*2.3. Micro-Computed Tomography*

We obtained X-ray micro-computed tomography (μCT) images from two specimens to examine the skull and skeleton of the new species. We scanned two voucher specimens (paratypes) stored in 70% ethanol in the Micro-CT Core facility at the University of Michigan. We placed these specimens inside a glass vial, which in turn was placed in a 34 mm diameter specimen holder, prior to scanning. We used a microCT system, μCT100 Scanco Medical (Bassersdorf, Switzerland), and scan settings were as follows: voxel size 11.4 μm, 55 kVp, 145 μA, 0.5 mm AL filter, 1000 projections around 180◦, integration time of 1000 ms, and average data of 3 replicates. We used Scanco's proprietary software to export data to DICOM files. We used the Amira-Avizo software to obtain three-dimensional renderings based on isosurface representations.

The main purpose of the CT-scans was to examine the condition of the tympanic middle ear (inspect if columella was present or not) and the number and shape of phalanges. Both of these characters are key for the diagnosis of species of *Noblella* and *Psychrophrynella*. Thus, images presented here will facilitate osteological comparisons with other species once additional CT-scan data become available.

## *2.4. Molecular Phylogenetic Analysis*

We determined the phylogenetic position of the new species with respect to other closely related taxa through analysis of DNA sequences. Our analysis included sequences obtained from tissue samples collected from type specimens (holotype and paratypes) as well as legacy data from GenBank (Table S1). Sequence data included a fragment of the 16S rRNA gene (16S), a fragment of the 12S rRNA gene (12S), the protein-coding gene cytochrome c oxidase subunit I (COI), the nuclear protein-coding gene recombination-activating protein 1 (RAG1), and the tyrosinase precursor (Tyr). We used *Phrynopus peruanus* to root the tree. We followed previously reported procedures [14,23] for lab work and sequencing, and we deposited new sequences in GenBank (Table S1).

We aligned the sequences with Geneious R6, v. 6.1.8 [24], using the built-in Geneious Aligner program. Subsequently, we used PartitionFinder, v. 1.1.1 [25] to select the appropriate models of nucleotide evolution. We determined the best partitioning scheme and substitution model for each gene using the Bayesian information criterion (BIC). The best partitioning scheme included six subsets (best fitting substitution model in parentheses) as follows. A first partition subset including both 12S and 16S sequences (GTR + I + G). For COI, the best partitioning scheme included three sets of sites (substitution models in parentheses): the first set with first codon position (K80 + G), the second set with second codon position (F81 + I), and the third set with the third codon position (HKY + G). The next subset included the first and second codon positions of RAG together with the first and third codon positions of Tyr (HKY + G). The last subset included the third codon position of RAG together with the second codon position of Tyr (K80 + G).

We used MrBayes, v. 3.2.0 [26] to infer a molecular phylogeny. Our analysis included 36 terminals and a 2571 bp concatenated partitioned dataset (16S, 12S, COI, RAG1, Tyr). We performed an MCMC Bayesian analysis that included two simultaneous runs of 10 million generations, sampled once every 1000 generations. Each run had one "cold" chain and three heated chains, and the burn-in was set to discard 25% samples from the cold chain. The average standard deviation of split frequencies at the end of the runs was 0.001661. Subsequently, we used Tracer version 1.5 [27] to examine the effective sample sizes (ESS), to verify convergence, and to verify that the runs reached stationarity. The observed effective sample sizes were sufficient for all parameters (ESS > 200). Lastly, we used FigTree v. 1.4.2 [28] to visualize the majority-rule consensus tree and assess node support (based on posterior probability values).

## *2.5. Registration of New Nomenclatural Acts*

According to the International Commission on Zoological Nomenclature (ICZN), which produces the International Code of Zoological Nomenclature, the electronic publication of this article in portable document format (PDF) represents a published work. Therefore, the new species name contained in the PDF is effectively published under the International Code of Zoological Nomenclature from the electronic edition alone. This publication and the nomenclatural acts contained in it have been registered in ZooBank, the online official register for the ICZN. The ZooBank Life Science Identifiers (LSIDs) can be accessed and viewed through standard web browsers by appending the LSID to the prefix http://zoobank.org/. The online version of this work is archived and available from the following digital repositories: *Diversity*, CLOCKSS, and e-Helvetica.
