Morphology-based cladistics splinters the century-old dichotomy of the pied harvestmen (Arachnida: Gonyleptoidea: Cosmetidae)

Abstract

Abstract The cosmetids are conspicuous harvestmen, remarkably diverse in size, shape and colour. However, the effectiveness of all these morphological traits for diagnosing groups is scarcely explored in the literature. Since the early 20th century, the family Cosmetidae has been divided into two subfamilies, Cosmetinae and Discosomaticinae, and there has been no further effort to delimit additional or alternative subfamilial groups. In this analysis, we aim to test the issue of the basal dichotomy of Cosmetinae and Discosomaticinae. Thus, we propose a more comprehensive phylogenetic analysis using both parsimony and Bayesian approach, comprising 103 terminals of Cosmetidae, plus seven outgroup terminals scored for 130 morphological characters. Discosomaticinae is revisited and all its species were included in our matrix. To offer a real challenge to the monophyly of Discosomaticinae, members of 36 genera of Cosmetinae have also been scored. Our results support neither Cosmetinae nor Discosomaticinae sensu Pickard-Cambridge/Roewer as monophyletic groups. We found that Cosmetidae may be organized into a few major clades, which are here diagnosed. Accordingly, taxonomic changes in the arrangement of the family are introduced: description of one new tribe, five new subfamilies and revalidation of a sixth, description of three new genera, and proposition of synonymies, transfers and revalidations at generic level.