Re-evaluation of Botryosphaeria


Over the years the concept of Botryosphaeria has been modified little by little, ever widening and embracing an array of morphologies.  Take, for example, the colour of the ascospores.  When the genus was first described, one of the main characteristics was that ascospores are hyaline, but they can become brown with age.  Von Arx and Müller (1954) included Dothidea visci Kalchbr. (with brown ascospores) in Botryosphaeria as B. visci (Kalchbr.) von Arx & Müller. Later they (von Arx and Müller, 1975) included the dark spored Neodeightonia subglobosa C. Booth in Botryosphaeria, and since this is the type species of the genus, they made Neodeightonia a synonym of Botryosphaeria.  In this way they effectively broadened the concept of Botryosphaeria to include species with brown ascospores.  Phillips et al (2005) resurrected the genus Dothiorella for species with one-septate conidia that darken at an early stage of development.  Teleomorphs of these species have brown, one-septate ascospores.  Phylogenetically (ITS) these species fell within Botryosphaeria and given the broad concept adopted by von Arx & Müller (1954, 1975), Phillips et al (2005) described the teleomorphs as two new species of Botryosphaeria with brown, one-septate ascospores.  Subsequently, Luque et al (2005) described a further dark-spored Botryosphaeria, namely B. viticola.  In this way, the concept of Botryosphaeria was gradually shifting away from the idea that ascospores can become brown and septate with age to the acceptance that in some species the ascospores are brown and one-septate.  Phylogenetically (ITS) these species all fall within Botryosphaeria, but morphologically they seem to be a collection of different genera.

Considering the morphology of the anamorphs, it is well-established that there are several anamorph genera associated with a single teleomorph genus.  This is obviously illogical. 

Crous et al (2006) were of the opinion that the morphological diversity in Botryosphaeria was becoming too wide to be accommodated within a single genus.  To resolve this issue, they made a phylogenetic study based on sequences of the 28S rDNA gene.  This clearly showed that Botryosphaeria is composed of several lineages that correspond to individual genera.  Furthermore, these lineages correspond to the morphology of the associated anamorph genera.  To prevent the unnecessary introduction of new genus names, Crous et al (2006) used the existing anamorph genus names even when a teleomorph was known rather than introducing new genus names for the teleomorphs.  The following genera are now recognized within what was once called Botryosphaeria:

Botryosphaeria (restricted to B. dothidea, B. corticis and possible including B. mamane).
Diplodia (examples include D. mutila, D. seriata, D. pinea amongst others)
Lasiodiplodia (L. theobromae, L. gonubiensis)
Macrophomina
Neoscytalidium
Dothiorella (teleomorphs similar to Dothidotthia)
Neofusicoccum (teleomorphs similar to Fusicoccum)
Pseudofusicoccum
Saccharata
"Botryosphaeria" quercuum/"Botryosphaeria" melanops

Although there are several taxonomic problems still to be resolved, I have updated the names in this website in accordance with those proposed by Crous et al (2006).  I still have to include many of the new species that have been described over the last year or so, but this will be done with time.

 An additional note to plant pathologists.  I am a plant pathologist myself and know how disruptive and confusing a revision like this can be.  Our aim is not to cause confusion, but rather to clarify and bring some sort of order to a taxonomically diverse group such as this one.  It wil take time for everyone to accept these new names, but the end result will be that the group of fungi we once knew as Botryosphaeria will be more understandable in terms of the diseases they cause and they will be easier to identify.

If you have any comments, suggestions or want to contribute anything, talk to me, I am always happy to hear your favourable or unfavourable comments and opinions.


Home


Re-evaluation. Version 01 saved 8 October 2007
Alan J. L. Phillips, alp@fct.unl.pt
Centro de Recursos Microbiológicos, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
Page copyright © 2007 A. J. L. Phillips