A new species of Brachycephalus (Anura: Brachycephalidae) from southern Brazil

Abstract

A new miniaturized frog of the genus Brachycephalus (Anura: Brachycephalidae) is described from Morro Santo Anjo in the municipality of Massaranduba, Santa Catarina, southern Brazil. Specimens were collected from the leaf litter between 470 and 540 above sea level. The new species is distinguished from all its congeners by the combination of the following characters: (1) body robust and bufoniform; (2) size snout-vent length 9.9-11.7 mm for males and 10.0-12.9 mm for females; (3) smooth dorsum; (4) general color (in life) orange with white dots and stripe in the middle of the head and along its vertebral column; (5) iris completely black; (6) advertisement call composed of note groups; (7) isolated notes with 1-3 pulses; and (8) short isolated notes (0.002-0.027 s). An estimate of the male density of the new species is also presented. Phylogenetic information indicates that the new species is part of the southernmost clade of Brachycephalus, which includes Brachycephalus fuscolineatus, B. albolineatus, and B. boticario. The severe anthropogenic impacts in and around the type locality indicate that immediate actions should be taken to ensure the long-term preservation of the new species.

Keywords: Atlantic forest; Brachycephalus mirissimus; Brachycephalus pernix group; Conservation; Linea masculina; Montane forest; Note-centered approach; Serra do Mar.

Figure 1. Holotype of Brachycephalus mirissimus (MHNCI 10793), adult male, in preservative in dorsal (A) and (B) ventral view of the body.

White bar = 5 mm. Photographs by Luiz F. Ribeiro.

Figure 2. Drawings of the holotype of Brachycephalus mirissimus.

Holotype of Brachycephalus mirissimus (MHNCI 10793), adult male: (A) dorsal view of the body; (B) lateral view of the head; (C) ventral view of right hand; (D) ventral view of right foot. Drawing by Verônica R. Apolônio.

Figure 3. Holotype of Brachycephalus mirissimus (MHNCI 10793), adult male, in life in lateral (A), dorsal (B) and ventral view (C).

Notice in C, from the left to right, two white arrows indicated the presence of the linea masculinea, a pair of bands of fibrous connective tissue present only in males of the species and the vocal sac. Black bar in C = 5 mm. Photographs by Luiz F. Ribeiro.

Figure 4. Variation in coloration of paratypes of Brachycephalus mirissimus.

(A–F) dorsal view; (G and H) ventral view. (A) MHNCI 10802; (B) MHNCI 10799; (C) MHNCI 10803; (D) MHNCI 10794; (E) MHNCI 10801; (F) MHNCI 10800; (G) MHNCI 10796; (H) MHNCI 10803. Notice in H the white arrow indicated the linea masculinea. Black bar in H = 5 mm. Photographs by Luiz F. Ribeiro.

Figure 5. Relationships between species of the Brachycephalus pernix species group based on a partial sequence of the 16S mitochondrial gene.

Phylogenetic analysis was carried out using Bayesian inference and values above branches correspond to node posterior probabilities. Nodes with posterior probabilities lower than 50% were collapsed.

Figure 6

Map indicating the location of the type locality of Brachycephalus mirissimus (yellow dot), as well as other species of the genus that are found in the region (state of Santa Catarina, southern Brazil) (indicated clockwise): B. mirissimus, B. fuscolineatus, B. boticario and B. albolineatus. Original photographs by Luiz F. Ribeiro. Map data © 2018 Google.

Figure 7. Advertisement call of Brachycephalus mirissimus.

Example of an entire advertisement call and also notes of other advertisement calls of Brachycephalus albolineatus. (A) Entire advertisement call (MHNCI 059, voucher MHNCI 10795). (B, D) All examples observed of isolated notes, with one pulse in B (MHNCI 067) and two pulses in D (MHNCI 073, voucher MNHCI 10794). (C, E) Examples of note groups, with 1–1 pulses in C (MHNCI 067) and 2–2 pulses in E (MHNCI 082, voucher MHNCI 10797). Spectrograms are produced with a FFT size of 8192 points, Hann window, and overlap of 90% in A and FFT 512 points, Hann window, and overlap of 90% in B–E.

Figure 8. Vegetation at the type locality of Brachycephalus mirissimus, at 535 m above sea level, characterized by high-elevation forest (Floresta Ombrófila Densa Montana).

(A) The middle and low strata of the forest, evidencing the habitat of Brachycephalus mirissimus in the leaf litter. (B) General view of the Morro Santo Anjo’s forest. Photographs by Luiz F. Ribeiro.

Figure 9. Impacts at the type locality of Brachycephalus mirissimus.

In (A) Morro Santo Anjo with plantation of Pinus sp. along the slope. In (B) forest boundary with palm plantation of Archontophoenix alexandrae. Photograph by Luiz F. Ribeiro.