Alsodes cantillanensis

Variation. Outside of the obvious differences due to the sex of the specimens of the type series (patches of spines on the chest and arms thicker in the male), the most remarkable difference between them is the dorsum background coloration: the holotype is ochre, with a lighter triangle on the head, and the paratype is orange, with the triangle reddish-orange. The holotype and other individuals observed in the type locality and in Quebrada Lisboa (see below) had a thin yellow vertebral line in the posterior part of the dorsum. These individuals exhibited an overall ochre coloration, but with different tones. Measurements of the paratype (in mm) are, SVL: 44.2; HL: 14.9; HW: 18.7; IOD: 5.3; ID: 4.7; EL: 6.4; ThL: 24.6; TL: 25.3; FL: 39.6.

Diagnosis. Alsodes cantillanensis can be distinguished from all other congeneric species for the following combination of characters: 1) thorny patches of the chest of males with spines uniformly distributed; 2) head with a triangle between the posterior border of the eyes and the snout tip, which contrasts with the background coloration; 3) superior part of the iris gold-yellowish brilliant, almost uniform; 4) postocular fold well-developed, extending beyond of the insertions of arms; 5) snout slightly truncated in dorsal and lateral profile; 6) dorsal skin smooth; 7) dorsal coloration ochre (holotype) or orange (paratype), with small and diffuse dark spots irregularly distributed; and 8) posterior legs slightly barred.

Distribution and natural history. The new species is only known from the type locality and one nearby site, Quebrada Lisboa (33 ° 55 ’ 33.6 ” S, 71 ° 01 ’ 05.3 ” W, 729 m a. s. l), both within the Natural Sanctuary San Juan de Piche, in the western slopes of the Altos de Cantillana mountains (Fig. 3). Altos de Cantillana mountains have a maximum height of 2281 m a. s. l. and are located in an area with Mediterranean climate that has less than 600 mm of rain per year and an average temperature of 10.7 ° C (Costa 2002). Alsodes cantillanensis inhabits mixed old grown forest of Nothofagus macrocarpa, Drymis winteri, Mirtacea sp., and vains of the genus Proustia. Specimens of the type series were found under rocks under the water during spring in the morning. Others (not collected) were found under a thick cover of litter fall near the stream (30 cm) and under logs close to the water. Additional specimens were observed at night walking along the stream of Quebrada Lisboa. In the creek at the type locality, the amphibians Alsodes nodosus (“ sapo arriero ”) and Pleurodema thaul (four-eyed frog) also were found. Molecular data and phylogenetic relationships. The combined alignment of the four fragments had 3024 nucleotide sites in length (318 of cytb, 1999 of the fragment 12 S- 16 S, 310 of rhod, and 397 of SINA). Only the fragment 12 S- 16 S showed gaps (36 sites, including the outgroup). MP analysis including the sites with gaps was based on 359 parsimony-informative characters. Thirteen most parsimonious trees were found, with a length of 878 steps, which differ only in the relative position of A. gargola, A. igneus, A. neuquensis, A. norae, and A. pehuenche (data not shown; see consensus tree in Fig. S 1). MP analysis treating gaps as missing also produced 13 trees (829 steps, 339 parsimony-informative characters) differing only in the relative position of the same taxa (data not shown). Regarding the BI, the post burn-in mean ln-likelihood values of the two independent analyses were - 8296.26 and - 8297.08. Convergence and mixing of chains were achieved according to ASDSF (<0.002), ESS (> 200), and PSRF (0.9999 – 1.0001) values. Results of these analyses are shown as the 50 % majority-rule consensus tree (Fig. 4), where bootstrap values of MP analysis including sites with gaps were added. Topologies of MP and BI analyses were highly congruent, showing two main clades for the genus with high statistical support (Fig. 4), which agrees with the hypothesis of Blotto et al. (2013). One clade is comprised by A. nodosus, A. cantillanensis, and A. vanzolinii, including the specimen identified a priori as A. cf. vanzolinii, and the other by the rest of Alsodes species. Within this main clade, two groups can be recognized also with high MP bootstrap support and Bayesian posterior probability: one comprised by all samples of A. nodosus (including one specimen from Pemehue, here labeled as A. aff. nodosus, a candidate species according to Blotto et al. 2013) and the two samples of the new species, and the other by the specimen of A. vanzolinii from Ramadillas (type locality) and the specimen of A. cf. vanzolinii from R. N. Los Queules. Within the second main clade, the group comprised by A. coppingeri, A. valdiviensis, and A. verrucosus diverges first, followed successively by A. hugoi plus A. tumultuosus, and A. barrioi (Fig. 4). The rest of species, A. gargola, A. igneus, A. neuquensis, A. norae, and A. pehuenche, form a politomy in the consensus tree. In summary, MP and BI analyses show that all samples of A. nodosus group with high support values and constitutes the sister group of the new species, ratifying the morphological distinction between both taxa (Fig. 1). However, the more compelling evidence to support the specific status of A. cantillanensis is that is sympatric and clearly diagnosable of A. nodosus at Quebrada Infiernillo.

Etymology. The specific name of the new taxon is the genitive Latin form of Cantillana, part of the name (Altos de Cantillana) of a mountain system with foothills covered by forests close to Santiago (65 km).

Holotype. A male (SSUC-Am- 168; Fig. 1 A and Fig. 2) collected by Andrés Charrier and Alexander Baus in Quebrada Infiernillo, Fundo San Juan de Piche, Altos de Cantillana mountains (33 ° 55 ’ 32.6 ” S, 71 ° 02 ’ 34.6 ” W, 850 m a. s. l.; Fig. 3), on 3 August 2011. Paratype. A female (SSUC-Am- 169) collected by Andrés Charrier and Alexander Baus at the same place and date as the holotype.