High intercontinental migration rates and population admixture in the sapstain fungus Ophiostoma ips

Ophiostoma ips is a common fungal associate of various conifer-infesting bark beetles in their native ranges and has been introduced into non-native pine plantations in the Southern Hemisphere. In this study, we used 10 microsatellite markers to investigate the population biology of O. ips in native (Cuba, France, Morocco and USA) and non-native (Australia, Chile and South Africa) areas to characterize host specificity, reproductive behaviour, and the potential origin as well as patterns of spread of the fungus and its insect vectors. The markers resolved a total of 41 alleles and 75 haplotypes. Higher genetic diversity was found in the native populations than in the introduced populations. Based on the origin of the insect vectors, the populations of O. ips in Australia would be expected to reflect a North American origin, and those in Chile and South Africa to reflect a European origin. However, most alleles observed in the native European population were also found in the native North American population; only the allele frequencies among the populations varied. This admixture made it impossible to confirm the origin of the introduced Southern Hemisphere (SH) populations of O. ips. There was also no evidence for specificity of the fungus to particular bark beetle vectors or hosts. Although O. ips is thought to be mainly self-fertilizing, evidence for recombination was found in the four native populations surveyed. The higher genetic diversity in the North American than in the European population suggests that North America could be the possible source region of O. ips

Emendation of the genus Bactrodesmiastrum (Sordariomycetes) and description of Bactrodesmiastrum monilioides sp. nov. from plant debris in Spain

Bactrodesmiastrum monilioides sp. nov. is described and illustrated from the twig of an unidentified plant collected in Spain. This fungus is characterized by sporodochial conidiomata with moniliform conidiophores, its conidia being solitary, broadly navicular to obovoid, mostly 2-septate, dark brown, with a black band at the septa and basal cell pale brown to brown. Analysis of the ITS region and D1/D2 domains of the LSU of rDNA sequences confirms the placement of this fungus in Bactrodesmiastrum (Sordariomycetes). Because the genus Bactrodesmiastrum was originally characterized by solitary or aggregated conidiophores reduced to a single brown monoblastic conidiogenous cell, an emended description of the genus is provided to accommodate the novel species. A key to species of Bactrodesmiastrum is provided.Spanish Ministerio de Economia y Competitividad, Grant CGL 2011–27185.http://link.springer.com/journal/115572016-06-30hb201