A new endemic lineage of the Andean frog genusTelmatobius(Anura, Telmatobiidae) from the western slopes of the central Andes

Back to the water: Tongue morphology associated to contrasting lifestyles in two Andean frogs of the genus Telmatobius

The evolution of the tongue in tetrapods is associated with feeding in the terrestrial environment. This study analyzes the tongue morphology of two closely related frog species, Telmatobius oxycephalus and T. rubigo, which exhibit contrasting feeding mechanisms. Telmatobius oxycephalus, a semi-aquatic species, relies on its tongue to capture terrestrial prey whereas T. rubigo, a secondarily aquatic species, uses suction feeding not involving the tongue. Through anatomical, histological and scanning electron microscopy analyses, we revealed remarkable differences in tongue morphology between these species. Telmatobius oxycephalus exhibits a well-developed tongue whose dorsal epithelium has numerous and slender filiform papillae. The epithelial cells of the papillae are protruded and have a complex array of microridges. In contrast, T. rubigo possesses a reduced tongue with flat and less numerous filiform papillae. The epithelial cells are completely flat and lack microridges. These findings highlight the remarkable adaptability of lingual morphology in Telmatobius to respond to the contrasting ecological niches and prey capture mechanisms. This study sheds light on the relationship between tongue shape and the different functional demands, contributing to our understanding of the evolution of prey capture mechanisms in amphibians.

Phylogeny of Telmatobius marmoratus complex (Anura, Telmatobiidae) reveals high cryptic diversity in the Andean Altiplano

Telmatobius is the most diverse group of anurans in the Andean Altiplano (highlands) Morphologically, these amphibians have a generally conserved morphology but in turn present large intraspecific variation, which has led to a complex taxonomy and systematics. T. marmoratus has the widest distribution of the genus and forms a complex composed of at least two Telmatobius species. Partial systematic studies based on molecular evidence reveal the existence of three lineages with a complex spatial distribution. However, these studies did not include the entire distribution of T. marmoratus. Our study aims to reassess the current systematic scenario including the complete distribution of the complex. For this, we used a multilocus approach based on mitochondrial (16S, Cytb) and nuclear (RAG1-1, BFIB) DNA sequences to build a phylogenetic hypothesis based on Bayesian inference, maximum likelihood and maximum parsimony. Subsequently, we performed single-locus (ABGD and PTP) and multilocus (STACEY) species delimitation analyses to verify the diversity of nominal species within the complex. The analyses suggest seven non-sibling lineages and 6-10 candidate species within the marmoratus complex. Only one of the two lineages restricted to the central northern plateau correspond to T. marmoratus sensu stricto. South-central marbled water frogs belong to completely new lineages closer to T. gigas and T. culeus, evidencing the polyphyletic condition of the marmoratus complex. The findings of several sympatric lineages in some localities reveal a complex history of ancient water connections in south-central Altiplano.

The definitive rediscovery of Telmatobiushalli (Anura, Telmatobiidae) at its historic type locality and its synonymy with T.dankoi and T.vilamensis

Telmatobiushalli was the first representative of its genus to be described exclusively for Chile, yet for 85 years no new individuals could be located due to the vagueness with which its type locality was described. The type series was collected by one of the members of the International High Altitude Expedition to Chile (IHAEC) of 1935. Recently, three studies successively claimed to have located the type locality in different places. The third study proved, according to the chronicles of the IHAEC, that the actual locality is Miño, at the origin of the Loa River, where currently there are no published records of Telmatobius. In this study, additional documentary antecedents and graphic material are provided that corroborate that Miño is indeed the type locality of T.halli. Additionally, the recently rediscovered Telmatobius population from Miño and the environment it inhabits are described. The external characteristics of the frogs are consistent with the description of T.halli. Furthermore, molecular phylogenetic analyses were performed that showed that T.halli, T.dankoi, and T.vilamensis, all known only from their type localities in Chile, comprise a clade without internal resolution. A detailed comparison of the diagnoses of the three species revealed that the few phenotypic differences between these taxa were based on characteristics that vary widely within and between populations of the genus, hence their conspecificity is proposed. The implications of this synonymy for the taxonomy, biogeography, and conservation of the Telmatobius from the extreme south of its distribution in Chile are discussed.

Genome sequencing and transcriptomic analysis of the Andean killifish Orestias ascotanensis reveals adaptation to high-altitude aquatic life

Orestias ascotanensis (Cyprinodontidae) is a teleost pupfish endemic to springs feeding into the Ascotan saltpan in the Chilean Altiplano (3,700 m.a.s.l.) and represents an opportunity to study adaptations to high-altitude aquatic environments. We have de novo assembled the genome of O. ascotanensis at high coverage. Comparative analysis of the O. ascotanensis genome showed an overall process of contraction, including loss of genes related to G-protein signaling, chemotaxis and signal transduction, while there was expansion of gene families associated with microtubule-based movement and protein ubiquitination. We identified 818 genes under positive selection, many of which are involved in DNA repair. Additionally, we identified novel and conserved microRNAs expressed in O. ascotanensis and its closely-related species, Orestias gloriae. Our analysis suggests that positive selection and expansion of genes that preserve genome stability are a potential adaptive mechanism to cope with the increased solar UV radiation to which high-altitude animals are exposed to.

A solution to the enigma of the type locality of Telmatobiushalli Noble, 1938 (Anura, Telmatobiidae), a frog lost for 86 years

For 80 years, there were no sightings of the Andean frog, Telmatobiushalli, due to the ambiguity with which its type locality was described ("warm spring near Ollagüe", northern Chile). The type specimens were collected during the International High Altitude Expedition to Chile (IHAEC) in 1935 and were subsequently described in 1938. In 2018 and 2020, two studies independently reported the rediscovery of the species, but they reached different conclusions about its identity and geographic distribution. In fact, the populations identified as T.halli in those studies are more phylogenetically related to other species than to each other, so they clearly do not belong to the same taxon. Although the study of 2020 is more in line with the geographic information of the description, it does not consider some bibliographic details and the transport limitations of the IHAEC. Here, based on a detailed analysis of the chronicles of the IHAEC and other bibliographic sources, I first refute the proposals of the 2018 and 2020 studies and then provide a possible solution. The combined information from the chronicles indicates that the type locality of T.halli is found at the sources of the Loa River, a different place from those identified in the two previous studies. By also incorporating geographic information of the time, I conclude that its true type locality is Miño, an abandoned mining camp located near the origin of the Loa River, where currently no populations of the genus have been described.

An update of the geographical distribution of Pleurodema marmoratum (Duméril & Bibron, 1840) in the Chilean Altiplano

This study summarizes new and historical records of one of the least known anuran species from the Chilean Altiplano, Pleurodema marmoratum (Duméril & Bibron, 1840). The discovery of a new population in the Altiplano of the Región de Antofagasta extends the known distribution of this species in Chile approximately 100 km south.

Integrative taxonomic reassessment of Odontophrynus populations in Argentina and phylogenetic relationships within Odontophrynidae (Anura)

Amphibians are the most vulnerable vertebrates to biodiversity loss mediated by habitat destruction, climate change and diseases. Informed conservation management requires improving the taxonomy of anurans to assess reliably the species' geographic range. The genus Odontophrynus that is geographically refined to Argentina, Bolivia, Brazil, Uruguay and Paraguay includes currently 12 nominal species with many populations of uncertain taxonomic assignment and subsequently unclear geographic ranges. In this study, we applied integrative taxonomic methods combining molecular (mitochondrial 16S gene), allozyme, morphological and bioacoustic data to delimit species of the genus Odontophrynus sampled from throughout Argentina where most species occur. The combined evidence demonstrates one case of cryptic diversity and another of overestimation of species richness. The populations referred to as O. americanus comprise at least three species. In contrast, O. achalensis and O. barrioi represent junior synonyms of the phenotypically plastic species O. occidentalis. We conclude that each of the four species occurring in Argentina inhabits medium to large areas. The Red List classification is currently "Least Concern". We also propose a phylogenetic hypothesis for the genus and associated genera Macrogenioglottus and Proceratophrys (Odontophrynidae).

Influenced but not determined by historical events: genetic, demographic and morphological differentiation in Heleobia ascotanensis from the Chilean Altiplano

In the present study, we focus on the phylogeographic pattern, demographic history and morphological differentiation of Heleobia ascotanensis, a freshwater gastropod restricted to the Ascotán saltpan in the Chilean Altiplano. The current distribution of the species is limited to twelve isolated or partially isolated springs that were affected by transitions between humid and arid periods during last glaciations. The genetic analysis of 322 specimens showed that H. ascotanensis is subdivided into three genetically divergent populations, with low and moderate degrees of historical gene flow among them and incipient morphological differentiation as a consequence of genetic and geographical isolation. Molecular analyses revealed different demographic histories among populations which seem to respond independently to climatic events, probably due to an environmental imposition and idiosyncratic strategies developed to cope with water availability. The results of this study and co-distributed taxa support the hypothesis that contemporary and historical events have influenced microevolutionary differentiation of these snails, although there is a need to complement further information to predict genetic or morphological divergence at microgeographic scale.

Development and characterization of 22 polymorphic microsatellites of the Andean frog Telmatobius chusmisensis (Anura, Telmatobius) and cross amplification in seven Chilean species of the genus

The genus Telmatobius Wiegmann, 1834 is composed of a wide variety of species and is one of the most diverse native components of the high-altitude Andean environments. The species of the genus present in Chile are considered as endangered, critically endangered or data deficient. We isolated and evaluated 44 microsatellites in 80 individuals of 8 species of Telmatobius present in Chile, obtaining 22 polymorphic microsatellite loci for Telmatobius chusmisensis. The cross-amplification test was successful in all other species tested. For the first time, microsatellite markers are described for Telmatobius. The description of these primers will be useful for further genetic studies for T. chusmisensis and other species of the same genus; allowing further analyses of population structuring, dispersal patterns, recent demographic history and population effective size. This information is also significant to undertake conservation actions for the species of the genus Telmatobius, since most species have conservation issues.

Unraveling the diversification history of grasshoppers belonging to the "Trimerotropis pallidipennis" (Oedipodinae: Acrididae) species group: a hotspot of biodiversity in the Central Andes

The Andean Mountain range has been recognized as one of the biodiversity hotspots of the world. The proposed mechanisms for such species diversification, among others, are due to the elevation processes occurring during the Miocene and the intensive glacial action during the Pleistocene. In this study we investigated the diversification history of the grasshopper Trimerotropis pallidipennis species complex which shows a particularly wide latitudinal and altitudinal distribution range across the northern, central and southern Andes in South America. Many genetic lineages of this complex have been so far discovered, making it an excellent model to investigate the role of the central Andes Mountains together with climatic fluctuations as drivers of speciation. Phylogenetics, biogeographic and molecular clock analyses using a multi-locus dataset revealed that in Peru there are at least two, and possibly four genetic lineages. Two different stocks originated from a common ancestor from North/Central America—would have dispersed toward southern latitudes favored by the closure of the Panama Isthmus giving rise to two lineages, the coastal and mountain lineages, which still coexist in Peru (i.e., T. pallidipennis and T. andeana). Subsequent vicariant and dispersal events continued the differentiation process, giving rise to three to six genetic lineages (i.e., clades) detected in this study, which were geographically restricted to locations dispersed over the central Andes Mountains in South America. Our results provide another interesting example of “island diversification” motored by the topography plus unstable climatic conditions during the Pleistocene, pointing out the presence of a hotspot of diversification in the Andean region of Peru.

Silent sounds in the Andes: underwater vocalizations of three frog species with reduced tympanic middle ears (Anura: Telmatobiidae: Telmatobius)

Underwater vocalization in anurans is restricted to a few, distantly related species. In some of them, sound is transmitted through tympanic and extra-tympanic pathways. Members of the Andean genus Telmatobius Wiegmann, 1834 lack a tympanic membrane, and earlier reports assumed the absence of vocalizations in the genus. We recorded underwater vocalizations and examined the middle-ear morphology in three species of Telmatobius with different lifestyles: Telmatobius oxycephalus Vellard, 1946 (semiaquatic, riverine); Telmatobius hintoni Parker, 1940 (markedly aquatic, riverine); Telmatobius culeus (Garman 1876) (fully aquatic, lacustrine). Males emit underwater calls, which in the three species are simple and stereotyped; they consist of a repeated train of notes, with a low fundamental frequency (309–941 Hz). In each of the three species, the tympanic membrane is absent and the tympanic cavity is extremely reduced or absent, whereas the opercular system is well developed. Our data, along with prior knowledge in other species of anurans, suggest that the species examined here probably perceived sound through extra-tympanic pathways. Given the limited knowledge about underwater calling in anurans, Telmatobius seems a logical candidate to study the functional and evolutionary bases of underwater hearing and tympanic middle-ear reduction in anurans.

The complete mitochondrial genome of the Chilean endemic frog Telmatobius chusmisensis Formas, Cuevas & Nuñez, 2006 (Anura, Telmatobiidae)

Telmatobius chusmisensis is an endemic frog of northern Chile that is only known at its type locality, Chusmisa. In this study, the complete mitochondrial genome of Telmatobius chusmisensis was assembled using high-throughput sequencing data, yielding a circular genome of 19 312 bp with a nucleotide composition of A = 30.8%, C = 24.4%, G = 13.6% and T = 31.2%. Its gene composition and structure were similar to other anuran genomes available: 13 protein-coding genes, two rRNA genes, 22 tRNA genes and the D-loop region. Phylogenetic analysis using Bayesian inference (BI) and maximum likelihood (ML) showed that Telmatobius chusmisensis, T. bolivianus and T. vellardi are a highly supported monophyletic group. This genome information will allow us to gain a better understanding into phylogenetic and phylogeographic relationships in the genus Telmatobius.

Independent Evolution of Suction Feeding in Neobatrachia: Feeding Mechanisms in Two Species of Telmatobius (Anura:Telmatobiidae)

The most common feeding mechanism among aquatic vertebrates as fishes, turtles, and salamanders is inertial suction. However, among the more than 6,400 species of anurans, suction feeding occurs only in pipids. Pipidae is a small basal lineage relative to Neobatrachia, an enormous clade that contains about 96% of extant anurans. The Andean neobatrachian frogs of the genus Telmatobius include strictly aquatic and semiaquatic species. Diet analyses indicate that some species of Telmatobius feed on strictly aquatic prey, but until now their feeding mechanisms have been unknown. Herein, the feeding mechanisms in two species of Telmatobius, that represent the two predominant modes of life in the genus, are explored. The semiaquatic T. oxycephalus and the fully aquatic T. rubigo are studied using high-speed cinematography and standard anatomical techniques to provide a qualitative approach to feeding behavior and a detailed morphological description of the mouth, tongue, hyoid and related muscles. T. oxycephalus uses similar mechanisms of aquatic prey capture as do the vast majority of anurans that are capable of forage in water, whereas the fully aquatic T. rubigo is an inertial suction feeder. This is the first report of an objective record of this unique feeding behavior in a Neobatrachian. Several morphological characters seem to be related with this function and are convergent with those of pipids.

Evolution and Conservation on Top of the World: Phylogeography of the Marbled Water Frog (Telmatobius marmoratus Species Complex; Anura, Telmatobiidae) in Protected Areas of Chile

The Andean Altiplano has served as a complex setting throughout its history, driving dynamic processes of diversification in several taxa. We investigated phylogeographic processes in the Telmatobius marmoratus species complex occurring in this region by studying the geographic patterns of genetic variability, genealogies, and historical migration, using the cytochrome b (cyt-b) gene as a marker. DNA sequences from Telmatobius gigas and Telmatobius culeus, Bolivian species with an uncertain taxonomic status, were also included. Additionally, we evaluated the phylogenetic diversity (PD) represented within Chilean protected areas and the complementary contribution from unprotected populations. Phylogenetic reconstructions from 148 cyt-b sequences revealed 4 main clades, one of which corresponded to T. culeus. T. gigas was part of T. marmoratus clade indicating paraphyletic relationships. Haplotypes from Chilean and Bolivian sites were not reciprocally monophyletic. Geographic distribution of lineages, spatial Bayesian analysis, and migration patterns indicated that T. marmoratus displays a weaker geographic structure than expected based on habitat distribution and physiological requirements. Demographic and statistical phylogeography analyses pointed out to a scenario of recent population expansion and high connectivity events of a more recent age than the post Last Glacial Maximum, probably associated to more humid events in Altiplano. PD of T. marmoratus populations within protected areas represents 55.6% of the total estimated PD. The unprotected populations that would contribute the most to PD are Caquena and Quebe (21%). Recent evolutionary processes and paleoclimatic changes, potentially driving shifts in habitat connectivity levels and population sizes, could explain the phylogeographic patterns recovered herein.

Comparative phylogeography of co-distributed Phrygilus species (Aves, Thraupidae) from the Central Andes

The Neotropical ecoregion has been an important place of avian diversification where dispersal and allopatric events coupled with periods of active orogeny and climate change (Late Pliocene-Pleistocene) have shaped the biogeography of the region. In the Neotropics, avian population structure has been sculpted not only by geographical barriers, but also by non-allopatric factors such as natural selection and local adaptation. We analyzed the genetic variation of six co-distributed Phrygilus species from the Central Andes, based on mitochondrial and nuclear markers in conjunction with morphological differentiation. We examined if Phrygilus species share patterns of population structure and historical demography, and reviewed the intraspecific taxonomy in part of their geographic range. Our results showed different phylogeographic patterns between species, even among those belonging to the same phylogenetic clade. P. alaudinus, P. atriceps, and P. unicolor showed genetic differentiation mediated by allopatric mechanisms in response to specific geographic barriers; P. gayi showed sympatric lineages in northern Chile, while P. plebejus and P. fruticeti showed a single genetic group. We found no relationship between geographic range size and genetic structure. Additionally, a signature of expansion was found in three species related to the expansion of paleolakes in the Altiplano region and the drying phase of the Atacama Desert. Morphological analysis showed congruence with molecular data and intraspecific taxonomy in most species. While we detected genetic and phenotypic patterns that could be related to natural selection and local adaptation, our results indicate that allopatric events acted as a major factor in the population differentiation of Phrygilus species.

A new species of Telmatobius (Amphibia, Anura, Telmatobiidae) from the Pacific slopes of the Andes, Peru

We describe a new species of Telmatobius from the Pacific slopes of the Andes in central Peru. Specimens were collected at 3900 m elevation near Huaytará, Huancavelica, in the upper drainage of the Pisco river. The new species has a snout–vent length of 52.5 ± 1.1 mm (49.3–55.7 mm, n = 6) in adult females, and 48.5 mm in the single adult male. The new species has bright yellow and orange coloration ventrally and is readily distinguished from all other central Peruvian Andean species of Telmatobius but Telmatobiusintermedius by having vomerine teeth but lacking premaxillary and maxillary teeth, and by its slender body shape and long legs. The new species differs from Telmatobiusintermedius by its larger size, flatter head, and the absence of cutaneous keratinized spicules (present even in immature females of Telmatobiusintermedius), and in males by the presence of minute, densely packed nuptial spines on dorsal and medial surfaces of thumbs (large, sparsely packed nuptial spines in Telmatobiusintermedius). The hyper-arid coastal valleys of Peru generally support low species richness, particularly for groups such as aquatic breeding amphibians. The discovery of a new species in this environment, and along a major highway crossing the Andes, shows that much remains to be done to document amphibian diversity in Peru.