View source for Tailed frog

{{Short description|Genus of frogs}}
{{Automatic taxobox
| name = Tailed frogs
| image = Ascaphus_truei_web.jpg
| display_parents = 2
| parent_authority = Fejérváry, 1923
| taxon = Ascaphus
| authority = [[Leonhard Hess Stejneger|Stejneger]], 1899
| subdivision_ranks = Species
| subdivision =
*''Ascaphus montanus'' <small>(Mittleman and Myers, 1949)</small>
*''Ascaphus truei'' <small>([[Leonhard Hess Stejneger|Stejneger]], 1899)</small>
| range_map = Ascaphus range.png
| range_map_caption = Distribution of Ascaphidae (in black)
}}

The '''tailed frogs''' are two [[species]] of [[frog]]s in the genus '''''Ascaphus''''',<ref name=frost>{{cite web |url=https://amphibiansoftheworld.amnh.org/Amphibia/Anura/Ascaphidae/Ascaphus |title=''Ascaphus'' Stejneger, 1899 |author=Frost, Darrel R. |year=2024 |work=Amphibian Species of the World: an Online Reference. Version 6.2 |publisher=American Museum of Natural History |doi=10.5531/db.vz.0001 |access-date=2 June 2024 }}</ref> the only taxon in the family '''Ascaphidae''' {{IPAc-en|æ|ˈ|s|k|æ|f|ᵻ|d|iː}}.<ref>{{cite web |url=https://amphibiansoftheworld.amnh.org/Amphibia/Anura/Ascaphidae |title=Ascaphidae Fejérváry, 1923 |author=Frost, Darrel R. |year=2024 |work=Amphibian Species of the World: an Online Reference. Version 6.2 |publisher=American Museum of Natural History |doi=10.5531/db.vz.0001 |access-date=2 June 2024 }}</ref> The "tail" in the name is actually an extension of the male [[cloaca]]. The tail is one of two distinctive anatomical features adapting the species to life in fast-flowing streams.  These are the only North American frog species that reproduce by [[internal fertilization]].<ref>{{cite web |url=http://www.greendiamond.com/environment/wildlife.asp |title=Wildlife |publisher=Green Diamond Resource Company |access-date=2020-07-19 |url-status=dead |archive-url=https://web.archive.org/web/20081119151137/http://www.greendiamond.com/environment/wildlife.asp |archive-date=2008-11-19 }}</ref> They are among the most primitive known families of frogs.

Its scientific name means 'without a spade', from the privative prefix ''[[privative a|a-]]'' and the Ancient Greek ''{{Transliteration|grc|skaphís}}'' ({{lang|grc|σκαφίς}}, 'spade, shovel'), referring to the [[metatarsal]] spade, which these frogs do not have.<ref>{{LSJ|skafi/s1|σκαφίς|ref}}</ref><ref>{{cite book|last=Dodd|first=C. Kenneth|title=Frogs of the United States and Canada|url=https://books.google.com/books?id=2Hwfz9P9gS0C&pg=PR20|volume=1|date=2013|publisher=The Johns Hopkins University Press|isbn=978-1-4214-0633-6|page=20}}</ref>

==Taxonomy==
Until 2001, the genus was believed to be [[monotypic]], the single species being the tailed frog (''Ascaphus truei'' [[Leonhard Hess Stejneger|Stejneger]], 1899). However, in that year, Nielson, Lohman, and Sullivan published evidence that promoted the Rocky Mountain tailed frog (''Ascaphus montanus'') from a [[subspecies]] to its own species.<ref>{{Cite journal | last1 = Nielson | first1 = M. | last2 = Lohman | first2 = K. | last3 = Sullivan | first3 = J. | doi = 10.1111/j.0014-3820.2001.tb01280.x | title = Phylogeography of the tailed frog (''Ascaphus truei''): Implications for the biogeography of the Pacific Northwest | journal = Evolution | volume = 55 | issue = 1 | pages = 147–160 | year = 2001 | pmid = 11263735 | s2cid = 118785 | doi-access = free }}</ref> Since then, the former species has been formally called the coastal tailed frog.

The genus ''Ascaphus'', through [[mitochondrial DNA|mtDNA]] comparisons, has been grouped into a [[clade]] with the genus ''[[Leiopelma]]'' creating a [[sister group|sister taxon]] to all modern [[frogs|anurans]].<ref name="Irisarri 2010">{{Cite journal | last1 = Irisarri | first1 = I. | last2 = Diego | first2 = S.M. | last3 = Green | first3 = D.M. | last4 = Zardoya | first4 = F. | doi = 10.3109/19401736.2010.513973 | title = The complete mitochondrial genome of the relict frog ''Leiopelma archeyi'': Insights into the root of the frog Tree of Life | journal = Mitochondrial DNA | volume = 21 | issue = 5 | pages = 173–182 | year = 2010 }}</ref>

==General morphology==
[[Image:tailed frog.gif|thumb|left|Tailed frog size compared to a [[Dime (United States coin)|dime]]]]
The existence of the visible "tail" appendage makes this frog family distinct from all other frogs. It is usually classified in the ancient frog suborder [[Archaeobatrachia]] and further organized into a basal clade with ''Leiopelma'' that is considered a sister taxon to all other frogs.<ref name="Irisarri 2010" />

The "tail" is found only in males, and is actually part of the cloaca, used to insert sperm into the female during mating. This anatomical feature improves breeding success by minimizing loss of sperm in the turbulent, fast-flowing streams inhabited by this species.  Thus, the tailed frogs exhibit internal fertilisation, rather than the [[external fertilisation]] found in other frogs.<ref name=EoR>{{cite book |editor=Cogger, H.G. |editor2=Zweifel, R.G.|author= Zweifel, Richard G.|year=1998|title=Encyclopedia of Reptiles and Amphibians|publisher= Academic Press|location=San Diego|pages= 84–85|isbn= 0-12-178560-2}}</ref>

Ascaphidae and [[Leiopelma]]tidae are [[Plesiomorphy and symplesiomorphy|primitive]] to almost all other frogs in having nine [[amphicoelous]] [[vertebrae]] and a caudalipuboischiotibialis tail-wagging muscle in adults,<ref>{{Cite journal|last1=Green|first1=D.M.|last2=Cannatella|first2=D|date=1993|title=Phylogenetic significance of the amphicoelous frogs, Ascaphidae and Leiopelmatidae|journal=Ethology Ecology & Evolution|volume=5|issue=2 |pages=233–245|doi=10.1080/08927014.1993.9523107}}</ref>  a type of vertebrae seen mostly in [[fish]] and early terrestrial [[tetrapod]] fossils (such as fossil [[salamander]]s and fossil [[frog]]s). The joints in amphicoelous vertebrae allow for significant lateral movement of the vertebral column, seen most clearly when fish use their tail to generate propulsive force. An additional plesiomorphy is the presence of free ribs in adults, a characteristic only present in the basal group [[archaeobatrachia]].<ref>{{Cite journal|last1=Blanco|first1=M.J.|last2=Sanchiz|first2=B.|date=2000|title=Evolutionary Mechanisms of Rib Loss in Anurans: A Comparative Developmental Approach|journal=Journal of Morphology|volume=244|pages=57–67|doi=10.1002/(SICI)1097-4687(200004)244:1<57::AID-JMOR6>3.0.CO;2-7}}</ref>

Ascaphids lack the ability to [[Animal communication|vocalise]], are small – around {{convert|2.5|to|5.0|cm|in|abbr=on}} long – and are found in steep, fast-flowing streams in Montana, Idaho, Washington, Oregon, and northern California in the northwest United States, and southeastern [[British Columbia]] (Rocky Mountain Tailed Frog) and coastal BC (Coastal Tailed Frog).

Unique to the tailed frogs is the ability to secrete a series of antimicrobial peptides called ascaphins. These peptides share minimal genetic characteristics with other peptides secreted by frogs, yet show some similarities with antibacterial peptides found in African scorpions ''[[Pandinus imperator]]'' and ''[[Opistophthalmus carinatus]]''. The ascaphin peptides are secreted through the skin and imperative in fighting bacteria such as ''E. coli'' and ''S. aureus''.<ref>{{Cite journal|last1=Conlon|first1=Michael|last2=Sonnevend|first2=Agnes|last3=Davidson|first3=Carlos|last4=Smith|first4=David|last5=Nielsen|first5=Per|date=July 16, 2004|title=The ascaphins: a family of antimicrobial peptides from the skin secretions of the most primitive extant frog, ''Ascaphus truei'' |url=https://www.sciencedirect.com/science/article/pii/S0006291X04011520#!|journal=Biochemical and Biophysical Research Communications|volume=320|issue=1 |pages=170–175|doi=10.1016/j.bbrc.2004.05.141|pmid=15207717 |via=Elsevier|url-access=subscription}}</ref>

The tailed frogs share certain characteristics with the ''[[Leiopelmatidae|Leiopelma]]'', a genus of primitive frogs native to [[New Zealand]], with which they are a phylogenetic sister taxon to all other [[frogs|anurans]].<ref name="Irisarri 2010" />

== Mating behaviour ==
When attempting to mate, males will lunge at the female, wrapping a forelimb around them to secure them initially in an inguinal amplexus formation (males wrap their digits around female anterior to the pelvic region, placing their head on the back and close to the rear of the female) and then in a ventral amplexus formation (female is flipped over and male and female venters face each other). From here, the male inserts the "tail" into the female, and squeezes the female to gain leverage before thrusting. During this process the female is relatively still, occasionally kicking during the insertion process.<ref name=":0">{{Cite journal|last1=Stephenson|first1=Barry|last2=Verrell|first2=Paul|date=March 12, 2002|title=Courtship and mating of the tailed frog (''Ascaphus truei'') |url=https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1017/S095283690200331X|journal=Journal of Zoology|volume=259|pages=15–22|doi=10.1017/S095283690200331X |url-access=subscription}}</ref>

In some situations there is male-male competition for the female. In these situations, both males compete to enter the amplexus formation, eventually one establishing a better hold on the female and expelling the other male from the breeding process.  Usually the male that is larger is more likely to succeed.<ref name=":0" />

==General habitat==
[[File:Ascaphus montanus tadpole.JPG|thumb|''Ascaphus montanus'' tadpole ([[Supine position|supine]] position), showing the large [[oral sucker]]]]
The habitat of the tailed frog is cold, fast-moving streams with cobblestone bottoms. They are mostly aquatic, but adults may emerge during cool, wet conditions to forage terrestrially. [[Breeding season]] lasts from May through September, and females deposit their [[Egg (biology)#Frog eggs|eggs]] in strings under rocks in fast-moving streams. [[Larva]]e take one to four years to metamorphose in the cool, fast-moving mountain streams. The amount of cobbles and fines (sand and similarly sized fine particles) in streams have been shown to be good indicators of tadpole abundance, with tadpole abundance being inversely proportional to concentration of fines and proportional to concentration of cobbles.<ref>Committee on the Status of Endangered Wildlife in Canada, ''COSEWIC assessment and status report on the Coastal Tailed Frog, Ascaphus truei, in Canada'', Canadian Wildlife Service, 2011, https://publications.gc.ca/collections/collection_2012/ec/CW69-14-639-2012-eng.pdf</ref><ref>United States, Congress, Bull, Evelyn L., and Bernard E. Carter. ''Tailed Frogs: Distribution, Ecology, and Association with Timber Harvest in Northeastern Oregon'', U.S. Forest Service, Pacific Northwest Forest and Range Experiment Station, 1996.</ref>

Thermal tolerance range in adults is exceptionally low relative to other North American anurans, with eggs rarely found above 20&nbsp;°C and adults and larvae regularly migrating along microhabitats to reach temperatures below 20&nbsp;°C whenever possible. It would appear that they prefer temperatures 16&nbsp;°C and below. Eggs develop best at temperatures between 5° and 13.5&nbsp;°C.<ref name="Thermal use">{{cite journal |last1=Adams |first1=Susan B. |last2=Frissell |first2=Christopher A. |title=Thermal habitat use and evidence of seasonal migration by Rocky Mountain Tailed Frogs, ''Ascaphus montanus'', in Montana, USA |journal=Canadian Field-Naturalist |date=2001 |volume=115 |issue=2 |pages=251–256 |doi=10.5962/p.363786 |url=https://www.biodiversitylibrary.org/part/363786|doi-access=free }}</ref>

Because of this very narrow thermal tolerance, adults may exhibit [[philopatry]] where temperatures are stable and low. However, it has also been hypothesized that they may migrate to colder waters in autumn. Unfortunately, movements and migrational habits in ''Ascaphus'' have not been well documented, preventing any conclusive statements on migratory behavior or [[philopatry]] from being made with confidence.<ref name="Thermal use" />

Adults forage primarily terrestrially along stream banks, but also occasionally feed underwater. A wide variety of food items is taken, including both aquatic and terrestrial larval and adult [[insect]]s, other [[arthropod]]s (especially [[spider]]s), and [[snail]]s. [[Tadpole]]s consume small quantities of filamentous green [[alga]]e and [[desmid]]s. Large quantities of conifer [[pollen]] are consumed seasonally by tadpoles.<ref name="life history">{{cite journal |last1=Morey |first1=S |last2=Papenfuss |first2=T |last3=Harris |first3= RDJ |last4=CWHR Program Staff |date=2000 |title=Life history account for coastal tailed frog, ''Ascaphus truei''  |url=https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=1466 |journal=California Wildlife Habitat Relationships System }}</ref>

During the day, adults seek cover under submerged substrates in the stream, or occasionally under similar surface objects close to the stream. Individuals have also been found in crevices in spray-drenched cliff walls near [[waterfalls]]. During winter, individuals are less active, especially inland, and appear to retreat beneath large logs and boulders. Tadpoles require cool streams with smooth-surfaced stones with a minimum diameter of {{convert|55|mm|in|abbr=on}}. Tadpoles probably spend most of their time attached to such substrates by a large [[suckermouth|oral sucker]]. The large, sucker-like mouth parts of the tadpoles are a second distinctive feature of the species, enabling survival in turbulent water unsuitable for other frogs.  They prefer turbulent water to smooth, swiftly flowing water.<ref name="life history" />

==References==
{{Reflist}}
*{{cite journal|last1=Gissi|first1=Carmela|title=Mitochondrial phylogeny of Anura (Amphibia): A case study of congruent phylogenetic reconstruction using amino acid and nucleotide characters|doi=10.1016/j.gene.2005.07.034|journal=Gene|volume=366|pages=228–237|date=February 2006|author2=Diego San Mauro|author3=Graziano Pesole|author4=Rafael Zardoya|pmid=16307849|issue=2}}
*{{cite journal|last1=Roelants|first1=Kim|title=Archaeobatrachian paraphyly and pangaean diversification of crown-group frogs|journal=Systematic Biology|volume=54|pages=111–126|date=February 2005|author2=Franky Bossuyt|doi=10.1080/10635150590905894|pmid=15805014|issue=1|doi-access=free}}
*{{cite journal|last1=San Mauro|first1=Diego|title=Initial diversification of living amphibians predated the breakup of Pangaea |journal=American Naturalist|volume=165|pages=590–599|date=May 2005|author2=Miguel Vences|author3=Marina Alcobendas|author4=Rafael Zardoya|author5=Axel Meyer|doi=10.1086/429523|pmid=15795855|issue=5|s2cid=17021360|url-status=}}{{dead link|date=September 2023}}
*[https://web.archive.org/web/20070317071449/http://www.dfg.ca.gov/bdb/pdfs/tailedfrog.pdf Excerpt from Zeiner et al. 1988 describing tailed frogs]

==External links==
{{Commons category|Ascaphus}}

{{Anura}}
{{Taxonbar|from=Q1155115 |from2=Q2925426 |from3=Q996518 |from4=Q3116498}}
{{Authority control}}

{{DEFAULTSORT:Tailed Frog}}
[[Category:Archaeobatrachia]]
[[Category:Amphibians of Canada]]
[[Category:Amphibians of the United States]]
[[Category:Fauna of California]]
[[Category:Fauna of the Western United States]]
[[Category:Endemic fauna of the Pacific Northwest]]
[[Category:Taxa named by Leonhard Stejneger]]