Phylogeny of pholcid spiders

Pholcids are among the most diverse and widely distributed spiders. They have been used extensively as model organisms for single-species studies, and stand out among spiders in that a large comparative data set on the functional morphology of their complex genitalia exists. Such comparative data are still rare in high rank arthropod taxa, yet are fundamental prerequisites for our understanding of basic evolutionary phenomena, such as rapid evolution of genitalia, or coevolution of male and female copulatory structures. However, the results of many of these studies are difficult to interpret evolutionarily without a sound phylogenetic framework. In pholcids, a preliminary phylogeny has been provided recently, but this cladogram rests on morphological characters only and is biased toward New World taxa. Therefore, we aim at producing a stable phylogenetic hypothesis by (a) adding relevant taxa and potentially informative characters to the morphological data set, (b) building up a largely independent, molecular (DNA sequences) data set, and (c) analyzing these data by a variety of tree constructing algorithms.

Pholcid spiders are among the most diverse and dominant tropical web-weaving spiders. During the last decade they have become prominent objects in single-species studies as well as in comparative studies investigating the evolution of copulatory organs. The main goal of our interest in the spider family Pholcidae is a complete systematic revision and the analysis of the intra- and suprafamiliar phylogeny following a combined approach using both morphological and molecular data. In the course of this project we generated the first molecular data for phylogenetic analysis of the Pholcidae and provided an extensive morphological revision of some poorly known African and Asian taxa resulting in the description of a number of new species. In the molecular approach four different gene regions were sequenced (12S rRNA and 16S rRNA, Cytochrome c oxidase subunit I, 28S rRNA), resulting in a total of about 2500 bases for 36 taxa. The data were analysed using a variety of tree constructing algorithms, both for individual genes, combined molecular data, and molecular plus morphological data. Some phylogenetic hypotheses obtained previously using morphology alone could be supported, some were discarded with some confidence, others need further investigation. The data obtained provide an excellent basis both for future investigations of phylogenetic patterns within the family and among spider families. The morphological revisions and cladistic analyses focused on African taxa previously assigned to the waste-basket genus Spermophora. Malagasy taxa turned out to represent two widely separate endemic genera; high levels of endemism and species richness were also found in Eastern and Southern Africa. A total of about 70 new species were described, and redescriptions were prepared for several previously poorly known species. During the course of the project, one paper was published on the functional morphology of copulatory organs in Spermophora senoculata, using freeze-fixation and histological serial sections. Another paper concerns the constraints in taxonomic work that might bias our basal understanding of the evolution of animal copulatory organs and which is therefore of general interest for taxonomists working on other animal taxa.