Monday, May 23, 2016

More characters!!

So I've been keeping coding "new" morphological traits and including more taxa in the matrix. I stopped with the Chasmogenus species at sp. 9, so there are 12 Chasmogenus species included in the matrix so far. I've also included related genera, one species each: Agraphydrus, Globulosis, QuadriopsRadicidusTobochares and three undescribed genera, as well as one species of Cymbiodyta and one species of Sphaeridium, which as expected (for it being the only truly terrestrial included so far) is strikingly different.
As before, new characters and character states appeared, and some characters had to be split, so the matrix is now 230 characters and 28 taxa.
Here a small sample of variation on characters of the hind legs (and also an spoiler of my poster for the Evolution meeting 2016). You can see variation in the proportions, the size of the spines and area covered by hydrofuge pubescence. Images not at scale.


I also started my first full disarticulations to look at mouthparts, thorax (mesofurca, metafurca, tergum), wings, abdominal segments (tergites, laterosternites, terminal segments), male and female genitalia... thing is that the available specimens for that at this moment belong to the Hydrophilinae: Tropisternus, Berosus, Hydrophilus and Oocyclus. So far, having dedicated more time to careful fragmentation rather than to detailed observation (as I don't have a microscope yet), I have already seen interesting features that might be useful for phylogenetic purposes.
Here also just a sample (with not as pretty pictures, not at scale either) of the mandibles, showing very prominent differences, where the mandibles of Tropisternus are apparently the more common condition (at least for Hydrophilines); mandibles were illustrated by Hansen (1991, figs. 167-170), but it is astounding to see them in real life. It is the first time that I see brushes of setae on mandibles!!


This is only the tip of the iceberg, just a quick preview of many more structures to explore, to see, to compare, to code... this is still interesting!!


References
  • Hansen, M. (1991). The hydrophiloid beetles. Phylogeny, classification and a revision of the genera (Coleoptera: Hydrophilidae). Biologiske Skrifter, 40, 1–367.

No comments:

Post a Comment