Tachiramantis lassoalcalai (Rojas-Runjaic & Echevarría & Becerra-Rondón & Infante-Rivero, 2010)

Rojas-Runjaic, Fernando J. M., Echevarría, Lourdes Y., Becerra-Rondón, Adriana C. & Infante-Rivero, Edwin E., 2020, Tachiramantis lassoalcalai (Barrio-Amorós, Rojas-Runjaic & Barros, 2010) (Anura, Craugastoridae): a new combination revealed by molecular evidence, with a description of its advertisement call, Zootaxa 4778 (2), pp. 372-382 : 375-376

The

evolutionary relationships of Tachiramantis within Craugastoridae are yet unclear as its position varied in all previous phylogenetic hypotheses in which samples of this genus were included ( Heinicke et al. 2015; Guayasamin et al. 2017; Heinicke et al. 2018). However, all of these hypotheses were congruent in recovering Tachiramantis as monophyletic, not closely related to Pristimantis , and deeply divergent to its sister linage. Our phylogeny ( Fig. 2 ) also differs from previous hypotheses with regard to the intergeneric relationships of Tachiramantis with other craugastorids but it is concordant with the results of Heinicke et al. (2015) and Guayasamin et al. (2017) in recovering the three species of Tachiramantis as closely related, with T. lentiginosus and T. douglasi as sister species, and T. prolixodiscus as the most external of the genus. The only difference with these two previous hypotheses corresponds to the position of the newly included P. lassoalcalai , which is well-nested within Tachiramantis as sister to T. lentiginosus + T. douglasi (rendering Tachiramantis paraphyletic). This newly discovered phylogenetic position confirms previous suspicions of a close evolutionary relationship between this species and Tachiramantis based on its overall morphological resemblance with T. lentiginosus and T. douglasi . Based on this result and in order to promote a taxonomy based on monophyletic groups, we transfer Pristimantis lassoalcalai Barrio-Amorós, Rojas-Runjaic & Barros, 2010 to Tachiramantis as Tachiramantis lassoalcalai comb. nov. With the new addition, Tachiramantis is now composed by four species distributed on the northern part of the Cordillera Oriental of Colombia, Tamá massif, Sierra de Perijá and Cordillera de Mérida.

Tachiramantis remains a poorly known genus, distributed in a region undersampled by systematic studies using molecular data ( Heinicke et al. 2015) and with vast areas poorly inventoried for amphibians, as the Sierra de Perijá ( Rojas-Runjaic et al. 2011; Meza-Joya 2016; Rojas-Runjaic et al. 2018) and the Tamá massif ( Acevedo et al. 2014; Meza-Joya et al. 2019). Thus, we expect that the inclusion of both new and already described terraranas currently allocated to Pristimantis , in future molecular phylogenies, will result in the discovery of additional members of Tachiramantis .

On the other hand, although no external morphology synapomorphies are known for Tachiramantis , the occurrence of pale spots on the posterior surface of thighs ( Rivero 1984) is shared by T. douglasi , T. lassoalcalai , and T. lentiginosus (absent in T. prolixodiscus ). Thus, this character state can be useful to diagnose these three species from other sympatric terraranas by external morphology. The phylogenetic relevance of this phenotypic character should be objectively assessed. In addition, osteological characterization of T. lassoalcalai will be required in order to corroborate the occurrence in this species of the putative cranial synapomophies defined by Heinicke et al. (2015) for Tachiramantis .

As it is known, acoustic signals play a critical role in mate recognition and mate choice, and in most cases are species-specific ( Wells 2007), which make them a useful source of evidence for anuran systematics and taxonomy (Khöler et al. 2017). Until very recently there was no bioacoustic information available for any Tachiramantis , but the almost simultaneous publication of the call description of T. douglasi ( Mendoza-Roldán et al. 2020) with our description of the advertisement call of T. lassoalcalai allow us to confirm that bioacoustics also constitutes a valuable tool to diagnose species in this group. These two species exhibit strikingly different advertisement calls (values for T. lassoalcalai in parentheses): T. douglasi calls last ca. 1.7 s and consist of trills of 7–9 notes, with the first being the longest (calls represented by single notes of ca. 0.7 s), with dominant frequency of ca. 5.1 kHz (dominant frequency between 2.9–3.0 kHz). Considering that the known geographic distributions of T. lassoalcalai and T. douglasi are relatively close ( Mendoza-Roldán et al. 2020; Barrio-Amorós et al. 2010) and that both species are morphologically similar (see Fig. 1 ), their bioacoustical characterizations will be valuable to diagnose them during fieldwork and in the absence of molecular data.

Figures

FIGURE 1. Species currently known in the Andean frog genus Tachiramantis. a. T. douglasi; b. T. lassoalcalai comb. nov.; c. T. lentiginosus; d. T. prolixodiscus. Photos: F.J.M. Rojas-Runjaic (a, c–d); P. Velozo (b).

FIGURE 2. Maximum Likelihood tree with branch lengths, inferred from a 3,649 bp fragment of the mitochondrial genes 12S rRNA, 16S rRNA, and the nuclear RAG1 and Tyr, depicting phylogenetic relationships of Tachiramantis lassoalcalai comb. nov. with Tachiramantis and some selected species of other 17 Terrarana genera. Bootstrap support values higher than 50 % are presented for each node. Values of 100 % are represented by an asterisk.