New species from the Fusarium solani species complex derived from perithecia and soil in the Old World tropics

Abstract

A large collection of strains belonging to the Fusarium solani species complex (FSSC) was isolated from soil and perithecia in primary forests in Sri Lanka (from fallen tree bark) and tropical Australia (Queensland, from fallen tree fruits and nuts). Portions of the translation elongation factor 1-alpha (tef1) gene, the nuclear large subunit (NLSU) and internal transcribed spacer regions (ITS) of the nuclear ribosomal RNA genes were sequenced in 52 isolates from soil and perithecia. The FSSC was divided previously into three clades with some biogeographic structure, termed Clades 1, 2 and 3. All Sri Lankan and Australian soil isolates were found to be members of Clade 3, most grouping with the cosmopolitan soil-associated species F. falciforme. All but two Sri Lankan perithecial isolates were associated with a set of five divergent phylogenetic lineages that were associated with Clade 2. Australian perithecial isolates resided in a subclade of Clade 3 where most of the previously defined mating populations of the FSSC reside. Isolates from perithecia and those cultured from soil were always members of different species lineages, even when derived from proximal locations. The previous biogeographic assignment of Clade 2 to South America is now expanded to the worldwide tropics. Sri Lanka appears to be an important center of diversity for the FSSC. Nectria haematococca is epitypified with a collection from the type locality in Sri Lanka; its anamorph is described as a new species, Fusarium haematococcum. Neocosmospora E.F. Smith is adopted as the correct genus for Nectria haematococca. These new species are described: F. kurunegalense/Neo. kurunegalensis, F. rectiphorus/Neo. rectiphora/, F. mahasenii/Neo. mahasenii/, F. kelerajum/Neo. keleraja.

Epitypification of Fusisporium (Fusarium) solani and its assignment to a common phylogenetic species in the Fusarium solani species complex

“…Several species in this clade have been named (Summerbell and Schroers 2002, Nalim et al 2011, Short et al 2013. Four of the most common species in the F. solani species complex (F. petroliphilum = FSSC 1, F. keratoplasticum = FSSC 2, F. falciforme = FSSC 3+4 and F. solani = FSSC 5) all show a good deal of intraspecific morphological variation, and overlapping morphological traits (Mehl andEpstein 2007, Short et al 2013).…”

“…2) (2000) and is possibly endemic to Sri Lanka (Nalim et al 2011). Fusarium solani, as we have defined it here, corresponds to phylogenetic species 5 within FSSC clade 3, which is known to accommodate opportunistic human or animal pathogens (O'Donnell et al 2008).…”

“…Each of these mating groups represented one of the formae speciales that corresponded to pathogenicity on specific plant host species and cultivars. Phylogenetic analyses have consistently demonstrated that F. solani represents a complex of mostly morphologically cryptic species, now known as the F. solani species complex (FSSC;O'Donnell 2000, O'Donnell et al 2008, Zhang et al 2006, Nalim et al 2011, Short et al 2013. These analyses suggest that the FSSC consists of three major clades encompassing over 60 phylogenetic species.…”

“…Some of these species have been named (e.g. O'Donnell 2000, Covert et al 2007, Nalim et al 2011, Short et al 2013 or connected to previously known species Schroers 2002, O'Donnell 2000), but most remain unnamed. One barrier to developing a taxonomy for the FSSC is a lack of understanding of the identity of F. solani sensu stricto.…”

Recent incidence of collar canker and dieback of tea (Camellia sinensis) caused by Fusarium solani species complex in Sri Lanka

“…Fusarium pseudensiforme and F. cf. ensiforme are not known to be associated with ambrosia beetle (Nalim et al 2011;Kasson et al 2013). These two species and the isolates associated with collar canker and dieback of tea differ from F. ambrosium by having typical fusiform macroconidia, the latter produces a clavate macroconidia (Gadd and Loos 1947).…”