscila -

Submitted to: Fungal Diversity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 21, 2014
Publication Date: N/A

Interpretive Summary: Fungi are a large and diverse group of organisms that cause serious diseases of crop and forest plants. Although some fungal species are thought to be widely distributed, increasingly research is showing that what was considered to be one species may actually be a number of different species that look very similar; these are known as cryptic or hidden species. Such is the case with a seemingly ubiquitous species that occurs widely on hardwoods such as cacao and rubber in tropical regions. In this research numerous specimens of what was considered to be one species were analyzed. It was determined that this supposedly ubiquitous species is actually sixteen different species. Each cryptic species has a slightly different appearance and biology i.e. some are plant pathogenic while others are not. In this paper each of the sixteen species is described and illustrated with a key for identification. This research will help plant pathologists to accurately identify these fungi.

Technical Abstract: Thelonectria discophora (Thelonectria, Nectriaceae, Hypocreales) is a conspicuous group of saprobic fungi on decaying plant material, characterized by red perithecia each with a broad mammiform (nipple-like) apex. The anamorphic state is characterized by a cylindrocarpon-like morphology, with 3–5 septate macroconidia. Unicellular microconidia and chlamydospores are rarely produced in culture. In the past, T. discophora was regarded as one species with a wide geographic distribution. However, a recent study rejected the monophyly and cosmopolitan distribution of this species and showed the existence of at least sixteen cryptic species based solely on molecular data. In the present paper, we revise the taxonomy of the T. discophora species complex by describing twelve new species and four new combinations based on historic names. Individual diagnostic morphological characters for each species could not be identified; however, discrete morphological traits corresponding to each of the three main groups of species were discovered. Lineages could be differentiated by average values of morphological traits as well as presence/absence of characteristic asexual propagules and colony growth at 30 C. Descriptions, illustrations and keys for identification are provided for the recognized species.

Last Modified: 7/23/2014
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