06 September 2013

Solution to Rampant Monotypy: Subgenera

Genus names are stupid. They have two jobs, and they do them both poorly:
  1. Refer to a taxon.
  2. Form the first part of the names of all species within that taxon.
They do #1 poorly because they're defined typologically. The definition for a genus is just, "Some taxon that includes the type species." But they could do this task well if they were given phylogenetic definitions instead.

But that doesn't work, either, because it conflicts with #2. Taxa defined by phylogenetic definitions may overlap, or be empty. For #2 to work, every single species has to be part of one genus (and only one genus). Phylogenetically-defined taxa don't really work that way.

So genus names are stupid. But we have to use them, because there's no other system for naming species.

Because they refer to taxa poorly, different disciplines often have wildly different ways of using genus names. In entomology, a genus may have hundreds of species. But, increasingly in dinosaur paleontology, each genus gets one species. Nearly every single Mesozoic dinosaur genus is monotypic.

This is a pattern we see over and over in recent years:
  1. A new dinosaur species is discovered.
  2. Researchers do a cladistic analysis and determine that it is the sister group to another species, already named, Originalgenus oldschoolensis.
  3. At this point, most researchers in other fields would name the new species something like Originalgenus noobius. But, no, even though it's barely different from O. oldschoolensis, it gets a new genus, so it's Newguy noobius.
Today's researchers do have an excuse prepared for #3. It goes like this:
  1. "Sure, this analysis shows it as the sister group of Originalgenus oldschoolensis. But what if a future analysis shifts it a bit so that they no longer form a clade? Cladistic taxonomies may require it to be placed it in a new genus."
  2. "We sure as hell aren't going to let anyone else name that genus; not after all the work we did describing it!"
Ignoring the mild egomania in #2, this sounds reasonable enough. But this way of thinking has given us a huge number of completely redundant names, as well as pushing dinosaur paleontology into an extreme corner of the "splitter vs. lumper" debate. Isn't there a better way?

There Is a Better Way

Just give your species a new subgenus!

GenusOriginalgenus Original Author 1900
SubgenusNewguy subgen. nov.
SpeciesOriginalgenus noobius sp. nov.

Now, as long as O. noobius continues to be regarded as the sister group (or otherwise "close enough") to O. oldschoolensis, you just keep the status quo. But if things get shaken up and O. noobius requires a different genus name, by the rules of the ICZN, it has to be Newguy. And you still get the credit!

I know, it's stupid ... but it works!


  1. Just to point out, the normal way you refer to subgenera is a parenthetical statement in the middle of the trivial nomen. So in this case:

    Originalgenus (Newguy) noobius

    1. Oh wait, should "Subgenus: Newguy subgen. nov." be "Subgenus: Originalgenus (Newguy) subgen. nov."? I may be confused from looking at a lot of botanical citations lately.

    2. OMG, Mike, no. Ranks, ranks, everywhere. OThis isn't me invoking the slippery slope, this is me pointing out that this is going back to a slippery slope that already exists. There really won't be a stop to anything here! One almost finds this argument an attempt to make the ICZN more relevant than it really is.

      There is no effective difference between Alphataxon speciosa (Alphataxon (Alphataxon) and Alphataxon (Betataxon) aspeciosa) and Superclada (Alphataxon speciosa and Betataxon aspeciosa). The relevance to extant nomenclature aside, for new, fossil taxa, it is far more effective to define a new binomen and worry about synonymy or enclading with other taxa later.

    3. Jaime, not following your Alphataxon example.

  2. Sorry, but this is not a good alternative.
    From a mnemonic point of view, instead of remembering a lot of genera (as usual), it forces to remember a lot of subgenera AND the relationships each subgenus has with its genus.

    Even more confusing than using monotypic genera.

    1. This may actually translate well to phylogenetic nomenclature -- need to work on a follow-up post.

  3. Subgenera are widely used in the invertebrate (paleo- and neontological) literature: especially mollusks and arthropods.

  4. I don't have a problem with subgenera in principle, but it seems like this solution is just designed to fix the underlying issue while at the same time allowing egotistical researchers to add as many newly coined names to their resumes as possible. You may as well write the examples as "Originalgenus (Vanityraptor) noobius"!

    An alternate solution might be to establish a norm in order to fix #1 at the top of the post. You write "They do #1 poorly because they're defined typologically. The definition for a genus is just, "Some taxon that includes the type species."" But actually, more specifically it's "A taxon with diagnosis x that includes the type species."

    People come up with a vague concept of what their new genus is and diagnose it. Then, when somebody revises the taxonomy when a new, related monotypic genus is inevitably found, they emend the original diagnosis ad nauseum in order to exclude every new form that WOULD have been included. I think that's the problem. Ignore emended diagnoses. Done. Treat the original diagnosis as the de-facto definition! This may result in all of Titanosauria falling under the genus Titanosaurus, but um... so what? It's still a tiny genus compared to some beetles.

    1. Diagnoses are not definitions -- that is not how a genus is defined under the ICZN. And it wouldn't work if it was, because the ICZN relies on all genera being disjoint (non-overlapping) sets. Diagnoses allow for a species to fall into multiple genera.