Caribbean Ditchfrog, San Miguel Island Frog
Species Description: Resurrected Barbour species from 1906. Heyer WR, de Sa RO 2011 Variation, systematics, and relationships of the Leptodactylus bolivianus complex (Amphibia: Anura: Leptodactylidae). Smithsonian Contrib Zoology 635:1-58.
© 2017 Twan Leenders (1 of 5)
For larval description, please see Heyer and Heyer (2013).
Based on morphological characteristics, geographical range, and genetics L. insularum is placed in the Leptodactlus bolivians complex, which includes L. bolivianus, and L. guianensis. Originally, these frogs were thought to be one species. Differences in adult male thumb spines is an easy way to distinguish between the species: L. insularum possesses two rounded and pointed spines on each of their thumbs while L. guianensis has a modestly chisel-shaped bone on a single spine and L. bolivianus has an extremely chisel-shaped spine bone (Heyer and Heyer 2013).
Their dorsum has dark mottled marks scattered between their dorsolateral folds. Both the supratympanic folds and the folds from behind the eye to their sacrum are distinct and dark. They also possess a dark, interrupted stripe from their nostril to their eye. Their posterior thighs display a boldly dark mottled pattern with large light irregular spots on a dark background, and their flank bares irregular dark brown spots on a tan to brown background. They have very light tan bellies with small tan dots, visible under a microscope, growing slightly darker towards the throat (Heyer and Heyer 2013).
Leptodactylus insularum displays morphological variation based on sex. Secondary sexual characters in males include central chest of tubercules and thumb spines. Coloration may also vary in lateral ridge stripe and posterior thigh color based on geography (Heyer and Heyer 2013).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Colombia, Costa Rica, Panama, Trinidad and Tobago, Venezuela
The species lives in a range of habitats such as forests and swamplands. They are found in lower elevations, but no known maximum elevation has been recorded (IUCN 2020).
Life History, Abundance, Activity, and Special Behaviors
Males call at night from shallow waters, often after heavy rainfall (Hurme 2014). Leptodactylus insularum calls are short and quick, single notes with a minimum call rate of 0.63 per second and a maximum of 2.47 per second, averaging at 1.17 calls per second. There are three harmonic frequencies that each raise to a higher frequency than the last. The total ranges of frequencies are between 340 Hz to 2440 Hz (Heyer and Heyer 2013).
The species uses inguinal amplexus for mating in shallow water. Nest creation occurs with the female producing a thick mucus that the male aerates into a foam nest. The eggs are deposited into the nest, floating but hidden underneath leaves (Hurme 2014).
Females watch over the nest and tadpoles, signaling to them by a “pumping” action of their abdomen that encourages the tadpoles to keep close and follow her. If the tadpoles are in a small water body that is close to drying up, the mother will dig a route for them to swim into a nearby water source (Hurme 2014).
Leptodactylus insularum are generalist predators and eat many aquatic insects such as Elateridae, Formicidae, Belastomatidae, and Lycosidae (Mageski et. al 2014).
Tadpoles feed on decaying matter that falls to the lentic systems and benthic zones they inhabit (Heyer and Heyer 2013).
Adults use aposematic coloring on their hind legs, which they will showcase by stretching out their legs and inflating their abdomens in a defensive behavior (Franzen 2017).
Trends and Threats
Relation to Humans
Possible reasons for amphibian decline
Climate change, increased UVB or increased sensitivity to it, etc.
This species was featured as News of the Week on 2 August 2021:
Most amphibians secrete distasteful or toxic substances from their skin. Several groups wield toxins that can be lethal to other animals, or even to themselves. Animals can evolve resistance to toxins through mutations in proteins that prevent toxins from binding. Although these mutations can provide resistance, they often occur in important regions of a protein, such as those critical to nervous system functions. Thus, a problem arises: how can animals avoid the negative effects of mutations that also provide resistance? A pair of recent studies, one on the toxic salamanders Taricha (Gendreau et al. 2021) and another on frogs of the genus Leptodactylus (Mohammadi et al. 2021), which consume toxic toads, suggest that gene duplication is the key; one gene copy can help animals develop toxin resistance while the other copy maintains a functional nervous system. Both studies also show evidence for a fascinating molecular process known as gene conversion, wherein duplicate copies of one gene retain more similar-than-expected DNA sequences. During homologous recombination, two copies of a genome line up and exchange pieces of DNA; however, when two copies of a gene are near each other in the genome, the wrong genes can line up and exchange genetic material, maintaining genetic similarity between duplicate copies of a gene. In newts, gene conversion appears to have copied resistance-conferring mutations from one gene domain to another. In Leptodactylus frogs, strong natural selection countered the force of gene conversion, resulting in one toxin-resistant gene and one toxin-sensitive gene. How newts and frogs regulate the use of these different gene copies remains unknown and will be an exciting future research topic. (RT)
Barran, G., Kolodziejek, J., Coquet, L., Leprince, J., Joulenne, T., Nowotny, N., Conlon, M., Mechkarska, M. (2020). "Peptidomic analysis of skin secretions of the Caribbean frogs Leptodactylus insularum and Leptodactylus nesiotus (Leptocactylidae) identifies an Ocellatin with broad spectrum antimicrobial activity." Antibiotics, 9(10), 1-15. [link]
Franzen, M. (2017). "Leptodactylus insularum (San Miguel Island frog) defensive behavior." Herpetological Review, 48(3), 607-608. [link]
Hedges, S. B., Powell, R., Henderson, R. W., Hanson, S., Murphy, J. C. (2019). "Definition of the Caribbean Islands biogeographic region, with checklist and recommendations for standardized common names of amphibians and reptiles." Caribbean Herpetology, 67, 1-53.
Heyer, W. R., Heyer, M. M. (2013). "Systematics, distribution, and bibliography of the frog Leptodactylus insularum Barbour, 1906 (Amphibia: Leptodactylidae)." Proceedings of the Biological Society of Washington, 126(3), 204-233. [link]
Hurme, K., J. (2014). "Reproductive and spatial ecology of Leptodactylus insularum (Anura, Leptodactilidae) in Panama." Journal of Herpetology, 48(4), 1-11. [link]
IUCN SSC Amphibian Specialist Group. 2020. "Leptodactylus insularum". The IUCN Red List of Threatened Species 2020: e.T85854383A85910948. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T85854383A85910948.en. Downloaded on 17 February 2021.
Mageski, M., Falcao, A., Ferreira, R. B. (2014). "Leptodactylus insularum (San Miguel Island frog) diet." Herpetological Review, 45(1), 113-114. [link]
Originally submitted by: Marguerite Schlutius, Victoria Cao, Vanessa Martinez (2021-06-21)
Description by: Marguerite Schlutius, Victoria Cao, Vanessa Martinez (updated 2021-06-21)
Distribution by: Marguerite Schlutius, Victoria Cao, Vanessa Martinez (updated 2021-06-21)
Life history by: Marguerite Schlutius, Victoria Cao, Vanessa Martinez (updated 2021-06-21)
Trends and threats by: Marguerite Schlutius, Victoria Cao, Vanessa Martinez (updated 2021-06-21)
Relation to humans by: Marguerite Schlutius, Victoria Cao, Vanessa Martinez (updated 2021-06-21)
Comments by: Marguerite Schlutius, Victoria Cao, Vanessa Martinez (updated 2021-06-21)
Edited by: Ann T. Chang (2021-08-03)
Species Account Citation: AmphibiaWeb 2021 Leptodactylus insularum: Caribbean Ditchfrog <https://amphibiaweb.org/species/7722> University of California, Berkeley, CA, USA. Accessed Jul 1, 2022.
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Citation: AmphibiaWeb. 2022. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 1 Jul 2022.
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