Field of Science

A Minor Complaint about Google, and a Major Complaint about Ranked Taxonomy

There's a couple of things bugging me today, so please forgive me if I take the opportunity to vent (albeit in as genteel a manner as I can).

First, what has happened to the "web search" option on Google Scholar? Google Scholar is a fantastic resource, and one that has made itself indispensable to my life, so I'm certainly not complaining about Scholar as a whole. But until recently, each of the reference search results that came back would have a "web search" link among the options beneath it, which if clicked would automatically search for that reference on ordinary Google. This came in handy on a regular basis - often an online and/or free copy of the article might not be found by Scholar, but would be found by Google Normal (for instance, if the copy was hosted by a researcher's personal webpage). But just recently that option seems to have vanished, meaning I have to cut and past results from Scholar to Google myself. Grumble, grumble, they're stealing seconds from my life...

The second thing that's bugging me is a little more significant than a moment's inconvenience in searching, though (at least, I think it is, and it's my blog after all). My thesis is rapidly approaching completion (or to be more accurate, perhaps, rapidly approaching deadline) and that includes the big phylogenetic analysis of Monoscutidae. One of the problem areas in this family involves the previously poorly-defined and heterogeneous genus Spinicrus, and recently (in Taylor & Hunt, 2009) I segregated one of the more distinctive species (plus some previously unpublished species) as part of the new genus Neopantopsalis. I hadn't yet done any of the phylogenetic analysis at that time - rather, Neopantopsalis was established purely on the basis of its distinctive characters.

Fast-forward to now, when the greater part of the analysis is taking shape, and one interesting result is that the greater part of the genus Spinicrus looks like it belongs to a single clade after all, with Neopantopsalis nested within that clade. The relevant part of the tree currently looks like this:

 0--Spinicrus tasmanicum
 `--+--Spinicrus stewarti
      `--+--+--Spinicrus minimum
           |    `--Spinicrus porongorupense
           `--Neopantopsalis (5 spp.)

In other words, Spinicrus minus Neopantopsalis is paraphyletic. Neopantopsalis itself is still well-supported as a clade (more so than the Spinicrus clade as a whole, in fact), and from a diagnostic perspective the differences between the remaining Spinicrus species are less obvious than the differences between any of them and Neopantopsalis. So these are my options:

  1. Sink Neopantopsalis back into Spinicrus: This has the advantage of re-instating Spinicrus as a monophyletic unit, but disguises the distinctiveness of the 'Neopantopsalis' group. It also means that Spinicrus is back to being horribly heterogeneous again.

  2. Retain Spinicrus as a paraphyletic grouping, excluding Neopantopsalis as a separate genus: I'm not entirely prejudiced against paraphyla when they appear to be useful, and I do regard this as a viable option diagnostically. However, it disguises the point that some Spinicrus are closer to Neopantopsalis than others, and I would remind you all that monophyly-based classifications are likely to have more predictive power in the long run.

  3. Divide Spinicrus into a number of genera - one for each successive outgroup to Neopantopsalis: This manages to both recognise the distinctiveness of Neopantopsalis and avoid paraphyla, but it's not an option I find appealing at present. The problem is that the diagnostic characters for the other ex-Spinicrus isolates would probably end up being fine scale characters such as spiracle ultrastructure and the appearance of the sensory pores on the genitalia. Significant characters phylogenetically, but very difficult (if not impossible) to distinguish without the use of an electron microscope. When it comes to working classifications, I am sympathetic to the view that practicality trumps strict accuracy.

  4. Synonymise Neopantopsalis with Spinicrus, but as a distinct subgenus: This is the option that is currently appealing to me the most - Neopantopsalis remains distinguished, and Spinicrus is still monophyletic. However, there are two potential complaints I can see. One is that, really, who uses subgenera anyway? The second is that I wouldn't establish subgenera for the other species (for the same reasons as I wouldn't establish separate genera for them), and I can imagine reviewers complaining about some species being placed to subgenus while others are not.

Of course, I still have a couple of species left to include in the analysis, and it's possible that once they're in there, Neopantopsalis might move out of Spinicrus and the whole problem will go away. But let's assume for now that it doesn't.

The punchline to all this, which I'm sure some of you have realised long before now, is that it is only the use of a ranked taxonomic system, and hence my need to decide which clade(s) I'll recognise at the rank of "genus", that even makes this a problem in the first place. If I was dealing with an entirely unranked system, I could simply recognise a clade Neopantopsalis, positioned within a larger clade Spinicrus, and that would be an end to it. I could go ahead and use a genus-free taxonomy as has been done by some authors, but at the present time that would almost guarantee that no-one uses my nomenclature - not the result I'm going for. So I sit here, forced to mull over the pros and cons about how to solve a problem that, really, shouldn't even be a problem at all.


Taylor, C. K., & G. S. Hunt. 2009. New genus of Megalopsalidinae (Arachnida: Opiliones: Monoscutidae) from north-eastern Australia. Zootaxa 2130: 41-59.


  1. Why don't you implement option 4) with a twist:

    - Synonymise Neopantopsalis with Spinicrus, but keep Neopantopsalis as an informal species group.

    This will keep people off the temptation of creating a (paraphyletic) Spinicrus subgenus to hold the former species. Going the "subgenus" route just pushes the problem one rank down.

  2. The advantage of the subgenus approach is that is the most congruent one to the phylogenetic approach. That is, once the PhyloCode is implemented, it would be easier to convert the ranked names into clade names. It allows the most harmony between the codes, as I see it.

    As for a subgenus for the rest of them, is there a problem with having a paraphyletic subgenus, Spinicrus (Spinicrus)?

  3. This comment has been removed by the author.

  4. I've been following your blog for a long time, but never commented on it. Now, however, i feel I should comment that in my opinion paraphyletic taxa are definitely unaccetable under the phylogenetic systematics paradigm! Evolutionary relationships are more important than usefulness or diagnosabilty, whatever the case! So, personally I believe that keeping Spinicrus paraphyletic is not an option at all. I don't like subgenera either, so in your place I would go with the 3rd option, because it reflects evolutionary relationships and avoids using one more rank (subgenera).

  5. As nobody really uses subgenera it should not be problematic to use obscure characters in characterizing some of them.


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