Spix’s Saddleback Toad
   HOME

TheInfoList



OR:

The pumpkin toadlet (''Brachycephalus ephippium''), or Spix's saddleback toad, is a small and brightly coloured species of
frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...
in the family
Brachycephalidae The Brachycephalidae () are a family of frogs confined to eastern and southern Brazil and northern Argentina. The family is composed of two externally quite different genera: the tiny, often (but not always) colourful and plump saddleback toads ...
. This diurnal species is
endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
to southeastern Brazil where it is found among
leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituen ...
on the floor of Atlantic rainforests at an altitude of . It is found in
Espírito Santo Espírito Santo (; ) is a state in southeastern Brazil. Its capital is Vitória, and its largest city is Serra. With an extensive coastline, the state hosts some of the country's main ports, and its beaches are significant tourist attracti ...
,
Rio de Janeiro Rio de Janeiro, or simply Rio, is the capital of the Rio de Janeiro (state), state of Rio de Janeiro. It is the List of cities in Brazil by population, second-most-populous city in Brazil (after São Paulo) and the Largest cities in the America ...
, southeastern
São Paulo São Paulo (; ; Portuguese for 'Paul the Apostle, Saint Paul') is the capital of the São Paulo (state), state of São Paulo, as well as the List of cities in Brazil by population, most populous city in Brazil, the List of largest cities in the ...
and southeastern
Minas Gerais Minas Gerais () is one of the 27 federative units of Brazil, being the fourth largest state by area and the second largest in number of inhabitants with a population of 20,539,989 according to the 2022 Brazilian census, 2022 census. Located in ...
. Although its
type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...
supposedly was collected in
Bahia Bahia () is one of the 26 Federative units of Brazil, states of Brazil, located in the Northeast Region, Brazil, Northeast Region of the country. It is the fourth-largest Brazilian state by population (after São Paulo (state), São Paulo, Mina ...
about 200 years ago, there are no confirmed localities in this state and recent reviews consider it more likely that it was from Rio de Janeiro. ''B. ephippium'' is locally common, quite widespread compared to most other species of '' Brachycephalus'' and it is not considered
threatened A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensatio ...
. ''B. ephippium'' feeds on tiny
invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...
s and breeding is by direct development, with the female laying a few eggs on land that hatch into young toadlets (no tadpole stage).


Appearance and toxicity

''B. ephippium'' is a very small frog with a snout–to–
vent Vent or vents may refer to: Science and technology Biology *Vent, the cloaca region of an animal *Vent DNA polymerase, a thermostable DNA polymerase Geology *Hydrothermal vent, a fissure in a planet's surface from which geothermally heated water ...
length of in adults, but it is among the largest in its genus together with species like '' B. darkside'', '' B. garbeanus'' and '' B. margaritatus''. Females tend to be larger than males. When newly hatched ''B. ephippium'' typically measure just . ''B. ephippium'' is overall bright yellow-orange and this is considered
aposematic Aposematism is the Advertising in biology, advertising by an animal, whether terrestrial or marine, to potential predation, predators that it is not worth attacking or eating. This unprofitability may consist of any defenses which make the pr ...
(warning colours) since its skin and organs contain
tetrodotoxin Tetrodotoxin (TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an Order (biology), order that includes Tetraodontidae, pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin. Alt ...
and similar toxins. Newly hatched ''B. ephippium'' are well-camouflaged and brown overall. 11-oxoTTX (11-oxotetrodotoxin), an isolated analogue is extremely rare to be found in other animals, even marine animals, this analogue is considered four to five times more potent than the tetrodotoxin itself. Other analogues isolated of this toad include the tetrodonic acid, 4-epipetrodotoxin, 4.9 anhydrotetrodotoxin and 11-nortetrodotoxin. The toxins can be found in their skin and ovaries, but mostly concentrated in the liver. In 2019, scientists discovered that the head and back of this toadlet and the closely related red pumpkin toadlet (''B. pitanga'') glowed under
ultraviolet light Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of th ...
, due to their
fluorescent Fluorescence is one of two kinds of photoluminescence, the emission of light by a substance that has absorbed light or other electromagnetic radiation. When exposed to ultraviolet radiation, many substances will glow (fluoresce) with color ...
skeleton A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal fra ...
s. Young that have gained the bright yellow-orange adult colours still lack their fluorescence. It was initially speculated that the fluorescent colour also is aposematic or that it is related to
mate choice Mate choice is one of the primary mechanisms under which evolution can occur. It is characterized by a "selective response by animals to particular stimuli" which can be observed as behavior.Bateson, Paul Patrick Gordon. "Mate Choice." Mate Choi ...
(
species recognition Intra-species recognition is the recognition by a member of an animal species of a conspecific (another member of the same species). In many species, such recognition is necessary for procreation. Different species may employ different methods, ...
or determining fitness of a potential partner), but later studies indicate that the former explanation is unlikely, as predation attempts on the toadlets appear to be unaffected by the presence/absence of fluorescence.


Call and hearing

Peculiarly, this species and the closely related red pumpkin toadlet are unable to hear the
frequency Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...
of their own advertising calls, as their ears are underdeveloped. Instead their communication appears to rely on certain movements like the
vocal sac The vocal sac is the flexible Biological membrane, membrane of skin possessed by most male frogs and toads. The purpose of the vocal sac is usually as an amplification of their mating or advertisement call. The presence or development of the voca ...
that inflates when calling, mouth gaping and waving of their arms. It is speculated that their calling is a
vestigiality Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...
from the ancestral form of the genus, whereas their reduced hearing ability (they do have some hearing ability in frequencies outside their call) is a novel change in these species. Sounds make them more vulnerable to predators, but there has likely been little direct
evolutionary pressure Evolutionary pressure, selective pressure or selection pressure is exerted by factors that reduce or increase reproductive success in a portion of a population, driving natural selection. It is a quantitative description of the amount of change o ...
to lose it because of their toxicity.


See also

* Polka-dot tree frog (''Hypsiboas punctatus'') — the first frog discovered to be fluorescent, in 2017


References

{{Taxonbar, from=Q1499291 epphippium Amphibians of the Atlantic Forest Endemic frogs of Brazil Amphibians described in 1824 Taxonomy articles created by Polbot