Alsodes

Di­ver­sity

The genus Al­sodes con­sists of 19 species, and 2 sis­ter gen­era, Eu­p­so­phus (6 species) and Lim­nome­dusa (1 species), that make up the fam­ily Al­so­di­dae (Am­phib­i­aWeb, 2022). The genus Hy­lo­rina was in­cluded within the same fam­ily after Gen­Bank dis­cov­er­ies found DNA sim­i­lar­i­ties to other Eu­p­so­phus species, but no tax­on­omy clas­si­fi­ca­tions have been of­fi­cially changed (Pyron & Wiens, 2011). Al­sodes is often dis­tin­guished by the males of its species, who have patches of spines on their chests and smaller spines on their first and sec­ond dig­its, both of which are most promi­nent dur­ing mat­ing sea­sons. As such, these frogs are often re­ferred to as “spiny-chest frogs” with other mem­bers of the fam­ily com­monly called “ground frogs” or “rapid frogs” (Am­phib­i­aWeb, 2022). De­spite some tad­poles of the genus dis­play­ing var­i­ous col­or­ings and char­ac­ter­is­tics, they are all cat­e­go­rized ac­cord­ing to their medium body size with rounded tail tips and that they often found in sim­i­lar fresh­wa­ter en­vi­ron­ments. The adults can be clas­si­fied ac­cord­ing to char­ac­ter­is­tics be­yond that of spiny struc­tures on the chest and fin­gers, such as well-de­vel­oped hum­meral crests and in­ter­nal mor­phol­ogy (For­mas & Cuevas, 2017). Al­sodes mon­ti­cola was the first species of the genus to be de­scribed, ob­served by Charles Dar­win and named by Thomas Bell in 1843 in The Zo­ol­ogy of the Voy­age of H.M.S Bea­gle (1832-1836) Vol­ume IV., Rep­tiles (Lynch, 1968). (Am­phib­i­aWeb, 2022; For­mas and Cuevas, 2017; Lynch, 1968; Pyron and Wiens, 2011)

Ge­o­graphic Range

Species within Al­sodes are re­stricted to small ge­o­graph­i­cal areas through­out cen­tral and south­ern Chile, such as the Chilean Coastal Range and in­land Ar­gentina; par­tic­u­larly the shared re­gion be­tween the two coun­tries, known as Patag­o­nia, where they are con­sid­ered to be the most species-rich frog fam­ily of the area (For­mas & Cuevas, 2003; Blotto et al., 2013). Al­sodes pe­huenche and Al­sodes gar­gola are the two species found on both sides of the An­dean Moun­tain Range, in both Chile’s west­ern slopes and Ar­gentina’s east­ern slopes (Blotto et al., 2013). The tem­per­ate Nothofa­gus forests of Chile’s coastal moun­tain ranges are found to house species from both the Eu­p­so­phus and Al­sodes gen­era (Cuevas & For­mas, 2005). Spiny-chest frogs are found in a va­ri­ety of provinces, such as Ar­gentina's Men­doza, Chubut, and Rio Negro, and Chile’s Maule, Los Lagos, and San­ti­ago, among oth­ers (IUCN, 2022). (Blotto, et al., 2013; Cuevas and For­mas, 2005a; For­mas and Cuevas, 2003; IUCN, 2022)

Habi­tat

Re­gard­less of which side of the Andes the spiny-chest frogs are found on, the habi­tat is usu­ally ter­res­trial fresh­wa­ter and in­land wet­lands. Al­ti­tudes and exact habi­tats may vary from species to species, such as A. gar­gola and A. can­til­la­nen­sis, both of which are also found in shrub­lands and/or forests (IUCN, 2022). Species found in forested lo­ca­tions may be re­stricted to meadow areas. They com­monly oc­cupy snowmelt streams/ponds with neu­tral pH’s, alpine lakes or for­est streams, and/or under lay­ers of leaf lit­ter and de­bris near wet­lands (IUCN, 2022). The tad­poles re­side at the bot­tom (ben­thic area) of still bod­ies of water known as lentic water sys­tems, in­clud­ing wet­lands, ponds, and lakes (Flem­ing, 2019; For­mas & Cuevas, 2017). (Flem­ing, 2019; For­mas and Cuevas, 2017; IUCN, 2022)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • coastal

Sys­tem­atic and Tax­o­nomic His­tory

Al­sodes be­longs solely to the fam­ily Al­so­di­dae, along with Eu­p­so­phus and Lim­nome­dusa, but spiny chest frogs boast the great­est num­ber of species of all three gen­era. Re­cent re­search has sug­gested that Hy­lo­rina should be in­cluded within the fam­ily Al­so­di­dae, while ge­netic sup­port in­di­cates that Lim­nome­dusa should be con­sid­ered for re­moval from the clade (Pyron & Wiens, 2011). The defin­ing char­ac­ter­is­tic of spines upon their fin­gers and chests work to iden­tify Al­sodes as one col­lec­tive genus with lit­tle de­bate. For re­searchers who pre­scribe to sub-group­ings, ev­i­dence sug­gests the fam­ily Al­so­di­dae is a sub­fam­ily of the larger fam­ily Cy­clo­ram­phi­dae. Spiny chest frogs and other Eu­p­so­phus species were first named in 1843 by Thomas Bell and ob­served by Dar­win on his fifth voy­age; how­ever, later re­search sug­gests that the A. mon­ti­cola in­di­vid­u­als de­scribed may have ac­tu­ally been part of Eu­p­so­phus (Lynch, 1968). Lynch (1968) there­fore sug­gests that Al­sodes should used as a syn­onym for Eu­p­so­phus based on Bell’s de­scrip­tions. (Cuevas and For­mas, 2005a; Lynch, 1968; Pyron and Wiens, 2011)

  • Synonyms
  • Synapomorphies
    • Round thorny excrescences on thumb and pectorals
    • Diploid number of 2n=22,26, or 34

Phys­i­cal De­scrip­tion

Al­sodes species are mostly smooth-skinned, small/medium frogs, falling within the length range of 25-70mm and dis­play­ing sex­ual di­mor­phism in terms of size and the pres­ence of rounded spiny adorn­ments on males' chests and fin­gers. Both males and fe­males dis­play con­sis­tent col­ors (which are mostly yel­low or brown) and retic­u­lated, stripped, or spot­ted pat­terns which can fea­ture white or black ac­cents. This is dis­played in one of the larger species of the fam­ily Al­so­di­dae, A. val­divien­sis, which are brown frogs that dis­play a faint yel­low tri­an­gle on their head and have com­mon size dif­fer­ences be­tween sexes, with males length rang­ing from 39.5 - 59.8mm in com­par­i­son to 39.7 - 63.4 mm fe­males. Most species lack web­bing be­tween fin­gers and only have lim­ited web­bing of their hind feet (Am­phib­i­aWeb, 2022). There have been sug­ges­tions for two gen­eral groups within Al­sodes to be dis­tin­guished: one hav­ing “sim­ple” spiny or­na­men­ta­tion on the fin­gers due to poor ker­a­tinized nup­tial pads on the front hands, and the other being “com­plex” in which species boast stronger and darker thorny pro­tru­sions (Blotto et al., 2013). (Am­phib­i­aWeb, 2022; Blotto, et al., 2013)

De­vel­op­ment

Re­pro­duc­tion

Al­sodes species are known for their males, who pro­duce nup­tial rounded spiny thorns on their chests dur­ing the re­pro­duc­tive sea­son and have in­creased pres­ence of fin­ger spines, most com­monly on the thumb and fore­fin­ger (Cuevas & For­mas, 2005b). (Cuevas and For­mas, 2005b)

No mat­ing calls have been recorded in this genus. Due to Chile and Pato­go­nia’s neotrop­i­cal cli­mate, breed­ing sea­sons vary slightly de­pend­ing on the species. A. val­divien­sis's breed­ing sea­son is around No­vem­ber-De­cem­ber, which co­in­cides with their ten­dency to re­pro­duce in colder streams (Am­phib­i­aWeb, 2022). A. pe­huenche fe­males lay eggs in clumps at the be­gin­ning of the sum­mer (Cor­balan et al, 2014). A. can­til­la­nen­sis fe­males lay eggs in clutches of roughly 60 and share breed­ing sites with other am­phib­ians and fish, most no­tably their sis­ter taxa, A. no­dosus. No re­pro­duc­tive iso­la­tion mech­a­nisms are cur­rently known for these two species. A. van­zolinii in­di­vid­u­als have a re­pro­duc­tive sea­son around Jan­u­ary-Feb­ru­ary, lay­ing yel­low-tinted eggs with a 2.33mm di­am­e­ter, and are often only ac­tive at night (Am­phib­i­aWeb, 2022). Over­all, more re­search and ob­ser­va­tions are needed for Al­sodes's re­pro­duc­tion meth­ods. (Am­phib­i­aWeb, 2022; Cor­balan, et al., 2014)

Al­sodes fe­males carry and lay eggs (Am­phib­i­aWeb, 2022). New re­search in­di­cates that some species, like A. pe­huenche may have lar­val cy­cles that can stretch be­tween four or five years (Cor­balan et al, 2014). More ob­ser­va­tions re­gard­ing parental care and pro­tec­tive ten­den­cies in this genus are re­quired. (Am­phib­i­aWeb, 2022; Cor­balan, et al., 2014)

  • Parental Investment
  • no parental involvement

Lifes­pan/Longevity

Al­sodes frogs' lifes­pans in their nat­ural en­vi­ron­ment is not well doc­u­mented, and some adult species have yet to be ob­served more than a hand­ful of times. How­ever, re­search sug­gests that sev­eral Patag­on­ian species are sen­si­tive to chang­ing water qual­ity and may face is­sues re­gard­ing habi­tat loss and al­ter­ca­tion, which may strongly re­duce pop­u­la­tion size and longevity (Cor­balan et al., 2010; Am­phib­i­aWeb, 2022). (Am­phib­i­aWeb, 2022; Cor­balan, et al., 2010)

Be­hav­ior

Some spiny chest frog species have yet to have in­for­ma­tion recorded re­gard­ing in­ter­ac­tive be­hav­iors amongst other Al­sodes species or other am­phib­ian species. Due to the mi­cro­hab­i­tats they re­side in, re­search sug­gests most species seem to in­ter­act fairly peace­fully. This is fur­ther demon­strated by the co­ex­is­tence of species like A. tu­mul­tu­o­sus and A. mon­tanus, which have been found to in­habit the same streams with minor spa­tial seg­re­ga­tion seen through their pref­er­ence for lower stream mar­ginal pools and high stream larger pools, re­spec­tively (Diaz & Va­len­cia, 1985). Like­wise, peace­ful co­hab­i­ta­tion be­tween A. can­til­la­nen­sis and A. nodosus, along with other am­phib­ians in the same water source, have been noted (Am­phib­i­aWeb, 2022). (AmphibiaWeb, 2022; Diaz and Valencia, 1985)

Communication and Perception

There is no available information within the literature regarding communication/perception techniques in this genus. However, the lack of observed mating calls of Alsodes species may indicate communication via methods other than acoustic signaling. Likewise, the protruding spiny thorn on males' chests during breeding season suggests the structure may play a role in mating and communication.

Food Habits

As tadpoles, Alsodes species are phytophagous and detritivorous with their main dietary components being periphytic algae and protozoa (Baffico & Ubeda, 2006). As adults, Alsodes are insectivores like most amphibians. Slight variations occur based on habitats differences, but their most common prey include beetles, springtails, flies, spiders, and isopods, with the frogs' diets focused on the larval stages of beetles, flies and moths (Alveal et al., 2015). (Alveal, et al., 2015; Baffico and Ubeda, 2066)

Predation

Most Alsodes species experience long larval periods (about 2 years), which can leave them vulnerable to predation. Recent studies suggest that invasive fish species, specifically rainbow trout (Oncorhynchus mykiss), rapidly increase predation rates of spiny chest frogs and decrease populations of Alsodes in both adult and larval stages (Zarco et al., 2020). (Zarco, et al., 2020)

Ecosystem Roles

Alsodes species fulfill an important ecological role as insectivores. Spiny chest frog populations help balance populations because their diets consist of prominent larval insect species. Many species are considered critically endangered or vulnerable according to both the Chilean government and IUCN Red List, which has further implications for how Patagonian ecosystems will shift in response to a reduction or total loss of spiny chest frog populations (Correa et al., 2018). (Correa, et al., 2018)

Economic Importance for Humans: Positive

Alsodes's insectivorous diets work to regulate insect populations of Patagonia within their microhabitats (Alveal et al., 2015). Available literature lacks information directly linking Alsodidae presence to protection of human agriculture or lumber, but it may be implied. (Alveal, et al., 2015)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

Presently, there is no suggestion of any negative economic repercussions of Alsodes species on humans. Their non-poisonous and non-invasive status supports this statement.

Conservation Status

According to the IUCN Red List (2022), the conservation status of five Alsodes species are unknown, and the other 15 species are categorized from vulnerable to critically endangered, with two species (A. nodosus and A. gargola) considered the most stable and therefore of least conservation concern. Populations have been impacted by invasive fish species and changes in climate, both of which increase habitat loss and impact microhabitats and water quality. This reduces lifespan and overall population size (Zarco et al., 2020; Corbalan et al., 2010). (Corbalan, et al., 2010; IUCN, 2022; Zarco, et al., 2020)

  • IUCN Red List [Link]
    Not Evaluated

Contributors

Alexandra Wettengel (author), Colorado State University, Audrey Bowman (editor), Colorado State University, Sydney Collins (editor), Colorado State University.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

freshwater

mainly lives in water that is not salty.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

insectivore

An animal that eats mainly insects or spiders.

marsh

marshes are wetland areas often dominated by grasses and reeds.

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

planktivore

an animal that mainly eats plankton

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

sexual ornamentation

one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

References

Alveal, N., H. Diaz, A. Henriquez, O. Vergara. 2015. Dietary aspects of Alsodes coppingeri Günther, 1881 (Anura: Alsodidae) in Chile. Gayana, 79 (1): 5-10. Accessed March 06, 2022 at https://www.researchgate.net/publication/279752211_Dietary_aspects_of_Alsodes_coppingeri_Gunther_1881_Anura_Alsodidae_in_Chile.

AmphibiaWeb, 2022. "Alsodidae" (On-line). Information on amphibian biology and conservation.. Accessed February 03, 2022 at https://amphibiaweb.org/lists/Alsodidae.shtml.

Baffico, G., C. Ubeda. 2066. Larval diet of the frog Alsodes gargola (Leptodactylidae: Telmatobiinae) and some ecological considerations on its role in alpine and mountain aquatic environments in Patagonia. Amphibia-reptillia, 1: 161-168. Accessed March 06, 2022 at https://www.academia.edu/17039324/Larval_diet_of_the_frog_Alsodes_gargola_Leptodactylidae_Telmatobiinae_and_some_ecological_considerations_on_its_role_in_alpine_and_mountain_aquatic_environments_in_Patagonia.

Blotto, B., J. Nunez, N. Basso, C. Ubeda, W. Wheeler, J. Faivovich. 2013. Phylogenetic relationships of Patagonian frog radiation, the Alsodes + Eupsophus clade (Anura: Alsodidae), with comments on the supposed paraphyly of Eupsophus. Cladistics, 1: 113-131. Accessed February 03, 2022 at https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1096-0031.2012.00417.x.

Charrier, A., C. Correa, C. Castro, M. Mendez. 2015. A new species of Alsodes (Anura: Alsodidae) from Altos de Cantillana, central Chile. Zootaxa, 4: 540-550. Accessed February 03, 2022 at https://repositorio.uchile.cl/bitstream/handle/2250/132515/A-new-species-of-Alsodes-Anura-Alsodidae-from-Altos-de-Cantillana.pdf?sequence=1.

Corbalan, V., G. Debandi, F. Martinez, C. Ubeda. 2014. Prolonged larval development in the Critically Endangered Pehuenche’s frog Alsodes pehuenche: implications for conservation. Amphibia-reptillia, 35:3: 282-292. Accessed February 20, 2022 at https://doi.org/10.1163/15685381-00002951.

Corbalan, V., G. Demandi, F. Martinez. 2010. Alsodes Pehuenche (Anura: Cycloramphidae): Past, present and future. Cuadernos de Herpetologia, 24 (1): 17-23. Accessed February 27, 2022 at https://www.researchgate.net/publication/258223561_Alsodes_pehuenche_Anura_Cycloramphidae_Past_present_and_future.

Correa, C., P. Godoy, N. Lagos, H. Salinas, R. Palma, D. Vasquez. 2018. New populations of two threatened species of Alsodes (Anura, Alsodidae) reveal the scarce biogeographic knowledge of the genus in the Andes of central Chile. Zoosystematics and Evolution, 94 (2): 349-359. Accessed March 06, 2022 at https://www.researchgate.net/publication/326430007_New_populations_of_two_threatened_species_of_Alsodes_Anura_Alsodidae_reveal_the_scarce_biogeographic_knowledge_of_the_genus_in_the_Andes_of_central_Chile.

Cuevas, C., J. Formas. 2005. A new frog of the genus Alsodes (Leptodactylidae) from the Tolhuaca National Park, Andes Range, southern Chile. Amphibia-reptillia, 26: 39-48. Accessed February 20, 2022 at https://www.academia.edu/4744790/A_new_frog_of_the_genus_Alsodes_Leptodactylidae_from_the_Tolhuaca_National_Park_Andes_Range_southern_Chile.

Cuevas, C., R. Formas. 2005. Novel diploid number and chromosomal formula in a south American frog of the genus Alsodes. Italian Journal of Zoology, 72 (2): 87-91. Accessed February 03, 2022 at https://www.academia.edu/7316229/Novel_diploid_number_and_chromosomal_formula_in_a_south_American_frog_of_the_genus_Alsodes.

Darwin, C., T. Bell. 1843. THE ZOOLOGY OF THE VOYAGE OF H.M.S. BEAGLE, UNDER THE COMMAND OF CAPTAIN FITZROY, R.N., DURING THE YEARS 1832 TO 1836.. London: SMITH, ELDER AND CO. 65, CORNHILL.. Accessed February 03, 2022 at http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F9.5&pageseq=1.

Diaz, N., J. Valencia. 1985. Microhabitat utilization by two leptodactylid frogs in the Andes of central Chile. Oecologia, 66 (3): 353-357. Accessed February 27, 2022 at https://pubmed.ncbi.nlm.nih.gov/28310861/.

Fleming, E. 2019. "What is the difference between lentil and lotic bodies of water?" (On-line). SidmartionBio. Accessed February 13, 2022 at https://www.sidmartinbio.org/what-is-the-difference-between-lentic-and-lotic-bodies-of-water/.

Formas, R., C. Cuevas. 2017. The tadpole of Alsodes cf. norae (Anura: Alsodidae) with comments on the diagnosis of the genus Alsodes. Salamandra, 50 (1): 131-136. Accessed February 03, 2022 at https://ia801901.us.archive.org/35/items/salamandra-53-131-136/salamandra-53-131-136.pdf.

Formas, R., C. Cuevas. 2003. Cytogenetic analysis of four species of the genus Alsodes (Anura: Leptodactylidae) with comments about the karyological evolution of the genus. Hereditas, 138 (2): 138-147. Accessed February 03, 2022 at https://onlinelibrary.wiley.com/doi/full/10.1034/j.1601-5223.2003.01677.x.

IUCN, 2022. "IUCN Red List of Threatened Species. Version 2021-3" (On-line). Alsodes. Accessed February 13, 2022 at https://www.iucnredlist.org/search?query=alsodes&searchType=species.

Lynch, J. 1968. The Identity of a Chilean Frog, Alsodes monticola Bell, and the Status of the Genus Alsodes (Amphibia: Leptodactylidae). Herpetologica, 24 (3): 255-257. Accessed February 03, 2022 at https://www.jstor.org/stable/3891024.

Pyron, A., J. Wiens. 2011. A large-scale phylogeny of Amphibia including over 2800 species, and a revised classification of extant frogs, salamanders, and caecilians. Molecular Phylogenetics and Evolution, 61 (2): 543-583. Accessed February 03, 2022 at https://www.sciencedirect.com/science/article/pii/S105579031100279X.

Vitt, L., J. Caldwell. 2009. Herpetology An Introductory Biology of Amphibians and Reptiles. Oxford, UK: Elsevier. Accessed February 03, 2022 at https://www.sciencedirect.com/book/9780123743466/herpetology#book-info.

Zarco, A., V. Corbalan, G. Debandi. 2020. Predation by invasive rainbow trout on the critically endangered Pehuenche Spiny-chest Frog. Journal of Fish Biology, 98(3): 878-880. Accessed March 06, 2022 at https://doi.org/10.1111/jfb.14609.