[Taxacom] How many genera (was Re: Drosophila melanogaster name change?)

[Kim van der Linde]

Dear Karl,

Please allow me to clarify a few points about what we knew back when we 
submitted the application, the changes over time that we actually have 
seen, and how limited the effect is on the the circumscription of the 
new genera before you claim that our proposal is just based on the 
flavor-of-the-day.

On 4/16/2010 2:47 PM, Karl Magnacca wrote:
> Kim van der Linde wrote:
>> The split of Drosophila is not based on the flavor of the day, but
>> consistent with lots of research done over the past decades.
>
> Demonstrating that Drosophila is paraphyletic is.  The actual
> proposal to split it up *is* flavor-of-the-day, since the
> relationships are not settled (the diagram on your website now shows
> 11 new genera instead of 8 as in 2008).  See the difference?  If the
> relationships were all clear, the only argument would be about the
> names, which is not the case.

Karl, you are right, with every study, it becomes more apparent that our 
original idea is far too conservative, and the longer we wait, the more 
genera we have to erect. But our splitting proposal was never meant to 
be the be-all, end-all proposal in the first place. That is not how 
taxonomy is done to start with. The increased understanding comes 
incrementally, but I have seen several people demand from us that we 
should know everything before we make any change in the genus 
Drosophila. Sorry, the genus is neither untouchable nor God not the 
property of someone. The good things is. taxonomy is not done that way. 
But to answer you question, yes, we know now more than three years ago.

So, what do we know now that we did not know then:

1. The position of Hirtodrosophila duncani. Based on the literature, 
this was expected.
2. More clarity about the position of Dettopsomyia.
3. We have now molecular evidence confirming the inclusion of 
Xenophorticella and Zygotrica as expected.
4. And yes, we know now confirmation that the quadrilineata species 
group is indeed closer related to the other striped clades.

And what did we already know at that time but were not included in what 
has been published until now:
1. The tumiditarsus species group is a separate small clade, closely 
related to the other striped clades.
2. The position of the polycheata species group is unclear.

Originally, we wanted to split the genus in four major genera 
corresponding with the four major clades (Hawaiian 'Drosophila' => 
Idiomyia; sg Sophophora => Drosophila; virilis-repleta radiation => 
Siphlodora; immigrans-tripunctata => Chaetodrosophilella), with five 
smaller genera, all currently subgenera ion the genus Drosophila 
(Chusqueophila, Dorsilopha, Dudaica, Phloridosa, Psilodorha). A total of 
9 genera.

Now, we want to split the genus in four major genera corresponding with 
the four major clades (Hawaiian 'Drosophila' => Idiomyia; sg Sophophora 
=> Sophophora; virilis-repleta radiation => Siphlodora; 
immigrans-tripunctata => Drosophila), with five smaller genera, all 
currently subgenera ion the genus Drosophila (Chusqueophila, Dorsilopha, 
Dudaica, Phloridosa, Psilodorha).  A total of 9 genera.

O wait, there is no change other than the names (thanks to the ICZN). 
What changed is that we now know that some smaller clades might be 
outside the new genus Drosophila. In the interim, none of those species 
will change its name, so, no confusion there with new names that need to 
be changed again.

No, the commission has made my job a lot easier, because retaining the 
frequently studied Drosophila funebris as a type species for the 
immigrans-tripunctata clade is far easier than to decide which of the 
rarely studied available types species is actually appropriate.

To summarize the change in our knowledge with regard to the genus 
Drosophila during the past three years, we now have proof that the 
quadrilineata clade is indeed not within the immigrans tripunctata 
radiation. That's all. And revising the genus does not result in more 
name changes that later need to be changed again because they stay in 
Drosophila.

So, in short, the changes in our knowledge hasn't changed how the genus 
is going to be revised while the newer publications confirm what we know 
about the phylogeny of the genus and its many included genera.

Regards,

Kim van der Linde