Friday, November 4, 2016

[Herpetology • 2016] Brachycephalus albolineatus • A New Species of Brachycephalus (Anura: Brachycephalidae) from Santa Catarina, southern Brazil

Brachycephalus albolineatus   
Bornschein, Ribeiro, Blackburn, Stanley & Pie, 2016

DOI:  10.7717/peerj.2629  


A new species of Brachycephalus (Anura: Brachycephalidae) is described from the Atlantic Forest of northeastern state of Santa Catarina, southern Brazil. Nine specimens (eight adults and a juvenile) were collected from the leaf litter of montane forests 790–835 m above sea level (a.s.l.). The new species is a member of the pernix group by its bufoniform shape and the absence of dermal co-ossification and is distinguished from all its congeners by a combination of its general coloration (dorsal region of head, dorsum, legs, arms, and flanks light, brownish green to dark, olive green, with darker region in the middle of the dorsum and a white line along the vertebral column in most specimens) and by its smooth dorsum. The geographical distribution of the new species is highly reduced (extent of occurrence estimated as 25.04 ha, or possibly 34.37 ha). In addition, its habitat has experienced some level of degradation, raising concerns about the future conservation of the species. Preliminary density estimates suggest one calling individual every 3–4 m2 at 815–835 m a.s.l. and every 100 m2 at 790 m a.s.l. Together with the recently described Brachycephalus boticario and B. fuscolineatus, the new species is among the southernmost species of Brachycephalus known to date.

Figure 1: Holotype of Brachycephalus albolineatus in life.
DOI:  10.7717/peerj.2629   

Diagnosis. Brachycephalus albolineatus is a member of the genus Brachycephalus based on diagnostic morphological traits, including phalangeal reduction, an arciferal pectoral girdle in which the ossified procoracoid and epicoracoid cartilages are fused to the clavicle, coracoid, and scapula, a suprascapula expanded with a prominent cleithrum, and the absence of a sternum (modified from Kaplan (2002), Izecksohn (1971), Ford & Cannatella (1993), Ribeiro et al. (2005), Alves et al. (2006) and Da Silva, Campos & Sebben (2007); Fig. 5). Brachycephalus albolineatus is a member of the pernix group, as defined by Ribeiro et al. (2015), by having a bufoniform body and lacking dermal co-ossification. Within Brachycephalus, B. albolineatus is distinguished from all of the species in the genus by the following combination of characters: (1) body bufoniform; (2) absence of dermal co-ossification; (3) adult size SVL 9.9–11.4 mm; (4) dorsum smooth (Fig. 1); (5) fusion of the last presacral (VIII) and sacral vertebrae; (6) general color (in life) of the dorsal region of head, dorsum, legs, arms and flanks light, brownish green to dark, olive green, always with a dark green region along the middle of the dorsum and a white line along the vertebral column in most specimens.

Figure 3: Variation in dorsal coloration among paratypes of Brachycephalus albolineatus(A), MHNCI 10295; (B), MHNCI 10299.
Figure 5: Juvenile of Brachycephalus albolineatus (MHNCI 10293). (A) dorsal view; (B) ventral view; (C) general view next to the tip of a pencil, for scale.
DOI:  10.7717/peerj.2629   

Figure 3: Variation in dorsal coloration among paratypes of Brachycephalus albolineatus.
 (A), MHNCI 10295; (B), MHNCI 10299; (C), MHNCI 10297; (D), MHNCI 10298; (E), MHNCI 10300; (F), MHNCI 10296. Notice a line of protruding glands on the dorsolateral region of body (although the degree of conspicuousness of this line varied among individuals). Also, the white line on the middle of the dorsum is completely absent in specimen “F”.
DOI:  10.7717/peerj.2629  

Etymology. The specific epithet is from the Latin albus (“white”) and lineatus (“of a line”), in reference to the characteristic white stripe across the dorsum of the new species, present in most specimens.

Distribution. Brachycephalus albolineatus is known only from the type locality, being found in altitudes between 790–835 m a.s.l. Given the dense sampling of other potential locations with climatic and vegetation conditions similar to the type locality (Fig. 7), it likely that B. albolineatus has a microendemic distribution, as found in other species of the pernix group (Bornschein et al., 2016). For instance, we searched for the new species on a mountain named Pedra Branca just 4.8 km from the type locality (26°32′52″S, 49°05′11″W) on the border of the municipalities of Jaraguá do Sul and Massaranduba, Santa Catarina, on 6 March 2016. In this mountain, we worked from 700 m a.s.l. up to the top, at 730 m a.s.l., and we did not find the new species.  ....

Figure 8: General view of the vegetation in the type locality (at 830 m above sea level). 

Ecology. Brachycephalus albolineatus lives on the leaf litter of the forest floor of montane forests (Floresta Ombrófila Densa Montana; with a canopy between 10–18 m in height; Fig. 8). While we disturbed the litter while searching for specimens, some individuals were seen moving further down, with some specimens being detected in the soil between roots. It was raining on 25 October 2012 we heard no calling activity; we only collected one individual by randomly searching the leaf litter. On 5 and 6 February 2016, the species showed high calling activity on the upper limit of their occurrence (830 m a.s.l.), becoming gradually scarcer downward. We estimate about one calling individual in each 3–4 m2 at 815–835 m a.s.l. and every 100 m2 at 790 m a.s.l., respectively in the highest and lowest altitudinal limits of records of the species. On 05 and 06 February 2016, we verified that the species became silent after the sunset (at least for 30 min, when we left the site), and on 6 March 2016 we did not hear any individual calling at night (we arrived at the site 30 min after sunset and waited for 20 min).

Marcos R. Bornschein, Luiz F. Ribeiro, David C. Blackburn, Edward L. Stanley and Marcio R. Pie​. 2016. A New Species of Brachycephalus (Anura: Brachycephalidae) from Santa Catarina, southern Brazil.  PeerJ. 4:e2629. DOI:  10.7717/peerj.2629


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