Two new species of Thomasomys (Cricetidae: Sigmodontinae) from the western Andes of Ecuador and an updated phylogenetic hypothesis for the genus

Jorge Brito; Rubí García; Francisco X. Castellanos; Gabriela Gavilanes; Jenny Curay; Julio C. Carrión-Olmedo; Daniela Reyes-Barriga; Juan M. Guayasamin; Jorge Salazar-Bravo; C. Miguel Pinto

doi:10.3897/vz.74.e128528

Abstract

The Andean cloud forests of Ecuador are home to numerous unique mammals. Rodents of the tribe Thomasomyini are particularly abundant in many Andean localities, with Thomasomys – the largest genus in the subfamily Sigmodontinae (51 species) – especially species-rich and diverse. Despite recent advances on the systematics of the genus, where seven species have been described in the last five years, there is tantalizing evidence that its true diversity remains completely understood. Over the course of approximately ten years of fieldwork in Ecuador, a significant number of Thomasomys specimens were collected from various localities in both, the eastern and western Andean ranges. Through an extensive genetic study of these specimens, augmented with what is available in public databases, we argue that there exist at least 20 undescribed species in the genus, with no less that twelve potential new species in Ecuador alone. In this paper, we describe two of these species belonging to the group cinereus, one recently collected and the other previously referred to as Thomasomys sp. 1; further, we present an updated cyt b gene tree of the genus. The gene tree includes at least 56 valid and putative species and supports the monophyly of the genus, while at the same time suggest a paraphyletic “aureus” group. Our findings suggest that the genus likely exhibits additional hidden diversity in significant portions of Colombia, Peru, and Bolivia which calls for the need for a comprehensive reassessment of the entire genus. The recognition of these two new species brings the total number of known Thomasomys to 53 species, 19 of which occur in Ecuador, including 17 that are endemic to this country.

Key words

Andes, Thomasomyini, Thomasomys igor sp. nov., Thomasomys otavalo sp. nov., Thomasomys silvestris, Thomasomys ucucha

Introduction

The genus Thomasomys Coues, 1884 (Cricetidae: Sigmodontinae: Thomasomyini) is endemic to the Andes, with a distribution spanning from northern Venezuela to central Bolivia (Pacheco 2003, 2015) and one of the most interesting taxonomic complexes of the South American Andean forests, and other high Andean ecosystems (Salazar-Bravo and Yates 2007). The greatest proportion of its diversity is concentrated in Peru, Ecuador and Colombia, with 21, 17 and 14 species, respectively (Pacheco 2015; Brito et al. 2019; Pacheco and Ruelas 2023). So far, the eastern part of Ecuador seems to hold a rich and so far undiscovered hotspot of diversity of the genus (Voss 2003). This extraordinary concentration of species diversity is probably a consequence of the joint action of the emergence of biogeographic barriers in the Andes (Brumfield and Edwards 2005; Antonelli et al. 2018; Schenk and Steppan 2018), and the wide variety of microhabitats resulting from the complex interactions between altitude, temperature, and rainfall (Young et al. 2007).

Currently, 51 species of Thomasomys are recognized, leading Sigmodontinae in species richness (Pacheco 2015; Pardiñas et al. 2017). The taxonomic complexity of Thomasomys is high given that it contains at least seven species groups: aureus, baeops, cinereus, gracilis, incanus, macrotis, and notatus (Pacheco 2003; Salazar-Bravo and Yates 2007; Brito et al. 2019; Pacheco and Ruelas 2023), being the “cinereus group” the most diverse with approximately 50% of the species richness in the genus (Pacheco 2015; Brito et al. 2019; Pacheco and Ruelas 2023). Despite this remarkable diversity, only 39% of the species have been adequately covered in molecular phylogenies (see Brito et al. 2021; Pacheco and Ruelas 2023).

During the last ten years and under the aegis of the INABIO, we secured new Thomasomys samples from throughout Ecuador, including topotypic localities with the goal of increasing our understanding of the genus’ diversity and in order to improve comparisons. Some specimens within a large sample of Thomasomys from the northwestern slope of the Andes of Ecuador (in the western Provincia de Imbabura), presented morphologies discrepant from those of typical Thomasomys silvestris Anthony, 1924, and T. ucucha Voss, 2003. This led to new comparisons with representative material of all forms recognized for Ecuador (17 species according to Brito et al. 2019 and Pacheco and Ruelas 2023), including Thomasomys sp. 1, referred to in Brito et al. (2019) as an undescribed species. In this context and based on morphological and molecular characters, we herein describe two new species of Thomasomys in the cinereus group. Further, and based on the most comprehensive database to date, including, when possible, type and topotypic material for species in the genus and outgroup taxa, we provide an updated phylogenetic hypothesis for Thomasomys.

Materials and methods

Studied specimens

This study involves the study of qualitative and metric characters of 97 specimens of Thomasomys corresponding to the Clade C of the cinereus group (see fig. 3B in Brito et al. 2019) from populations of Ecuador (File S1). A portion of the specimens studied were collected by the senior author and collaborators during recent field trips conducted in northwestern Ecuador, between Mojanda (0.154560, –78.275360, 3,690 m), and the Cordillera de Cayapas (0.53640, –78.47506, 3,440 m). The remainder of the material corresponds to the museum specimens collected during the last ten years. In the first case, the studies involved a cumulative trapping effort of 1500 trap/night. During our surveys we follow the guidelines set forth by the American Society for Mammalogy (Sikes et al. 2016) and the Ministerio del Ambiente, Agua y Transición Ecológica of Ecuador (scientific research authorizations: MAE-DNBCM-2019-0126, MAAE-ARSFC-2020-0642, MAATE-ARSFC-2022-2583, and MAATE-DBI-CM-2023-0334).

The studied material was compared with specimens housed in the mammal collections of the following institutions: Instituto Nacional de Biodiversidad (INABIO), (MECN; formerly known as Museo Ecuatoriano de Ciencias Naturales), Quito, Ecuador; Museo de la Escuela Politécnica Nacional (MEPN), Quito, Ecuador; Museo de Zoología de la Pontificia Universidad Católica del Ecuador (QCAZ), Quito, Ecuador, and Museum of Southwestern Biology at the University of New Mexico (MSB), United States of America. In addition, 68 Ecuadorian specimens from different localities (including topotypical localities for several species; File S1) were selected for genetic analyses in order to update the phylogenetical hypothesis of Thomasomys.

Anatomy, age criteria and measurements

Terms used to describe cranial anatomy follow the proposals by Carleton and Musser (1989), Musser et al. (1998), Pacheco (2003), and Voss (1993); occlusal molar morphology was based on Reig (1977) with upper and lower molars identified as M/m, respectively. We followed the terminology and definitions employed by Tribe (1996) and Costa et al. (2011) for age classes and restricted the term “adults” to those individuals categorized between ‘age 3’ and ‘age 6’. The description of the coloration was made based on Köhler (2012). Soft anatomy was assessed according to the concepts discussed by Carleton (1973) and Vorontsov (1982) on stomach, by Myers (1990) and Pardiñas et al. (2017) on soft palate, and by Pacheco (2003) on anus. We obtained the external measurements in millimetres (mm); for most specimens, external measurements were recorded in the field and taken from specimen tags: head and body length (HB), tail length (TL), hind foot length (HF, including claw), ear length (E), and body mass (W, in grams). Cranial measurements were obtained with a digital calliper to the nearest 0.01 mm, and included the following characters (see Tribe 1996; Musser et al. 1998; and Voss 2003 for definitions and illustrations): Condylo-incisive length (CIL), length of upper diastema (LD), crown length of maxillary toothrow (LM), breadth of the first maxillary molar (BM1), length of incisive foramina (LIF), breadth of incisive foramina (BIF), breadth of the palatal bridge (BPB), breadth of zygomatic plate (BZP), least interorbital breadth (LIB), zygomatic breadth (ZB), depth of upper incisor (DI), breadth across both upper incisor tips (BIT), length of rostrum (LR), length of nasals (LN), breadth of rostrum (BR), breadth of bony palate (BBP), orbital fossa length (OL), breadth of mesopterygoid foramen (BMF), breadth between occipital condyles (BCO), braincase breadth (BCB), length of mandible (LMN), and depth of mandibular ramus (DR).

Morphometric Analyses

We analysed 97 male and female specimens of the cinereus group of Thomasomys cinereus (Pacheco 2015), including representatives of Thomasomys silvestris, T. ucucha Voss, 2003, and two putative new species. The matrix of quantitative characters comprised 1791 values, and was analysed in R version 4.2.1 (R Core Team 2022). Non-parametric methods were preferred for all morphometric analyses to avoid faulty assumptions on data distribution or incorrect methods of data transformation (Feng et al. 2014). The missing data, accounted 1.86% of the original dataset and was imputed using the missMDA package (Josse and Husson 2016) with the iterative expectation maximization (EM) algorithm with a maximum of 1000 iterations. The estimated number of components was determined by running 100 simulations with the leave-one-out cross-validation method. Morphological characters were checked for high level of correlation using Spearman’s coefficient, and none of these were discarded since correlation values were ≤0.95.

Two multivariate analyses, namely Principal Component Analysis (PCA) and K nearest neighbour classificatory discriminant analyses (KNN), were performed with the MorphoTools2 package in R (Šlenker et al. 2022) to assess and quantify potential differences among groups. A stepwise discriminant analysis was initially employed to identify invariant and non-linear characters for the KNN analysis, from which 14 were selected (BIT, TL, BZP, BM1, BMF, LIF, HB, OL, LR, LMN, CIL, LN, BPB, BIF). Notably, all members of Thomasomys sp. nov. 1 were excluded since the number of measured specimens (n=4) was smaller than the total number of analysed characters (Šlenker et al. 2022). The KNN results were visually represented by centering and scaling the two variables significantly contributing to group discrimination based on the R² and F-values obtained in the stepwise discriminant analysis.

The k-nearest cross-validatory classification of individuals with the leave-one-out method was made using three different numbers of neighbours (k=3, 7, 9) as estimated by the knn.select function from MorphoTools2. An optimal number of k-neighbours, k=3, was finally chosen to decrease the false positive rate. The accuracy of the classification was estimated as a percentage by comparing the model prediction to the a priori classification mentioned previously.

DNA amplification and sequencing

We worked in two different laboratories applying two different sequencing technologies to generate 66 new DNA sequences (Table S1) of the mitochondrial cytochrome b gene (cyt b). At the Laboratorio de Biología Evolutiva of the Universidad San Francisco de Quito (USFQ) we processed 30 samples and used Sanger sequencing. At INABIO’s Laboratorio de Sequenciamiento de Ácidos Nucleicos we processed 35 samples and used Oxford Nanopore Technologies (ONT).

For Sanger sequencing, DNA was extracted and purified from cryopreserved liver tissues (freshly obtained samples and museum material) using a guanidine thiocyanate protocol (Peñafiel et al. 2019). We amplified the entire mitochondrial gene cyt b in two partially overlapping fragments: the first fragment with the primers MTCB_F and CYTb870R, and the second with the primers cyt b F.1 and MTCB_R (Peppers et al. 2002; Whiting et al. 2003; Naidu et al. 2012). The thermal profile for the PCR amplification followed the touchdown thermocycling protocol of Murphy and O’Brien (2007). We purified the PCR amplicons with ExoSAP. Cycle sequencing reactions with the same amplification primers (i.e., both directions), and Sanger sequencing were performed by Macrogen Sequencing Labs (Magrogen Inc., South Korea).

For the samples sequenced using ONT, DNA was extracted and purified from cryopreserved liver tissues using GeneJET Genomic DNA Purification Kit (K0722). We amplified a partial fragment (ca. 800 bp) of the cyt b gene with the forward primer MVZ05 and the reverse primer MVZ16 (Smith and Patton 1993). The PCR were performed on a MiniPCR thermocycler machine with the following program 95 °C for 120 seconds, annealing at 45°C for 30 seconds, extension at 72 °C for 80 seconds with 32–35 cycles. The master mix was assembled using 12.5 µL of DreamTaq Green PCR MasterMix (2×) (11816843), 2 µL each primer, 6.5 µL DNAse free water and 2 µL gDNA. Following the PCR amplification, the purified products were then transformed into a high-fidelity sequencing library using the Oxford Nanopore Technologies Rapid Barcoding Kit 96 (SQK-RBK110.96). The subsequent sequencing was performed on the MinION MK1C equipment, paired with a flongle flowcell (R9.4.1 model) from Oxford Nanopore Technologies manufacturer. Nanopore sequencing data was High-accuracy (HAC) basecalled and demultiplexed with guppy 6.4.6. Demuxed fastqs were filtered at a Qscore of 9, and consensus sequences were generated using NGSpeciesID (Sahlin et al. 2021). All consensus sequences produced had between 100–1,000 supporting reads, with an expected divergence from Sanger between 0.00–0.04% (Vasiljevic et al. 2021). This level of divergence is considered negligible for phylogenetic implications.

The cyt b sequences were edited and assembled with Geneious ver. R11 and ver. Prime 2020.0.3 (https://www.geneious.com). Then verified to represent endogenous mitochondrial DNA of Thomasomys by looking for premature stop codons that might indicate nuclear copies of mitochondrial DNA (numts) and by performing independent searches with the Basic Local Alignments Search Tool (BLAST) (Altschul et al. 1990; Triant and DeWoody 2007).

Phylogenetic analyses

Our original cyt b sequences were aligned with previously published sequences (Brito et al. 2019; Pacheco and Ruelas 2023; Pavan et al. 2024) and with other sequences available in GenBank for Thomasomys, Chilomys, and Rhipidomys using the Geneious Alignment tool in Geneious Prime 2024.0.4 (https://www.geneious.com). This alignment tool is versatile because it can detect, and automatically transform, the direction of the sequences. The final matrix consisted of 222 sequences, and has a length of 1,140 bp. We inferred maximum likelihood phylogenetic gene trees with three commonly used approaches: 1) automatic selection of codon substitution model with IQ-Tree, 2) automatic selection of nucleotide substitution model with IQ-Tree, and 3) GTRCAT approximation in RAxML. Particularly, we wanted to contrast the topological differences of using codon vs. nucleotide substitution models because codon based models are thought to be more realistic (Seo and Kishino 2009; Gil et al. 2013). For approaches 1 and 2 we used IQ-Tree 1.6.12 (Nguyen et al. 2015) to determine in the same analysis the best-fitting evolutionary model, the best maximum likelihood tree, and three measures of nodal support; nodal support was estimated with the SH-like approximate likelihood ratio test (SH-aLRT), using 1000 bootstrap replicates (Guindon et al. 2010), the aBayes test, which is a Bayesian-like transformation of aLRT (Anisimova et al. 2011), and the ultrafast bootstrap approximation, using 1000 replicates (Minh et al. 2013; Hoang et al. 2018). For approach 1 we used the following commands: /iqtree -s alignment.phy -m MFP -st CODON2 -bb 1000 -alrt 1000 -abayes -nt AUTO -o Rhagomys_rufescens; the commands -m MFP -st CODON 2 called ModelFinder (Kalyaanamoorthy et al. 2017) to select the best-fitting model of codon substitution (i.e., MGK+F3X4+R5). For approach 2 we used the following commands: /iqtree -s alingment.phy -m MFP -bb 1000 -alrt 1000 -abayes -nt AUTO -o Rhagomys_rufescens; the best fitting model was GTR+F+G4. We performed approach 3 in RAxML 8.2.12 (Stamatakis 2014) using the following commands: /raxmlHPC-AVX -f a -s alignment.phy -n output -m GTRCAT -p 45321 -x 54321 -N 1000 -o Rhagomys_rufescens; the nodal support was estimated with 1,000 bootstrap replicates.

Pairwise genetic distances with the K2P model were calculated in Mega 10.1.8 (Kumar et al. 2018) with subsets of sequences, including one sequence per species and trimmed to avoid missing data. These distances were calculated mainly for two new species of the cinereus group, which belong to a small monophyletic clade of five species (Thomasomys ucucha, T. sp. Zuleta-Guandera, T. silvestris, and the 2 new species).

Species concepts and operational criteria to delimit species

As a conceptualization of what is a species, we followed the unified species concept, which states that “species are (segments of) separately evolving metapopulation lineages” (de Queiroz 2007: 881). Under that conceptual umbrella, the secondary defining properties of a species (e.g., monophyly and diagnosability) serve as operational criteria for delimiting species (de Queiroz 2007). In this work, our lines of evidence for delimiting species were morphological and molecular data. The morphological diagnosability was based on discrete internal and external morphological characters, and multivariate analyses of continuous morphometric measurements; both approaches are common for delimiting species (see Sneath 1976; Wilkins 2009; Zachos 2016). The molecular diagnosability was based on approaches considered standard for differentiating species: genetic distances and the recovery of reciprocally monophyletic groups. In their review of intra and interspecific genetic distances, Bradley and Baker (2001), indicated that cyt b distances higher than 2.5% among groups of rodents, usually indicate species-level differentiation of such groups; however, we note that any genetic threshold should also consider potential intraspecific variation across geographic distance. High genetic distances coupled with reciprocally monophyletic groups serve as strong indicators of species and are commonly used as delimiting criteria (Mishler and Theriot 2000; Baker and Bradley 2006; Schrago and Mello 2020).

Results

In this study we focus with particular emphasis on Ecuadorian populations that currently include the clade Thomasomys ucucha + Thomasomys silvestris (see Brito et al. 2019; Pacheco et al. 2023). However, to place this clade in geographic and phylogenetic context we sampled and analysed species in the genus Thomasomys from throughout Ecuador.

The specimens obtained in the vicinity of the Tatahuazo River in Provincia de Bolívar were originally reported as Thomasomys caudivarius by Salazar-Bravo and Yates (2007); however, detailed analyses of topotypical material of T. caudivarius, prompted Brito et al. (2019) to reevaluate the taxonomic affiliation of the Tatahuazo populations and to suggest that this represented an unnamed species. Subsequent collections in western Provincia de Imbabura showed the presence of trenchant differences between these species. These field observations aroused our interest in conducting an exhaustive analysis of the cyt b sequences of the specimens collected. In addition, the large sample of the genus Thomasomys collected from different localities in Ecuador (including topotypic localities of T. cinnameus, T. fumeus, T. ucucha, and T. vulcani) allowed us to expand the genetic knowledge for all formally described Thomasomys species from Ecuador. Combining the topology of the cyt b species tree, genetic distances, and accounting for ontogenetic variation, we conclude that the currently understood T. silvestris + T. ucucha clade represents a species complex. In the following sections, we present the main results of the phylogenetic and metric analyses conducted for this contribution.

Phylogenetic analyses

The newly generated sequences (66 terminals) improved our understanding of the cyt b variability of Thomasomys, making this cyt b gene tree the most complete with 36 recognized species and 20 candidate species represented by 203 ingroup sequences (Fig. 1: Parts A and B). We recovered the genus Thomasomys as monophyletic in the two analyses based on evolutionary models of nucleotide substitutions: however, nodal supports were not strong (Fig. 1C). The analysis with codon models resulted in a paraphyletic Thomasomys (Fig. 1B).

Figure 1.

Cyt b gene tree of the genus Thomasomys and close outgroups. The tree was inferred by maximum likelihood (ML) using a nucleotide substitution model (GTR+F+G4); it contains 222 terminals belonging to 36 named species of Thomasomys, including the two new species here described (indicated with black arrows), it also contains at least 20 putative new species of Thomasomys, and 20 outgroups of the genera Rhipidomys, Chilomys and Rhagomys. Nodal support statistics for the analyses in IQ-Tree are from: ultrafast bootstrap approximation (UF), SH-like approximate likelihood ratio test (aL), and the aBayes test (aB). White sections of the circles indicate UF and aL bootstrap frequencies <75% and aB posterior probabilities <0.95, whereas black sections of the circles indicate UF and aL bootstrap frequencies ~75% and aB posterior probabilities ~0.95. Insets represent differences in topology and branch lengths of three ML approaches. Inset A: Collapsed gene tree of the main figure. Inset B: Collapsed gene tree inferred with a codon substitution model. Inset C: Collapsed gene tree estimated with the RAxML tree with the CAT approximation; black circles represent bootstrap values ~75%. Terminals are labeled with GenBank accession number, museum voucher number and scientific name—in case that the species have not been described, the sequences are indicated with ‘sp’ and a geographical proxy—‘ONT’ indicates that the sequence was obtained with MinION Oxford Nanopore Technologies.

Named and putative species of Thomasomys herein analyzed can be clustered into various loosely recognized supraspecific groups: cinereus, baeops, notatus, incanus, gracilis, and aureus (Pacheco 2015; Pacheco and Ruelas 2023) plus some species not yet analyzed morphologically (for example, Thomasomys sp4 of Pavan et al. 2024). It should be noted that according to our analysis the aureus group is paraphyletic, consisting of two clades (Fig. 1B). The first clade contains species distributed from northern Ecuador to central Peru, including an undescribed species from central Bolivia. The second clade contains one species from north-central Peru, including an undescribed species, and one species from southern Peru, including another undescribed species.

Two putative new species are nested within a clade comprised of the Ecuadorian Andean species T. silvestris, T. ucucha, and an unnamed species here labeled as T. sp. Zuleta-Guandera; this clade is herein referred to as the silvestris+ucucha clade. Within this clade, members of each putative new species identified here differ by a genetic distance of 6.4% (Table 1), and Thomasomys sp. nov. 2 is sister to Thomasomys sp. Zuleta-Guandera with a genetic distance of 4.6% (Table 1), and the clade formed by both species is sister to T. ucucha. The T. silvestris+ucucha clade is highly supported, and it is sister to a larger clade that includes T. caudivarius Anthony, 1923, T. cinereus (Thomas, 1882), T. hudsoni Anthony, 1923, T. lojapiuranus Pacheco & Ruelas, 2023, T. pagaibambensis Pacheco & Ruelas, 2023, T. paramorum Thomas, 1898, T. salazari Brito et al., 2019, and T. shallqukucha Pacheco & Ruelas, 2023. The combination of both clades conforms clade B of Pacheco and Ruelas (2023).

Table 1.

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Pairwise genetic distances (K2P model) of the silvestris clade of Thomasomys which includes the species: T. igor sp. nov., T. otavalo sp. nov., T. silvestris, T. ucucha, and the undescribed T. sp. Zuleta-Guandera.

		1	2	3	4	5
1	T. igor sp. nov.
2	T. otavalo sp. nov.	0.089
3	T. silvestris	0.064	0.074
4	T. ucucha	0.084	0.046	0.071
5	T. sp. Zuleta-Guandera	0.077	0.046	0.076	0.040	–

Morphometric analyses

The first three principal components explained 53.34% of the total variance, with the initial two explaining 43.18% of the variation (Table 2). The application of dimensionality reduction through PCA resulted in the clustering of three of the four taxa included in this analysis. Thomasomys sp. nov. 1, was nested within the T. silvestris cluster, whereas T. ucucha and Thomasomys sp. nov. 2, exhibited minimal overlap and were distinctly separated from all other species (Fig. 2A). The KNN classification discriminated T. ucucha, T. silvestris and Thomasomys sp. nov. 2, successfully (95%; Table 3), and scarce overlap was observed in the bivariate plot (Fig. 2B) of the variables; the variable with the highest contribution to group discrimination was BIT (R²⁼0.81; F=97.25; p < 1e-25) and LT (R²⁼0.59; F=32.14; p < 1e-13).

Figure 2.

Morphometric analyses. A A two-dimensional PCA biplot illustrates morphological data from the species studied, with variable loadings represented by arrows, where the length and direction indicate the magnitude and contribution to each component, and the data points denote the scores in morphometric space. B KNN classification of three species using scaled and centered data of the two variables contributing the most to group differentiation based on R² and F-values of the stepwise discriminant analyses.

Table 2.

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Summary of the two principal components used in the analyses. The overall contribution of each component is shown between parentheses, and the loading of each character is displayed in rows, the absolute values contributing the most to each component are bolded. Characters’ abbreviations are detailed in the text.

	PC1 (31.9%)	PC2 (11.3%)
HB	0.056243236	–0.24635668
LT	0.085614110	–0.43144200
HF	0.037336621	–0.43134162
E	–0.004218832	0.17414881
CIL	0.323421859	–0.05005954
LD	0.313341343	0.03603659
LM	–0.123954570	–0.13128457
BM1	–0.132649972	–0.29644343
LIF	0.119697525	–0.26933645
BIF	0.116497355	–0.04918255
BPB	0.293638166	–0.04172246
BZP	0.315262343	0.08173068
LIB	–0.134038734	–0.02490623
ZB	0.258944689	0.17414099
DI	0.020220768	0.14367985
BIT	0.287913403	0.24602189
LR	0.104345980	–0.34885112
LN	0.129050462	–0.20940888
BR	0.264528947	–0.07830623
OL	0.317922432	0.01538576
BCO	0.138431570	–0.21314565
BMF	0.079779714	0.06985532
BCB	0.179152910	0.02260335
LMN	0.252112270	–0.01397996
DR	0.225251986	0.09711389

Table 3.

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Evaluation of the k nearest neighbor classification of three Thomasomys species. n represents the number of individuals per species used as input in the model. The values in the ‘as species’ columns represent the assignment of individuals by the algorithm to each taxon. The accuracy of the prediction is given as a percentage in the last column.

Taxon	n	as T. otavalo sp. nov.	as *T. silvestris*	as *T. ucucha*	correct (%)
T. otavalo sp. nov.	14	12	0	2	85.71
T. silvestris	30	0	30	0	100.00
T. ucucha	25	1	0	24	96.00
Total	69	13	30	26	95.65

Taxonomy

Family Cricetidae Fischer, 1817

Subfamily Sigmodontinae Wagner, 1843

Tribe Thomasomyini Steadman & Ray, 1982

Genus Thomasomys Coues, 1884

Thomasomys otavalo sp. nov.

https://zoobank.org/F5BF874C-50B4-4703-9C76-45BCE3EB2F61

Otavalo’s Andean mouse, ratón andino de los Otavalo (in Spanish)

Holotype

MECN 6912 (field number JBM 2574), an adult female collected 19 January, 2022, by Jorge Brito, Rubí García and Fausto Rodríguez, preserved as dry skin, skull, postcranial skeleton, and muscle and liver biopsies in 95% ethanol.

Measurements of the holotype (in mm, mass in g)

HB=120; TL=161; HF=29, E=19; W=36; CIL=28.62; LD=8.49; LM= 4.7; BM1=1.53; LIF=5.54; BIF=2.11; BPB=3.58; BZP=2.54; LIF=5.13; ZB=16.63; DI=1.54; BIT=2.03; LR=11.12; LN=11.84; BR=5.94; OL=10.02; BMF=2,29; BCO=7,54; BCB=14.67; LMN=19.1; DR=3.3. External and craniodental measurements of additional specimens are listed in Table 4.

Table 4.

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Summary of morphometric measurements of all specimens in mm. Species names are accompanied by the number of analyzed individuals between parentheses. Minimum and maximum values are accompanied by mean and standard deviation between parentheses. Abbreviations of characters are detailed in the text.

	T. igor sp. nov. (4)	T. otavalo sp. nov. (14)	T. silvestris (30)	T. ucucha (22)
HB	102–122 (113.75±8.66)	110–125 (115.79±4.68)	93–138 (109.17±10.65)	91–117 (105.93±6.64)
LT	133–160 (147.25±14.77)	150–180 (166.79±8.66)	130–160 (146.93±8.05)	127–153 (140.54±5.45)
HF	27–29 (28.25±0.96)	27–31 (29.43±1.02)	24–30 (27.33±1.63)	18–30 (26.31±2.39)
E	18–20 (19.25±0.96)	18–20 (18.86±0.53)	16–21 (18.98±1.34)	15–28 (19.07±2.38)
CIL	25.94–27.48 (27.06±0.75)	28.05–30.29 (28.86±0.83)	25.21–27.66 (26.5±0.55)	27.25–29.34 (28.45±0.51)
LD	7.53–8.54 (8.2±0.47)	8.13–9.98 (9.2±0.7)	6.65–8.32 (7.71±0.39)	8.4–9.94 (9.1±0.34)
LM	4.74–4.83 (4.8±0.04)	4.02–5.44 (4.5±0.4)	4.41–5.05 (4.73±0.14)	4.29–5.5 (4.57±0.24)
BM1	1.55–1.63 (1.6±0.03)	1.41–1.63 (1.52±0.08)	1.47–1.68 (1.58±0.06)	1.43–1.7 (1.51±0.06)
LIF	5.53–6.28 (5.86±0.31)	5.11–7.09 (5.89±0.77)	4.8–5.71 (5.19±0.25)	4.97–5.65 (5.25±0.2)
BIF	1.75–2.21 (1.98±0.22)	1.85–2.36 (2.17±0.14)	1.81–2.48 (2.12±0.14)	1.89–2.32 (2.15±0.12)
BPB	3.06–3.53 (3.22±0.22)	3.45–4.56 (3.96±0.3)	2.16–3.78 (3.25±0.31)	3.48–4.22 (3.76±0.18)
BZP	2.14–2.27 (2.17±0.06)	2.28–2.93 (2.53±0.16)	1.69–2.28 (2.08±0.13)	2.36–2.73 (2.56±0.11)
LIB	5.15–5.21 (5.18±0.03)	4.1–5.51 (4.75±0.52)	4.8–5.56 (5.09±0.18)	4.65–5.17 (4.9±0.12)
ZB	14.62–15.27 (15.05±0.29)	14.55–17.73 (16.19±1.22)	14–15.84 (15.12±0.46)	16–17.46 (16.69±0.33)
DI	1.35–1.67 (1.48±0.14)	1.43–1.68 (1.53±0.07)	–3.42–2.1 (1.28±0.9)	1.51–159 (7.93±31.47)
BIT	1.62–1.83 (1.77±0.1)	1.75–2.14 (1.98±0.11)	1.56–1.91 (1.75±0.09)	2.08–2.6 (2.24±0.12)
LR	8.62–10.57 (9.58±0.8)	9.71–11.17 (10.4±0.45)	9.11–11.89 (10.01±0.73)	9.19–10.75 (9.87±0.4)
LN	10.08–11.61 (11.13±0.71)	10.08–11.96 (11.14±0.64)	9.55–11.82 (10.68±0.5)	10.15–11.57 (10.89±0.45)
BR	4.96–5.4 (5.19±0.18)	5.4–7.07 (6.12±0.7)	4.76–5.69 (5.19±0.23)	5.39–6.07 (5.77±0.17)
OL	7.6–9.3 (8.1±0.8)	9.27–10.35 (9.96±0.26)	7.27–9.65 (8.37±0.77)	9.57–10.43 (10.1±0.23)
BCO	6.83–7.14 (7.04±0.15)	7–7.61 (7.24±0.21)	6.32–7.46 (7±0.25)	6.89–7.4 (7.09±0.13)
BMF	1.74–2.52 (2.2±0.35)	2.01–2.42 (2.24±0.11)	1.85–2.68 (2.26±0.18)	1.95–2.7 (2.29±0.16)
BCB	13.31–13.46 (13.39±0.07)	10–15.95 (14.23±1.39)	10.27–14.31 (13.23±0.8)	13.44–14.55 (14.13±0.25)
LMN	14.35–15.07 (14.84±0.33)	14.95–16.64 (15.56±0.42)	13.74–16.88 (15.08±0.76)	14.91–16.6 (15.98±0.4)
DR	3.05–3.25 (3.14±0.09)	2.89–4.72 (3.47±0.59)	2.92–3.6 (3.16±0.13)	3.4–3.77 (3.62±0.09)

Type locality

Ecuador, Provincia de Imbabura, Área de Protección Hídrica Otavalo Mojanda (0.15456, –78.27536, WGS84 coordinates taken by GPS at the site of collection, elevation 3,690 m).

Paratypes

MECN 6909, MECN 6911, adult males, all preserved as dry skins and cleaned skulls, collected in Provincia de Imbabura, Área de Protección Hídrica Otavalo Mojanda (0.15456, –78.27536, 3,680 m) by J. Brito, M. Yánez and C. Paucar on 19 January, 2022. MECN 6916, adult female, preserved as dry skins and cleaned skull, collected in Área de Protección Hídrica Otavalo Mojanda (0.15824°S, –78.28259, 3,550 m) by J. Brito on 21 January, 2022. MECN 6920, 6921, adult males, all preserved as dry skins and cleaned skulls, collected in Área de Protección Hídrica Otavalo Mojanda (0.15456, –78.27536, 3,685 m) by J. Brito, R. García and F. Rodríguez on 21 January, 2022. MECN 5603, juvenile female, MECN 5604, juvenile male, all preserved as dry skins and cleaned skulls, collected in Área Protegida Privada Neblina Norte (0.337535°S, –78.432619, 2,990 m) by J. Brito, J. Curay, E. Beltrán and M. Esparza on 23 March, 2017. MECN 5698, MECN 5700, adult males, MECN 5701, adult female, all preserved as cleaned skulls and the rest of the body in ethanol, collected in Tabla Chupa (0.336465, –78.413066, 3,055 m) by J. Brito, J. Curay, E. Beltrán and M. Esparza on 24 March, 2017. MECN 7869, adult female, MECN 7870, adult male, preserved as dry skin and cleaned skull, collected in Cayapas Chupa (0.54117, –78.48343, 3,290 m) by J. Brito, A. Yacelga on 28 September 2023. MECN 7873, adult female, MECN 7874, adult male, preserved as dry skin and cleaned skull; MECN 7877, adult female, MECN 7881, 7882, adult males, all preserved as cleaned skulls and alcoholic bodies, all collected in Cayapas Chupa (0.53640, –78.47506, 3,440 m) by J. Brito, A. Yacelga, L. Rodríguez on03 October 2023. MECN 7871, adult female, preserved as cleaned skulls and alcoholic bodies, collected in Provincia de Esmeraldas, Cordillera de Cayapas, Loma Negra (0.54574, –78.49796, 3,230 m) by J. Brito, L. Rodríguez on 01–02 October, 2023.

Etymology

The specific epithet “Otavalo” honors the Otavalo culture, here treated as a noun in apposition. The Otavalo people are recognized for their music and ability for weaving and comercializing textiles. For decades, the Otavalos have been one of the most recognizable and proud indigenous cultures of South America (Meisch 2002).

Diagnosis

A species of Thomasomys unique due to the following combination of characters: Head-body length 110–125 mm, very long tail (~144 of head-body length), with white apical portion (15–35 mm); narrow interorbital region with rounded supraorbital margins; narrow zygomatic arches; long incisive foramina covering approximately ~63% of the diastema, but not extending posteriorly between molar series; upper first molars aligned with posterior margin of the zygomatic plate; subsquamosal fenestra larger than the postglenoid foramen; upper incisors opisthodont.

Morphological description of the holotype and variation

Pelage fine, dense, and soft, about 10 –12 mm long over the back and rump (Fig. 3); somberly colored (dark drab) with low countershading. Dorsal coloration Dark Drab (Color 45) along flanks, shading to Hair Brown (color 277) mid-dorsally. Ventral pelage Medium Neutral Gray (Color 298) basally, with superficial of Ground Cinnamon Medium Neutral Gray (Color 270); not sharply demarcated from dorsal coloration (Fig. 4A, C, E). Mystacial vibrissae long, extending beyond pinnae when laid back alongside head. Ears sparsely covered with short, blackish hairs, not contrasting conspicuously with color of head. Hairs over metapodials and digits of manus and pes dark, but with white ungual tufts, abundant and extending well beyond the edge of the claws (Fig. 5A, B). Tail longer than the combined length of head and body (LT about 144% of HB), uniformly dark, with white apical portion (between 15–35 mm, Fig. 6A); with short hairs, but end with some larger hairs; it is covered with rectangular scales (13 or 14 rows/cm near the base), with three dark brown hispid hairs emerging from the base of each scale, no longer than 1–1.5 scale rows, ventral hairs are whitish in color. Mammae six in inguinal, abdominal, and postaxial pairs.

Figure 3.

Live specimen of Thomasomys otavalo sp. nov. (Cordillera Cayapas, Imbabura, Ecuador), in its natural habitat (MECN 7869 paratype). Please note the color of the apical portion of the tail. Photographed by J. Brito on September 28, 2023.

Figure 4.

Dry skin in dorsal (A, B), lateral (C–E), and ventral (E, F) views of Thomasomys otavalo, sp. nov. (A, C, E; MECN 6912, holotype), and T. igor sp. nov. (B, D, F; MECN 702, holotype). Scale bar: 20 mm.

Figure 5.

Selected external and soft anatomical traits of Thomasomys: A, C dorsal and (B, D) plantar surface of right pes (A, B: T. otavalo sp. nov, MECN 5604, paratype; C, D T. igor sp. nov, MECN 708, paratype); E soft palate (T. otavalo sp. nov, MECN 6921, paratype); F, G gross morphology of the stomach (T. otavalo sp. nov, MECN 5700, paratype). Abbreviations: 1–5, digits; b, bordering fold; co, cornified epithelium; d, duodenum; d1–d3, diastemal rugae; ge, glandular epithelium; i, incisura angularis; i1–15, interdental rugae. Scale bars: 5 mm.

Figure 6.

Distal portion of the tail of some species of Thomasomys: A T. otavalo sp. nov. (MECN 5604, paratype); B T. ucucha (MECN 2691); C T. igor sp. nov. (MECN 708, paratype); D T. silvestris (MECN 5054). Scale bar: 10 mm.

Cranium medium for the genus (28.1–30.2 mm of CIL). Long rostrum, somewhat acuminate and narrow with the nasal and premaxillary bones extending beyond the anterior face of the incisors (giving the appearance of an incipient rostral tube); poorly developed gnathic process. Posterior margin of the nasal bone not reaching the plane of the lacrimal bone. Shallow zygomatic notches. Small and rounded lacrimal bones. Narrow interorbital region with smooth outer edges, leaving the alveolar maxillary processes exposed in dorsal view (Fig. 7A). Anteriorly narrowed zygomatic arches. Supraorbital region with divergent posterior borders (sensu Steppan 1995). Frontoparietal suture “V”-shaped. Broad and rounded braincase, slightly flattened at the outer edges. Small and concave exoccipital. Dorsal profile (in lateral view) distinctively flattened from nasal tips to midfrontal region; anterior margin of zygomatic plate slightly tilted backward. No further development in the ethmoturbinals is distinguished. Small lambdoidal crest. First maxillary molar aligned with the posterior edge of the zygomatic plate (Fig. 8A). Zygomatic arches sturdy with long jugals spanning a major segment in the zygomatic process of the maxillary bone. Alisphenoid strut wide and short. Carotid circulation primitive (Pattern 1, sensu Voss 1988), as indicated by the presence of a large stapedial foramen, prominent squamosal-alisphenoid groove, and sphenofrontal foramen. Subsquamosal fenestra larger than the postglenoid foramen; hamular process of squamosal thin, long, slightly curved, and distally applied on the mastoid capsule; tegmen tympani broadly overlapping posterior suspensory process of squamosal. Upper edge of the mastoid not exceeding the edge of the subsquamosal fenestra (Fig. 9A). Bullae small; pars flaccida of tympanic membrane present, large; orbicular apophysis of malleus well developed. Paraoccipital process small. Hill foramen very small; long and narrow incisive foramina (averaging 64% of diastemal length), not approaching M1. Premaxillary process wide in the middle and narrow at the posterior end, maxillary septum of incisive foramina slender and long. Palate short and broad (sensu Hershkovitz 1962), with mesopterygoid fossa reaching the hypoflexus of M3. Posterolateral palatal pit small and inconspicuous. Mesopterygoid fossa broad, straight sided, extending anteriorly between third molars; bony roof complete or perforated by narrow, slit-like sphenopalatine openings flanking the presphenoid/basisphenoid suture. Basisphenoid wide with slightly flat edges. Foramen ovale small. Parapterygoid fossae narrow, approximately triangular, with moderately (excavated) anterior limits. Middle lacerate foramen broad. Lateral expressions of parietals present. Auditory bullae small and uninflated with large and wide Eustachian tubes. Dentary moderately long, with long and narrow coronoid process (extends beyond upper edge of condylar process); postcondylar and mental processes poorly developed; deep sigmoid notch. Semilunar recess symmetrical, with lower edge ends pointed. Capsular projection of the root of the incisor inconspicuous.

Figure 7.

Thomasomys otavalo sp. nov. (Área de Protección Hídrica Otavalo Mojanda, Imbabura, Ecuador): Cranium in (A) dorsal, (B) ventral, and (C) lateral views, and mandible in (D) labial view (MECN 6912 holotype). Scale bar: 10 mm.

Figure 8.

Morphological comparisons. Comparison of diastemal and palate region in four species of Thomasomys. A T. otavalo sp. nov. (MECN 6912, holotype); B T. ucucha (MECN 7937); C T. igor sp. nov. (MECN 702, holotype); D T. silvestris (MECN 4928). Arrow in (A) indicates that the anterior border of the M1 at the same level of the posterior end of the zygomatic plate; the lower dotted line indicates the penetration of the mesopterygoid fossa in relation to the hypoflexus of the M3; abbreviations: hf, hypoflexid; if, incisive foramina; mpf, mesopterygoid fossa; pal, palate; ppp, posterolateral palatal pit; zp, zygomatic plate. Scale bar: 5 mm.

Figure 9.

Alisphenoid-mastoid region comparisons in lateral view in four species of Thomasomys: A T. otavalo sp. nov. (MECN 6912, holotype); B T. ucucha (MECN 7937); C T. igor sp. nov. (MECN 702, holotype); D T. silvestris (MECN 4928). Arrow in (B) illustrated to upper edge of the mastoid that exceed the edge of the subsquamosal fenestra; while the oblique dotted line indicates the suture between the squamosal and parietal. Abbreviations: hp, hamular process of squamosal; exo, exoccipital; ip, interparietal; pa, parietal; lpp, lateral parietal portion; mas, mastoid; mf, mastoid fenestra; pgf, postglenoid foramen; sq, squamosal; ssf, subsquamosal fenestra; zps, zygomatic process of the squamosal bone. For ease of comparison are not included to scale

Upper incisors large, broad, and opisthodont (Thomas’s angle of 80°, Thomas 1919; see Fig. 10A), with front enamel Light Chrome Orange (color 76); brachydont and pentalophodont molars (sensu Hershkovitz 1962). Parallel upper molars small, pentalophodont, hypsodont in juveniles, and lacking cingula; coronal surfaces crested when unworn; main cusps slightly opposite and sloping backwards when viewed from side (Fig. 11A). M1 rectangular in outline with procingulum divided by anteromedian flexus into unequal anterolabial and anterolingual conules; thin anteroloph; wide mesoloph. M2 squared in outline; mesoloph showing the same condition as in M1. M3 rounded in outline with conspicuous anteroloph; shallow paraflexus; mesolph, metaflexus and hypoflexus distinctive, when unworn. Lower molars with main cusps alternating and sloping backwards when viewed from side. First lower molar (m1) with short anteromedian flexid that divides the procingulum into subequal anterolabial and anterolingual conules (Fig. 12A); ectolophid thin and short mesolophid. Protoflexid of m2 slim; thin and short mesolophid; m3 slightly shorter than m2.

Figure 10.

Comparison of the left anterior portion of the rostrum, viewed from left side, in four species of Thomasomys: A T. otavalo sp. nov. (MECN 6912, holotype); B T. ucucha (MECN 7937); C T. igor sp. nov. (MECN 702, holotype); D T. silvestris (MECN 4928). Thomas’ angles according to incisive and molar planes are indicated as well as the extension of the molar series. Arrow in (A) point to the anterior border of the nasal bone extending beyond the anterior face of the incisors relative to (B); abbreviations: n, nasal; nc, nasolacrimal capsule; p, premaxillary; sf, supraorbital foramen; zp, zygomatic plate. Scale bar: 5 mm

Figure 11.

Comparison of the upper right molar series in occlusal view among some species of Thomasomys: A T. otavalo sp. nov. (MECN 6912, holotype); B T. ucucha (MECN 7937); C T. igor sp. nov. (MECN 702, holotype); D T. silvestris (MECN 4928); abbreviations: af, anteromedian flexus; al, anteroloph; ml, mesoloph; mfl, metaflexus; pf, paraflexus; prf, protoflexus. Scale bar: 1 mm.

Figure 12.

Comparison of the lower right molar series in occlusal view among some species of Thomasomys: A T. otavalo sp. nov. (MECN 6912, holotype); B T. ucucha (MECN 7937); C T. igor sp. nov. (MECN 702, holotype); D T. silvestris (MECN 4928); abbreviations: ml, mesolophid; prf, protoflexid. Scale bar: 1 mm.

Tuberculum of first rib articulating with transverse processes of seventh cervical and first thoracic vertebrae; second thoracic vertebra with differentially elongated neural spine; vertebral column composed of 19 thoracicolumbar, 16th with moderately developed anapophyses and 17th with little developed anapophyses, 4 sacrals (fused), and 42–45 caudal vertebrae; usually the second and third caudal vertebrae with small but complete hemal arches; 12 ribs.

Soft palate with 3 slightly arched diastemal palatal rugae and 5 pairs of interdentals (Fig. 5E). The second and third interdental wrinkles are well arched. The interdental wrinkles are short and leave a conspicuous midline “channel”. Large gall bladder present in all specimens examined (n=11). The stomach is of the unilocular and hemiglandular type. The cornified epithelium dominates the corpus and is characterized by its spongy surface; the glandular epithelium is widely distributed over the mostly smooth antrum (Fig. 5F, G). The boundary between the two epithelia (= bordering fold, sensu Carleton 1973) is manifested by a thick ridge and exceeds the level corresponding to the esophageal opening to the left. While the angular incisura is barely marked, both the esophageal canal and the angular plica are conspicuous.

Comparisons

Thomasomys otavalo sp. nov. is most closely related to T. ucucha, and a candidate species from Zuleta (Fig. 1: Part A). To construct this section, we used specimens referred to Thomasomys ucucha (sensu stricto) near Papallacta, Provincia de Napo, type locality of the species (Voss 2003). Thomasomys otavalo sp. nov. is a medium-sized species (Table 5), differing from T. ucucha (features in parentheses) in having shorter dorsal hairs between 10–12 mm (13–15 mm); tail noticeably long ~144% of HB (~128%); white tail tip 15–35 mm (<5 mm). Qualitative craniodental differences between the two species are conspicuous: the nasal and premaxillary bones in T. otavalo sp. nov. are long, extending well in front of the anterior face of the incisors (short, just beyond the anterior surface of the incisors); upper incisors opisthodont (orthodont, slightly procumbent, see Fig. 10B); Thomas angle 80° (86°); M1 goes beyond the posterior edge of the zygomatic plate (not so); M1 with short paraflexus and indistinct mesoflexus (short and short); mesolophid of m1 very short (large).

Table 5.

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Selected morphological differences with species that could be confused with the new species, compiled from Voss (2003), Brito et al. (2019) and our own observations.

T. otavalo sp. nov.	*T. ucucha*	T. igor sp. nov.	*T. silvestris*
Tail very long (LT about 144% of HB)	Tail long (LT about 128% of HB)	Tail long (LT about 130% of HB)	Tail long (LT about 140% of HB)
White tail tip (15–35 mm)	Tail tip usually not white (when present <5 mm)	Tail tip usually not white (when present <5 mm)	Tail tip usually not white (when present <5 mm)
Dorsal pelage uniformly grayish brown	Dorsal pelage uniformly dark grayish brown	Dorsal pelage verona Brown, darker in the midline	Dorsal pelage uniformly dark grayish brown
Incipient rostral tube present	Rostral tube absent	Rostral tube absent	Rostral tube absent
Thomas angle 80°	Thomas angle 86°	Thomas angle 80°	Thomas angle 80°
Zygomatic arches converge anteriorly	Widely flaring zygomatic arches	Zygomatic arches converge anteriorly	Zygomatic arches converge anteriorly
Upper first molar aligned with posterior edge of the zygomatic plate	First upper molar does not reach the posterior edge of the zygomatic plate	First upper molar does not reach the posterior edge of the zygomatic plate	Upper first molar reaches beyond the posterior edge of the zygomatic plate
Incisive foramina long (LIF about 63% of LD), usually not extending posteriorly between molar alveoli	Incisive foramina vey short (LIF about 57% of LD), not approaching level of molar alveoli	Incisive foramina long (LIF about 72% of LD), usually not extending posteriorly between molar alveoli	Incisive foramina long (LIF about 65% of LD), usually not extending posteriorly between molar alveoli
Upper edge of the mastoid does not exceed the edge of the subsquamosal fenestra	The superior border of the mastoid goes above the subsquamosal fenestra.	Upper edge of the mastoid does not exceed the edge of the subsquamosal fenestra	Upper edge of the mastoid does not exceed the edge of the subsquamosal fenestra
Capsular process of lower incisor alveolus usually indistinct	Capsular process of lower incisor alveolus usually distinct	Capsular process of lower incisor alveolus indistinct or absent	Capsular process of lower incisor alveolus indistinct or absent
Upper incisors opisthodont, not procumbent	Upper incisors orthodont, conspicuously procumbent	Upper incisors opisthodont, not procumbent	Upper incisors opisthodont, not procumbent
Subsquamosal fenestra larger than the postglenoid foramen	Subsquamosal fenestra usually smaller than postglenoid foramen	Subsquamosal fenestra larger than the postglenoid foramen	Subsquamosal fenestra larger than the postglenoid foramen
M3 Paraflexo short and metaflexo indistinct	Paraflexus and metaflexus short	Paraflexus and metaflexus length and fused	Paraflexus and mesoflexus short
M3 comparatively large	M3 comparatively small	M3 comparatively large	M3 comparatively small
Procingulum of m1 divided	Procingulum of m1 undivided	Procingulum of m1 divided	Procingulum of m1 undivided or indistinct

Other Thomasomys species that could be confused with T. otavalo sp. nov. are T. silvestris and T. igor sp. nov. However, T. otavalo sp. nov. can be differentiated from these species by the white tail tip between 15–35 mm (<5 mm in T. silvestris and T. igor). Regarding the cranium, T. otavalo sp. nov. can be distinguished by the incisive foramina (64% of LD), while T. silvestris and T. igor are longer (65 and 71% of LD, respectively); in T. otavalo the alisphenoid strut slender while in T. silvestris and T. igor they are wide. As for the molars, in T. otavalo sp. nov. and in T. silvestris the M3 paraflexus short and mesoflexus indistinct, while in T. igor they are long and fused giving the appearance of a horseshoe. Another species with which Thomasomys otavalo sp. nov. could be confused is Thomasomys vulcani (sympatric species), however they are easily distinguished because the new species has noticeably long tail ~144% of HB (~90%).

Distribution

Known so far from less than 10 localities, all between the Otavalo-Mojanda Hydric Protected Area (Área de Protección Hídrica Otavalo Mojanda), from the highlands of Intag in Provincia de Imbabura, up to the Cordillera de Cayapas at the provincial boundary between Esmeraldas and Imbabura, at elevations of 2,290–3,685 m. Thomasomys otavalo sp. nov. is geographically delimited by the basins of the rivers Mira (north), Guayllabamba (south), to the west by the inter-Andean valley and to the east by the tropical rainforest.

Natural history

Thomasomys otavalo sp. nov. is, thus far, endemic to the temperate and high Andean zoogeographic areas (Albuja et al. 2012) of the montane forest (Ministerio del Ambiente del Ecuador 2013), an environment characterized by trees with abundant orchids, ferns, and bromeliads. Thomasomys otavalo sp. nov. was collected in mature and disturbed forest where the understory is visually dominated by herbaceous families such as Poaceae (Chusquea sp. and Neurolepis sp.), Araceae and Melastomataceae. Visually the canopy is dominated by encino (Weinmannia spp.), árbol de papel (Polylepis spp.) and guandera (Clusia spp.). The species was collected in sympatry with the shrew-opossum, Caenolestes fuliginosus (Tomes, 1863), the shrew Cryptotis equatoris (Thomas, 1912), and the rodents Akodon mollis Thomas, 1894, Nephelomys moerex (Thomas, 1914), Neomicroxus latebricola (Anthony, 1924), Microryzomys minutus (Tomes, 1860), T. vulcani (Thomas, 1898), Thomasomys sp. Mojanda (cinereus group), and Thomasomys sp. Imbabura-Mojanda (aureus group).

Thomasomys igor sp. nov.

https://zoobank.org/327585BC-3B50-4A21-BE50-0188BC24D8B1

Igor’s Andean mouse, ratón andino de Igor (in Spanish)

Thomasomys caudivarius – Salazar-Bravo and Yates (2007: fig. 2); partim, not Thomasomys caudivarius Anthony, 1923.

Thomasomys caudivarius – Steppan and Schenk (2017: fig. 2); partim, not Thomasomys caudivarius Anthony, 1923

Thomasomys sp. 1 – Brito et al. (2019).

Holotype

MECN 702, an adult female collected 15 July 1994, by Jorge Salazar-Bravo (field number JSB 716), originally catalogued at Museum of Southwestern Biology MSB:Mamm:70717 (NK 27680), preserved as dry skin, skull and postcranial skeleton.

Measurements of the holotype (in mm, mass in g)

HB=118; TL=160; HF=27, E=19; W=30; CIL=27.44; LD=8.49; LM= 4.74; BM1=1.6; LIF=5.77; BIF=1.75; BPB=3.53; BZP=2.14; LIF=5.19; ZB=15.15; DI=1.45; BIT=1.81; LR=9.51; LN=11.61; BR=5.18; OL=7.73; BMF=2.43; BCO=7,13; BCB=13.31; LMN=15.07; DR=3.25. External and craniodental of additional specimens are listed in Table 4.

Type locality

Ecuador, Provincia de Bolívar, Río Tatahuazo, 2.5 km NE de Cruz de Lizo (–1.716667, –78.98333, WGS84 coordinates taken by GPS at the collection site, elevation 2,875 m).

Paratypes

MECN 700, juvenile male, MECN 701, adult male, preserved as dry skins and cleaned skulls, by Jorge Salazar-Bravo on 15 July 1994. MECN 703, male adult, preserved as dry skins and cleaned skulls, by Nelson Monar. MEPN 6203, adult female preserved as dry skin and cleaned skull, by Igor Castro on 17 and 18 July 1994, respectively, collected at 2.5 km NE de Cruz de Lizo the same locality of the holotype. MSB 70712, juvenile female, collected at Cruz de Lizo (–1.716667, –78.95000, 3,000 m) preserved as dry skins and cleaned skulls, by I. Castro on 18 July 1994.

Etymology

This species is named in honor of Igor A. Castro Revelo (1971–2022), Ecuadorian, prominent collector of rodents and curator of the mammal collection at the Museo Ecuatoriano de Ciencias Naturales (MECN) during the period 1994–2001. The species epithet is formed from the name “Igor” taken as a noun in apposition.

Diagnosis

Species of Thomasomys with a unique combination of characters, as follows: Head-body length 102–122 mm, with long tail (~130% of head-body length); interorbital region narrow with rounded supraorbital margins; zygomatic arches converging anteriorly; long incisive foramina covering approximately ~72% of the diastema, but not extending posteriorly between the molar series; M1 without reaching the posterior edge of the zygomatic plate; subsquamosal fenestra larger than the postglenoid foramen; upper incisors opisthodont; M3 with paraflexus and mesoflexus long and fused; M3 comparatively large; procingulum of m1 divided.

Morphological description of the holotype and variation

Fine, dense, and soft coat, about 11–13 mm long on the back and rump. Dorsal coloration Prouts Brown (Color 47), along the flanks changing to Drab (color 19). Ventral coat Medium Neutral Gray (Color 298) basally, with superficial Raw Umber (Color 24); not clearly separated from the dorsal coloration (Fig. 4B, D, F). Mystacial vibrissae long, extending beyond the pinnae when placed backward along the head. Ears covered with short, blackish hairs not contrasting with the color of the head. Hairs on metapodials and fingers and toes white and dark giving a gray-haired appearance; ungual tufts white, abundant and extending beyond the edge of the claws (Fig. 5C, D). Tail longer than the combined length of head and body (about 130% of HB), uniformly dark, but with white tips (<5 mm, Fig. 6C); with short sparse hairs, giving a naked appearance at least up to the proximal half, while the distal half is somewhat more hairy; tail end with some larger hairs (<5 mm); tail covered with rectangular scales (14 or 15 rows/cm near base), with three dark brown hairs emerging from base of each scale, no longer than 1.5–2 scale rows, ventral hairs with whitish tips. Mammae six in inguinal, abdominal, and postaxial pairs.

Skull medium for the genus (25.9–27.4 mm CIL). Rostrum long and narrow (Fig. 13A), with nasal and premaxillary bones extending beyond anterior face of incisors; gnathic process poorly developed. Posterior margin of nasal bone reaches and exceeds the plane of the lacrimal bone. Shallow zygomatic notches. Enlarged lacrimal bones, triangular in appearance. Narrow interorbital region with smooth external borders, leaving the maxillary alveolar processes and labial part of the molars exposed in dorsal view. Zygomatic arches narrow anteriorly. Supraorbital region with divergent posterior borders (sensu Steppan 1995). Frontoparietal suture “V” shaped. Broad and rounded braincase, slightly flattened at the outer edges. Broad and concave exoccipital. Dorsal profile (in lateral view) distinctly flattened from nasal tips to middle frontal region; anterior margin of zygomatic plate slightly sloping backward. No further development of the ethmoturbinals. Narrow infraorbital foramen. Not distinguishable lambdoidal crest. M1 without reaching the posterior edge of the zygomatic plate (Fig. 8C). Slender zygomatic arches, with long jugals spanning a similar segment in the zygomatic process of the maxillary and squamosal bone. Alisphenoid strut wide and short. Carotid circulation primitive (Pattern 1, sensu Voss 1988), as indicated by large stapedial foramen, prominent squamosal-alisphenoid groove, and sphenofrontal foramen. Postglenoid foramen approximately twice as large as the subsquamosal fenestra; hamular process of squamosal thin, long, slightly curved and applied distally over the mastoid auditory capsule; tegmen tympani broadly overlapping the posterior suspensory process of squamosal. Upper edge of the mastoid does not exceed the edge of the subsquamosal fenestra (Fig. 9C). Bullae small; pars flaccida of tympanic membrane present, large; orbicular apophysis of malleus well developed. Paraoccipital process small. Hill foramen very small; long and narrow incisive foramina (averaging 72% of diastemal length), not approaching first molar alveoli. Narrow premaxillary process, maxillary septum of the incisive foramen very thin and long. Short and broad palate (sensu Hershkovitz 1962), with the mesopterygoid fossa entering between the molars and reaching the protocone of M3. Posterolateral palatal pit small and inconspicuous. Wide, slightly divergent-sided mesopterygoid fossa, extending anteriorly between third molars; bony roof perforated by wide, slit-like sphenopalatine openings flanking the basisphenoid. Basisphenoid wide with slightly flat edges. Small foramen ovale. Parapterygoid fossae narrow, approximately triangular, with shallow (unexcavated) anterior limits. Middle lacerate foramen narrow. Lateral expressions of the parietals present, small (Fig. 9C). Auditory bullae small and uninflated with short and wide Eustachian tubes. Dentary moderately long, with long and narrow coronoid process (extending beyond upper edge of condylar process); postcondylar and mental processes poorly developed; deep sigmoid notch. Semilunar recess symmetrical, with lower edge ends pointed. Capsular projection of the root of the incisor inconspicuous.

Figure 13.

Thomasomys igor sp. nov. (Río Tatahuazo, Bolívar, Ecuador): cranium in (A) dorsal, (B) ventral, and (C) lateral views, and mandible in (D) labial view (MECN 702, holotype). Scale bar: 1 mm.

Upper incisors small, slender, and opisthodont (Thomas’s angle of 80°, Thomas 1919; see Fig. 10C), with front enamel Light Chrome Orange (color 76); brachydont and pentalophodont molars (sensu Hershkovitz 1962). Upper molars in left and right parallel series, small and pentalodont; hypsodont and cingulate in juveniles; coronal surfaces crested when unworn; main cusps slightly opposite and inclined backward when viewed from the side. M1 rectangular in outline with procingulum divided by the anteromedian flexus into subequal anterolabial and anterolingual conules; anteroloph large; mesoloph short and/or segmented. M2 squared in outline; mesoloph showing the same condition as in M1. M3 enlarged relative to M2, rounded in outline with conspicuous anteroloph; paraflexus and metaflexus long and fused (Fig. 11C); mesoloph present in juvenile specimens; hypoflexid conspicuous. Lower molars with alternate, posteriorly inclined main cusps viewed from the side. First lower molar (m1) with anteromedian flexid dividing procingulum into subequal anterolabial and anterolingual conules (Fig. 12C); mesolophid short; mesolophid of m2 short, hypoflexid deep; m3 slightly shorter than m2.

Tuberculum of first rib articulates with transverse processes of seventh cervical and first thoracic vertebrae; second thoracic vertebra with differentially elongated neural spine; vertebral column composed of 19 thoracolumbar, 4 sacral (fused), and 30–39 caudal vertebrae; usually the second and third caudal vertebrae with small but complete hemal arches; 12 ribs. Details of soft anatomy and genitalia unknown.

Comparisons

Thomasomys igor sp. nov. is retrieved as the sister species to T. silvestris (Fig. 1: Part A). To construct this section, we used specimens referred to Thomasomys silvestris (sensu stricto) from western Provincia de Cotopaxi and Pichincha (Anthony 1924a, 1924b; Brito et al. 2019). Thomasomys igor sp. nov. is a medium-sized species (Table 4), which differs from T. silvestris (characteristics in parentheses) by having slightly shorter tail ~130% of HB (~140%). Craniodentally, qualitative differences between the two species are conspicuous: M1 without reaching the posterior edge of the zygomatic plate (beyond); M3 with paraflexus and metaflexus long and fused (short); procingulum of m1 divided (undivided or indistinct).

Other Thomasomys species who could be confused with T. igor sp. nov. are T. otavalo and T. ucucha. However, T. igor sp. nov. can be differentiated from these species by the white tail tip <5 mm (15–35 mm in T. otavalo and <5 T. ucucha). Regarding the skull, T. igor sp. nov. can be distinguished by the incisive foramina (72% of LD), while T. otavalo and T. ucucha are shorter (63 and 57% of LD, respectively). As for the molars, in T. igor sp. nov. in M3 the paraflexus and metaflexus long and fused, while in T. otavalo and T. ucucha they are short. Thomasomys igor sp. nov. was previously referred to as T. caudivarius by Salazar and Yates (2007), Pacheco (2015), and Steppan and Schenck (2017), however, T. caudivarius is larger in size (see Brito et al. 2019: table 2) and has a disjunct distribution on the southwestern slope of the Andes. Another species with which Thomasomys igor sp. nov. could be confused is T. aureus (sympatric species), however they are easily distinguished because the new species is notoriously smaller ~113% of HB (~ 336).

Distribution

Thomasomys igor sp. nov. is known only from one locality, near to Cruz de Lizo, Provincia de Bolívar, in the intersections of the Bosque Protector Cashca Totoras, at elevations of 2,875–3,000 m. The new species is geographically delimited by the basins of the rivers Angamarca (north), Chanchán (south), to the east by the inter-Andean valley and to the west by the tropical rainforest (see Fig. 14).

Figure 14.

A relief map of Ecuador is depicted with hypsometric tints that show the elevation variations across the region. The sampling localities of five Thomasomys species are marked on the map.

Natural history

Thomasomys igor sp. nov. is found within the temperate and high Andean zoogeographic areas (Albuja et al. 2012). The ecosystem corresponds to montane forest (Ministerio del Ambiente del Ecuador 2013), which is characterized by trees with abundant orchids, ferns and bromeliads. The species was collected in sympatry with the shrew-opossum, Caenolestes fuliginosus, the shrew Cryptotis equatoris and the rodents Akodon mollis, Nephelomys albigularis (Tomes, 1860), and Thomasomys aureus (Tomes, 1860).

Discussion

In this survey, we incorporated new molecular data (66 new cyt b sequences; Table S1) of Thomasomys for Ecuador which proved critical to recognize the species diversity in the genus. Of particular taxonomic relevance is the inclusion, for the first time, of genetic data for topotypic material for six species: Thomasomys cinnameus Anthony, 1924, T. fumeus Anthony, 1924, T. vulcani (Thomas, 1898), T. ucucha (Voss, 2003), T. otavalo sp. nov. and T. igor sp. nov. (Fig. 1: Part A). Of note, the first three species were described more than a century ago, while T. ucucha was described at the start of this century. Thus, so far, we have sampled all Thomasomys species formally recognized for Ecuador (Table S1). This sampling allowed for the support of some species complexes (see below), and to correct the identifications of several terminal taxa previously sequenced by Lee et al. (2015).

The genus Thomasomys, with 53 species described to date (Pacheco 2005; Brito et al. 2011, 2019; Pacheco and Ruelas 2023, this study) is positioned as the most speciose among the subfamily Sigmodontinae (Pacheco 2015; Pardiñas et al. 2017). However, there is evidence that the species richness of Thomasomys is considerably underestimated. For example, 19 species have been recorded so far in Ecuador alone, and no less than 12 entities are awaiting formal description (Fig. 1: Part A and B). There are also at least five putative species in Peru (Ruelas and Pacheco 2021; Pavan et al. 2024) and one in Bolivia (Salazar-Bravo and Yates 2007).

The cyt b gene trees presented here (Fig. 1) show important variations in topology and branch length. Thomasomys was recovered as monophyletic in both trees estimated with substitution models, as it has been demonstrated in other contributions (Pardiñas et al. 2021; Brito et al. 2022; Pacheco and Ruelas 2023). However, given that codon models are being encouraged to be used as more realistic than nucleotide models (Seo and Kishino 2009; Gil et al. 2013; Crespo-Perez et al. 2023) it is intriguing that the codon-model tree analysis resulted in a paraphyletic Thomasomys (Fig. 1C), Another interesting discrepancy was the differences among branch lengths in the analyses performed with nucleotide substitution models in IQ-tree and RAxML, two of the most commonly used programs for ML phylogenetic inference (Fig. 1A vs. Fig. 1C). These differences may impact the results of traditional species delimitation methods for single loci, such as PTP that depends heavily on branch lengths (Zhang et al. 2013). We hypothesize that species delimitation results using approaches like PTP could provide different answers depending on the software used to generate the input tree.

The Thomasomys silvestris clade is so far treated as endemic to the temperate rainforests of the northern Andes of Ecuador, ranging from the central-western highlands on the border of the Provincias de Chimborazo and Bolívar, to the northwest of the Provincia de Imbabura, and in the northeast of the Provincias de Napo and Carchi (Fig. 14). We hypothesize that in the west, the rivers Chanchán-Angamarca (for T. igor sp. nov.), Angamarca-Guayllabamba (for T. silvestris), Guayllabamba-Mira (for T. otavalo) may act as geographic barriers for the T. silvestris clades. The geographic range of T. ucucha is still extremely poorly known, but it is thus far only known from a handful of localities around Papallacta (Voss 2003; this study, see File S1). The specimens (referred to in this work as T. sp. Zuleta-Guandera) reported as T. ucucha for the Provincias de Carchi (Arcos et al. 2007; Lee et al. 2015) and Imbabura (Brito et al. 2019) maintain a genetic distance of 4% (Table 1) with respect to T. ucucha sensu stricto; therefore, it is necessary to conduct integrative taxonomic studies to determine the taxonomic status of these non-topotypical forms.

The inclusion in this work of topotypic material of Thomasomys cinnameus (MECN 7685) sensu stricto (east of Ambato, Patate), contributed to a better understanding of the geographic and taxonomic context of the species; for example, the Carchi-Imbabura lineage (northeastern Ecuador) previously referred to as T. cinnameus by Tirira and Boada (2009), Lee et al. (2015), Pinto et al. (2018), and Brito et al. (2019) apparently corresponds to an undescribed species (Fig. 1: Part A), and it is sister to the Chalpi lineage (MECN 7940, a putative undescribed species) from the Río Papallacta slope. Our analyses show that T. cinnameus sensu stricto is a sister species of T. hudsoni, and these two species are members of the T. paramorum complex (Boada 2013). It is worth mentioning that the populations of Thomasomys cinnameus reported for Colombia by Pacheco (2015) need to be revised and confirmed given the high genetic divergences observed in the Ecuadorian material.

This work also includes topotypic material of Thomasomys vulcani (western Pichincha) and T. fumeus (east of Ambato, Patate), which led to reconfiguration of the clade (the ‘short-tailed Clade’; see Fig. 1: Part B). Thus, the population of Guandera in northeastern Ecuador referred by Lee et al. (2015) as T. vulcani apparently corresponds to an undescribed species, which in this work we refer to it as T. sp. Guandera. This candidate species was recovered as a sister lineage to T. sp. Reserva Drácula, and was previously referred to as T. cf. bombycinus by Brito et al. (2019) and T. sp. Golondrinas in this study (Fig. 1: Part B), both from western Provincia de Carchi. On the other hand, the population of Sangay National Park, reported as T. fumeus by Brito and Arguero (2016) apparently corresponds to an undescribed species, together with the population of Bosque Corazón de Oro (Fig. 1: Part B), which also appears to be an undescribed species. Additionally, the material recently referred to as T. fumeus in Tapichalaca by Lee et al. (2023) also needs to be reviewed and confirmed.

Genetically, our analyses suggest that the baeops group is a species complex formed by T. baeops and T. taczanowskii (Fig. 1: Part B), expanding on previous findings for this group (Pinto et al. 2018) and resulting from the inclusion in this work of several Ecuadorian populations from both the eastern and western Cordillera (File S1). However, genetic sampling of the topotype material of T. baeops (Río Pita, Pichincha) is still pending. Therefore, efforts to sample the species at its type locality are necessary to conduct the necessary morphological, morphometric and genetic studies that will help us better understand the group and the limits among its constituting species.

Further, it is necessary to discuss the aureus group. This group is composed of species characterized by large body size and mostly arboreal habits (Gardner and Romo 1993; Leo and Gardner 1993; Brito et al. 2012); the latter characteristic poses a degree of difficulty at the moment of acquiring an adequate number of samples for morphological studies. However, from the Ecuadorian material alone, no less than three populations could be thought of as species candidates (Brito et al. 2021; this study). It is worth mentioning that, once the type locality of Thomasomys aureus sensu stricto was restricted to Ecuador by Brito et al. (2021), the material referred to as T. aureus for Venezuela, Colombia, Peru and Bolivia (Pacheco 2015) requires to be re-examined for identity confirmation. Already three species in the aureus group were described (T. antoniobracki Ruelas & Pacheco, 2021, T. burneoi Lee et al., 2022, and T. pardignasi Brito et al., 2021) since the restriction of the type locality of T. aureus. There is evidence that at least one additional species, geographically distributed in Peru and Bolivia, is awaiting formal recognition.

Finally, molecular methods have dramatically improved our ability to discover species (Bickford et al. 2007), but, the magnitude of cryptic diversity remains unknown, especially in diverse regions such as the tropical Andes, and even more so in diverse and complex genera such as Thomasomys. In this work, we found that the species richness of Thomasomys is underestimated, with at least 12 putative undescribed species for Ecuador. It is possible that this number will continue to increase as collections are made in unexplored areas (Pavan et al. 2024), and existing museum material is reinterrogated using museomics (Raxworthy and Smith 2021). Further, the use of new, affordable and relatively simple to implement technologies such as the ONT have the potential to revolutionize the acquisition of genetic information, at least from fresh samples (Pomerantz et al. 2018). All the evidence provided here points towards the importance of allocating evermore increasing research efforts and fund acquisitions to understand the species richness of Thomasomys. Much remains to be learned about the radiation of thomasomyines and unraveling their systematics may be crucial to illuminate the processes of biodiversity generation in the Andes, a hotspot of speciation (e.g., Brito et al. 2022; Lee et al. 2022; Pavan et al. 2023).

Acknowledgements

We are very grateful to Anthony Aguilar, Rocío Vargas, Jhandry Guaya, Julady Castro, Diego Padilla, Glenda Pozo, and Fernando Rodríguez, for their invaluable assistance during field collection. To fellow expedition members: Mario Yánez, Miguel Urgilés, Mauricio Herrera, Efraín Freire, Ricardo Flores, Jorge Paez, Andres Marcayata, and Cristian Paucar for the pleasant company in those arduous but rewarding field campaigns. To Pamela Loján, Mishell Criollo, Daniela Alvarez, Jonathan Salcedo, Erick Moreno, Fulton Barros, and Cinthia Chávez for their impeccable laboratory work. To Diego Inclán, Francisco Prieto, and Pablo Jarrín-V of INABIO, for their sponsorship and permanent support. To Santiago Burneo, Alejandra Camacho, Ana Pilatasig (QCAZ), and Edith Montalvo (MEPN) for access to collections and topotypic material. Part of JB’s field work is part of the project: “Conservation of the Mira-Mataje Binational Watershed”, funded by the MacArthur Foundation and executed by the “Binational Consortium for the Conservation of the Mira-Mataje Watershed” of which INABIO is a member; and Acción Andina Program, led by Global Forest Generation and Asociación Ecosistemas Andinos – ECOAN, the Secretaría de Gestión Ambiental del Gobierno Autónomo Descentralizado Municipal del Cantón Otavalo (GADMCO), and Charlieg Ingeniería y Remediación Cía. Ltda, who managed the necessary funds to carry out the field trips. INABIO extends a special recognition to Eckart von Reitzenstein and Staedtler Forestal Staforco Cia. Ltda., Aves y Conservación, and Fundación EcoMinga for their significant support in equipment and supplies to INABIO’s Nucleic Acid Sequencing. Further, financial support provided by the National Science Foundation (OISE 9417252) to JSB was instrumental in collecting the typical series of Thomasomys igor. We are deeply indebted to the above-mentioned people and institutions. Thanks to Ulyses Pardiñas, Marek Uvizl and an anonymous reviewer for comments and suggestions that helped improve the quality of the manuscript.

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Supplementary materials

Supplementary material 1

File S1

Brito J, García R, Castellanos FX, Gavilanes G, Curay J, Carrión-Olmedo JC, Reyes-Barriga D, Guayasamin JM, Salazar-Bravo J, Pinto CM (2024)

Data type: .pdf

Explanation notes: List of analysed specimens (including the genetic material referred to in Fig. 1).

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

Download file (178.33 kb)

Supplementary material 2

Table S1

Brito J, García R, Castellanos FX, Gavilanes G, Curay J, Carrión-Olmedo JC, Reyes-Barriga D, Guayasamin JM, Salazar-Bravo J, Pinto CM (2024)

Data type: .pdf

Explanation notes: Specimens included in the phylogenetic analysis. For each terminal species, GenBank accession and catalog numbers, country, and collection locality are provided.

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

Download file (164.27 kb)