Extension of the known geographic distribution of Atelopus cruciger in northern Venezuela/Extension de la distribucion conocida de Atelopus cruciger en el norte de Venezuela.
A new locality is reported for Atelopus cruciger in the Interior
Serrania of the Coastal Cordillera of Venezuela, based on field
observations in a cloud forest of Guatopo national park in 1984. This is
evidence of a broader geographical distribution for the species. The
need to expand herpetological surveys to the rest of the Cordillera,
given it is a "critically endangered" species which could be
present in other localities, is stressed. It is highlighted the
importance of Guatopo as a protected area for this species and the need
to check its persistence in the park.
Key words: Amphibia, Anura, Atelopus cruciger, distribution, Guatopo National Park, Venezuela.
Se reporta una nueva localidad para Atelopus cruciger en la Serrania del Interior de la Cordillera de La Costa de Venezuela con base en observaciones de campo realizadas en 1984 en un bosque nublado del parque nacional Guatopo. Esto evidencia que la especie tiene una distribucion mayor a la conocida. Se resalta la necesidad de extender las exploraciones hacia el resto de la cordillera por cuanto la especie, catalogada como en "peligro critico", podria estar presente en otras localidades. Se destaca la importancia de Guatopo como area protegida para esta especie y la necesidad de constatar su existencia actual en el parque.
Palabras clave: Amphibia, Anura, Atelopus cruciger, distribucion, Parque Nacional Guatopo, Venezuela.
Endangered species (Distribution)
Rivero Blanco, Carlos
|Publication:||Name: Herpetotropicos: Tropical Amphibians & Reptiles Publisher: Herpetotropicos Audience: Academic Format: Magazine/Journal Subject: Zoology and wildlife conservation Copyright: COPYRIGHT 2007 Herpetotropicos ISSN: 1690-7930|
|Issue:||Date: Jan-June, 2007 Source Volume: 4 Source Issue: 1|
|Topic:||Event Code: 690 Goods & services distribution; 310 Science & research Advertising Code: 59 Channels of Distribution Computer Subject: Company distribution practices|
|Product:||Product Code: 9106283 Endangered Species NAICS Code: 92412 Administration of Conservation Programs|
|Geographic:||Geographic Scope: Venezuela Geographic Code: 3VENE Venezuela|
Atelopus cruciger Lichtenstein and Martens 1856, is a "critically endangered" species (Manzanilla and La Marca 2004, Manzanilla et al. 2004), belonging to a vertebrate group considered as of great concern from the conservationist point of view (La Marca et al. 2005). The habitat for this species is humid mountain forests (Sexton 1958) of the Coastal Cordillera of Venezuela (Manzanilla et al. 2004, Rivas 1998, Lotters 1996, Rivero 1961), specifically within the Litoral and the Nirgua-Tinaquillo mountain ranges (Fig. 1), which belong to the Coastal Range biogeographical region (Pefaur and Rivero 2000). Improving knowledge on its geographical distribution is essential to optimize conservation efforts. This report shows the species was present, at least until 1984, in Guatopo national park, located in the Interior Serrania of the same Cordillera, therefore implying an extension on its geographical distribution. We provide here details on this finding and discuss some possible consequences of it.
NEW DISTRIBUTION RECORD
As a part of a characterization study of Guatopo national park (Yerena 1985), the first author did an on-foot trip to the summit of Cerro Azul (1500 m elevation), from February 24th to 26 th 1984, following the Rio de Piedra, a permanent mountain stream (Lagartijo river basin), helped by a field assistant, a pathfinder and a park-ranger. The goal of this trip was to gather evidence on the possible occurrence of non-previously reported cloud forest in the park.
Along the trip, in diurnal hours, it became evident a relatively high abundance of a toad species along the route, close and away from the water stream, between 600 and 1100 m of elevation, on a perimeter around 66[degrees]33'29"W-10[degrees]01'35"N (Fig.1). We visually identify the toad as Atelopus cruciger (Fig. 2), confirmed by other herpetologists (E. La Marca, C. Barros-Amoros, pers. com.). This finding was previously reported although not formally published (Yerena 1985).
The habitat where it was observed is uninhabited by humans (Yerena and Escalona 1995), although some scattered and abandoned orchards still can be found, and neither trails nor hikers occur, except for occasional poachers. The time of the sighting (February) is usually the annual extreme driest month on this portion of the park; the nearest pluviometer station (Rio de Piedras, 400 m elevation) records a mean annual precipitation of 1117 mm (Yerena 1985). Precipitation on the upper watershed portion where A. cruciger was seen might be higher.
From a physiographic point of view (Freiles 1969, Fig. 1), the Coastal Cordillera of Venezuela is a "province" comprised by three "regions": Nirgua-Tinaquillo Serrania, Litoral Mountain Chain and Interior Serrania. The distribution map reported by Manzanilla and La Marca (2004) spatially corresponds only to the former two, despite they name it under the generic name of Cordillera de La Costa of Venezuela; while Guatopo belongs exclusively to the third region. Therefore, the recent distribution of A. cruciger should be considered extended to the three mountain regions of the Coastal Cordillera (Fig. 1), within the altitudinal range corresponding with that reported for the species (La Marca et al. 2005), confirming Lotters et al. (2004) contention that its distribution could extend to the whole Coastal Cordillera. The only record outside this mountain range appears to be that of "Curanna (Cumana, Gunther, 1858)" of Rivero (1961). La Marca (1992) recommended to take out this distribution record from Sucre State (NE Venezuela) due to its uncertainty.
[FIGURE 1 OMITTED]
[FIGURE 2 OMITTED]
Most of the biological studies in Guatopo have been carried out in areas along the asphalted highway, mainly because access to the higher (above 700 m) elevations of the park is difficult (Yerena 1985). James R. Dixon (Wildlife and Fisheries Science Department, Texas A&M University) conducted extensive herpetological surveys on such accessible localities in 1980 (unpublished data, in Yerena 1985), all of them within the altitudinal range reported for A. cruciger (30-2200 m, La Marca et al. 2005), but never reported it. We presume that A. cruciger may have a habitat preference above 900 m in Guatopo national park. This would explain why this species had not been previously reported. We recommend conducting future biological surveys on the higher elevations.
Continuity of evergreen forests has existed between the Interior Serrania (Guatopo national park) and the Litoral Mountain Chain (El Avila national park), through the humid Interior Valley region (Smith, no date, Fig. 1), which today is fragmented by human activity. Therefore, at least in historical times, a drastic vegetation barrier had not existed that could isolate biologically both mountain regions. In consequence, the populations of humid forest amphibians could have exchanged between them.
We highlight the relevance of Guatopo national park as a protected area for this species, since it preserves 428 km2 of lands above the 600 m altitude (35% of its total surface). Also, we point to the necessity of extending the explorations in the Interior Serrania, in order to verify whether the species possesses an even broader distribution along this physiographic unit where other remnants of humid forest actually exist (Meier 2002).
The report here described, from 23 years ago, does not imply that the species is actually present in Guatopo. Atelopus cruciger was considered as possibly extinct between 1988 and 2004 (Manzanilla et al. 2004) after having been relatively abundant. Its decline in Venezuela might be caused by a chytrid fungus infection (Bonaccorso et al. 2003). The extinction phenomenon of the Atelopus frogs has been documented and it is of great concern (La Marca et al. 2005, Bonaccorso et al. 2003), therefore it is important to carry out new explorations in Rio de Piedra in order to verify whether the species is still extant in Guatopo national park.
We thank our field assistant Gustavo Marquina[dagger], park ranger Juan Alayon and pathfinder Juan Reyes, who joined the senior author in the field trip. We also thank Enrique La Marca and Cesar Barrio-Amoros for stimulating the publication of this report, Jorge Naveda for the elaboration of the map, as well as Stefan Lotters and Jesus Manzanilla for comments and observations on the manuscript. To Luis Escalona[dagger] and Rafael Duran, both former superintendents of Guatopo national park, we dedicate this article.
Received / Recibido 17 FEB 2007 Accepted / Aceptado 28 MAY 2007
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Yerena, E. and L. Escalona. 1995. Guatopo National Park: relocation of settlers in the interest of public utility. Pp. 423-436 In S. Amend and T. Amend (eds.). National Parks without people?: The South American experience. IUCN / Parques Nacionales y Conservacion Ambiental No. 5. Quito. Ecuador.
EDGARD YERENA (1,3) AND CARLOS RIVERO BLANCO (2,3)
(1) Departamento de Estudios Ambientales, Universidad Simon Bolivar, Sartenejas, Baruta, Caracas, Venezuela.
(2) Apartado 63011, Chacaito, Caracas 1067-A, Venezuela.
(3) Send correspondence to / Enviar correspondencia a: Edgard Yerena: email@example.com Carlos Rivero Blanco: firstname.lastname@example.org
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