How (not) to name a snail

Taxonomists strive to bring order to the chaos we call the diversity of life by naming species and sorting them into higher taxa, like genera and families. Needless to say that this undertaking comes with its own problems.

Whoever discovers a new species has the right to give it its name; with that, I mean, its scientific name. Over the years I have had the privilege of finding and naming a few new species and, just occasionally, I couldn’t resist coming up with a mouthful. How do you like Madagasikara zazavavindrano, for example?

Sometimes, I am asked if you can pick any name when finding a species, or if the choice of possible names is somehow restricted. The answer is yes … and no. There are few restrictions for the actual word one chooses or creates, but there is in fact a large body of rather complicated rules that one needs to follow for any new name to be valid and accepted by the scientific community. These rules are written down in the International Code of Zoological Nomenclature (in the case of animals); similar codes exist for plants or microorganisms. This code is an international convention that was enacted in 1896 and has since been updated a few times in order to deal with emerging problems and new technologies, such as online publications.

The rules are straightforward – or so it seems at first. A scientific name for animals always has two parts, a genus name and a species name – this is similar to your given and family name. So, in the abovementioned case, the word Madagasikara is the name of the genus and zazavavindrano is the name of the actual species. Both words combined make up the scientific name of – in this case – a freshwater snail from Madagascar, which I described as new in 2010.

And then there are a few more rules. When describing a new species, one is allowed to use any word for a species name, except that it must never have been used before for another species in the same genus. So there can only ever be one Madagasikara zazavavindrano. A new name could even be just a random selection of letters. However, it must not contain numbers, hyphens, apostrophes, umlauts, accents, or letters from a non-Latin alphabet. Names can be nouns, adjectives or participles, but they can’t be verbs. And if a name looks like a Greek or Latin word, then it must be treated as such - unless the original author explicitly stipulates otherwise. If the species name is an adjective, then it has to conform in gender with the genus name. If one chooses to name a species after a person, then the name must end in –i for a man, and in –ae for a woman. For a group of persons, the correct ending is –orum, unless they are all women, then it’s –arum. But this rule applies only if the name is a noun in the genitive case. Alternatively, one could choose the name to be a noun in apposition, in which case one can do whatever one likes.

Easy, right?! As long as we all have advanced Latin grammar skills! This illustrates how the rules of the International Code of Zoological Nomenclature are anything but simple and straightforward. The Code, as we taxonomists call it, is quite a complex collection of regulations that have accumulated and been refined for more than 100 years, to ensure a standardised and unambiguous use of taxonomic names. But taxonomists like myself don’t just describe new species or higher taxa. They sometimes also scrutinize the names introduced by other taxonomists. And this is where the trouble starts… Let me explain!

Occasionally, authors introduce new names that are not compliant with the rules of nomenclature and so, these names are invalid. A common mistake is that authors make use of an already existing name when describing a new taxon. The danger of this happening is actually a real one. Consider that there are already more than one million named animal species. It is not always easy to find out if a certain name has already been used before. To the horror of any member of Generation Y, the omnipotent Google is not a useful tool in this instant because the vast majority of animal names introduced since the beginning of binominal taxonomy in 1758 is still unbeknownst to it (to find them, one has to look in actual books). Picking a very unusual name (remember Madagasikara zazavavindrano?) is one possible way to ensure that the name has not been introduced before.

Not too long ago, a French colleague and I realised that a number of genus names for Australian land snails were not compliant with the Code; these snails had originally been described by the Australian Museum taxonomist Tom Iredale between 1933 and 1944. Therefore, these names are invalid and must not be used. What makes this tricky is that nobody had noticed this problem before, resulting in some of these names being used widely for the past 80 years, or so.

One of these names is Meridolum, a genus of land snails found around Sydney. This genus name is still widely used today and considered to contain nine species. At least one of these species is also listed as an Endangered Species. Now, because the genus name Meridolum does actually not exist in the strange world governed by the Code, we had to find a valid replacement. After some research, we decided that this is indeed the case. We concluded that the closely related genus name Sauroconcha can and should be used in lieu of Meridolum. Therefore, all species treated as members of Meridolum became members of Sauroconcha. This change may not seem like much, but it may take many years before this new arrangement is generally accepted and used. Such taxonomic changes can cause confusion, so consequently they are not desirable. On the other hand, what are the rules of nomenclature good for, if they are not applied and enforced?

I am aware that dusting off some old stuff may cause quite a stir. However, I also believe that the long term stability of nomenclature is worth the pain and hope that the necessary taxonomic changes do not cause widespread confusion.

Dr Frank Koehler, Senior Research Scientist, Malacology, Australian Museum Research Institute

More information:

Köhler, F., Glaubrecht, M. 2010. Uncovering an overlooked radiation: molecular phylogeny and biogeography of Madagascar’s endemic river snails (Caenogastropoda: Pachychilidae: Madagasikara gen. nov.). Biological Journal of the Linnean Society 99: 867–894. https://doi.org/10.1111/j.1095-8312.2009.01390.x

Köhler, F., Bouchet, P. 2020. On unavailable genus-group names introduced by Tom Iredale for Australian non-marine gastropods: nomenclatural clarifications and descriptions of new genera. Molluscan Research. https://doi.org/10.1080/13235818.2020.1724603