Hypsiboas gladiator is a mid-sized member of the H. pulchellus group. Frogs in this group are called “gladiator frogs” because males possess a prepollical spine on the hand, which they use for combats with other males. Adult females (47.8–55.3 mm) are slightly larger than adult males (35.3–49.4 mm SVL). Hypsiboas gladiator is characterized as having a slender body with a head as wide as the body. The skin of the flanks and of the dorsum is smooth and the ventral skin is granular. The ulnar fold is elevated and distinct. The hind limbs are moderately slender with a discrete inner tarsal fold (Köhler et al. 2010).
Members of H. gladiator are distinguished from other species by the presence of smooth dorsal skin with irregular blotches, a subacuminate snout that has a rounded profile, flanks and posterior regions of the thighs brown with cream blotches, an elevated tarsal fold, disk on digit III equal to the diameter of the tympanum, and by the unique characteristics of the male’s advertisement call. Compared to similar species, the call of H. gladiator has more pulses than that of H. balzani and is much longer than the call of H. marianitae. The morphologically similar H. melanopleura lacks the white blotches on flanks and the light dorsolateral line present in H. gladiator (Köhler et al. 2010).
In preservative, H. gladiator has a dark cream dorsal surface with irregular brown markings. A brown interorbital bar extending from the upper eyelids and connecting with brown posterior markings is observed. The region that surrounds the tympanum is dark brown while the posterior region of the upper lip is a cream color. The ventral region of the dentary is a yellowish cream that blends to brown on the throat. The flanks are dark brown with white specks that contrast with the dark cream dorsum coloration. The upper surfaces of the thighs are also dark cream with tan blotches and the posterior surfaces of the thighs are brown with white specks. A white supracloacal stripe can also be seen. The palmar and plantar surfaces are observed to be greyish-brown in color. The main difference between the coloration found in the live versus the preserved specimens is that in life there is more vivid coloration. An irregular green stripe can be seen which extends from the eye to the nostril, and a green fleck can be observed between the eyes and tympanum. The iris is silvery grey in color (Köhler et al. 2010).
Coloration in H. gladiator is variable. In preservative, the dorsal color can vary from brown to dark cream, and the markings on the body vary in shape and size. White blotches and markings on flanks are always present. Some males show signs of combat by having transversal scratch marks caused by the prepollical spines (Köhler et al. 2010).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Peru
Hypsiboas gladiator inhabits the moderate elevations (1100-2000 m) of the cloud forests of southern Peru in the regions of Cusco and Puno (Catenazzi et al. 2011, Köhler et al. 2010). Hypsiboas gladiator is commonly found in ditches along roads adjacent to primary and secondary rainforest of the eastern Andean slopes, where calling males are often heard.
Life History, Abundance, Activity, and Special Behaviors
The advertisement call of H. gladiator is composed of a single pulsed (110-150 pulses) note 257-531 ms in duration. The call increases in amplitude until reaching the maximum at the middle of the note. The call frequency varies from 600-4000 Hz with maximum call energy at 770-900 Hz (Köhler et al. 2010).
This species is a stream-breeding frog and breeding can occur all year under favorable conditions (Köhler et al. 2010; Catenazzi et al. 2011).
Trends and Threats
The amphibian pathogenic chytrid fungus Batrachochytrium dendrobatidis has caused local extinctions and severe population declines in the Kosñipata Valley and upper Manu National Park, Cusco Region. Infection with this fungus has been found in H. gladiator in tadpoles, juveniles and adults in this valley (Catenazzi et al. 2011) and in adults from the Marcapata Valley (Cusco) and San Juan del Oro (Puno; Köhler et al. 2010). It is unclear how Bd affects populations of H. gladiator, because in several streams this is the only stream-breeding species that survived recent outbreaks of chytridiomycosis (Catenazzi et al. 2011).
Batrachochytrium dendrobatidis causes the amphibian disease chytridiomycosis, which affects the superficial, keratin-containing layers of amphibian skin (Berger et al. 1998). As the infection advances, the skin becomes much thicker and sloughs off (Berger et al. 1998). Consequently, osmoregulation is compromised and electrolyte blood levels drop, leading to death from cardiac arrest (Voyles et al. 2009). Infection intensity appears to be a key factor in facilitating death (Vredenburg et al. 2010).
Possible reasons for amphibian decline
Habitat modification from deforestation, or logging related activities
The species authority is Köhler, J., Koscinski, D., Padial, J. M., Chaparro, J. C., Handford, P., Lougheed, S. C., and de la Riva, I. 2010. Systematics of Andean gladiator frogs of the Hypsiboas pulchellus species group (Anura, Hylidae). Zoologica Scripta, 39: 572–590.
According to the phylogeny of cytochrome b and 16S rRNA proposed by these authors, H. gladiator is the sister taxon of H. palaestes. This phylogeny did not include the morphologically similar and potentially closely related H. melanopleura. The name “‘gladiator’ is derived from Latin and refers to the prepollical spine used in male-to-male combats (Köhler et al. 2010).
Berger, L., Speare, R., Daszak, P., Green, D. E., Cunningham, A. A., Goggin, C. L., Slocombe, R., Ragan, M. A., Hyatt, A. D., McDonald, K. R., Hines, H. B., Lips, K. R., Marantelli, G., and Parkes, H. (1998). "Chytridiomycosis causes amphibian mortality associated with population declines in the rain forests of Australia and Central America." Proceedings of the National Academy of Sciences of the United States of America, 95(15), 9031-9036.
Catenazzi, A., Lehr, E., Rodriguez, L., and Vredenberg, V. (2011). ''Batrachochytrium dendrobatidis and the collapse of anuran species richness and abundance in the Upper Manu National Park, southeastern Peru.'' Conservation Biology, 5, 382-391.
Voyles, J., Young, S., Berger, L., Campbell, C., Voyles, W. F., Dinudom, A., Cook, D., Webb, R., Alford, R. A., Skerratt, L. F., and Speare, R. (2009). ''Pathogenesis of chytridiomycosis, a cause of catastrophic amphibian declines.'' Science, 326, 582-585.
Vredenburg, V. T., Knapp, R. A., Tunstall, T. S., and Briggs, C. J. (2010). ''Dynamics of an emerging disease drive large-scale amphibian population extinctions.'' Proceedings of the National Academy of Sciences, 107(21), 9689-9694.
Written by Brandon LaBumbard and Alessandro Catenazzi (acatenazzi AT gmail.com), SIUC
First submitted 2013-09-23
Edited by Ann T. Chang (2013-11-14)
Species Account Citation: AmphibiaWeb 2013 Hypsiboas gladiator: Gladiator Frog <http://amphibiaweb.org/species/7539> University of California, Berkeley, CA, USA. Accessed Jun 26, 2017.
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Citation: AmphibiaWeb. 2017. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 26 Jun 2017.
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