Staying up to date with names: The Chelodina subgenera and the species within.

 

First up just a quick mention here, I have been traveling the last week or so, looking at fossils of turtles in Lightning Ridge. As such it was a bit difficult to write this blog. But I will put up this post today. I am currently in Australia for 5 months but live in Brazil. So traveling has been a part of this, a lot of it.

The long necked turtles in Australia have long been recognized as the genus Chelodina and up until the 1980’s only half a dozen or so species were recognized. In this period the recognized species consisted of Chelodina longicollis (Eastern Longneck Turtle); Chelodina novaeguineae (New Guinea Longneck Turtle); Chelodina steindachneri (Dinner Plate Turtle); Chelodina expansa (Broad Shell Turtle); Chelodina rugosa (Northern Snakeneck Turtle [now Chelodina oblonga]); Chelodina oblonga (Oblong Turtle [now Chelodna colliei the South Western Snakeneck Turtle]); and Chelodina parkeri (Parker’s Snakeneck Turtle). Please do see my post on the Chelodina oblonga / rugosa issue. In any case about 5 species were recognized, people sometimes also recognized Chelodina siebenrocki (New Guinea Snakeneck Turtle) as a distinct species.

In 1974 it began to become clear that there were two or three distinctive lineages in the Chelodina and they became known as Chelodina A (C. longicollis and allies); Chelodina B (Chelodina expansa and allies) and sometimes a third group, Chelodina C (Chelodina oblonga [now Chelodina colliei]). This was based on the mode of feeding and on some early molecular work (Burbidge et al. 1974). This was supported by work using electrophoresis (Georges and Adams, 1992). All this of course is the beginnings of a major taxonomic overhaul but it had many nomenclatural implications. As the taxonomy evolved it has become necessary to change the nomenclature. This example is presented to show that nomenclature cannot be any more stable than the science of taxonomy that underpins it. Hence hoping for a stable nomenclature is largely impossible as science evolves.

One of these clades within the Chelodina was named Macrochelodina (Wells and Wellington, 1985) but for many years the name was not used. After this many new species were added to the Chelodina, including Chelodina reimanni, Chelodina pritchardi, Chelodina mccordi, Chelodina burrungandjii, Chelodina canni, Chelodina kuchlingi, Chelodina gunaleni and Chelodina walloyarrina. So as we can see this genus has now become rather large, and because of the deep clades that are supported by morphology, morphometrics and molecular work it became desirable to recognize them.

The name Macrochelodina was therefore resurrected to full genus status, with little idea of what to do with what had now become known as Chelodina colliei. The case of Chelodina colliei has been addressed in an earlier post. Eventually the name Macrodiremys was coined for the Chelodina C group and myself and Arthur Georges in our 2010 synonymy and keys sank these genera to subgenus. We did this because although the three clades are very different, they are also all long necks and this kept a level of recognition that all these species are closely related with respect to the short necked species.

There are many problems in the taxonomy of all the members of this large group of species that need to be addressed. Because of the many taxonomic issues, there are related nomenclatural issues. As I have said many times, nomenclature and taxonomy are linked and when you affect the taxonomy, you also affect the nomenclature.

One of the biggest issues has been the erection of species without any scientific evidence presented, or poor quality evidence, to demonstrate they are in fact species. Some of this is because of the poor review quality of the journals that have published these descriptions. The names Chelodina gunaleni and Chelodina walloyarrina have been described in a hobby magazine (Reptilia) as such the rigor required in a taxonomic work to formally name a species is absent. In neither case is the population represented by the name adequately diagnosed from its nearest relatives.

When I described Chelodina burrungandjii in 2000 I included in the analysis the population I then called Chelodina sp. (Kimberley) feel free to read my paper for this (Thomson et al. 2000). This population was not adequately differentiated from Chelodina burrungandjii and as such I kept it as an unnamed population, referring it to Chelodina burrungandjii. Hence the species was shown to have two population’s one in Arnhem Land and the other in the Kimberley. No evidence that this Kimberley population does represent a species has been presented to science. As a nomenclatural taxonomist I recognize the species, I have to, but I also know it is a very problematic and virtually un-diagnosable species.

Chelodina gunaleni is in the same situation, it is not adequately differentiated from Chelodina novaeguineae or Chelodina reimanni. It could be a localized population of either, I do not know. I have not examined this one yet, though it is on my to do list. If I find it does not stand up to scientific rigor, it will be sunk eventually. The same can be said for the sub-species of Chelodina mccordi, also no scientific evidence has been presented, it is not known if they are sub species, species or populations. Again this requires careful study.

Many people try to recognize the three major populations within the Chelodina oblonga complex. That is Chelodina oblonga (Northern Territory), Chelodina rugosa (Cape York), and Chelodina siebenrocki (New Guinea). This one is a very complicated situation; there is mass hybridization among the long necked turtles, between many of these northern species. There is also hybridization between these taxa and Chelodina expansa and Chelodina canni. Until such time as these issues are sorted it is not possible to recognize the taxa currently under Chelodina oblonga. These taxa cannot be subspecies, since there may be overlap, so it is important to wait for the scientific evidence to be in. The nomenclatural acts will be back and forth while this is underway. It’s better to just do it once.

Another rather poorly diagnosed species was Chelodina kuchlingi; it is based on a single specimen of unlikely and hence unknown providence. It seems it may come from an area to the north of Kalumbaru, which is the current type locality. Yes there is that word type again, species also have type localities, this can be used to narrow down exactly which population is being referred to. However, it is certainly not from the current type locality since this is where Chelodina walloyarrina is from. I had sunk it into Chelodina oblonga, my reasons were that I knew it was not from where it was claimed to have been from and the only species it was similar to was Chelodina oblonga. Since I could not attach it to a valid population I got rid of it. It has been recently resurrected and Gerald Kuchling is working on where it is actually from. So the data for this one is pending and will hopefully be available soon.

As you can see, names can change quickly, they can change radically. It is not fair on nomenclatural taxonomy to expect it to be this stable rock we can all pin our work on. However, it is also not right to use poor quality taxonomy to inflate the quantity of name changes unnecessarily. If you cannot do the taxonomy well, and get it submitted to and accepted by a first class peer reviewed journal, then you really have no business naming species. People want stability and sense from nomenclature, there are going to be some changes but a constant back and forth of changes cause by poor work is not acceptable and just makes people angry. It is hard to ignore nomenclature, we have all agreed to follow a set of rules on this. But I urge people, if you want to name species you must publish it appropriately, where it will be reviewed with rigor.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s