I have now compiled the results of the survey I previously posted here on Anole Annals. I asked readers at what point on the image below would they stop counting scales if conducting toepad scale counts?
Fig 1. Lamellae numbered 1-51 on the 4th digit of an Anolis lizard hindfoot
As expected, there was a lot of disagreement! However despite some confusion, scale 32, roughly coinciding with the joining of the second to the third phalanx, was a clear favourite (Fig 2, below) (see Kevin De Quieroz’s comment here regarding some confusion with phalanx numbering).
Fig 2. AA readers choice of where one should stop counting during toepad scale counts.
However, I was most interested in the demography of the surveyors. I have met other graduate students confused about this topic, and relevant guidance material seems limited to anecdotes. Would we then expect there to be most confusion among contributors who have never published scale count data?
Fig 3. Survey data broken down into publication record: a) those that have never published scientific articles which include toepad scale counts (blue), b) those that have published a scientific article including toepad scale count data (red), and c) those which have published but were not responsible for conducting the scale counts (green).
The majority (60%) of votes from published researchers fell among scales 32-33, suggesting fairly high agreement on the general area. Only 40% of non-published voters selected these scales, with moderate confusion from scales 24-33 (although a peak at 32 did mirror those of published researchers). Too few votes from researchers that had published but not conducted scale counts themselves were collected to be interpretable.
This survey was not intended to standardize the position at which researchers should conduct toepad scale counts. The functional significance of toepads changes between species, and therefore that should be an important consideration in respect to the ecological/evolutionary question at hand. Those votes towards the higher end of the spectrum (scales 50-51, comprising a scale count of the entire digit) could be important data for species identification and morphological taxonomy. There could be an opportunity for a neat review/methods paper here, contact me if you are interested in more details!
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Thomas Sanger
Has anyone systematically examined how far down the toe the setae go? I can’t remember if this is explicitly commented on in any of the classic toe pad papers that use electron microscopy to examine their detailed microstructure. Regardless of what is convenient and replicable for macroscopic scale counts there may be an interesting question of scale identity here if not all of those scales have enlarged adhesive setae.
(p.s. if anyone wants to send me anole feet/toes, I have a desktop SEM in my current lab.)
Kevin de Queiroz
Unfortunately, this post perpetuates the confusion about the numbering of the phalanges. The toe illustrated is toe IV of the hindfoot, which has 5 phalanges. The first is within the claw, the second corresponds to the narrow part of the digit between the claw and the toepad, the third corresponds to the widest part of the pad, the fourth to the tapering part of the pad, and the fifth to the long narrow segment that connects to the metatarsal part of the foot. Thus, lamella 32 in the photo lies near the joint between the fourth and fifth phalanges, not the second and third.
James Stroud
Hey Kevin, thank you for clarifying this! Apologies for the initial mistake!