The species epithet, "sylvatica", is from the Latin words, "silvae", which refers to the species' presence in lowland tropical forests (Ortiz et al. 2018).

Description
Oophaga sylvatica has a snout-vent length of 26.0 – 38.0 mm for both males and females (Ortiz et al. 2018). The snout is truncate, almost vertical from the profile view, with angular corners. The nostril is located slightly closer to the snout than the eye, positioned in line with the front corner of the eye, and is about three-fourths the length of the eye. They have an indistinct canthus rostralis and a vertical, slightly or not concave loreal region. Their internarial distance is equal to the interorbital distance and they eye. The width of the upper eyelid is equal to two thirds of the interorbital space, which is in turn equal to the eye. The tympanum is indistinct and is approximately half the length of the eye. The width of the head, behind the eyes, is about equal to the length of the head (Funkhouser 1956).

There is a single oval palmar tubercle on the palm along with easily visible, but not strongly developed subarticular tubercles on the fingers. Their finger I reaches the base of the disk of finger II, while finger II reaches to the second joint of finger III. Finger IV reaches slightly farther on finger III than it does finger II, giving a relative finger length of I < II < IV< III. The width of disks II, III, and IV are equal and about twice the width of their digits. The disk of finger I is narrower and about one and half times the width of the digits. The fingers are all free of webbing (Funkhouser 1956).

The snout to vent length is slightly more than four times the width of the sacrum. The heels overlap slightly when the legs are folded at right angles to the body. When the hind limbs are adpressed along the body the tibiotarsal articulation reaches the posterior corner of the eye. The tibia is longer than the femur and the foot is nearly twice the length of the tibia. There is a round outer metatarsal tubercle, an elliptic inner metatarsal tubercle, and an indistinct tarsal tubercle on the foot. The first toe reaches the first joint of toe II. Toe II reaches the midpoint of the first joint of toe III. Toe III reaches to the last subarticular tubercle of IV and is about two-thirds the length of toe IV. Toe V reaches just below the second subarticular tubercle of IV giving a relative toe length of I < II < V < III < IV. The disk of toe I is only slightly wider than the toe and is about half as wide as the disk of toe II and III, which are both almost twice as wide as toe II. The disk of toe IV is about equal to that of toe III. The disk of toe V is about one and a half times as wide as the toe and about two-thirds the widths of II, III, and IV. The weakly developed subarticular tubercles are nonetheless easily discernable (Funkhouser 1956).

The skin is smooth on all the surfaces (Funkhouser 1956).

Oophaga sylvatica is distinguished from most other western Ecuadorian dendrobatids by being the largest species. The most physically similar species is the Colombian O. histrionicus, from which O. sylvatica was split. The two can be distinguished by call and patterning. The markings on O. sylvatica are more irregular with indistinct margins that may merge together while O. histrionicus has well delimited markings (Funkhouser 1956, Ortiz et al. 2018). The call of O. sylvatica is most similar to O. lehmanni and O. occultator but they differ in that O. sylvatica has a longer note duration, lower minimum frequency, and a lower dominate frequency than O. lehmanni. Additionally, O. sylvatica has a longer note duration, longer inter-note duration, lower minimum frequency, and lower dominate frequency than O. occultator (Lotter et al. 1999)

In life, the dorsum ranges from gray, brown, orange, red, or black with whitish, yellow, orange, red, or light blue spots or reticulated markings. Spots often blur into the background color. Ventral coloration can be similar to the dorsum or red. Markings may be present or absent on the limbs, but when they are present, they are large with defined margins (Ortiz et al. 2018).

In preservative, the main coloration is grey-black and the markings are a lighter grey. For the dorsal markings are closely spaces with small irregular outlines that tend to merge or blend into the background. The ventral markings are larger and have a smoother outline but can be irregular in their shape and size. The limb markings may be present or absent, however when they are present the are usually large with smooth margins (Funkhouser 1956).

Funkhouser (1956) noted that the coloration and markings were similar in paratypes when he first described them. However, later specimens showed variation in both with some populations having the black background with reddish brown spots or large blue circles, while others are completely black, have orange or reddish coloration (Ortiz et al. 2018).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Colombia, Ecuador

View distribution map in BerkeleyMapper.

Oophaga sylvatica may be a species complex but the true species occurs in humid tropical forests on the coastal plains and Andean foothills of northwestern Ecuador. Other populations called O. sylvatica can be found in southwestern Colombia. The species can be found up to 1000 m asl. Its habitat includes lowland and submontane rainforest, and it can tolerate banana plantations in more humid parts of its range (Funkhouser 1956, IUCN 2019).

Life History, Abundance, Activity, and Special Behaviors
Oophaga sylvatica is diurnal. They are more active, with short walks, runs, or hops, during and directly after rain. They can also be found climbing to the tops of leaves. When they are not active they can be found hiding under logs, leaves, or debris. When captured, the frogs try to escape using walking or running motions with their limbs or become immobile before suddenly resuming activity (Funkhouser 1956).

Oophaga sylvatica tends to blend in with the red fungus that grows on the jungle floor (Funkhouser 1956).

Male vocalizations occur from between 6 in the morning and 7 in the evening. Their call is described as similar to the sound made by a wood borer in dead wood (Funkhouser 1956). Recordings were made from a captive individual at a temperature of 23.0^o C. The note duration was 86 – 100 ms and consisted of 16 – 21 pulses. There are 5 – 6 note repetitions with 100 – 121ms between notes. The frequency range is between 800 – 3000 Hz with dominate frequencies between 1750 – 1950 and 2300 – 2450 Hz (Lotters et al. 1999).

In the southern part of the species' range, mating does not occur during the reduced rainy season from July to November. There is no amplexus during mating. The male instead deposits his sperm on the ground before females deposit her eggs on top. Males care for the eggs, but females transport tadpoles, on the females' back, after hatching to bromeliads or other phytotelmatas where they complete their development, which lasts 6 - 8 weeks (Ortiz et al. 2018, IUCN 2019).

The female feeds the tadpoles infertile eggs and gravid females have been found to have 30 - 46 eggs (Ortiz et al. 2018). There is evidence that maternal provisioning of unfertilized eggs also transfers chemical defenses to the tadpoles (Fischer et al. 2019).

Oophaga sylvatica diet is based on ants (Ortiz et al. 2018).

Trends and Threats
The species is listed as “Near Threatened” on the IUCN Red List because of observed declines in numbers in the southern part of its range in Colombia (IUCN 2019).

Threats to this species include habitat loss, exploitation by the pet trade, and disease (chytridiomicosis). Habitat is lost to agricultural development, logging, mining, human settlements, and pollution (Ortiz et al. 2018, IUCN 2019).

Some populations occur in protected areas in Ecuador, such as La Perla Protected Forest, Río Palenque Scientific Center, Bilsa Biological Station, La Chiquita Wildlife Refuge, Mache Chindul Ecological Reserve, Mayronga Reserve, and Río Canandé Reserve (Ortiz et al. 2018). The species was formerly common in the Reserva Biotopo Selva Humeda, Colombia, but was not found during extensive surveys in 2006. As of 2016, the species is still common in Divisio and Iscuandé, Department of Nariño, Colombia (IUCN 2019).

Relation to Humans
This species is found in the pet trade (Ortiz et al. 2018, IUCN 2019).

Comments
When first described, Funkhouser (1956) thought O. sylvatica was a subspecies of O. histrionicus (originally named Dendrobates histrionicus sylvaticus) due to similar coloration, proximity of the populations. The species was moved from the genus Dendrobates to Oophaga following morphological analysis by Grant et al. (2006). Oophaga sylvatica was joined in this genus by O. arborea, O. granulifera, O. histrionica, O. lehmanni, O. occultator, O. pumilio, O. speciosa, and O. vicentei. Later call analysis by Lotters et al. (1999) found that the call of O. sylvatica most closely resembled O. lehmanniand O. occultator rather than O. histrionicus. This was supported by analyses from Santos et al. (2009) who used Maximum Likelihood and Bayesian Inference on a tree matrix of multiple genes, including 12s and 16s mtDNA and Rag-1 nuclear DNA, to conclude that the sister species of O. sylvatica is O. lehmanni.

A population genetics study, using Bayesian analysis of CO1, 16S, 12S mitochondrial, and Rag-1, TYR, and NCX nuclear sequences, found that O. sylvatica is split into two distinct lineages: one north of the Santiago River drainage, and one south. High genetic and morphological variation in the north suggest that there is ongoing gene flow in that lineage, while low genetic variation in the south suggests that those populations are the result of recent range expansions from the northern lineage (Roland et al. 2017).

This species was featured as News of the Week on January 21, 2020:

Parenting is an uncommon strategy among amphibians to raise offspring, and rarely takes the form of intense care compared to other vertebrates. For example, when species diversified and gained new niches to avoid competition for the same resources, maternal provisioning provides evolutionary benefits to surpass the cost of reduced access to nutrients. Fischer et al. 2019 demonstrated that in addition to supplying nutrients to offspring living in small isolated pools of water, maternal provisioning of unfertilized eggs is a way of passing along chemical defenses in some aposematic and poisonous frogs species. This mechanism of toxin transfer convergently evolved in two distant clades of frogs living in the antipodes, the Malagasy Climbing Mantella (Mantella laevigata) and the Ecuadorian Little Devil Poison Frog (Oophaga sylvatica), which diverged roughly 140 million years ago. Further, they showed that the neuronal basis of their maternal behavior relies on similar brain region activities but with distinct activation patterns, suggesting an evolutionary versatility in the molecular mechanisms sustaining maternal provisioning (Written by Alexandre B. Roland).

This species was featured as News of the Week on June 21, 2020:

The world's tropical rainforests hold the highest amphibian biodiversity, and increasing habitat modification and fragmentation in these ecosystems have untold cascading impacts on local food webs. Moskowitz et al. (2020) sheds light on how the replacement of tropical rainforests with pasture lands affects chemical defenses in Oophaga sylvatica through changes in prey item composition. The study, which was conducted with two U.S. high school science classes, examined how leaf litter, leaf litter invertebrate communities, and alkaloids in O. sylvatica related to each other in the two environments. Their results showed significant differences in diet and alkaloid profiles in frogs based on land changes. Furthermore, their findings indicate that O. sylvatica have a dietary preference for specific ant species that are not as common in pasture lands as in forests. These findings have real-world implications for the management of this Near Threatened species as their aposematic coloration may be uncoupled from their chemical defense (Ann T. Chang).

References

Funkhouser, J.W. (1956). "New frogs from Ecuador and southwestern Colombia." Zoologica: scientific contributions of the New York Zoological Society, 41(9), 73-80. [link]

Grant, T., Frost, D. R., Caldwell, J. P., Gagliardo, R., Haddad, C. F. B., Kok, P. J. R., Means, D. B., Noonan, B. P., Schargel, W. E., and Wheeler, W. C. (2006). ''Phylogenetic systematics of dart-poison frogs and their relatives (Amphibia: Athesphatanura: Dendrobatidae).'' Bulletin of the American Museum of Natural History, (299), 1-262.

IUCN SSC Amphibian Specialist Group 2019. Oophaga sylvatica. The IUCN Red List of Threatened Species 2019: e.T55203A85887077. https://dx.doi.org/10.2305/IUCN.UK.2019-2.RLTS.T55203A85887077.en. Downloaded on 30 March 2020.

Lötters, S., Glaw, F., Köhler, J., and Castro, F. (1999). ''On the geographic variation of the advertisement call of Dendrobates histrionicus and related forms from north-western South America.'' Herpetozoa, 12(1/2), 23-38.

Mechanisms of convergent egg provisioning in poison frogs [link]

Ortiz, DA, Coloma, LA, Frenkel, C. and Pazmiño-Armijos, G. 2018. Oophaga sylvatica In: Ron, SR, Merino-Viteri, A. Ortiz, DA (Eds). Amphibians of Ecuador. Version 2019.0. Museum of Zoology, Pontificia Universidad Católica del Ecuador. https://bioweb.bio/faunaweb/amphibiaweb/FichaEspecie/Oophaga%20sylvatica , accessed Thursday, January 28, 202

Roland, A.B., Santos, J.C., Carriker, B.C., Caty, S.N, Tapia, E.E., Coloma, L.A., O’Connell, L.A. (2017). "Radiation of the polymorphic Little Devil poison frog (Oophaga sylvatica) in Ecuador." Ecology and Evolution , 7(22), 9750-9762. [link]

Santos, JC, Coloma, LA, Summers, K, Caldwell, JP, Ree, R, Cannatella, DC (2010). "Correction: Amazonian amphibian diversity is primarily derived from late Miocene Andean lineages." PLOS Biology , 8(9), 10.1371. [link]

Species Account Citation: AmphibiaWeb 2024 Oophaga sylvatica: Little-devil poison frog <https://amphibiaweb.org/species/5910> University of California, Berkeley, CA, USA. Accessed Nov 12, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 12 Nov 2024.

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