A cladistic reconstruction of the ancestral mite harvestman (Arachnida, Opiliones, Cyphophthalmi): portrait of a Paleozoic detritivore.

Two character sets composed of continuous measurements and shape descriptors for mite harvestmen (Arachnida, Opiliones, Cyphophthalmi) were used to reconstruct the morphology of the cyphophthalmid ancestor and explore different methods for ancestral reconstruction as well as the influence of terminal sets and phylogenetic topologies. Characters common to both data sets were used to evaluate linear parsimony, averaging, maximum likelihood and Bayesian methods on seven different phylogenies found in earlier studies. Two methods-linear parsimony implemented in TNT and nested averaging-generated reconstructions that were (i) not predisposed to comprising simple averages of characters and (ii) in broad agreement with alternative methods commonly used. Of these two methods, linear parsimony yielded significantly similar reconstructions from two independent Cyphophthalmi data sets, and exhibited comparatively low ambiguity in the values of ancestral characters. Therefore complete sets of continuous characters were optimized using linear parsimony on trees found from "total evidence" data sets. The resulting images of the ancestral Cyphophthalmi suggest it was a small animal with robust appendages and a lens-less eye, much like many of today's species, but not what might be expected from hypothetical reconstructions of Paleozoic vegetation debris, where Cyphophthalmi likely originated. © The Willi Hennig Society 2012.