This guest editorial was submitted to MalariaWorld by Prof. Maureen Coetzee, Nora Besansky, Alessandra della Torre and Rick Wilkerson.
Comments are invited, please post these directly in the forum section.
In the past 10 years a huge body of information has become available on Anopheles gambiae M and S forms in West-Central Africa. It has become increasingly clear that these two forms are genetically distinct over most of their distribution. The evidence has come, amongst others, from classical population genetic studies, more recent studies on the mating behaviour of the two forms, and the comparative genome-wide sequencing study that has just been submitted to Science for consideration for publication.
The advantage of giving formal taxonomic names to M and S now is that it will facilitate future studies on these taxa, and make the community more aware of the potential impact of the two different species on malaria transmission and control.
In deciding on names for new species, one has to take into account which taxa occur at the type locality. In this case, both M and S are widespread throughout The Gambia (the type locality for An. gambiae s.s.), from the coast eastwards into Senegal. In 1998, Townson et al. successfully extracted DNA from the abdomen of one of two syntypes housed in the Natural History Museum in London and identified it as An. gambiae s.s. It is unfortunate that this sample of DNA was not stored for use in subsequent studies. Both existing syntypes are incomplete specimens and it is unlikely that permission will be granted to further destroy them in order to establish whether they are M or S.
Under these circumstances, we propose the following:
a) to retain the name Anopheles gambiae s.s. for the S form on the grounds that this is the most widespread of the two forms across the African continent;
b) to name the M form as a new species with the type locality in Mali and the type specimens based on a single wild female and her progeny, some of which will be mounted as museum specimens and others preserved on silica gel and in alcohol for future DNA studies. We are proposing to name the new species in honour of Prof Mario Coluzzi who spent his whole career working on the gambiae complex.
The fact that there is already evidence for genetic differentiation within both M and S, does not affect the naming of these species right now. There is no doubt that M and S will never be reunited as a single species given the current evidence, and further splitting of either of them will only result in yet more new species requiring new names. This is why the selection and preservation of type material for the M form is critical for the resolution of future taxonomic issues.
We invite comments from the vector community before going ahead with formal publication of the species descriptions.
Please submit your comments directly in the scientific topic section of the Forum, by clicking here.