New World Tarantulas

Chapter 1. An introduction to Theraphosid taxonomy: affinities and New World GroupsFernando 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 TheraphosidaeCarlos 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 approachStuart Longhorn, Oxford University Museum of Natural History, Parks Road, Oxford, UKChris 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 discuss how next generation methods can rapidly expand the scope of molecular datasets when combined with methods like Indexed Amplification for sequencing of multiple taxa and fragments simultaneously. We also discuss the relative utility of transcriptome sequencing, targeted-sequencing approaches (e.g., Anchored Hybrid Enrichment), or reduced representation library sequencing (e.g., RAD-tag) to investigate evolutionary questions. Finally we consider what may be gained in future from evaluating larger blocks of genomic data together, such intron position surveys or gene arrangements, as rare-events that may be vital to resolve intractable evolutionary questions.
Chapter 4. The Ischnocolinae and SchismatothelinaeJosé Paulo Guadanucci, Departamento de Zoología, Instituto de Biociencias, Universidad Estadual Paulista, Rio Claro, Sao Paulo, Brazil.Theraphosidae systematics has undergone some changes in the last 20 years, with many phylogenetic hypothesis supporting unforeseen relationships and several new genera described. Amongst all 11 subfamilies currently included in Theraphosidae, Ischnocolinae is the most problematic, as it was originally established based on a plesiomorphic feature, the divided tarsal scopula. A recent phylogenetic hypothesis based only on morphology showed that most of Ischnocolinae representatives do not form monophiletic units, and instead, are scattered across the family tree, except for those comprising Schismatothelinae: Sickius, Neoholothele, Guyruita, Euthycaelus and Schismatothele. Schismatothelinae is endemic to the Neotropics and its diversity is still underestimated, as many new species are described every year. Although well sampled in phylogeny mentioned above, the status of the remaining Neotropical Ischnocolinae genera (Catumiri, Dolichothele, Acanthopelma, Holothele) are far from being resolved, as morphological characters show high degrees of homoplasy. Not until a comprehensive sampling of Ischnocolinae is achieved with molecular data, no nomenclatural acts should be further proposed. The Neotropical spiders included in Ischnocolinae and Schismatothelinae occur on all different environments across Central and South America. The full diversity of Neotropical Ischnocolinae and Schismatothelinae will be considered in this chapter, with diagnoses for genera, identification keys and pictures.
Chapter 5. The AviculariinaeYeimy Cifuentes, Instituto Butantan, Laboratório Especial de Ecologia e Evolução, Av. Vital Brazil, 1500, CEP 05503-900, São Paulo, SP, BrazilCarlos Perafán, Entomología, Facultad de Ciencias, UDELAR, Montevideo, Uruguay.The aviculariines are mostly American arboreal tarantulas, although some species inhabit in the ground. They are characterized mainly by having legs or with no or few spines, scopulae in tarsus and metatarsus laterally extended giving a spatulate appearance to the appendices and absence of spiniform setae on prolateral maxillae. Together with Theraphosinae, they are the only tarantulas that show urticating setae as a defense mechanism; however, its main release mechanism is by direct contact, and setae are not expulsed to the air as happens in theraphosines. Aviculariinae has had considerable taxonomic and biological attention recently and its validity as a monophyletic group has been much discussed. Aviculariinae sensu lato has a distribution exclusively tropical and is composed by two occidental African genera and ten New World genera. In order to offer a broad overview of the group, we will provide taxonomic and morphological information of all valid Neotropical taxa and discuss the relationships within the group and the most recent cladistic reviews. Also, we will include the diagnosis of each genus, a taxonomic key and distribution maps.
Chapter 6. The TheraphosinaeFernando Pérez-Miles, Entomología, Facultad de Ciencias, UDELAR, Montevideo, Uruguay.Carlos Perafán, Entomología, Facultad de Ciencias, UDELAR, Montevideo, Uruguay.The Theraphosinae constitute the richest subfamily of tarantulas in the world, with about 500 known species. The group is endemic of the New World and its geographic distribution includes from Southern North America to Southern South America. The largest and most long-lived spiders of the world belong to this subfamily that inhabits almost all terrestrial environments up to 3000 m. Despite several morphological diagnostic characters, this group has a singular mechanism of defense implying abdominal urticating setae that they can release to the air when they are disturbed. During more than a century this subfamily remained poorly known from both biological and taxonomical aspects. In fact, most genera were established during the last decades as well as the production of several papers on behavior, ecology and reproduction. Due to their size, longevity, sex dimorphism, relative easy conditions for raising, and other biological characteristics, this group constitutes an interesting model for studies of metabolism, thermoregulation, biomechanics, communication, reproduction and development. The chapter will present an updated overview of the taxonomy and phylogeny of the group as well as a revision of recent scientific contributions in different aspects of general biology.
Chapter 7. Morphology of Theraphosidae: cuticular featuresJosé Paulo Guadanucci, Departamento de Zoología, Instituto de Biociencias, Universidad Estadual Paulista, Rio Claro, Sao Paulo, Brazil.Studying morphology of Theraphosidae spiders can be very challenging, especially if the main objective is assembling characters for systematics. Such spiders present a homogeneous morphology, which according to some specialists has driven the attention of systematics to other groups of Araneae. Nevertheless, a great diversity of cuticular structures has been overlooked until the widespread use of scanning electron microscopy (SEM) in the last years. Data regarding cuticular features are still incipient, but we have gathered SEM images of all parts of the spider body, revealing interesting structures to be used in systematics and investigated for functional morphology. In addition to the well-known tarsal adhesive setae of theraphosids and the urticating setae of Theraphosinae, we found putative chemosensitive setae, a great variety of stridulating setae, distinct morphologies of legs and palpal structures, including cuticular projections, labial and maxillary cuspules, trichobothria, as well as other enigmatic features. Among all mygalomorphs, Theraphosidae spiders possess the greatest variety of cuticular features. In this chapter, we aim to present a comprehensive revision of cuticular features of Theraphosidae spiders, with descriptions and micrographies.
Chapter 8. Physiological Ecology of tarantulas - Thermoregulation & Metabolism.Cara Shillington, Biology Department, Eastern Michigan University, USA.Tarantulas represent interesting models for examining metabolism and performance traits (e.g., sprintspeed) because of their large size and sex dimorphism at maturity that leads to different selectivepressures. As ectotherms, these traits are also dependent on body temperature and can have significantimpact on growth, survival and reproduction. After reaching sexual maturity, most males change theirhabits and leave their retreats or webs to search actively for females. Males are relatively short-livedand costs of locomotion may be high. Exposure to large fluctuations in environmental conditions makemales more vulnerable to heat stress, desiccation and predation. In comparison, females tend to remain in close proximity to their burrows and maintain a larger body size over a longer life span. Because of their sit-and-wait predatory strategy, they may undergo long periods with limited food availability and tend to have very low resting metabolic rates, which enables survival with low and unpredictable food resources. This chapter will review various aspects of thermoregulation, metabolism and performance in tarantulas with particular emphasis on differences between males and females, and will discuss these traits in the context of selection pressures due to the animal's natural history and life history strategies.
Chapter 9. Biomechanics of locomotion in tarantulasValentina Silva-Pereyra, Departamento de Biofísica, Facultad de Medicina, UDELAR, Montevideo, Uruguay.Carlo M. Biancardi, Laboratorio de Investigación en Biomecánica y Análisis del Movimiento, CENUR, UDELAR, Paysandu, Uruguay.Terrestrial multi-legged locomotion is an energy demanding activity. The limbs need to exert forces on the ground, support and move the body weight and negotiate uneven surfaces. In Theraphosidae the locomotor performances are limited by their poor aerobic capacities. Smaller body size and longer legs of the more active gender is considered an optimization to reduce the high metabolic cost of locomotion. Most mechanical work is performed against gravity, to raise the centre of mass step by step. Both the horizontal work (to push forward the centre of mass), and the internal work (done to move the limbs with respect to the centre of mass) represent a small part of the total work.Differently from other spiders, Theraphosidae employ all their limbs for locomotion. The first stepping pattern that had been described was an alternating tetrapod gait, in which the odds limbs on one side move together with the pair limbs of the other side. Nevertheless, we were able to discriminate different quadruped-similar gait patterns, such as lateral and diagonal walking and trot. Differently from quadrupedal vertebrates, highest speeds are reached mainly increasing the stride frequency, while stride length remains roughly constant.
Chapter 10. Adhesive features of the tarantulasFernando Pérez-Miles, Entomología, Facultad de Ciencias, UDELAR, Montevideo, Uruguay.Carlos Perafán, Entomología, Facultad de Ciencias, UDELAR, Montevideo, Uruguay.Tarantulas are large spiders with adhesive setae on their legs, which enable them to climb on smooth vertical surfaces. The mechanism proposed to explain adhesion in tarantulas is anisotropic friction, where friction is higher when the leg pushes compared to when it pulls. We studied static friction of live theraphosid spiders on different surfaces and at different inclines. We compared burrowing with arboreal species to test the hypothesis of higher friction in arboreal tarantulas. We found a complementary participation of claw tufts and scopula of anterior and posterior legs when the tarantula climbs. We studied also the morphology of scopula, and claw tufts setae and compared with similar structures in other families. Adhesive setae, as well as some other setae types found on ventral tarsi are described and characterized. The adhesive face of setae varied in the orientation in different parts of the tarsi, and this variation is more conspicuous in the spiders that have only claw tufts or scopula. The mechanics of climbing in association with the biological characteristics of the species are analyzed. We found an association of adhesive scopulae and claw tufts with burrowing/ cursorial mygalomorphs as Theraphosidae, as was suggested for free-hunter spiders. The morphology, functions and evolution of scopula and claw tufts are discussed.
Chapter 11. Predation and other interactionsYann Hénaut, El Colegio de la Frontera Sur, Chetumal, Quintanta Roo, Mexico.Theraphosids interact with numerous other species from invertebrates to humans. They prey on a large range of taxa including mammals, birds, reptiles and even fish; nevertheless, they eat mostly insects but also spiders and worms. They are even able to predate on toxic poison dart frogs. Practically blind, they detect prey by vibrations and may also use odors. Their predatory activity may affect the distribution of other predatory species such as other spiders or scorpions. Furthermore, predation may include cannibalism between females. Despite a variety of anti-predatory strategies as for example, burrows, or special coloration, theraphosids are preyed upon by vertebrates as coatis but also by invertebrates including giant earthworms and other spiders. Parasitoid hawk wasps hunt tarantulas and flies also parasitize them. Tarantulas may be found in commensalistic associations with toads or with bromeliads. In their natural range, they also interact with humans; native people from different regions of America used them for food or in their traditional medicine. The diversity of these interactions and adaptations may be considered, for this useful family of spiders, as the result of a long evolutionary history.
Chapter 12. Communication, Sex and Reproductive biology of tarantulasNelson Ferretti, Laboratorio de Zoología de Invertebrados II, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina.Theraphosidae spiders are commonly known as tarantulas, comprising the largest spiders. It is the most diverse family among the Mygalomorphae and the subfamily Theraphosinae is the richest one and endemic to the Neotropics. However, the knowledge on some aspects of their reproductive biology is still unknown. Usually, the sexual behavior of tarantulas has been considered as relatively simple, that is, males just walk searching for females and when they randomly find one, the mating should occur. This point of view is changing as the number of studies has grown during the last 20 years, suggesting that the sexual behavior of Theraphosidae is far away from simple. Such complexity may be represented by specific courtship behavior of males and the active role of females leading to an intricate intersexual communication before mating, by the copulatory courtship performed by males, and also by some complex patterns of palpal insertions. In this way, this chapter will describe the ways of communication of tarantulas during the sexual encounters. The patterns of courtship and mating of representatives of most subfamilies will be described based on a bibliographic review. Finally, general strategies of reproductive biology, such as phenology, mating system and progeny of tarantulas will be discussed.
Chapter 13. Defenses: the urticating setae of tarantulasRadan Kaderka, Tyrsovo námestí 1732, Roztoky u Prahy, Czech Republic.Urticating setae are modified setae located at abdomen or pedipalps, which represent an effective defensive mechanism against vertebrate and invertebrate predators and are also useful as morphological characteristics facilitating the systematics of the New World theraphosid spiders. To date, seven types of urticating setae, which differ in location, shape, size and orientation of barbs along the shaft and length/width ratio have been distinguished. The typology of urticating setae was revised, and types I, III and IV were re-described. The urticating setae in spiders with type I setae, which were originally among type III or were considered setae of intermediate morphology between types I and III, are newly considered to be ontogenetic derivatives of type I and are described as subtypes. Four systems of urticating seta ontogeny within Theraphosinae were recognized; two of them were described in detail. The hypothesis of urticating seta evolution is proposed based on published molecular analyses which gave the evidence that theraphosids with abdominal urticating setae of type I (Theraphosinae, part) and type II (Aviculariinae) evolved independently and represent two non-sister but monophyletic groups.
Chapter 14.- Status and conservation of tarantulas in the AmericasJorge Mendoza, Departamento de Zoología, Universidad Nacional Autónoma de México, Coyoacán, Distrito Federal, Mexico.Tarantulas are the world's largest spiders and they are more abundant in the Americas than in any other place. They are primarily found in tropical, semi-tropical and arid regions over the continent, some of them even have adapted to anthropogenic habitats. As other spiders, tarantulas play many important roles in ecosystems as predators and sources of food for other creatures. Despite this, it is somewhat singular that, although tarantulas are an integral part of biodiversity whose conservation is justified, they are not easily contemplated within this. It is evident that regardless the scientific and technical arguments for their protection, the cultural weight awash with prejudice and undervaluation can ruin the best reasons. Because of this, the sustainable use and management of tarantulas native to the Americas depends on the knowledge of its main threats, its relevance to the environment and creation of public policies that involve society for management, protection and conservation actions.
Chapter 15. Tarantulas in captivity: raising and breedingLaura Montes de Oca, Laboratorio de Etología, Ecología y Evolución. Instituto de Investigaciones Biológicas Clemente Estable. Av. Italia 3318. CP 11600. Montevideo, Uruguay.Jorge Mendoza, Departamento de Zoología, Universidad Nacional Autónoma de México, Coyoacán, Distrito Federal, Mexico.Tarantulas are animals that you can love or be scared. They are in the midst of a duality between people, with those who are fascinated by them, and those who fear them because of ignorance or aversion towards what they consider dangerous based on their appearance. Despite its reputation, many people study and maintain these spiders. The interest in keeping and propagating tarantulas has increased worldwide in recent decades. The aim of this chapter is to show the basic and ethical considerations about keeping these spiders in captivity (whether for research or as enthusiast), as well as being aware of the origin and conservation status of the most common commercial species. As more was learned about tarantula biology, there was a greater interest in how to breed them in captivity. However, few studies have addressed the reproductive biology of tarantulas. Despite this, enthusiasts propagate many species successfully and the conditions for their reproduction are empirically known. We approach this chapter by dividing it into four sections: (1) life history; (2) keeping and breeding in captivity, common diseases; (3) popular pets and husbandry; (4) traffic, endangered species and responsible breeding facilities.
Chapter 16. Tarantulas, Gods and MenAndrew Smith, 89 Ermine Road, London SE13 7JJ, England.Tarantula spiders have repelled much of humankind since the beginning of recorded time. But not all. For a minority the spider is fascinating. This chapter is all about such individuals. Firstly from the Curiosity Cabinets of Europe's trading elite - later in the spirit rooms of the new grandiose cathedrals of science that had sprung up in the cities of both the Old World and the New World. By 1900 no museum collection could be called complete - without a tarantula spider on display. From the earliest Neolithic image of a spider daubed on an Egyptian rock face, amongst sacred symbols that no longer have meaning - to the iconic image of a copper plate engraving of a Bird Eating Spider, by the seventeenth century naturalist and artist Madam Maria Sibylla Merian - this chapter traces the history of natural history. From the Victorian scientists of the heyday of European research, to the exciting DNA studies being undertaken today by a new generation of arachnologists - the heart of all that research remains one of the most awe inspiring animals to ever walk the face of this planet - The Tarantula Spider.