Pleurodema thaul is a small frog with a maximum SVL of 50 mm. Females are larger than males
(Diaz-Paez and Ortiz 2001).
Cei (1980) describes this species as follows: "The skin is smooth, with sparsely distributed flat warts on the back. Its head is slightly wider than large, with a rounded snout and prominent laterally located eyes. Nostrils are dorsally located, midway between the eye and the tip of the snout. The canthus rostralis is nearly indistinct and the loreal region slants gently to the upper lip. The tympanum is small, and somewhat indistinct. There is a moderate supratympanic fold. Lumbar glands reach to about 1/8 of the body length. The fingers are almost free, with fringes, and the relative finger lengths are 2=4<1<3. Subarticular, metacarpal, and palmar tubercles are blunt and prominent. The toes are slightly webbed and distinctly fringed. On the feet, subarticular tubercles are prominent and conical while the metatarsal tubercles are prominent and rounded. Males have grayish nuptial pads. When the hind limb is adpressed, the heel reaches the eye; when the femurs are bent at right angles to the body, the tibio-tarsal articulations touch. Both tarsal and discoidal folds are present."
Dorsally, this frog may be yellow, greenish or dark green, with scattered symmetrical brown spots. The venter is white or yellow, without spots. There is a bright central black spot on the inguinal gland
The tadpole of P. thaul has a wide, rounded body with a short tail. The mouth has broad lateral folds, which are surrounded by variable rows of papillae. There are two wide horny beaks, with tooth rows of 1, 1-1 / 1-1, 2. The spiracle is lateroventral and sinistral, with the anal opening almost sinistral. The body color is gray, with a few scattered spots dorsally
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Argentina, Bolivia, Chile
Note: Pleurodema thaul is native only to Chile and Argentina.
Pleurodema thaul occurs up to 2100 m above sea level
(IUCN 2004). In Chile, the northern end of this frog's range is found near Antofagasta, in the northern arid territories, with a disjunct distribution mainly near rivers such as the Copiapo and Huasco
(Duellman and Veloso 1977). It occurs down to the southern Nothofagus forest of the Aysen Region of Chile
(Duellman and Veloso 1977). This species has a wide east-west distribution, from sea level up to the vegetation line of the western slopes of the Central Chilean Andes range
(IUCN 2004). Pleurodema thaul is also found in the Andean-Antarctic region (Argentina), from Laguna Superior de Epulafquen, Departamento Minas (Neuquen) south to the area between La Plata and Chico lakes, Departamento Rio Senguer (Chubut)
(Ubeda 2001). It is absent in the Patagonian steppe where it is substituted by Pleurodema bufonina
Pleurodema thaul is generally found in Nothofagus forest. Other habitats include grassland, steppe, and transitional zones, as well as urban and disturbed areas. Adults are found below logs and rocks and within vegetation. Reproduction occurs preferentially in shallow ponds, producing free-swimming larvae, though any type of water body may be used.
Pleurodema thaul also occurs in Araucaria forests in southern Chile and Argentina (Duellman and Veloso 1977).
Life History, Abundance, Activity, and Special Behaviors
The breeding period begins between June and August, and continues until December
(Diaz-Paez and Ortiz 2001). The reproductive cycle of P. thaul is almost continuous, with gametogenetic activity in males and females during the fall, winter, and spring of the southern hemisphere
(Diaz-Paez and Ortiz 2001). As in other species of temperate regions, changes in temperature are the main influence on reproduction, followed by changes in rainfall
(Diaz-Paez and Ortiz 2001).
Eggs are deposited in strings or gelatinous masses in water, among the aquatic plants filling the lagoons
(Cei 1980; Duellman and Veloso 1977). Any body of water may be used, but shallow ponds are preferred.
The mating call of P. thaul is metallic and variable (Cei 1980). Males call from the water surface in marshes, where sound propagation is better than in bogs
(Penna and Solis 1998).
Duellman and Veloso (1977) stated that the call consists of a modulated trill having a duration of 0.2 to 9.0 seconds, and that the second (of five) harmonic at about 1500-2300 Hz is dominant. The fourth harmonic at about 5900 Hz is also emphasized
(Duellman and Veloso 1977). The short call durations given above are for single individuals. In contrast, males calling in large choruses sometimes call continuously for nearly one minute
(Duellman and Veloso 1977).
Duellman and Veloso (1977) also reported that a group of four males was observed to have an initially organized chorus structure. One male emitted short, loud, poorly modulated notes followed by the usual mating call. These two kinds of calls had different harmonic structures. As soon as the trill began, the other individuals began trilling
(Duellman and Veloso 1977).
This frog's diet consists mostly of a diverse selection of arthropods, with arachnids and dipterids the most common prey, but also includes a small amount of vegetation
(Diaz-Paez and Ortiz 2003).
Trends and Threats
Pleurodema thaul does not appear to be threatened, as it is abundant and ecologically versatile, tolerating a broad range of habitats. Individual populations may be affected by factors such as habitat burning, water pollution, and drought
Relation to Humans
Despite human-induced habitat loss and degradation, Pleurodema thaul appears to thrive in the following artificial habitats: pastureland, plantations; ponds water storage areas, irrigation channels, wastewater treatment areas, open excavations, and irrigated/seasonally flooded agricultural land. It has also adapted to introduced vegetation
Possible reasons for amphibian decline
General habitat alteration and loss
Duellman and Veloso (1977) proposed the separation of P. thaul into different specific entities, but
Rosset et al. (2001) published a morphometric analysis of Chilean and Argentine P. thaul populations, observing that among other characters, they shared an incised sternum.
Rosset et al., (2001) reported that their results did not support
Duellman and Veloso’s (1977) conclusion, and that P. thaul is a valid species exhibiting high levels of polymorphism, as previously believed
(Cei and Capurro 1957; Cei and Espina Aguilera 1957; Cei 1958; Cei 1962; Cei 1980).
Cei, J. M. (1958). ''Polimorfismo y distribucion geografica en poblaciones chilenas de Pleurodema bibroni Tschudi.'' Investigaciones Zoológicas Chilenas, 4, 300-327.
Cei, J. M. (1962). Batracios de Chile. Ediciones de la Universidad de Chile, Santiago.
Cei, J. M. (1980). ''Amphibians of Argentina.'' Monitore Zoologica Italiano, New Series Monografia, Firenze, 2, 1-609.
Cei, J. M., and Capurro, L.S. (1957). ''La distribucion de los patrones de coloracion en Pleurodema bibroni en relacion con la distribucion geografica y el habitat.'' Investigaciones Zoológicas Chilenas, 3, 156-161.
Cei, J.M., and Aguilera, S. E. (1957). ''La vibracion sexual preventiva (“warning vibration”) en Pleurodema chilenas.'' Investigaciones Zoológicas Chilenas, 4, 15-21.
Diaz-Paez, H., and Ortiz, J.C. (2001). ''The reproductive cycle of Pleurodema thaul (Anura, Leptodactylidae) in central Chile.'' Amphibia-Reptilia, 22(4), 431-445.
Diaz-Paez, H., and Ortiz, J.C. (2003). ''Feeding habits of Pleurodema thaul (Anura, Leptodactylidae), in Concepcion, Chile.'' Gayana (Concepcion), 67(1), 25-32.
Duellman, W. E., and Trueb, L. (1986). Biology of Amphibians. McGraw-Hill, New York.
Duellman, W.E., and Veloso A. (1977). ''Phylogeny of Pleurodema (Anura: Leptodactylidae): A biogeographic model.'' Occasional Papers of the Museum of Natural History, The University of Kansas, 64, 1-46.
IUCN, Conservation International, and NatureServe. 2006. Global Amphibian Assessment: Phyllobates vittatus. <www.globalamphibians.org>. Accessed on 5 May 2008.
Lynch, J. D. (1971). ''Evolutionary relationship, osteology, and zoogeography of leptodactyloid frogs.'' Occasional Papers of the Museum of Natural History, University of Kansas, 53, 1-238.
Matsui, M., Kokuryo, Y., Misawa, Y., and Nishikawa, K. (2004). ''A new species of salamander of the genus Hynobius from central Honshu, Japan (Amphibia, Urodela).'' Zoological Science, 21, 661-669.
Penna, M., and Solis, R. (1998). ''Frog call intensities and sound propagation in the South American temperate forest region.'' Behavioral Ecology and Sociobiology, 42(6), 371-381.
Rosset, S.D., Basso, N.G., and Lombardo, R.J. (2001). ''Analisis morfometrico de Pleurodema thaul (Lesson, 1826) (Anura, Leptodactylidae) y algunas consideraciones acerca de su morfologia esternal.'' Alytes (Paris), 19(2-4), 154-172.
Ubeda, C.A. (2001). ''Pleurodema thaul (sapito de cuatro ojos).'' Herpetological-Review, 32(4), 272.
Wake, M.H. (1995). ''The spermatogenic cycle of Dermophis mexicanus (Amphibia: Gymnophiona).'' Journal of Herpetology, 29, 119-122.
Written by Kellie Whittaker (biologist AT earthlink.net), UC Berkeley
First submitted 2005-01-13
Edited by Kellie Whittaker (2009-03-02)
Species Account Citation: AmphibiaWeb 2009 Pleurodema thaul: Chilean Four-eyed Frog <http://amphibiaweb.org/species/3432> University of California, Berkeley, CA, USA. Accessed Nov 15, 2018.
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Citation: AmphibiaWeb. 2018. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 15 Nov 2018.
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