Spikethumb frog

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Spikethumb frogs
Plectrohyla dasypus01.jpeg
Plectrohyla dasypus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Hylidae
Subfamily: Hylinae
Genus: Plectrohyla
Brocchi, 1877
Species

See text.

Spikethumb frogs are a genus (Plectrohyla) of frogs in the family Hylidae found in Central America from southern Mexico through Guatemala and northern El Salvador to central and northern Honduras. A major revision of the Hylidae moved an additional 21 species to this genus from the genus Hyla . [1] The additional species moved to Plectrohyla were identified as the Hyla bistincta group, also called the Plectrohyla bistincta group; a separate group from the initial Plectrohyla guatemalensis group. [2] This phylogenetic classification was later revised by moving the Plectrohyla bistincta group from the genus Plectrohyla into a new genus called Sarcohyla. Meanwhile, the guatemalensis group remained in Plectrohyla. [3] They are called spikethumb because of the spike on their thumbs, which is called a prepollex. The genus name comes from the Greek word plēktron ("spur") [4] and hyla (the genus in which it was formerly placed).

Contents

Species

The following species are recognized in the genus Plectrohyla:

Binomial name and authorCommon name
Plectrohyla acanthodes (Duellman and Campbell, 1992)Thorny spikethumb frog
Plectrohyla avia (Stuart, 1952)Greater spikethumb frog
Plectrohyla calvata (McCranie, 2017)
Plectrohyla chrysopleura (Wilson, McCranie & Cruz-Díaz, 1994)
Plectrohyla dasypus (McCranie & Wilson, 1981)Honduras spikethumb frog
Plectrohyla exquisita (McCranie & Wilson, 1998)
Plectrohyla glandulosa (Boulenger, 1883)Forest spikethumb frog
Plectrohyla guatemalensis (Brocchi, 1877)Guatemala spikethumb frog
Plectrohyla hartwegi (Duellman, 1968)Hartweg's spikethumb frog
Plectrohyla hazelae (Taylor, 1940)Hazel's tree frog
Plectrohyla ixil (Stuart, 1942)Ixil spikethumb frog
Plectrohyla lacertosa (Bumzahem & Smith, 1954)Pop-eyed spikethumb frog
Plectrohyla matudai (Hartweg, 1941)Matuda's spikethumb frog
Plectrohyla pokomchi (Duellman & Campbell, 1984)Rio Sananja spikethumb frog
Plectrohyla psiloderma (McCranie & Wilson, 1999)
Plectrohyla pycnochila (Rabb, 1959)Thick-lipped spikethumb frog
Plectrohyla quecchi (Stuart, 1942)Las Palmas spikethumb frog
Plectrohyla sagorum (Hartweg, 1941)Arcane spikethumb frog
Plectrohyla tecunumani (Duellman & Campbell, 1984)Cave spikethumb frog
Plectrohyla teuchestes (Duellman & Campbell, 1992)Alta Verapaz spikethumb frog

Appearance

Spikethumb frogs range from 44 to 90 mm in adults, and have thick, glandular skin. Coloration ranges between shades of green, brown, and red. [5] Plectrohyla have an enlarged prepollex, which is a rudimentary additional digit near the thumb, that contains a sharp projecting spine. [5] The premaxilla is a bone in the anterior portion of the skull that has a bony outgrowth called the alary process, which projects posteriorly and divides into two branches. [6] Secondary sex characteristics in males include elongated premaxillary and maxillary teeth, in addition to swelling of the upper lip during breeding. [5]

Habitat

The genus Plectrohyla inhabit cold streams and ravines in montane and cloud forests. [5] [7] Characteristics of these streams include many rocks, crevices, small waterfalls, and a current to maintain water oxygenation levels. [7] Species of Plectrohyla remain near these streams year-round, often utilizing the same rock crevices for feeding and reproduction. [5] [7]  

Reproduction

During copulation, external fertilization is exhibited. As a female spikethumb frog releases her eggs into the water, an amplectant male fertilizes her eggs. [3] Axillary amplexus is the process in which a male positions itself on the back of a female, using its arms to encircle the female's body, so that it can fertilize the female's eggs as they are released. [5] These fertilized eggs then develop along the edges and base of the mating site. [7]

Male-Male Competition

Male spikethumb frogs of some species, such as P. guatemalensis, are often found calling from the crevices between rocks of streams. They utilize the same location along a stream for extended periods of time, where they can call for females, mate with females, and guard their fertilized eggs. The vocalizations of males have been recorded, [3] however further research is required to determine whether vocalizations are used for displaying aggression towards nearby males. [7] Vocalization is not universal amongst males in the genus however, as P. Hartwegi lack vocal sacs and vocal slits. [8]

Research suggests that males engage in male-male combat to maintain control of their mating sites, located within the crevices between rocks, as mating sites are likely a limiting resource. [7] The prepollex may be used during this combat, leaving scars on the head and forelimbs of males. These scars are not observed on females. [5]

Copulation

Spikethumb frogs reproduce in streams using axillary amplexus, a process that can take hours or days. [5] [8] Male spikethumb frogs display two secondary sexual characteristics that are used during reproduction. These include swollen upper lips and long premaxillary and maxillary teeth that protrude down beyond the lip. [9] The upper lip of females contains ordinary mucous glands, and these differ from the glands in the male's upper lip, which largely contains specialized mucous glands, also called breeding glands. [8] Ordinary glands are often found equally distributed throughout the body, which differ from specialized glands that are specifically located, often to perform a specific function. [10]

In Plectrohyla, the specialized mucous glands in the lips of males produce sodefrin precursor-like factors (SPF), which function as allohormones. [8] Allohormones are substances that are directly transmitted from one individual to another, circumventing the special senses, and can have various effects on copulation, including increased female receptivity, inhibition of remating, and altered sperm storage in females. [11] Male spikethumb frogs deliver allohormones via tramautic mating, in which the male presses its swollen upper lip and protruding premaxillary and maxillary teeth into the back of the female, leaving scratches on the female's back. [5] These scratches allow for direct transmission of the SPF allohormone into the bloodstream of the female, preventing loss to the environment. [8] These differ from pheromones, which are released into the environment and detected via the special senses. [12] Upon transmission into the bloodstream, SPF allohormones function by shortening courtship duration, however the exact effect of SPF allohormones on the physiological and behavioral changes to the female have not been determined. [8] Shortened courtship duration reduces risks of predation during copulation, increasing fitness. [8]

This copulatory mechanism resembles the condition of the plethodontid salamander, in which males use their elongated teeth to scratch the backs of females to deliver allohormones directly from the mental glands on their chin. [5] These allohormones increase female receptivity, which results in increased probability that the female will accept the male's sperm. [11]

Related Research Articles

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Hylidae is a wide-ranging family of frogs commonly referred to as "tree frogs and their allies". However, the hylids include a diversity of frog species, many of which do not live in trees, but are terrestrial or semiaquatic.

<i>Charadrahyla</i> Genus of amphibians

Charadrahyla is a genus of frogs in the family Hylidae. It is endemic to tropical southern Mexico. The generic name was derived from Greek charadra ("ravine") and Hyla, in reference to the habits of these frogs. Accordingly, common name ravine treefrogs has been coined for the genus.

Megastomatohyla is a genus of frogs in the family Hylidae. They are endemic to the cloud forests of central Veracruz and Oaxaca, Mexico. All are rare species with restricted distributions. The generic name is derived from Greek mega (="large") and stem of the genitive stomatos (="mouth"), referring to the enlarged oral disc of the tadpoles, juxtaposed with Hyla, the genus in which the four Megastomatohyla species were previously placed. Common name large-mouthed treefrogs has been coined for this genus.

<i>Tlalocohyla</i> Genus of amphibians

Tlalocohyla is a genus of frogs in the family Hylidae, also known as rain treefrogs or Middle American yellow-bellied treefrogs. They occur in Middle America between Mexico and Costa Rica. This genus was created in 2005 following a major revision of the Hylidae. The five species in this genus were previously placed in the genus Hyla.

<i>Isthmohyla</i> Genus of amphibians

Isthmohyla is a genus of frogs in the family Hylidae. This genus was erected in 2005 following a major revision of the Hylidae. The 15 species in this genus were previously placed in the genus Hyla. They are endemic to Central America in Honduras, Costa Rica, and Panama.

<i>Ecnomiohyla</i> Genus of amphibians

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<i>Bokermannohyla</i> Genus of amphibians

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<i>Dendropsophus</i> Genus of amphibians

Dendropsophus is a genus of frogs in the family Hylidae. They are distributed in Central and South America, from southern Mexico to northern Argentina and Uruguay. They are sometimes known under the common name Fitzinger neotropical treefrogs or yellow treefrogs

<i>Dendropsophus marmoratus</i> Species of frog

Dendropsophus marmoratus is a species of frog in the family Hylidae. It is found in the Amazon rainforest and montane forests in the eastern piedmont, in Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname, and Venezuela. Its natural habitats are subtropical or tropical moist lowland forests, intermittent freshwater marshes, and heavily degraded former forest. "Marmoratus" in Latin means "marble," perhaps referring to the dorsal coloring pattern. It is threatened by habitat loss.

Plectrohyla avia, also known as the greater spikethumb frog, is a species of frog in the family Hylidae. It occurs in Guatemala and Mexico and is found on the Pacific slopes of the Sierra Madre between southeastern Chiapas (Mexico) and southwestern Guatemala.

Sarcohyla celata, also known as the Oaxaca treefrog, is a species of frog in the family Hylidae. It is endemic to Mexico and only known from the Sierra de Juárez in northern Oaxaca. After having not been seen after 1984, it was feared that the species might be extinct. However, the species was rediscovered in field surveys during 2011–2014 and some subpopulations are at healthy levels.

<i>Plectrohyla guatemalensis</i> Species of amphibian

Plectrohyla guatemalensis, also known as the Guatemala spikethumb frog, is a species of frog in the family Hylidae. It occurs in the highlands of the Sierra Madre from southeastern Chiapas, Mexico, and eastward through the central and southwestern highlands of Guatemala to northwestern El Salvador as well as the Sierra de Nombre de Dios in north-central Honduras. It might be a composite of more than one species.

Plectrohyla matudai is a species of frog in the family Hylidae. It is found along the Pacific slopes from southeastern Oaxaca, Mexico, through Chiapas and south-central Guatemala ; also in the Grijalva Depression in western Guatemala and on Cerro Azul in northwestern Honduras.

<span class="mw-page-title-main">Nuptial pad</span> Secondary sex characteristic on some mature male frogs and salamanders

A nuptial pad is a secondary sex characteristic present on some mature male frogs and salamanders. Triggered by androgen hormones, this breeding gland appears as a spiked epithelial swelling on the forearm and prepollex that aids with grip, which is used primarily by males to grasp females during amplexus. They can also be used in male–male combat in some species.

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<span class="mw-page-title-main">Hylinae</span> Subfamily of amphibians

Hylinae is a large subfamily of "tree frogs", family Hylidae.

<i>Atlantihyla</i> Genus of amphibians

Atlantihyla is a genus of frogs in the family Hylidae. It is endemic to Central America, specifically to Honduras and Guatemala. The generic name refers to its distribution on the Atlantic side of the isthmus. The members of the genus are known as stream frogs.

<i>Sarcohyla</i> Genus of amphibians

Sarcohyla is a genus of frogs in the family Hylidae. It is endemic to Mexico and is found in the montane parts of the country between Durango in the north and Guerrero in the south. These frogs typically occur in pristine habitats along streams in pine-oak woodland at elevations between 1,500 and 3,100 m above sea level. The generic name is derived from the Greek sarkodes meaning "fleshy" in combination with Hylas and refers to the thick, glandular skin characteristic of most of the species in the genus.

<i>Rheohyla</i> Genus of amphibians

Rheohyla is a genus of frogs in the family Hylidae. As currently recognized, it is monotypic, containing only Rheohyla miotympanum, also known as the small-eared hyla or small-eared treefrog. However, the nominal species likely is a complex of more than one species. It is endemic to eastern and central Mexico. The generic name refers to streams, the breeding habitat of this frog. The specific name is derived from Greek meion, a diminutive prefix, together with Greek tympanon (='drum') and refers to the small tympanum.

References

  1. ↑ Faivovich, J.; Haddad, C.F.B.; Garcia, P.C.A.; Frost, D.R.; Campbell, J.A.; Wheeler, W.C., 2005: Systematic Review of the Frog Family Hylidae, with Special Reference to Hylinae: Phylogenetic Analysis and Taxonomic Revision. Bulletin of the American Museum of Natural History, Num. 294, pp.1-240.
  2. ↑ Faivovich, J.; Haddad, C.F.B.; Garcia, P.C.A.; et al. (2005). "Systematic review of the frog family Hylidae, with special reference to Hylinae: phylogenetic analysis and taxonomic revision". Bulletin of the American Museum of Natural History. 294: 1–240. doi:10.1206/0003-0090(2005)294[0001:SROTFF]2.0.CO;2. S2CID   83925199 – via BioOne Complete.
  3. 1 2 3 Barrio-Amorós, C.L.; Grünwald, C.I.; Franz-Chávez, H.; et al. (2016). "Notes on natural history and call description of the Critically Endangered Plectrohyla avia (Anura: Hylidae) from Chiapas, Mexico" (PDF). Amphibian & Reptile Conservation. 10 (2): 11–17.
  4. ↑ Borror, Donald J. (1988). Dictionary of word roots and combining forms : compiled from the Greek, Latin, and other languages, with special reference to biological terms and scientific names (11. print. ed.). Mountain View, Calif.: Mayfield Pub. Co. ISBN   0874840538.
  5. 1 2 3 4 5 6 7 8 9 10 Duellman, W.E.; Campbell, J.A. (1992). "Hylid frogs of the genus Plectrohyla: systematics and phylogenetic relationships" (PDF). Museum of Zoology, University of Michigan (181).
  6. ↑ Duellman, W.E.; Marion, A.B.; Hedges, S.B. (2016). "Phylogenetics, classification, and biogeography of the treefrogs (Amphibia: Anura: Arboranae)" (PDF). Zootaxa. 4104 (1): 1–109. doi:10.11646/zootaxa.4104.1.1. PMID   27394762.
  7. 1 2 3 4 5 6 Gonzalez-Mollinedo, S.; Marmol-Kattan, A. (2020). "The underground sex life of the Guatemalan Spike-thumb Frog (Plectrohyla guatemalensis)". Neotropical Biology and Conservation. 15 (4): 551–559. doi: 10.3897/neotropical.15.e57142 . S2CID   231685632.
  8. 1 2 3 4 5 6 7 Schulte, L.M.; Martel, A.; Cruz-Elizalde, R.; et al. (2021). "Love bites: male frogs (Plectrohyla, Hylidae) use teeth scratching to deliver sodefrin precursor-like factors to females during amplexus". Frontiers in Zoology. 18 (59): 59. doi: 10.1186/s12983-021-00445-6 . PMC   8613984 . PMID   34823558.
  9. ↑ Luna, M.C.; Vásquez-Almazán, C.R.; Faivovich, J.; Brunetti, A.E. (2019). "Gland composition in sexually dimorphic skin structures of two species of Hylid frogs: Plectrohyla guatemalensis and Ptychohyla hypomykter". Amphibia-Reptilia. 40 (4): 523–529. doi:10.1163/15685381-20191221. S2CID   208584752 – via Brill.
  10. ↑ Brunetti, A.E.; Hermida, G.N.; Luna, M.C.; et al. (2015). "Diversity and evolution of sexually dimorphic mental and lateral glands in Cophomantini treefrogs (Anura: Hylidae: Hylinae)". Biological Journal of the Linnean Society. 114 (1): 12–34. doi:10.1111/bij.12406. hdl: 11336/20724 .
  11. 1 2 Koene, J.M.; ter Maat, A. (2001). "Allohormones: a class of bioactive substances favoured by sexual selection". Journal of Comparative Physiology A. 187 (5): 323–326. doi:10.1007/s003590100214. PMID   11529475. S2CID   24970507 – via Springer link.
  12. ↑ Koene, J.M.; ter Maat, A. (2002). "The distinction between pheromones and allohormones" (PDF). Journal of Comparative Physiology A. 188 (2): 163–164. doi:10.1007/s00359-002-0289-7. S2CID   40073946.


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