The biogeography and age of salticid spider radiations (Araneae: Salticidae)

Abstract

Globally distributed, jumping spiders (Salticidae) are species-rich and morphologically diverse. Recent molecular phylogenetic work has revealed that major clades are largely isolated to particular continental regions, suggesting their radiations postdated Mesozoic continental break up, but corroboration from a multi-gene time-calibrated phylogeny has been lacking, and an important tropical forest region, Central and West Africa, has been largely unsampled. Newly sampled species, many from Gabon, were included among taxa sequenced for the genes 28s, Actin 5C, 16sND1, and CO1. Likelihood and Bayesian analyses show that most of the Gabonese species from forest habitats fall into a single large clade, which we name the Thiratoscirtinae (new subfamily), within the broader Aelurilloida. The aelurilloids, together with the plexippoids, euophryines, heliophanines and smaller groups (e.g. Leptorchestae, Hasarieae, Philaeus group, Salticus), form a large clade that we name the Saltafresia. Most saltafresian diversification appears to have occured in Afro-Eurasia, with the exception of the euophryines (largely Neotropical, Australasian and Southeast Asian) and two radiations in the New World (Habronattus, freyines). Using Bayesian relaxed molecular-clock methods, calibrated by amber fossil data and a geological constraint, we estimate that most recent common ancestor of the family occurred 47–57 million years ago, when the continents would have already separated substantially. The Salticoida is dated to 41–50 million years, and its four major subclades Amycoida, Astioida, Marpissoida, and Saltafresia are each dated to 29–44 million years. By these inferred dates, salticids were radiating while the earth was warmer than today, with expanded megathermal forests and, most likely, diverse insect herbivores. Our phylogeny indicates mixing of radiating faunas from isolated regions has been limited, yet some long-range dispersal events, such as the arrival of the genus Habronattus to the New World, have occurred. Four African species formerly in Viciria are moved to Telamonia, establishing the new combinations Telamonia besanconi (Berland and Millot), Telamonia fuscimana (Simon), Telamonia longiuscula (Thorell), Telamonia thoracica (Thorell). The Marpissoida is expanded to include the Ballinae.