Pleurodema somuncurense (Cei, 1969)
El Rincon Stream Frog, Somuncura Frog, Valcheta Frog, Spanish: Rana de Somuncura, Castilian: Ranita del Valcheta | family: Leptodactylidae subfamily: Leiuperinae genus: Pleurodema |
Species Description: Originally described as Telmatobius somuncurensis by Cei, J. M. 1969. The Patagonian telmatobiid fauna of the volcanic Somuncura Plateau of Argentina. Journal of Herpetology 3: 1–18. |
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Description DIAGNOSIS: (How this species is differentiated from similar species) Originally described as Telmatobius somuncurensis, the species can be differentiated from other Telmatobius species by the markings on the iris and the light dorsal midline stripe, which other Telmatobius species lack (Cei 1980). COLORATION: (In life and/or in preservative) The dorsum is brown or yellowish with irregular spotting and a light yellowish medial line. The belly is purplish-yellow, having reticulate spots speckled throughout. There are two circular markings centered on the upper and lower iris. The nuptial pad is pale gray. It is unclear whether this is in life or preservative (Cei 1980). Distribution and Habitat Country distribution from AmphibiaWeb's database: Argentina
Life History, Abundance, Activity, and Special Behaviors The breeding season is likely in late spring, in October and early November. During this time, males can be observed to have very large testicles and tadpoles are seen in streams (Cei 1980). No tadpoles have been observed in winter. Pleurodema somuncurense exhibits reproductive behaviors that are characteristic of both prolonged and explosive breeders, including a breeding season of over five months, a lack of association between rain and reproduction, scramble competition, and males actively searching for mates (Velasco et al. 2017). Amplexus is pelvic and multiple males may attach to one female. Axillary amplexus is rare. Amplexus occurs on the water’s surface with the female grasping onto a rock or vegetation (Cei 1980, Velasco et al. 2017). Females lay an average of 78 eggs per clutch and can spawn multiple times per season. Breeding sites are completely covered by aquatic vegetation, namely Cardamine cordata and Hydrocotyle bonariensis. Oviposition only occurs in shallow lentic waters close to a thermal spring. Egg clutches are submerged, gelatinous, and string-like, with one end attached to the roots or stems of aquatic vegetation. Egg diameter is about 1.8 mm on average without the gelatinous capsule. The eggs are dark and have a black animal pole with a vegetal pole that begins pale and darkens to black over time. Tadpoles hatch about four days after oviposition (Velasco et al. 2017). When hunting for prey, P. somuncurense mainly displays sit-and-wait behavior, but may actively search for prey as well. Pleurodema somuncurense has been observed to ambush prey by staying concealed in aquatic vegetation. Though P. somuncurense has a mainly aquatic life, aquatic prey like amphipod shrimps only composes about a quarter of its diet. Other prey include woodlice and ants. Ash has been found in some P. somuncurense stomachs, which comes from grassland fires for livestock management. These fires and livestock negatively impact P. somuncurense populations (see Trends and Threats). Captive individuals were observed hunting for prey before eating them while completely submerged in the water, using their forearms to collect the prey into their mouth (Velasco et al. 2019a). Individuals can be infected with Hydracarina mites and have Leptus encapsulated beneath the skin (Cei 1980). Pleurodema somuncurense shares the habitat with the endemic fish Gymnocharicanus bergi (Cei 1980). Other amphibian species that occupy the Valcheta Stream with P. somuncurense include Rhinella arenarum and Odonotphrynus occidentalis, the former being the most abundant species in the habitat (Velasco et al. 2019b). Larva In life, the skin is dark. The dorsum is brownish gold while the ventral side is a reddish gray. Brownish spots mottle the caudal fins, which are transparent (Cei 1980). Tadpoles hatch about four days after oviposition (Velasco et al. 2017) and live on the bottom of the stream. As indicated by the protruding mouth and snout, the tadpoles are omnivorous and eat slime (Cei 1980). Tadpoles beginning metamorphosis have a total length of 46 - 49 mm, and froglets have a snout-vent length of 18 mm (Cei 1980). Trends and Threats As of 2019, seven P. somuncurense populations exist throughout the Valcheta Stream, four of which inhabit Rama Fría and three of which inhabit Rama Caliente. The invasive rainbow trout Onchorynchus mykiss is a predator and the introduced fish Cheirodon interruptus competes with P. somuncurense for trophic resources (Velasco et al. 2019b). In addition to introduced predators, the chytrid fungus Batrachochytrium dendrobatidis threatens P. somuncurense populations. However, at infection levels produced in a laboratory, it may be possible that P. somuncurense is resistant or tolerant of the fungus (Arellano et al. 2018). Together these threats cause species isolation and decline, with rainbow trout inhabiting all stream corridors and reducing the species range to 2 km2. Two P. somuncurense population extirpations, the El Destacamento and El Ariete populations, have occurred within recent decades. No individuals were found in El Destacamento after a dam construction in 2009, which resulted in water stagnation and livestock disturbance to native vegetation. Individuals have not been seen in El Ariete since 1969 (Velasco et al. 2019b, Velasco et al. 2018). Additionally, dependence on terrestrial prey makes P. somuncurense susceptible to human activity that affects prey populations, like intentional fires that promote pasture growth and livestock overgrazing (Velasco et al. 2019b). Insufficient pastures for livestock has also led to livestock trampling on breeding sites. Compared to populations in captivity, wild P. somuncurense populations have a low number of clutches throughout the stream, indicating that breeding sites with the right conditions are scarce (Velasco et al. 2017). Conservation efforts have been implemented to restore P. somuncurense populations, which involve limiting livestock in the area and removing the invasive toxic rosehip plant (Rosa sp., Velasco et al. 2018). A reintroduction program is also in place in the former El Destacamento habitat (Velasco et al. 2019b). According to population viability models, most current populations could support long-term populations if threats were removed. In the absence of threats, populations that would still be unsustainable in the long-term are affected by inbreeding and stochastic events, and would require the introduction of a mating pair every 17 - 19 years (Velasco et al. 2022). Relation to Humans Possible reasons for amphibian decline General habitat alteration and loss Comments PHYLOGENETIC RELATIONSHIPS:
Based on Bayesian analysis of cyt B, 12S, and 16S mtDNA as well as intervening tRNA, P. somuncurense is sister to P. bufonium and is included in the P. thaul clade. Besides P. somuncurense and P. bufonium, this clade also includes P. marmoratum and P. thaul. All of these species occur in Argentina or Chile (Faivovich et al. 2012). ETYMOLOGY (Origin or explanation of scientific name):
The species was originally described as Telmatobius somuncurensis (Cei 1969). It was then placed in the Somuncuria genus, which was considered the sister genus to Pleurodema, before being placed into the Pleurodema genus as Pleurodema somuncurense (Faivovich et al. 2012). OTHER INTERESTING INFORMATION: The skin of P. somuncurense contains antimicrobial peptides (AMPs) somuncurin-1, somuncurin-2, and thaulin-3. All three have been shown to be effective against Escherichia coli while somuncurin-1 can also inhibit Staphylococcus aureus (Cancelarich et al. 2020). References Cancelarich, N.L., Wilke, N., Fanani, M.L., Moreira, D.C., Pérez, L.O., Barbosa, E.A., Plácido, A., Socodato, R., Portugal, C.C., Relvas, J.B., de la Torre, B.G., Albericio, F., Basso, N.G., Leite, J.R., and Marani, M.M. (2020). Somuncurins: bioactive peptides from the skin of the endangered endemic Patagonian frog Pleurodema somuncurense. Journal of Natural Products 83(4), 972-984. [link] Cei, J. M. 1980. Amphibians of Argentina. Monitore Zoologico Italiano. Nuova Serie, Monographia. Firenze 2: ixii + 609. 248-252. Faivovich, J., N. G. Basso, C. F. B. Haddad, M. T. Rodrigues, W. C. Wheeler, E. O. Lavilla, and D. P. Ferraro (2012). A phylogenetic analysis of Pleurodema (Anura: Leptodactylidae: Leiuperinae) based on mitochondrial and nuclear gene sequences, with comments on the evolution of anuran foam nests. Cladistics 28: 460–482. [link] IUCN SSC Amphibian Specialist Group. 2016. Pleurodema somuncurense. The IUCN Red List of Threatened Species 2016: e.T20372A85948443. https://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T20372A85948443.en. Accessed on 26 October 2023. Velasco, M.A., Akmentins, M.S., Kass, C.A., Williams, J.D., and Kacoliris, F.P. (2019a). Diet of critically endangered Valcheta frog, Pleurodema somuncurense (Anura: Leptodactylidae), in the Somuncura Plateau, Patagonia, Argentina. North-Western Journal of Zoology, 15(2), 147-151. [link] Velasco, M.A., Berkunsky, I., Akmentins, M.S, Kass, C.A., Arellano, M.L., Martínez Aguirre, T., Williams, J.D, and Kacoliris, F.P. (2019b). “Status and population dynamics of the Critically Endangered Valcheta frog Pleurodema somuncurense in Somuncura Plateau, Patagonia.” Endangered Species Research 40, 163-169. [link] Velasco, M.A., Berkunsky, I., Di Pietro, D.O., Arellano, M.L., Williams, J.D. and Kacoliris, F.P. (2022). The Critically Endangered El Rincon stream frog: Population viability and management actions in Patagonia, Argentina. Aquatic Conservation: Marine and Freshwater Ecosystems, 32(11), 1842–1851. [link] Velasco, M. A., Úbeda, C. A., Williams, J. D., and Kacoliris, F. P. (2017). Reproductive biology of the critically endangered Valcheta frog, Pleurodema somuncurense (Anura: Leptodactylidae), from Patagonia, Argentina. South American Journal of Herpetology, 12(3), 205-211. [link] Originally submitted by: Madeline Ahn (2023-10-31) Description by: Madeline Ahn (updated 2023-10-31)
Distribution by: Madeline Ahn (updated 2023-10-31)
Life history by: Madeline Ahn (updated 2023-10-31)
Larva by: Madeline Ahn (updated 2023-10-31)
Trends and threats by: Madeline Ahn (updated 2023-10-31)
Relation to humans by: Madeline Ahn (updated 2023-10-31)
Comments by: Madeline Ahn (updated 2023-10-31)
Edited by: Ann T. Chang (2023-10-31) Species Account Citation: AmphibiaWeb 2023 Pleurodema somuncurense: El Rincon Stream Frog <https://amphibiaweb.org/species/9386> University of California, Berkeley, CA, USA. Accessed Oct 11, 2024.
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Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 11 Oct 2024. AmphibiaWeb's policy on data use. |