First record of the invasive greenhouse frog (Eleutherodactylus planirostris) in the Mexican Caribbean

Primer registro de la rana de invernadero invasora (Eleutherodactylus planirostris) en el Caribe mexicano

José Rogelio Cedeño-Vázquez^1*, Javier González-Vázquez², Arely Martínez-Arce¹ and Luis Canseco-Márquez³

¹ Departamento de Sistemática y Ecología Acuática. El Colegio de la Frontera Sur, Unidad Chetumal, Av. Centenario Km 5.5, 77014 Chetumal, Quintana Roo, México. * rcedenov@ecosur.mx

³ Departamento de Biología Evolutiva, Laboratorio de Herpetología, Facultad de Ciencias. Universidad Nacional Autónoma de México, Av. Universidad 3000, Ciudad Universitaria, Coyoacán, 04510, México, D.F., México.

Recibido: 04 noviembre 2013
Aceptado: 30 diciembre 2013

Abstract

Based on morphological identification and a molecular analysis of specimens collected in the urban zone of Playa del Carmen in the state of Quintana Roo, we report the first record of the invasive greenhouse frog (Eleutherodactylus planirostris) in the Mexican Caribbean. The presence of E. planirostris in the Yucatán Peninsula suggests an urgent need for research to evaluate its invasion and ecological impacts.

Key words: new record, DNA barcodes, morphological analysis, molecular analysis, Playa del Carmen, Yucatán Peninsula.

Con base en identificación morfológica y análisis molecular de ejemplares recolectados en la zona urbana de la ciudad de Playa del Carmen, Quintana Roo, informamos del primer registro de la rana de invernadero (Eleutherodactylus planirostris) en el Caribe mexicano. La presencia de E. planirostris en la península de Yucatán sugiere la necesidad de realizar urgentemente una investigación para evaluar su invasión y los posibles impactos ecológicos que puedan suscitarse.

Palabras clave: nuevo registro, códigos de barras de DNA, análisis morfológico, análisis molecular, Playa del Carmen, península de Yucatán.

Biological invasions are widely recognized as a significant component of human-caused global environmental change, often resulting in the loss of biological diversity and ecosystem function (Hulme, 2003). The greenhouse frog Eleutherodactylus planirostris has direct development (no aquatic stage) and deposits its eggs in moist soil, which facilitate human-mediated colonization (Christy et al., 2007) through transportation in potted plants (e.g. Kraus et al., 1999; Kraus and Campbell, 2002).

The greenhouse frog is native to the Caribbean islands of Cuba, Bahamas and Cayman Islands (Díaz and Cádiz, 2008; Olson et al., 2012a), but it has a wide non-native distribution in the United States, Mexico, Jamaica, Grenada, Caicos Islands, the Miskito Cays of Nicaragua, Honduras, Panama City, Panama, and the Pacific islands of Hawaii and Guam (Díaz and Cádiz, 2008; McCrane et al., 2008; Kraus, 2009; Heinicke et al., 2011; Crawford et al., 2011; Olson et al., 2012a, 2012b).

Empirical observations indicate that the greenhouse frog is a highly successful invasive species (Bomford et al., 2009). For instance, after natural and human-assisted introductions occurred in the early 1900s in Florida USA, the greenhouse frog is now found throughout the state. It is suspected that human-assisted introductions often occur by hitch-hiking on commercial nursery plants (Heinicke et al., 2011; Kraus et al., 1999) and probably this is the way the greenhouse frog arrived in Mexico. Here, we report the first record of E. planirostris in the Mexican Caribbean confirmed by morphological and molecular data.

On 19 November 2010 at 14:00 h following a heavy rain, 3 small frogs were collected (field numbers JGV 303-305; 16, 20 and 21 mm snout-vent length [SVL], respectively) around a swimming pool at a condominium built in 1993 in the urban zone of Playa del Carmen, Quintana Roo, Mexico, 20°37' 52" N, 87°04' 21" W (Fig. 1). Living specimens were photographed (Fig. 2), sacrificed and preserved in 96% ethanol, and then deposited in the herpetological collection of the Museo de Zoología Alfonso L. Herrera of the Facultad de Ciencias, Universidad Nacional Autónoma de México (UNAM) with catalogue numbers MZFC 27464-27466.

After the literature review of local amphibians, photographic comparisons, and use of taxonomic keys, we identified the specimens as belonging to the genus Eleutherodactylus, but based on information in Lee (1996, 2000), Campbell (1998), and Köhler (2011) morphological features of the collected frogs were inconsistent with any of the 9 species native to the Yucatán Peninsula. In order to identify our specimens to the species level, we conducted a genetic analysis using sequences from the mitochondrial gen Cytochrome Oxidase Subunit I (COI) (>600 bp). Tissue samples were obtained from each specimen by toe clipping.

Molecular protocols (DNA extraction, amplification and sequencing) were conducted in the barcoding laboratory of El Colegio de la Frontera Sur (ECOSUR) following the Canadian Center of DNA Barcoding (CCDB) public protocols (http://www.dnabarcoding.ca). To corroborate and compare our genetic material, we obtained 3 additional sequences of E. planirostris, including 2 from Panama and 1 from Cuba (Crawford et al., 2011), and 6 sequences of other species of Eleutherodactylus (E. glamyrus, E. eileenae, E. bartonsmithi, E. principalis, E. mariposa and E. ronaldi) (Rodríguez et al., 2010), all downloaded from the Barcode of Life Database (www.boldystems.org). A neighbor-joining (NJ) tree was reconstructed with a sequence of Leptodactylus fragilis as an outgroup (Fig. 3) using the software MEGA v. 4 (Tamura et al., 2007). Also, intra and interspecific p distances were calculated. Genetic sequences and metadata were deposited at Barcode of Life Data Systems (Ratnasingham and Hebert, 2007) under project Eleutherodactylus from Mexican Caribbean "EMC."

Morphological characters described by Díaz and Cádiz (2008) confirmed that our specimens belong to E. planirostris: a small frog, up to 27.3 mm SVL; long and thin toes with tubercles in the inferior surface, not webbed and small digital discs; dorsum variable overlaid with granules and tubercles. There are 2 basic colour patterns: 1) a mottled tan and brown, and 2) a mottled tan and brown, with 2 yellow dorsolateral stripes extending from the eye along the length of the body (Lynn and Grant,1940). The specimens we collected had the mottled tan and brown pattern (Fig. 2). This identification was confirmed with the intra and interspecific genetic p distances (1.4%, and 25.51% average value, respectively).

Clusters formed in our phenogram, indicate that the 3 specimens from Mexico belong to E. planisrostris and consist of 3 different haplotypes (Mexico, Panama and Cuba). Both results (morphological and genetic) confirm for the first time the presence of the greenhouse frog in the state of Quintana Roo.

According to Kraus et al. (1999), in Hawaii E. planirostris potentially could eat indigenous, endemic arthropods, including species of insects and spiders of conservation concern. In a recent study in Hawaii, Olson and Beard (2012) found that this frog feeds mostly on leaf litter invertebrates, and consumption was estimated be as great as 129,000 invertebrates ha/night. Despite these possible ecological impacts, the impacts of the greenhouse frog invasions remain largely unstudied (Olson et al., 2012a).

Ecological studies are therefore urgently needed to understand the effects of the greenhouse frog invasions. In Mexico E. planirostris was first reported in the state of Veracruz (Schwartz 1974), but subsequent records have not been forthcoming (Álvarez-Romero et al., 2008). In the case reported herein, after a heavy rain, on 18 June 2011 at 9:00 h, we collected another specimen (25 mm SVL; voucher deposited in the herpetological collection of the Museo de Zoología in ECOSUR campus Chetumal, Cat. Number ECO-CH 2949) in the facilities of the Xaman Ha Aviary, 20°37'6" N, 87°04'50" W (site 2; Fig. 1), located ca. 1650 m SW from the previous site, confirming the distribution of E. planirostris could be more widespread than previously thought. Furthermore, at the previous site we observed more adults (including calling males) and juveniles (only mottled individuals were found in both sites) in June 2013. This indicates an established population of E. planirostris now occurs in Playa del Carmen, which could be present over a wider area, and could spread beyond the urban zone in a short period of time. To address this concern, we strongly recommend that additional research be conducted to evaluate this invasion and its possible ecological impacts, and determine if control measures are necessary.

Sometimes invasive species are difficult to identify using only traditional morphology, and reference material for comparison often does not exist. For this reason, we suggest application of integrative taxonomy that includes morphological and molecular characters to correctly identify species as in this case.

We thank Samuel Pech Ramírez for his help finding frogs, Humberto Bahena-Basave for the images, and Janneth A. Padilla Saldívar for constructing the map. We also thank Steven G. Platt, Larry D. Wilson, Karen H. Beard, and Fred Kraus for comments on the manuscript.

Literature cited

Álvarez-Romero, J. G., R. A. Medellín, A. Oliveras-de Ita, H. Gómez-de Silva and O. Sánchez. 2008. Animales exóticos en México: una amenaza para la biodiversidad. Comisión Nacional para el Conocimiento y Uso de la Biodiversidad. Instituto de Ecología, UNAM, Secretaría de Medio Ambiente y Recursos Naturales. México, D.F., 218 p.         [ Links ]

Bomford, M., F. Kraus, S. C. Barry and E. Lawrence. 2009. Predicting establishment success for alien reptiles and amphibians: a role for climate matching. Biological Invasions 11:713-724.         [ Links ]

Campbell, J. A. 1998. Amphibians and reptiles of northern Guatemala, the Yucatán, and Belize. University of Oklahoma Press. Oklahoma. 380 p.         [ Links ]

Christy, M. T., C. S. Clark, D. E. Gee II, D. Vice, D. S. Vice, M. P. Warner, C. L. Tyrrell, G. H. Rodda and J. A. Savidge. 2007. Recent records of alien anurans on the Pacific Island of Guam. Pacific Science 61:469-483.         [ Links ]

Crawford, A. J., R. Alonso, C. A. Jaramillo, S. Sucre and R. Ibáñez. 2011. DNA barcoding identifies a third invasive species of Eleutherodactylus (Anura: Eleutherodactylidae) in Panama City, Panama. Zootaxa 2890:65-67.         [ Links ]

Díaz, L. M. and A. Cádiz. 2008. Guía taxonómica de los anfibios de Cuba. Abc Taxa Vol. 4. Royal Belgium Institute of Natural Sciences, Brussels. 294 p.         [ Links ]

Heinicke, M. P., L. M. Diaz and S. B. Hedges. 2011. Origin of invasive Florida frogs traced to Cuba. Biology Letters 7:407-410.         [ Links ]

Hulme, P. E. 2003. Biological invasions: winning the science battles but losing the conservation war? Oryx 37:178–193.         [ Links ]

Köhler, G. 2011.Amphibians of Central America. Herpeton Verlag Elker Köhler. Offenbach, Germany. 379 p.         [ Links ]

Kraus, F. 2009. Alien reptiles and amphibians: a scientific compendium and analysis. Springer Science and Business Media B. V. Dordrecht, Netherlands. 563 p.         [ Links ]

Kraus, F. and E. W. Campbell. 2002. Human-mediated escalation of a formerly eradicable problem: The invasion of Caribbean frogs in the Hawaiian Islands. Biological Invasions 4:327-332.         [ Links ]

Kraus, F., E. W. Campbell, A. Allison and T. Pratt. 1999. Eleutherodactylus frog introductions to Hawaii. Herpetological Review 30:21-25.         [ Links ]

Lee, J. C. 2000. A field guide to the amphibians and reptiles of the Maya world. The lowlands of Mexico, northern Guatemala, and Belize. Cornell University Press, Ithaca. 402 p.         [ Links ]

Lee, J. C. 1996. The amphibians and reptiles of the Yucatán Peninsula. Cornell University Press, Ithaca. 500 p.         [ Links ]

Lynn, W. G. and C. Grant.1940. The herpetology of Jamaica. Bulletin of the Institute of Jamaica Science Series 1:1-148.         [ Links ]

McCrane, J. R., J. R. Collart, F. E. Castañeda and J. M. Solis. 2008. Geographic distribution: Eleutherodactylus (Euhyas) planirostris. Herpetological Review 39:362.         [ Links ]

Olson, C. A. and K. H. Beard. 2012. Diet of the introduced greenhouse frog in Hawaii. Copeia 1:121-129.         [ Links ]

Olson, C. A., K. H. Beard and W. C. Pitt. 2012a. Biology and impacts of Pacific Island Invasive Species. 8. Eleutherodactylus planirostris, the Greenhouse Frog (Anura: Eleutherodactylidae). Pacific Science 66:255-270.         [ Links ]

Olson, C. A., K. H. Beard, D. N. Koons and W. C. Pitt. 2012b. Detection probabilities of two introduced frogs in Hawaii: implications for assessing non-native species distributions. Biological Invasions 14:889-900.         [ Links ]

Ratnasingham, S. and P. D. N. Hebert. 2007 BOLD: The barcode of life data system (http://www.barcodinglife.org). Molecular Ecology Notes 7:355-364.         [ Links ]

Rodríguez, A., M. Vences, B. Nevado, A, Machordom and E. Verheyen. 2010. Biogeographic origin and radiation of Cuban Eleutherodactylus frogs of the auriculatus species group, inferred from mitochondrial and nuclear gene sequences. Molecular Phylogenetics and Evolution 54:179-86.         [ Links ]

Schwartz, A. 1974. Eleutherodactylus planirostris. Catalogue of American Amphibians and Reptiles 154:1-4.         [ Links ]

Tamura, K., J. Dudley, M. Nei and S. Kumar. 2007 MEGA4: Molecular Evolutionary Genetics Analysis (MEGA) software version 4.0. Molecular Biology and Evolution 24:1596-1599.         [ Links ]