Asperisporium and Pantospora (Mycosphaerellaceae): epitypifications and phylogenetic placement

Abstract

The species-rich family Mycosphaerellaceae contains considerable morphological diversity and includes numerous anamorphic genera, many of which are economically important plant pathogens. Recent revisions and phylogenetic research have resulted in taxonomic instability. Ameliorating this problem requires phylogenetic placement of type species of key genera. We present an examination of the type species of the anamorphic Asperisporium and Pantospora. Cultures isolated from recent port interceptions were studied and described, and morphological studies were made of historical and new herbarium specimens. DNA sequence data from the ITS region and nLSU were generated from these type species, analysed phylogenetically, placed into an evolutionary context within Mycosphaerellaceae, and compared to existing phylogenies. Epitype specimens associated with living cultures and DNA sequence data are designated herein. Asperisporium caricae, the type of Asperisporium and cause of a leaf and fruit spot disease of papaya, is closely related to several species of Passalora including P. brachycarpa. The status of Asperisporium as a potential generic synonym of Passalora remains unclear. The monotypic genus Pantospora, typified by the synnematous Pantospora guazumae, is not included in Pseudocercospora sensu stricto or sensu lato. Rather, it represents a distinct lineage in the Mycosphaerellaceae in an unresolved position near Mycosphaerella microsora.

Mycosphaerellaceae: Chaos or clarity?

“…3 , clade 13). Conidiophores of Asperisporium caricae also emerge from dark stromata, are densely arranged and have polyblastic conidiogenous cells, but conidia are shorter and wider (14–22 × 8–13 μm), mostly ellipsoid and typically 1-septate ( Minnis et al. 2011 ).…”

“…by J.F. Bischoff from BPI 880773 ( epitype designated by Minnis et al. 2011 , is a dried culture on SDA (BPI 881135), ex-epitype culture CBS 130298); on fruit of Carica papaya , Mar.…”

Phylogenetic lineages in Pseudocercospora

“…Olive (based on H. caperonia ), now P. caperoniae , and Pantospora Cif. (based on P. guazumae ) (see Ellis 1971, Deighton 1976), the muriformly septate conidia of the latter are similar to those of Pseudocercospora pseudostigmina-platani , though Pantospora has been shown to be a genus in its own right (Minnis et al 2011). …”

Alternaria redefined

“…A recent study on Pantospora included ITS and LSU sequence data of the type species Pantospora guazumae , which placed the genus in Mycosphaerellaceae (Minnis et al 2011). This refutes the link with Alternaria.…”