New World Tarantulas: Taxonomy, Biogeography and Evolutionary Biology of Theraphosidae

Chapter 1. An introduction to Theraphosid taxonomy: affinities and New World Groups Fernando Pérez-Miles, Entomología, Facultad de Ciencias, UDELAR, Montevideo, Uruguay. The mygalomorph spiders of the family Theraphosidae, commonly named as tarantulas, are one of the most famous and diverse groups of arachnids, which include the largest spider species in the world. Theraphosidae contains almost 1000 species from all continents, except Antarctica and includes burrowing, terrestrial and arboreal taxa with diverse ecological adaptations and natural histories. Since the description of the family in 1869 their systematics was largely based on the study of morphological characters, and many authors agreed in the chaotic situation of their taxonomy. First phylogenetic studies were also based on morphological characters and molecular studies only started in the XXI century. Most authors recognize 11 subfamilies in the world; four of them occur in the New World. The most diverse subfamily, Theraphosinae includes about a half of the known species of tarantulas. In this chapter we introduce the phylogenetic position of the group within the Araneae, the general characteristics of the tarantulas including taxonomical, evolutionary and biological aspects of the group. We analyze Theraphosidae diagnostic characters and the affinities with other families and discuss the intrafamilial relationships and subfamilial characteristics focusing in New World groups.
Chapter 2. Biogeography of New World Theraphosidae Carlos Perafán, Entomología, Facultad de Ciencias, UDELAR, Montevideo, Uruguay. Nelson Ferretti, Laboratorio de Zoología de Invertebrados II, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina. Biogeography is the discipline responsible for explaining the biological diversity from the study of its distribution patterns and the reconstruction of its history in space and time. Theraphosidae spiders have sedentary habits and show limited dispersal abilities, basically restricted to terrestrial locomotion, so that represents a highly informative group in biogeographical studies. This chapter will delve into the current patterns of distribution of New World Theraphosidae spiders and explore the historical causes that led to this distribution. The current distributions of the superior taxonomic groups will be described, detailing the Southern, Northern and altitudinal limits of their distribution. Some of their adaptations to the environment where they live will be discussed. Likewise, we will explain the distribution of the family according to the historical factors of the Earth. For this, we will carry out an exhaustive bibliographic review, highlighting mainly the most recent results, and we will present some unpublished results. Discussions will be accompanied by original maps, tables and graphs.
Chapter 3. Evolution and phylogeny of Theraphosidae: a molecular approach Stuart Longhorn, Oxford University Museum of Natural History, Parks Road, Oxford, UK Chris Hamilton, Department of Biological Sciences and Auburn University Museum of Natural History, Auburn University, Auburn, USA. Molecular data are increasingly informing our knowledge of tarantulas, particularly their evolutionary relationships. New molecular insights are helping to re-define taxon groupings at many levels; from clarifying species limits and matching genders, to elucidating the boundaries of genera, and beyond. Here, we review the insights from genetic data currently used in molecular projects on tarantulas, and discuss the range of fragments already generated from targeted amplifications. We also re-evaluate the core processes and pressures that can affect their molecular evolution, and discuss how those might confound molecular phylogenetic reconstruction unless recognized. Yet importantly, the recently completely genome for the first tarantula now gives a solid baseline for future molecular projects. We d