In 2006, the collaboration of 19 leading authorities led to a new estimate of amphibian phyologeny. It was published in The Bulletin of the American Museum of Natural History(Volume 297, Issue 1, March, 2006). The title of the publication is The Amphibian Tree of Life. In this section of the website, I planned to place scanning electron microscope images of APs from a fairly wide variety of anurans (frogs, toads and their allies). They were part of a large study I carried out, beginning in the mid-1970s, to provide inferences about AP evolution. The species were selected strategically on the basis of the generally accepted estimates of phylogeny at that time. They were published largely in a journal (Scanning Electron Microscopy) that is not widely available, so I thought it appropriate to place representative examples here.

In the process of doing so, I learned of the 2006 work (through Wikipedia), and, on studying the new tree of life realized that there were new tales to tell about the evolution of the anuran amphibian papilla. The new estimate of phylogeny is based not only on morphological characters, but also on analyses of mitochondrial and nuclear DNA. The base of the new tree, representing the anura with the most ancient pedigrees, is similar to that of the old estimates of phylogeny, and is reasonably well covered by my original selection of species. For the most ancient branch, the Leiopelmatidae, I have APs from two of the four living species, including both genera (Ascaphus and Leiopelma). For the next branch, the Xenoanura, I have APs from four species (two genera) from the Pipidae, one of two families in the branch. For the third branch, the Costata, I have APs for two species from one family (Bombinatoridae) and APs for one species from the other family (Alytidae). For the fourth branch, Anomocoela, I have APs for species from two of the four families (from Pelobatidae and Scaphiopodidae).

At this point the new tree proceeds into the neobatrachia, the anurans of more modern origins. I have no APs from species in the first neobatrachian branch, the Heleophrynidae- - the ghost frogs of Southern Africa. If I were continuing the study today, that would be the first group of frogs I would go for. The remaining neobatrachians have been grouped as the Phthanobatrachia, comprising two major limbs-- each of which needs to be climbed separately in our comparative morphology. For each limb, the Hyloides and the Ranoides, I have APs from species at the first branch (Sooglossidae for Hyloides, Allodapanura for Ranoides). For the Hyloides, I also have representative APs from an early middle branch, Brachycephalidae, a later middle branch, Hylidae, and terminal, or near terminal branches, Dendrobatidae and Bufonidae. For the Ranoides, I have no representatives from the middle branches, but I do have APs for species from terminal or near-terminal branches, Rhacophoridae and Ranidae. If I were continuing the study today, I would go for species in the mid-branches of the Ranoides limb (Ptychadenidae, Ceratobatrachidae, Micrixalidae, Phrynobatrachia); but most excitedly, I would go for frogs in the Terrarana of Hedges et al., see APs on an Eleutherodactylus Tree

 

Ascaphus truei Tailed frog Leiopelmatidae

Xenopus tropicalis an African-clawed-frog species Pipidae

Alytes obstetricans Common midwife toad Alytidae

Pelobates fuscus Common spadefoot Pelobatidae