Dendrobatidae

Dyeing poison dart frog Dendrobates tinctorius, copyright H. Zell.

Belongs within: Hyloidea.
Contains: Hyloxalus, Colostethus.

The Dendrobatidae, arrow poison frogs, are a Neotropical family of terrestrial frogs in which adults carry tadpoles to water on their backs (Frost et al. 2006). Many species are brightly coloured and notorious for the powerful toxins that they sequester from their diet.

Synapomorphies (from Frost et al. 2006): M. rectus cervicis inserted on proximal ceratobranchialia III and IV; adrostral cartilage present but small; cartilaginous roofing of cavum cranii formed by taeniae tecti medialis only; larvae picked up at oviposition site and transported to body of water adhering to dorsum of adult; amplectic position cephalic; guiding behaviour; firmisterny; terminal phalanges T-shaped.

Arrow poison and arrow without poison
Published 6 December 2020

Central and South America are home to a remarkable diversity of frogs, coming in nearly all the shapes and sizes a frog can possibly come in. Among this diversity, probably the most famous representatives are the arrow-poison frogs of the Dendrobatidae.

Two dendrobatid frogs of two different subfamilies: dyeing dart frog Dendrobates tinctorius (Dendrobatinae, left) and phantasmal poison frog Epipedobates tricolor (Colostethinae, right), copyright H. Krisp. Offhand, has someone been playing silly buggers with dendrobatid species names? Dendrobates auratus is green and black, not gold, and I’m sure I only see two colours on that E. tricolor.

The Dendrobatidae are themselves a diverse family, with somewhere in the area of two hundred currently recognised species. Many of these have only recently been recognised: nearly half of the currently known species have been named since 1985 (Grant et al. 2006). There are also ninety or so species in the closely related family Aromobatidae that were historically treated as dendrobatids and still may be in some sources. The Dendrobatidae are currently divided between three subfamilies: about half the species belong to the subfamily Dendrobatinae, a bit less than a quarter to the Colostethinae, and close to sixty species are placed in the genus Hyloxalus that forms its own subfamily (Grant et al. 2006).

Panama rocket frog Colostethus panamensis, copyright Brian Gratwicke.

Members of the Dendrobatidae are best known, of course, for their remarkable toxicity, associated with bright, striking warning colours. The name ‘arrow-poison frog’ reflects this trait as an arrow scraped across a frog’s skin would pick up some of the frog’s own lethality. The toxin, comprising various alkaloids, is not produced directly by the frog itself but is instead acquired through its arthropod diet. Most of the alkaloids sequestered by arrow-poison frogs come from ants (Darst et al. 2005) but other potential sources include beetles, millipedes and oribatid mites. However, not all dendrobatids are toxic and colourful. In fact, these features are largely characteristic of the Dendrobatinae only. Members of the Colostethinae and Hyloxalus are mostly cryptic in coloration and largely do not sequester alkaloids. The distinction is not an unshakeable rule: some non-dendrobatine dendrobatids are quite colourful in their own right and a handful of colostethines (members of the genus Epipedobates) are toxic, having seemingly evolved the ability to secrete alkaloids independently of the dendrobatines. Laboratory studies indicate that at least some non-toxic colostethines are able to consume alkaloid-bearing prey without ill effects, suggesting that alkaloid resistance is ancestral for the family as a whole.

Male Hyloxalus nexipus carrying tadpoles, copyright Santiago Ron.

More characteristic of dendrobatids as a whole is their breeding behaviour. As a rule, dendrobatids are more or less terrestrial, not habitually living in water, though many species are found alongside the margins of water bodies and may dive into the water to escape danger. Others will be found among leaf litter or be completely arboreal. Eggs are laid in damp terrestrial locations such as under leaves; males may deposit their sperm before or after the female deposits her eggs. Hatching tadpoles are then carried on the back of one of the parents to a suitable body of water such as a pool or stream. In members of the Dendrobatinae, tadpoles are deposited in phytotelmata, water-filled hollows in vegetation (such as in the cenre of bromeliads or holes in trees). Adelphobates castaneoticus, found in Pará in Brazil, has a habit of using the fallen husks of Brazil nuts. In some species, tadpoles are transferred one at a time; in others, groups of tadpoles will be carried en masse. In most genera, the male parent is the primary or sole transporter of tadpoles. Females of some species may also carry tadpoles; in others, a female finding an unattended cache of eggs will simply eat them. In the dendrobatine genus Oophaga, tadpole transport is the sole responsibility of the female. Following deposition, developing tadpoles of many species live on a diet of detritus. Others, particularly among the phytotelm-inhabiting species, are carnivorous, feeding on insects and other aquatic vertebrates, or even on their own siblings. In the aforementioned Oophaga, the transporting female will also lay a deposit of unfertilised eggs at the same time as she drops off the tadpoles. As well as providing food for the developing larvae, these eggs may also carry a shot of alkaloids to provide a head start in developing their defenses.

Strawberry poison-dart frogs Oophaga pumilio, two different colour morphs, copyright Pavel Kirillov.

Despite their often bright colours, many dendrobatids are poorly known due to cryptic habits and many species are only found in restricted ranges. As well as the usual threats to their survival from habitat destruction and the like, many dendrobatid species are threatened by collection for the pet trade. Their bright colours make dendrobatids popular specimens and captive individuals lose their toxicity if not provided with the prey from which alkaloids are derived. Unfortunately, about a quarter of dendrobatid species are currently recognised as endangered, many severely so. The highest diversity of endangered species is in the northern Andean region, in Venezuela, Colombia and Peru, which is also the centre of diversity for the family as a whole (Guillory et al. 2019). Urgent action may be required if we are to preserve these tiny, shiny, toxic beauties.

Systematics of Dendrobatidae
<==Dendrobatidae
| i. s.: Cryptophyllobates Lötters, Jungfer & Widmer 2000FG06
| `--C. azureiventrisDM-G05
| Nephelobates La Marca 1994FG06
| Eubaphus Bonaparte 1831 [Eubaphidae]FG06
| Hysaplesia Boie 1826 [=Hylaplesia Boie 1827; Hylaplesidae]FG06
| Phobobates Zimmermann & Zimmermann 1988FG06
| `--P. silverstoneiFG06
|--DendrobatinaeGM19
| |--+--+--+--‘Dendrobates’ captivusPW11
| | | | `--Excidobates Twomey & Brown 2008GM19
| | | | `--*E. mysteriosusGM19 [=Dendrobates mysteriosusPW11]
| | | `--+--+--+--Andinobates Twomey et al. 2011GM19
| | | | | | `--*A. bombetesGM19 [=Dendrobates bombetesPW11, Ranitomeya bombetesGM19]
| | | | | `--‘Dendrobates’ virolinensisPW11
| | | | `--+--‘Dendrobates’ fulguritusPW11
| | | | `--+--‘Dendrobates’ claudiaePW11
| | | | `--‘Dendrobates’ minutusPW11
| | | `--+--+--+--‘Dendrobates’ biolatPW11
| | | | | `--‘Dendrobates’ lamasiPW11
| | | | `--+--‘Dendrobates’ flavovittatusPW11
| | | | `--+--‘Dendrobates’ imitatorPW11 [=Ranitomeya imitatorFB17]
| | | | `--‘Dendrobates’ vanzoliniiPW11
| | | `--+--+--‘Dendrobates’ amazonicusPW11
| | | | `--‘Dendrobates’ uakariiPW11
| | | |--+--‘Dendrobates’ variabilisPW11
| | | | `--‘Dendrobates’ ventrimaculatusPW11
| | | `--+--‘Dendrobates’ fantasticusPW11
| | | `--+--‘Dendrobates’ duellmaniPW11
| | | `--Ranitomeya Bauer 1986GM19
| | | `--*R. reticulataGM19 [=Dendrobates reticulatusPW11]
| | `--+--+--Minyobates Myers 1987GM19, FG06
| | | | |--*M. steyermarki Myers 1987GM19 [=Dendrobates steyermarkiPW11]
| | | | `--M. claudiaeFG06
| | | `--+--‘Dendrobates’ quinquevittatusPW11
| | | `--+--Adelphobates Grant et al. 2006GM19
| | | | `--*A. castaneoticusGM19 [=Dendrobates castaneoticusPW11]
| | | `--‘Dendrobates’ galactonotusPW11
| | `--+--Dendrobates Wagler 1830GM19, FG06
| | | | i. s.: D. typographusF15
| | | |--+--*D. tinctorius (Cuvier 1797)GM19, PW11, GM19 [=Rana tinctoriaGM19]
| | | | `--D. leucomelasPW11
| | | `--+--D. auratusPW11
| | | `--D. truncatusPW11
| | `--+--‘Dendrobates’ granuliferusPW11
| | `--+--‘Dendrobates’ histrionicusPW11
| | `--+--+--‘Dendrobates’ lehmanniPW11
| | | `--‘Dendrobates’ sylvaticusPW11
| | `--+--‘Dendrobates’ arboreusPW11
| | `--+--‘Dendrobates’ speciosusPW11
| | `--+--Oophaga Bauer 1994GM19
| | | `--*O. pumilioGM19 [=Dendrobates pumilioPW11]
| | `--‘Dendrobates’ vicenteiPW11
| `--Phyllobates Bibron 1840PW11, GM19 [Phyllobatae]
| | i. s.: P. limbatusF15
| |--+--P. lugubrisPW11
| | `--P. vittatusPW11
| `--+--*P. bicolorGM19, PW11
| `--+--P. aurotaeniaPW11
| `--P. teribilisPW11
`--+--HyloxalinaeGM19
| |--HyloxalusFB17
| |--Ectopoglossus Grant et al. 2017GM19
| | `--*E. saxatilisGM19
| `--Paruwrobates Bauer 1994GM19
| `--*P. andinusGM19
`--ColostethinaeGM19
| i. s.: Leucostethus Grant et al. 2017GM19
| `--*L. argyrogasterGM19
|--ColostethusPW11
`--+--Silverstoneia Grant et al. 2006PW11, GM19
| |--*S. nubicola [=Colostethus nubicola]GM19
| `--S. flotatorPW11
`--Epipedobates Myers 1987FB17, FG06
|--E. boulengeriPW11 [=Ameerega boulengeriFG06]
`--+--E. espinosaiPW11
`--+--E. machalillaPW11 [=Colostethus machalillaDM-G05]
`--+--*E. tricolorGM19, PW11
`--E. anthonyiPW11

*Type species of generic name indicated

References

[DM-G05] Darst, C. R., P. A. Menéndez-Guerrero, L. A. Coloma & D. C. Cannatella. 2005. Evolution of dietary specialization and chemical defense in poison frogs (Dendrobatidae): a comparative analysis. American Naturalist 165 (1): 56–69.

[FB17] Feng, Y.-J., D. C. Blackburn, D. Liang, D. M. Hillis, D. B. Wake, D. C. Cannatella & P. Zhang. 2017. Phylogenomics reveals rapid, simultaneous diversification of three major clades of Gondwanan frogs at the Cretaceous–Paleogene boundary. Proceedings of the National Academy of Sciences of the USA 114 (29): E5864–E5870.

[F15] Fowler, H. W. 1915. Cold-blooded vertebrates from Florida, the West Indies, Costa Rica, and eastern Brazil. Proceedings of the Academy of Natural Sciences of Philadelphia 67 (2): 244–269.

[FG06] Frost, D. R., T. Grant, J. Faivovich, R. H. Bain, A. Haas, C. F. B. Haddad, R. O. de Sá, A. Channing, M. Wilkinson, S. C. Donnellan, C. J. Raxworthy, J. A. Campbell, B. L. Blotto, P. Moler, R. C. Drewes, R. A. Nussbaum, J. D. Lynch, D. M. Green & W. C. Wheeler. 2006. The amphibian tree of life. Bulletin of the American Museum of Natural History 297: 1–370.

Grant, T., D. R. Frost, J. P. Caldwell, R. Gagliardo, C. F. B. Haddad, P. J. R. Kok, D. B. Means, B. P. Noonan, W. E. Schargel & W. C. Wheeler. 2006. Phylogenetic systematics of dart-poison frogs and their relatives (Amphibia: Athesphatanura: Dendrobatidae). Bulletin of the American Museum of Natural History 299: 1–262.

[GM19] Guillory, W. X., M. R. Muell, K. Summers & J. L. Brown. 2019. Phylogenomic reconstruction of the Neotropical poison frogs (Dendrobatidae) and their conservation. Diversity 11: 126.

[PW11] Pyron, R. A., & J. 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: 543–583.

Leave a comment

Your email address will not be published. Required fields are marked *