Editorial Type:
Article Category: Research Article
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Online Publication Date: 20 Oct 2022

A New Species of Brachycephalus (Anura, Brachycephalidae) from a Montane Atlantic Rainforest of Southeastern Brazil, with a Reappraisal of the Species Groups in the Genus

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Page Range: 585 – 601
DOI: 10.1643/h2020144
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Toadlets of the genus Brachycephalus are endemic to the Brazilian Atlantic Rainforest, where they inhabit the forest floor leaf litter. These miniaturized frogs are commonly known as flea-toads or pumpkin toadlets depending on their phenotypic characteristics. Herein, we describe a new species of the genus Brachycephalus from montane forests (970–1200 m a.s.l.) in the Serra dos Órgãos mountain range, in the state of Rio de Janeiro, southeastern Brazil. The new species is characterized by having a small body size within the genus (maximum SVL 9.6 mm in males and 10.9 mm in females), a noticeably granular dorsum with an X-shaped mark and a median row of small yellow tubercles, a yellow background color with red blotches on ventral surfaces, a lateral dark brown stripe, and the absence of hyperossification in the skeleton. Morphological features of the new taxon resemble those of both flea-toads and pumpkin toadlets. Based on our molecular phylogenetic hypothesis, the new species is recovered sister to the clade formed by the monophyletic B. ephippium and B. vertebralis species groups (previously considered as lineages of a more inclusive B. ephippium group). We also reinforce the suggestion of not using the name B. didactylus group because it does not represent a monophyletic taxon. The new species probably has an extremely restricted geographic distribution, and its discovery reinforces the importance of the Serra dos Órgãos mountains for the conservation of the Atlantic Rainforest anuran biodiversity.

Copyright: © 2022 by the American Society of Ichthyologists and Herpetologists
Fig. 1.
Fig. 1.

Holotype of Brachycephalus clarissae, new species (MNRJ 66543). Head in (A) dorsal and (B) lateral views; ventral views of (C) hand and (D) foot. Scale bar = 1 mm.

Fig. 2.
Fig. 2.

Holotype of Brachycephalus clarissae, new species (MNRJ 66543). (A) Dorsal, (B) ventral, and (C) lateral views of the body; ventral views of foot (D) and hand (E). Scale bar = 1 mm.

Fig. 3.
Fig. 3.

Lateral (A, C) and ventral (B, D) views of Brachycephalus clarissae, new species, in life. Paratypes (A, B) MNRJ 56505, and (C, D) MNRJ 56516 from Theodoro de Oliveira, municipality of Nova Friburgo, state of Rio de Janeiro, Brazil.

Fig. 4.
Fig. 4.

Dorsal variation in preserved specimens of Brachycephalus clarissae, new species. (A) MNRJ 56506 (male, SVL 9.4 mm), (B) MNRJ 56509 (male, SVL 9.0 mm), (C) MNRJ 56510 (female, SVL 10.9 mm), (D) MNRJ 51470 (female, SVL 10.4 mm), (E) MNRJ 56505 (male, SVL 8.7 mm), and (F) MNRJ 56504 (male, SVL 8.7 mm). Scale bar = 1 mm.

Fig. 5.
Fig. 5.

Ventral variation in preserved specimens of Brachycephalus clarissae, new species. (A) MNRJ 51470 (female, SVL 10.4 mm), (B) MNRJ 56506 (male, SVL 9.4 mm), (C) MNRJ 56511 (female, SVL 10.4 mm), (D) MNRJ 56509 (male, SVL 9.0 mm), (E) MNRJ 56510 (female, SVL 10.9 mm), and (F) MNRJ 56508 (male, SVL 8.8 mm). Scale bar = 1 mm.

Fig. 6.
Fig. 6.

Known distribution of Brachycephalus clarissae, new species, in the municipality of Nova Friburgo, state of Rio de Janeiro, Brazil (star).

Fig. 7.
Fig. 7.

Bayesian inference tree (lnL = –32991.073) from a concatenated matrix of 12S, 16S, cytb, RAG1, tyr sequences (4,678 aligned base pairs, 79 ingroup terminals) of species of Brachycephalus. Gray circles show high clade support values (posterior probabilities above 0.95). Bars to the right of the tree are colored according to the classification of species into B. ephippium (green), B. vertebralis (yellow), and B. pernix (blue) groups, as suggested in the present study. Brachycephalus clarissae, new species, is highlighted in red. Photos provided by C. de Luna-Dias (B. ephippium), R. Sawaya (B. nodoterga and B. hermogenesi), and T. H. Condez (B. guarani), or modified from Haddad et al. (2010; B. toby) and Ribeiro et al. (2015; B. auroguttatus, B. fuscolineatus). Frog images are not to scale. See Data Accessibility for tree file.

Fig. 8.
Fig. 8.

High-resolution computed tomography (Micro-CT) scans of a paratype of Brachycephalus clarissae, new species (MNRJ 89565). (A) Dorsal and (B) ventral views of the skeleton; (C) left hand in palmar view; (D) right foot in plantar view; (E) dorsal, (F) ventral, and (G) lateral views of the skull (without the lower jaw); (H) dorsal view of vertebral column; (I) pelvic girdle in dorsal view; and (J) pectoral girdle in ventral view. Scale bars = 1 mm.

Fig. 9.
Fig. 9.

Views of (A) hyolaryngeal skeleton, and (B) dorsal hand and (C) foot of a paratype of Brachycephalus clarissae, new species (MNRJ 56512). Scale bar = 1 mm.

Contributor Notes

1 Departamento de Vertebrados, Museu Nacional, Universidade Federal do Rio de Janeiro, Quinta da Boa Vista, 20940-040 Rio de Janeiro, Brazil; Email: (MF) follymga@gmail.com; and (JPP) pombalmn@gmail.com.
Send correspondence to MF.
2 Departamento de Zoologia, Universidade Federal do Estado do Rio de Janeiro, Av. Pasteur 458, Urca, 22240-290 Rio de Janeiro, Brazil; Email: davor.vrcibradic@gmail.com.
3 Departamento de Ecologia, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier 524, Maracanã, 20550-013 Rio de Janeiro, Brazil; Email: (CCS) carlacsiqueira@yahoo.com.br; and (CFDR) cfdrocha@gmail.com.
4 Instituto Alberto Luiz Coimbra de Pós-graduação e Pesquisa em Engenharia, Laboratório de Instrumentação Nuclear, Universidade Federal do Rio de Janeiro, 21941-450 Rio de Janeiro, Brazil; Email: (ASM) alessandra.machado@coppe.ufrj.br; and (RTL) ricardo@lin.ufrj.br.

Associate Editor: J. Faivovich.

Received: 22 Oct 2020
Accepted: 06 May 2022
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