Multiple gene sequences delimit Botryosphaeria australissp. nov. from B. lutea

Botryosphaeria lutea(anamorph Fusicoccum luteum) most easily is distinguished from other Botryosphaeriaspp. by a yellow pigment that is formed in young cultures. This fungus has been reported from a number of cultivated hosts in New Zealand and Portugal. During a survey of Botryosphaeriafungi that occur on native Acaciaspecies in Australia, a yellow pigment was observed in some cultures. These isolates were morphologically similar to B. lutea,but the pigment differed slightly from the one formed by authentic B. luteaisolates. Preliminary data also revealed small differences in ITS rDNA sequence data. The aim of this study was to determine whether these small differences were indicative of separate species or merely variations within B. lutea.Anamorph, teleomorph and culture morphology were compared between B. luteaand Acaciaisolates from Australia. Sequence data of two other genome regions, namely the β-tubulin and EF1-α gene and intron regions, were combined with ITS rDNA sequence data to determine the phylogenetic relationship between these isolates. Isolates of B. luteaand those from Australian Acaciaspecies were not significantly different in spore morphology. The yellow pigment, however, was much more distinct in cultures of B. luteathan in cultures from Acacia.There were only a few base pair variations in each of the analyzed gene regions, but these variations were fixed in the two groups in all regions. By combining these data it was clear that B. luteaand the isolates from Acaciawere distinct species, albeit very closely related. We, therefore, propose the new epithet B. australisfor the fungus from Australia. Botryosphaeria australisalso was isolated in this study from exotic Sequoiadendrontrees in Australia. Re-analyses of GenBank data in this study showed that B. australisalso occurs on other native Australian hosts, namely a Banksiasp. and a Eucalyptussp., as well as a native Proteasp. in South Africa and on Pistachioin Italy. These records from GenBank have been identified previously as B. lutea.The common occurrence of B. australison a variety of native hosts across Australia suggests that this fungus is native to this area.