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

Abstract

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 B. boticario and B. fuscolineatus, the new species is among the southernmost species of Brachycephalus known to date.

Keywords: Abundance; Atlantic Rainforest; Conservation; Microcomputed tomography; Microendemism; Montane forest; Serra do Mar.

Figure 1. Holotype of Brachycephalus albolineatus in life.

Figure 2. Holotype of Brachycephalus albolineatus (MHNCI 10290).

The image was obtained a few minutes after being sacrificed and fixed in formalin. (A) Dorsal view of the body; (B) ventral view of the body; (C) lateral view of the head; (D) ventral view of right hand; and (E) ventral view of right foot. Vertical scale bars = 1 mm. Horizontal scale bars = 5 mm.

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”.

Figure 4. Comparison between B. albolineatus and other species of Brachycephalus that are geographically close, in preservative.

(A) dorsal variation in B. albolineatus;(B) ventral variation in B. albolineatus (from left MHNCI 10290, 10297, 10295, 10296); (C) dorsal variation in B. olivaceus; (D) ventral variation in B. olivaceus (MHNCI 9815, 9814, 9813, 9816); (E) dorsal variation in B. fuscolineatus; (F) ventral variation in B. fuscolineatus (MHNCI 10236, 10231, 10235, 10237); (G) dorsal variation in B. boticario; (H) ventral variation in B. boticario (from the left MHNCI 10731, 10253, 10257, 10255); (I) dorsal variation in B. verrucosus; (J) ventral variation in B. verrucosus (MHNCI 10223, 10219, 10226, 10225). Dorsal and ventral views are shown with specimens in the same order. We selected the specimens with the most variation in color to illustrate intraspecific variation. Scale bars = 5 mm.

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.

Figure 6. High-resolution computed tomography (Micro-CT) scans of a paratype of Brachycephalus albolineatus (MHNCI 10295) showing key osteological features.

(A) Dorsal view of the skeleton; (B) dorsal, lateral, and ventral views of the skull (without the lower jaw); (C) ilium in lateral view; (D) pectoral girdle in ventral view; (E) right foot in plantar view; and (F) right hand in palmar view. Abbreviations: n, neopalatine; qj, quadrojugal; s, sesamoid; vf, vertebral fusion between presacral vertebra VIII and sacral vertebra. Scale bars equal 2 mm.

Figure 7. Map indicating the location of the type locality of Brachycephalus albolineatus(red), as well as other species of the genus that are found in the region (state of Santa Catarina, souhtern Brazil).

B. fuscolineatus (yellow), B. boticario (blue), B. olivaceus (gray), and B. verrucosus (purple). White crosses indicate areas with climatic and vegetation features that are characteristic of montane Brachycephalus that were surveyed, but no record has been obtained to date.

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