Chapter 9. Amphibians of the Neotropical Realm
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0 CHAPTER 9. AMPHIBIANS OF THE NEOTROPICAL REALM Cochranella vozmedianoi (Data Deficient) is Federico Bolanos, Fernando Castro, Claudia Cortez, Ignacio De la Riva, Taran a poorly known species endemic to Cerro El Grant, Blair Hedges, Ronald Heyer, Roberto Ibaiiez, Enrique La Marca, Esteban Humo, in the Peninsula de Paria, in northern Lavilla, Debora Leite Silvano, Stefan Loiters, Gabriela Parra Olea, Steffen Venezuela. It is a glass frog from the Family Reichle, Robert Reynolds, Lily Rodriguez, Georgina Santos Barrera, Norman Centrolenidae that inhabits tropical humid Scott, Carmen Ubeda, Alberto Veloso, Mark Wilkinson, and Bruce Young forests, along streams. It lays its eggs on the upper side of leaves overhanging streams. The larvae fall into the stream below after hatch- THE GEOGRAPHIC AND HUMAN CONTEXT ing. © Juan Manuel Guayasamin The Neotropical Realm includes all of mainland South America, much of Mesoamerica (except parts of northern Mexico), all of the Caribbean islands, and extreme southern Texas and Florida in the United States. South America has a long history of geographic isolation that began when this continent separated from other Southern Hemisphere land masses 40-30 Ma. The Andes, one of the largest mountain ranges on earth and reaching 6,962m at Acongagua in Argentina, began to uplift 80-65Ma as South America drifted west from Africa. The other prominent mountainous areas on the continent are the Tepuis of the Guianan Shield, and the highlands of south- eastern Brazil. The complex patterns of wet and dry habitats on the continent are the result of an array of factors, including the climatic effects of cold ocean currents interacting with these mountain ranges, orographic barriers to winds carrying humidity within the continent, and the constant shifting of the intertropical convergence zone, among others. Figure 1. Summary of Red List categories for The geological history of Mesoamerica is very complex and still not completely under- amphibians in the Neotropical Realm. stood. The land north of the Isthmus of Tehuantepec in southern Mexico is historically part ANURA Plectrohyla hazelae of the North American continent, with the highest point at Pico de Orizaba at 5,610m asl. Bufonidae Plectrohyla siopela The land south of the Isthmus to the southern Nicaragua lowlands is a mosaic of plates that Andinophryne colomai Plectrohyla thorectes Red List Category dumber of species have rearranged themselves and alternately been submerged and exposed by the sea several Atelopus arthuri Scinax heyeri • Extinct (EX] 7 times during the last 65 million years. The region encompassed by Panama, Costa Rica, and Atelopus balios Leptodactylidae Extinct in the Wild (EW| 0 southern Nicaragua formed over the last three to ten million years through a combination of Atelopus carbonerensis Craugastor anciano • Ctitically Endangeted (CFi) 358 volcanic activity and uplift. The result is a jumble of mountain ranges interrupted by valleys Atelopus chiriquiensis Craugastor andi • Endangeted (EN) 456 and lowlands, with the highest point being Volcan Tajumulco at 4,220m asl in Guatemala. Atelopus chrysocorallus Craugastor angelicus Vulnerable (VU| 324 The closing of these different blocks of land in present-day Nicaragua during the Pliocene Atelopus coynei Craugastor coffeus Near Threatened (NT) 140 (5.3 -1.8 Ma) has had a marked impact on the distribution of amphibians today. Atelopus famelicus Craugastor cruzi • Least Concern (EC) 956 The geological history of the Caribbean also remains under intense study, but most Atelopus guanujo Craugastor escoces Data Deficient (DD) 675 geologists now agree that the Greater Antilles (Cuba, Jamaica, Hispaniola, and Puerto Rico) Atelopus halihelos Craugastor fecundus Total Number ol Species 2,916 are geological cousins of the plates that make up northern Central America. Some 100 Ma, Atelopus lozanoi Craugastor fleischmanni these islands were lined up more or less between North and South America in approximately Atelopus lynchi Craugastor guerreroensis the location of present day Central America. Over the last 70 million years, these islands Atelopus mindoensis Craugastor merendonensis have drifted east to their current positions. The trailing edge of this parade of islands has Atelopus muisca Craugastor omoaensis fused to North America and now makes up northern Central America. Some of the Greater Atelopus nanay Craugastor polymniae Antilles may have had temporary land connections with North and/or South America as Atelopus oxyrhynchus Craugastor saltuarius 0 they drifted eastward. The Lesser Antilles formed in a completely different manner. As the Atelopus pachydermus Craugastor stadelmani # Caribbean Plate carrying the Greater Antilles moved eastward, the America Plate subducted Atelopus peruensis Craugastor trachydermus beneath it, creating an island arc known today as the Lesser Antilles. Atelopus pinangoi Crossodactylus trachystomus The region is enormously varied ecologically. Eguatorial South America is dominated by the Atelopus planispina Cryptobatrachus nicefori lowland rainforest of the Amazon Basin. South of this the habitats become progressively drier Atelopus sorianol Cycloramphus ohausi and less suitable for amphibians, with the exception of the now extensively cleared Atlantic Atelopus senex Eleutherodactylus bernali Forest of southern and eastern Brazil, eastern Paraguay, and north-eastern Argentina, and the Atelopus sernai Eleutherodactylus emleni temperate forests of Chile. There are important wetland areas in the Llanos of Venezuela and Bufo fastidlosus Eleutherodactylus eneidae Colombia, and the Pantanal of Brazil, Paraguay and Bolivia. The topographically varied Andean Bufo fluviatlcus Eleutherodactylus glandullferoides region includes all varieties of habitats,from some of the wettest lowland rainforest in the Pacific Bufo holdridgei Eleutherodactylus jasperi 2 lowlands of Colombia to the Atacama Desert in northern Chile (the driest place on earth), and Melanophryniscus macrogranulosus Eleutherodactylus karlschmidti from cold temperate habitats in the extreme south of the continent to high mountain paramos in Bhamphophryne rostrata Eleutherodactylus olanchano the tropics. In Mesoamerica there is a very complex patchwork of natural habitats, with humid Centrolenidae Eleutherodactylus orcutti mountain slopes rising above both dry (generally on the Pacific side) and wet (Caribbean side) Centrolene ballux Eleutherodactylus schmidti lowland habitats. The Caribbean islands are also a complex mosaic of habitats, with low-lying Centrolene heloderma Eleutherodactylus semipalmatus islands tending to be semi-arid, and wetter environments occurring where trade winds encounter Hyalinobatrachium crybetes Eleutherodactylus zongoensis the higher Caribbean mountains giving rise to a variety of moist tropical forest types. Dendrobatidae Gastrotheca lauzuricae On average, the Neotropics have a relatively low human population density (approxi- Aromobates nocturnes Holoaden bradei mately 27 people per square kilometre in 2005), only 22% of which lives in rural areas, and Colostethus dunni Odontophrynus moratoi a population growth rate (1.4% per annum) that is decreasing. However, some Caribbean Colostethus edwardsi Paratelmatobius lutzii islands are among the most densely populated places on Earth. Historically, South America Colostethus jacobuspetersi Paratelmatobius mantiqueira has been subject to relatively low levels of anthropogenic disturbance, but human impact Colostethus ruizi Phrynopus spectabilis has been higher in northern Mesoamerica and on the Caribbean islands. The low impact Colostethus vertebralis Telmatobius cirrhacelis in much of the region is related to low human population densities. The gross income per Dendrobates abditus Telmatobius niger capita was around US$3,500 in the region in 2004. However, 33% of the region's Gross Mannophryne neblina Telmatobius vellardi Domestic Product is concentrated in Mexico and a further 30% in Brazil, where the human Hylidae Ranidae impacts on natural ecosystems and biodiversity have been much more severe. Economic Aplastodiscus flumlneus Rana omiltemana growth rates in the region have been modest (2.7% in 2003). Bromeliobyla dendroscarta Rana pueblae The human impact on ecosystems is very variable through the region. Natural habitats Bokermannobyla clareslgnata Rana tiaioci'' have been particularly severely damaged on many of the Caribbean islands (and especially Bokermannobyla izecksohni Rhinodermatidae in Haiti), and in the northern part of Mesoamerica (from central Mexico, south to Guatemala, Charadrahyla altipotens Rhinoderma rufum Honduras and El Salvador). There has also been extensive habitat loss through much of the Cbaradrahyla trux Andes, and especially in the Atlantic Forests and Cerrado of central, southern and eastern Ecnomiohyla echinata CAUDATA Brazil, and in the native southern temperate forests of Chile. The forests of the Amazon Hyla bocourti Plethodontidae Basin and Guianan Shield are still largely intact, although there is much clearance currently Hyla chlorostea Bolitoglossa jacksoni taking place along the southern edge of the forest zone in Brazil. Habitat loss in the region Hypsiboas cymbalum Bradytriton silus has been driven largely by expanding subsistence agriculture to support growing human Isthmohyla calypsa Chiropterotriton magnipes* populations, and also by commercial agriculture and logging. Isthmohyla debilis Ixalotriton parva Isthmohyla graceae Oedipina paucidentata Isthmohyla rivularis Pseudoeurycea aquatica