Dazzling, diverse Dictynidae: A molecular phylogeny of a Tailor's drawer spider family

The family Dictynidae is a spider family composed mostly of small, brown spiders that are distributed worldwide. Dictynidae has been labeled a “tailor’s drawer” family because it contains taxonomically unorganized and often evolutionarily distant species. With adaptations that allow dictynids to thrive in habitats ranging from the frozen Arctic to Death Valley, one of the hottest places on Earth, and from hypersaline alkali sinks to freshwater ecosystems, there is remarkable diversity found in the family. However without the context of a phylogeny, we cannot begin to study the extreme adaptations found in this group. Furthermore, previous molecular studies using target-gene molecular data recovered several genera that are currently classified as dictynids outside of the dictynid clade, and the clade generally had low branch support values for internal relationships. Other hypotheses of dictynid relationships have relied solely on morphological data and utilized synapomorphies that are often variable within a genus or even in a single species. The genera comprising the family, and the relationships among those genera, have never been rigorously tested using modern phylogenetic methods or genomic-scale data. Using exemplar dictynid species from most currently recognized dictynid genera, and UCEs recovered in silico from low coverage whole-genome sequencing, we have resolved the phylogenetic placement and relationships of genera within the family Dictynidae. This study begins to remedy the dearth of systematic knowledge about this incredibly diverse spider group and fills knowledge gaps in the tree of life for little brown spiders.