Brachycephalus nanicus

Brachycephalus nanicus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Clade: Brachycephaloidea
Family: Brachycephalidae
Genus: Brachycephalus
Species:
B. nanicus
Binomial name
Brachycephalus nanicus
Nunes et al., 2025

Brachycephalus nanicus is a species of small frog in the family Brachycephalidae endemic to the Atlantic Forest of Brazil. It is one of more than 40 named species within the genus Brachycephalus, and is most closely related to Brachycephalus puri. B. nanicus is a very small species; adult males range from 6.9–9.0 millimetres (0.27–0.35 in) (SVL), while females are slightly larger, at 9.2–9.6 mm (0.36–0.38 in). It is characterized as a "flea-toad", having a more slender body and more dull coloration than the rounder and brighter "pumpkin toadlet" members of the genus. It has smooth skin, a rounded snout when seen from above, a lacking first toe, and a brown coloration with scattered golden spots and a dark stripe running down the side and thigh.[1]

Taxonomy

Brachycephalus, along with Ischnocnema, comprise the family Brachycephalidae, which is a member of the larger clade Brachycephaloidea. Brachycephaloids are uniquely characterized by undergoing direct development, meaning individuals hatch from eggs as tiny versions of the adult, rather than tadpoles.[2] The placement of Brachycephalus within this clade is shown in the cladogram below:[3]

Brachycephaloidea

More than 40 species of Brachycephalus are recognized,[4] generally divided into two major subcategories, both of which are polyphyletic groups:[5] the more speciose "pumpkin toadlets", characterized by their brighter colors (red, orange, yellow, and green patterns) and bufoniform (more stout) body blan, and the less diverse "flea-toads", characterized by their dull colors and leptodactyliform (more slender) body plan. B. nanicus is one of the seven named flea-toads (B. clarissae exhibiting an intermediate anatomy between the two groupings). In their 2025 description of B. nanicus, Nunes and colleagues tested the phylogenetic relationships of Brachycephalus species, recovering B. nanicus as the sister taxon to B. puri. The results from their analysis are displayed in the cladogram below, with flea-toads noted indicated. ⊞ buttons can be clicked to expand nodes.[1]

Brachycephalus

Brachycephalus pulex

B. puri

Brachycephalus puri

Brachycephalus sp. 8

Brachycephalus nanicus

Brachycephalus didactylus

Brachycephalus clarissae

B. ephippium

Brachycephalus garbeanus

Brachycephalus ephippium

Brachycephalus ibitinga

Brachycephalus darkside

Brachycephalus rotenbergae

Brachycephalus sp. 6

Brachycephalus margaritatus

species group
B. vertebralis

Brachycephalus bufonoides

Brachycephalus herculeus

Brachycephalus alipioi

Brachycephalus toby

Brachycephalus nodoterga

Brachycephalus vertebralis

Brachycephalus crispus

Brachycephalus pitanga

Brachycephalus guarani

Brachycephalus pitanga

Brachycephalus sp. 3

species group

Brachycephalus sulfuratus

B. pernix

Brachycephalus boticario

Brachycephalus albolineatus

Brachycephalus mirissimus

Brachycephalus fuscolineatus

Brachycephalus actaeus

species group

   flea-toads

References

  1. ^ a b Nunes, Ivan; Lyra, Mariana L.; Machado, Thaynara M.; Carrasco-Medina, Andres Santiago; Andrade, Felipe Silva De; Haga, Isabelle Aquemi; Botelho, Lucas M.; Pedrozo, Mariana; Velasco, Isabel G.; Jacinavicius, Fernando De Castro; Gray, Jaimi A.; Blackburn, David C.; Kohlsdorf, Tiana; Muscat, EdéLcio; Toledo, L. Felipe (September 9, 2025). "A new species of flea-toad of the genus Brachycephalus Fitzinger, 1826 (Anura: Brachycephalidae) from the cloud forests of Serra do Mar, southeastern Brazil". Zootaxa. 5691 (2): 231–256. doi:10.11646/zootaxa.5691.2.3. ISSN 1175-5334.
  2. ^ Hedges, S. Blair; Duellman, William E.; Heinicke, Matthew P. (2008-03-31). "New World direct-developing frogs (Anura: Terrarana): Molecular phylogeny, classification, biogeography, and conservation". Zootaxa. 1737 (1): 1–182–1–182. doi:10.11646/zootaxa.1737.1.1. ISSN 1175-5334.
  3. ^ Fouquet, Antoine; Kok, Philippe J.R.; Recoder, Renato Sousa; Prates, Ivan; Camacho, Agustin; Marques-Souza, Sergio; Ghellere, José Mario; McDiarmid, Roy W.; Rodrigues, Miguel Trefaut (February 2024). "Relicts in the mist: Two new frog families, genera and species highlight the role of Pantepui as a biodiversity museum throughout the Cenozoic". Molecular Phylogenetics and Evolution. 191 107971. doi:10.1016/j.ympev.2023.107971.
  4. ^ Frost, Darrel R. (2025). "Search for Taxon: Brachycephalus". Amphibian Species of the World, an Online Reference. Version 6.0. American Museum of Natural History, New York. Retrieved 11 September 2025.
  5. ^ Condez, Thais H; Haddad, Célio F B; Zamudio, Kelly R (2020-01-16). "Historical biogeography and multi-trait evolution in miniature toadlets of the genus Brachycephalus (Anura: Brachycephalidae)". Biological Journal of the Linnean Society. 129 (3): 664–686. doi:10.1093/biolinnean/blz200. hdl:11449/196654. ISSN 0024-4066.