Bacterial community of ticks (Acari: Ixodidae) and mammals from Arauca, Colombian Orinoquia.

Ticks are obligate hematophagous ectoparasites of vertebrates and are relevant worldwide due to the number of bacterial and other pathogens they can transmit. To date, the knowledge about the microorganisms that ticks harbor and transmit to their hosts is incipient. In this study, 24 samples of mammals belonging to four taxonomic orders and ticks of the genera Amblyomma and Rhipicephalus from the Orinoco region of Colombia were analyzed to described and compare the bacterial microbiome. Genetic extraction was performed, and the V3-V4 region of the 16S rRNA gene was amplified by PCR. Libraries were created, and those samples with adequate quality indices were sequenced using Illumina MiSeq technology. Bacterial taxonomic assignment analyses were conducted through Amplicon Sequence Variants (ASVs) and Operational Taxonomic Units (OTUs). The results correspond to 16 samples that passed the quality filters, with 3218 OTUs (415 families). Although a considerable number of unknown bacteria was found, Enterobacteriaceae, Beijerinckiaceae, Moraxellaceae, and Burkholderiaceae are the most prevalent families, and the presence of the genera Coxiella, Escherichia-Shigella, Enterobacter, which can harbor pathogenic species was confirmed. In individuals of Amblyomma mixtum found actively feeding on Hydrochoerus hydrochaeris, bacteria of the genera Escherichia-Shigella and Enterobacter were documented. Similarly, Rhipicephalus microplus found actively feeding on Odocoileus virginianus cariacou shared Escherichia-Shigella. Ralstonia was shared among the blood samples of H. hydrochaeris, while Anaplasma and Eubacterium were shared in blood and liver samples of O. v. cariacou. Shared bacteria between A. mixtum and R. microplus included Bacillus, Coxiella, and Escherichia-Shigella. The results highlight the need of additional studies in other natural regions of Colombia and other American countries where tick-borne diseases have been detected. Likewise, the recorded data are the first at the level of bacterial communities in ticks of the family Ixodidae and provide valuable knowledge for the understanding host-tick and pathogen interactions.

A new species of terrestrial toad of the Rhinellafestae group (Anura, Bufonidae) from the highlands of the Central Cordillera of the Andes of Colombia.

The genus Rhinella (Bufonidae) comprises 92 species of Neotropical toads. In Colombia, Rhinella is represented by 22 recognized species, of which nine belong to the Rhinellafestae group. Over the past decade, there has been increasing evidence of cryptic diversity within this group, particularly in the context of Andean forms. Specimens of Rhinella collected in high Andean forests on both slopes of the Central Cordillera in Colombia belong to an undescribed species, Rhinellakumandaysp. nov. Genetic analyses using the mitochondrial 16S rRNA gene indicated that the individuals belong to the festae species group. However, they can be distinguished from other closely related species such as Rhinellaparaguas and Rhinellatenrec by a combination of morphological traits including the presence of tarsal fold, a moderate body size, and substantial genetic divergence in the 16S rRNA gene (> 5%). Through this integrative approach, the specimens from the Central Cordillera of Colombia are considered an evolutionary divergent lineage that is sister to R.paraguas, and described as a new species. Rhinellakumandaysp. nov. is restricted to the Central Cordillera of Colombia inhabiting both slopes in the departments of Caldas and Tolima, in an elevational range between 2420 and 3758 m. With the recognition of this new species, the genus Rhinella now comprises 93 species with 23 of them found in Colombia, and ten species endemic to the country.

Extensive Phylogenomic Discordance and the Complex Evolutionary History of the Neotropical Cat Genus Leopardus.

Even in the genomics era, the phylogeny of Neotropical small felids comprised in the genus Leopardus remains contentious. We used whole-genome resequencing data to construct a time-calibrated consensus phylogeny of this group, quantify phylogenomic discordance, test for interspecies introgression, and assess patterns of genetic diversity and demographic history. We infer that the Leopardus radiation started in the Early Pliocene as an initial speciation burst, followed by another in its subgenus Oncifelis during the Early Pleistocene. Our findings challenge the long-held notion that ocelot (Leopardus pardalis) and margay (L. wiedii) are sister species and instead indicate that margay is most closely related to the enigmatic Andean cat (L. jacobita), whose whole-genome data are reported here for the first time. In addition, we found that the newly sampled Andean tiger cat (L. tigrinus pardinoides) population from Colombia associates closely with Central American tiger cats (L. tigrinus oncilla). Genealogical discordance was largely attributable to incomplete lineage sorting, yet was augmented by strong gene flow between ocelot and the ancestral branch of Oncifelis, as well as between Geoffroy's cat (L. geoffroyi) and southern tiger cat (L. guttulus). Contrasting demographic trajectories have led to disparate levels of current genomic diversity, with a nearly tenfold difference in heterozygosity between Andean cat and ocelot, spanning the entire range of variability found in extant felids. Our analyses improved our understanding of the speciation history and diversity patterns in this felid radiation, and highlight the benefits to phylogenomic inference of embracing the many heterogeneous signals scattered across the genome.

Exploring the relationship between bats (Mammalia, Chiroptera) and ectoparasitic flies (Diptera, Hippoboscoidea) of the Orinoquia Region in South America.

Bat flies (Nycteribiidae and Streblidae) have been used to study co-evolutionary patterns between ectoparasites and bats. In the world, Nycteribiidae and Streblidae are represented by approximately 276 and 237 species, respectively. In regions such as the Orinoquia located in the north of South America (Colombia and Venezuela), the richness of bats is high (more than 100 documented species), but studies on Nycteribiidae and Streblidae are scarce and discontinuous. To contribute to the knowledge of ectoparasitic flies in the Orinoquia, records of flies and their interactions with bats were reviewed, including new records and associations using interaction networks. We documented 124 species of Streblidae and only 12 of Nycteribiidae for the Orinoquia in approximately 102 bat species reported in Colombia and Venezuela. New records for six species of bat flies in Colombia were found (Mastopteraguimaraesi, Noctiliostreblamaai, Paradyschiriaparvuloides, Trichobiusjubatus, Trichobiusparasiticus, and Basiliaferrisi) associated with six species of bats (Cynomopsplanirostris, Desmodusrotundus, Myotishandleyi, Molossusrufus, Noctilioalbiventris, and Phyllostomushastatus). The bat-ectoparasite interaction networks in the Orinoquia revealed a pattern of antagonistic relationships, with high specialization, modularity, and low connectivity and nesting. The identified networks are between bat fly species belonging to different ecomorphological groups with unique host species. This supports the idea of ecological niche partitioning among ectoparasitic bat flies and hosts. Our study expanded the knowledge of the distribution of some fly species and the associations with bat hosts in Colombia, by presenting morphological descriptions and new observations, which are key to understanding the ecology, diversity, and distribution of these species.

Morphological and molecular confirmation of Ornithodoros hasei (Schulze, 1935) (Acari: Argasidae) in Colombia.

A large number of tick species are proven vectors for the transmission of bacteria, protozoa, and viruses. Soft ticks (Acari: Argasidae) in South America have been found to be the most frequent carriers of borreliae of the relapsing fever group (RFG); however, there are several information gaps specially on the taxonomy and distribution of some tick species. Here, we used light microscopy, scanning electron microscopy, and PCR amplification of a fragment of the mitochondrial 16S rRNA gene to evaluate 174 larvae of Ornithodoros (Argasidae) collected from three bat species (Eptesicus orinocensis, Molossus rufus and Noctilio albiventris) in the Orinoquia Region of Colombia. The morphological and molecular results confirmed that all the analyzed larvae corresponded to Ornithodoros hasei. Comparisons of mitochondrial 16S rDNA sequences showed low genetic divergence (0% - 0.3%) between larvae of the Department of Arauca in the Orinoquia Region and higher genetic divergence (3.4 - 4.7%) in sequences from other American countries. Our work represents the most recent collection of this species in Colombia and provides a molecular evaluation for the first time. Moreover, a new association of O. hasei with bats such as E. orinocensis is documented. Considering the wide distribution of O. hasei in the American Continent, and its putative role as vector for Borrelia, integrative studies that involve morphological, morphometric, molecular data and experimental crosses are needed to determine if the higher genetic distances are associated with cryptic speciation, as detected in other tick complexes, or represent genetic divergences among geographically different populations of O. hasei.

Revising the diversity within the Dwarf Dog-faced Bat, Molossopstemminckii (Chiroptera, Molossidae), with the revalidation of the endangered Molossopsgriseiventer.

The genus Molossops includes two monotypic species of insectivore bats distributed in South America: Molossopsneglectus and Molossopstemminckii. Both can be differentiated, based on sizes, M.temminckii being smaller (forearm less than 33 mm). Despite being monotypic, at least two additional subspecies have been described for M.temminckii, of which M.temminckiigriseiventer from the inter-Andean Valley of the Magdalena River in Colombia might represent a valid taxon. To test the taxonomic status of M.t.griseiventer, we reviewed specimens of M.temminckii from cis- and trans-Andean localities in Colombia. We used Cytochrome-b and Cytochrome Oxidase I comparisons to test the phylogenetic position of cis- and trans-Andean samples and compared qualitative morphology, morphometric and bioacoustics. Our results show that M.t.griseiventer is differentiated from cis-Andean specimens, providing further evidence of its validity at the species level. Furthermore, M.temminckii (sensu stricto) is also distributed in Colombia, but both M.griseiventer and M.temminckii are allopatric, with the Andes acting as a barrier. The specific identity of the specimens from the Caribbean Region of Colombia needs a new evaluation, but our results clearly show that the diversity of Molossops is underestimated.

Confirming the presence of Lasiurusfrantzii (Peters, 1870) (Chiroptera, Vespertilionidae) in South America: more questions than answers.

The western or desert red bat, Lasiurusfrantzii, is a cryptic insectivore species distributed in the Neotropics from Mexico south through Central America to Panama. L.frantzii was long considered a subspecies of the red bat, Lasiurusblossevillii, but recently it was elevated to full-species status based on genetic information. Here we present evidence of the presence of L.frantzii in the Andean Region of Colombia, confirming the species' presence in South America; the new record, from 3836 m a.s.l., is also the highest elevation known for the species. We suggest that L.frantzii might be widely distributed in trans-Andean areas of Colombia, Ecuador, Venezuela, and perhaps Peru and Bolivia. However, a review and exploration of additional morphological traits to identify the species are necessary because of the uncertainty of the distribution of L.frantzii.

Is Borrelia burgdorferi Sensu Stricto in South America? First Molecular Evidence of Its Presence in Colombia.

The genus Borrelia encompasses spirochetal species that are part of three well-defined groups. Two of these groups contain pathogens that affect humans: the group causing Lyme disease (LDG) and the relapsing fever group (RFG). Lyme disease is caused by Borrelia burgdorferi s.l., which is distributed in the Northern Hemisphere, and relapsing fevers are caused by Borrelia spp., which are found in temperate and tropical countries and are an emerging but neglected pathogens. In some departments of Colombia, there are records of the presence of Borrelia sp. in humans and bats. However, little is known about the impact and circulation of Borrelia spp. in the country, especially in wildlife, which can act as a reservoir and/or amplifying host. In this context, the objective of our research was to detect and identify the Borrelia species present in wild mammals in the departments of Caldas and Risaralda in Colombia. For morphological detection, blood smears and organ imprints were performed, and molecular identification was carried out through a nested PCR directed on the flagellin B (flaB) gene. A total of 105 mammals belonging to three orders (Chiroptera, Didelphimorphia and Rodentia) were analyzed, of which 15.24% (n = 16) were positive for Borrelia. Molecularly, the presence of Borrelia burgdorferi s.s. in lung tissues of Thomasomys aureus and blood of Mus musculus (Rodentia) was detected, with 99.64 and 100% identity, respectively. Borrelia sp. genospecies from a clade branch of a bat-associated LDG sister group were identified in seven individuals of bat species, such as Artibeus lituratus, Carollia brevicauda, Sturnira erythromos, and Glossophaga soricina. Furthermore, two Borrelia genospecies from the RFG in seven individuals of bats (A. lituratus, Artibeus jamaicensis, Platyrrhinus helleri, Mesophylla macconnelli, Rhynchonycteris naso) and rodents (Coendou rufescens, Microryzomys altissimus) were documented. Additionally, the presence of a spirochete was detected by microscopy in the liver of a Sturnira erythromos bat specimen. These results contain the first molecular evidence of the presence of B. burgdorferi s.s. in South America, which merits the need for comprehensive studies involving arthropods and vertebrates (including humans) in other departments of Colombia, as well as neighboring countries, to understand the current status of the circulation of Borrelia spp. in South America.

Infestation, histology, and molecular confirmation of Sarcoptes scabiei in an Andean porcupine (Coendou quichua) from the Central Andes of Colombia.

Sarcoptic mange is a highly contagious, worldwide disease that affects the skin of mammals, including humans. It is caused by the mite Sarcoptes scabiei, however, the information available in wild mammal populations in the world, and particularly in Colombia is limited. Here, we document a new case of sarcoptic mange in an Andean porcupine (Coendou quichua) from the Andean region of Colombia. We morphologically and molecularly confirmed the mite as S. scabiei and documented the histopathology associated with scabies, and show the different stages of the life cycle of S. scabiei from the Andean porcupine skin samples. Our review of reports of additional cases of scabies in wild mammal species in South America showed 15 species, mostly carnivores, artiodactyls, and rodents. Considering the limited information in Colombia, it is urgent to evaluate the risk of this condition on mammals which would contribute to the epidemiological knowledge and the potential implications of sarcoptic mange in the ecology and conservation of wild mammals in the country.

Bacteria related to tick-borne pathogen assemblages in Ornithodoros cf. hasei (Acari: Argasidae) and blood of the wild mammal hosts in the Orinoquia region, Colombia.

Interest in research on soft ticks has increased in recent decades, leading to valuable insight into their role as disease vectors. The use of metagenomics-based analyses have helped to elucidate ecological factors involved in pathogen, vector, and host dynamics. To understand the main bacterial assemblages present in Ornithodoros cf. hasei and its mammalian hosts, 84 ticks and 13 blood samples from bat hosts (Chiroptera) were selected, and the 16S rRNA gene V4 region was sequenced in five pools (each one related to each host-tick pairing). Bacterial taxonomic assignment analyses were performed by comparing operational taxonomic units (OTUs) shared between ticks and their host blood. This analysis showed the presence of Proteobacteria (38.8%), Enterobacteriaceae (25%), Firmicutes (12.3%), and Actinobacteria (10.9%) within blood samples, and Rickettsiaceae (39%), Firmicutes (25%), Actinobacteria (13.1%), and Proteobacteria (9%) within ticks. Species related to potentially pathogenic genera were detected in ticks, such as Borrelia sp., Bartonella tamiae, Ehrlichia sp. and Rickettsia-like endosymbiont, and the presence of these organisms was found in all analyzed bat species (Cynomops planirostris, Molossus pretiosus, Noctilio albiventris), and O. cf. hasei. About 41-48.6% of bacterial OTUs (genera and species) were shared between ticks and the blood of bat hosts. Targeted metagenomic screening techniques allowed the detection of tick-associated pathogens for O. cf. hasei and small mammals for the first time, enabling future research on many of these pathogens.

Extension of the distribution of Amblyomma triste Koch, 1844: Morphological and molecular confirmation of Morphotype I in Colombia.

Ticks of the Amblyomma maculatum (Acari: Ixodidae) group are represented by three species: Amblyomma maculatum, Amblyomma tigrinum, and Amblyomma triste. This group is widely distributed throughout the Nearctic and Neotropical regions, from the United States of America (USA) to Argentina. They parasitize several vertebrates, including domestic mammals and humans. Nonetheless, the identification and distribution of the species within the group have been controversial but can be solved with integrative studies on their taxonomy and ecology. In Colombia, a Neotropical country from which up to 58 tick species have been reported, only Amblyomma maculatum Koch, 1844 (sensu stricto - s.s.) - morphotype II - has been molecularly confirmed. Here, specimens of the A. maculatum group from three departments of Colombia were examined by morphological and molecular analyses. The results confirmed the wide distribution of A. maculatum s.s. in Colombia. Furthermore, the presence of A. triste s.s. - morphotype I was confirmed for the first time at the molecular level, which broadens the distribution of this species in the American continent. Considering that both taxa are vectors of pathogens such as Rickettsia parkeri s.s., additional taxonomic, reproductive compatibility and niche distribution studies are needed, as well as the application of new molecular markers due to the controversial taxonomy. This will allow us to explore cryptic diversity within the recently established putative groups.

Ticks (Acari: Ixodoidea) associated with mammals in Colombia: a historical review, molecular species confirmation, and establishment of new relationships.

Ticks are considered the second most important vectors of pathogens worldwide, after mosquitoes. This study provides a systematic review of vector-host relationships between ticks and mammals (domestic and wild) and consolidates information from studies conducted in Colombia between 1911 and 2020. Using the PRISMA method, 71 scientific articles containing records for 51 tick species (Argasidae and Ixodidae) associated with mammals are reported. The existing information on tick-mammal associations in Colombia is scarce, fragmented, or very old. Moreover, 213 specimens were assessed based on morphological and molecular analyses, which allowed confirming eight tick species associated with mammals: Amblyomma calcaratum, Amblyomma dissimile, Amblyomma mixtum, Amblyomma nodosum, Amblyomma ovale, Amblyomma varium, Ixodes luciae, and Ixodes tropicalis. Several tick species are molecularly confirmed for Colombia and nine new relationships between ticks and mammals are reported. This research compiles and confirms important records of tick-mammal associations in Colombia.

Body mass data set for 1,317 bird and 270 mammal species from Colombia.

Body mass is one of the most important phenotypic attributes in animal ecology and life history. This trait is widely used in the fields of ecology and macroevolution, since it influences physiology, morphological functions, and a myriad of ecological and social interactions. In this data set, our aim was to gather a comprehensive bird and mammal body mass data set from northern South America. We report body mass, discriminated by sex, for 42,022 individual birds and 7,441 mammals representing 1,317 bird species (69% of Colombia's avifauna) and 270 mammal species (51% of Colombian mammals) from the Neotropics. The data were sourced from vouchers collected between 1942 and 2020 and from individuals captured and released at banding stations over the last two decades for birds (2000-2020) and the last decade for mammals (2010-2020), by 10 research groups and institutions in Colombia. This data set fills gaps identified in other similar databases, as it focuses on northern South America, a highly diverse Neotropical region often underrepresented in morphological data sets. We provide wide taxonomic coverage for studies interested in information both at regional and local scales. There are no copyright restrictions; the present data paper should be appropriately cited when data are used for publication. The authors would appreciate learning about research projects, teaching exercises, and other uses given to this data set and are open to contribute in further collaborations using these data.

Rickettsia parkeri strain Atlantic rainforest in ticks (Acari: Ixodidae) of wild birds in Arauca, Orinoquia region of Colombia.

Birds are important hosts for the development of the immature stages of several tick species that are vectors for disease-causing microorganisms in animals and humans. Colombia has the highest number of bird species worldwide; however, there is scarce data on the role of birds in the circulation of ticks and their associated pathogens, such as rickettsiae. The department of Arauca has a high diversity of resident and migratory (boreal and austral) birds and ticks associated with the transmission of Rickettsia. The objective of this research was to identify tick species parasitizing birds and to detect Rickettsia species in these ectoparasites. We conducted samplings in the municipalities of Arauca, Cravo Norte, and Tame between November of 2018 and August of 2019. Birds were captured using mist nets and examined for the presence of tick species. The collected ticks were morphologically and molecularly identified. Furthermore, we detected rickettsiae in ticks by amplifying fragments of the citrate synthase (gltA) and outer membrane protein (ompB) genes. We captured 606 birds belonging to 25 families and 115 species. Tick infestation rate was 3.3% (20/606) in the birds captured and eight new associations between wild birds and ticks are reported for the American continent. We identified four tick species: Amblyomma nodosum, Amblyomma longirostre, Amblyomma mixtum, and Amblyomma sp.. Moreover, we confirmed the presence of Rickettsia parkeri strain Atlantic rainforest in A. nodosum, a medically-relevant rickettsia due to cases of rickettsiosis in the American continent. This finding manifests the importance of wild birds as hosts and dispersal agents of ticks infected with pathogenic rickettsiae, as well as the need to monitor migratory birds in the Orinoquia and other regions of Colombia and America.

Un registro de hipertrofia del trago del murciélago frugívoro de gran tamaño Artibeus lituratus (Chiroptera: Phyllostomidae) / A record of hypertrophy of the tragus of great fruit-eating bat Artibeus lituratus (Chiroptera: Phyllostomidae)

Resumen En este trabajo, reportamos y describimos evidencia de una anomalía en el trago de un individuo de Artibeus lituratus, capturado en los Andes Centrales de Colombia. En junio de 2019, durante un trabajo de campo en el Departamento de Caldas, municipio de Aranzazu, quedó atrapado un individuo de A. lituratus con inusual forma de trago. Este individuo tenía un trago de forma cilíndrica y asimetría. El individuo fue recogido y depositado en el Museo de Historia Natural de la Universidad de Caldas (MHN-UCa). Se realizó una revisión de la literatura para encontrar casos similares utilizando motores de búsqueda, pero no se encontraron informes previos de la anomalía. Además, revisamos el trago de los especímenes en el MHNUCa y ninguno de ellos presentaba malformaciones similares. Concluimos que esta anomalía no se había registrado previamente en Chiroptera.

Abstract In this work, we report and describe evidence of an anomaly in the tragus of an individual of Artibeus lituratus, captured in the Central Andes of Colombia. During field work in the Department of Caldas, municipality of Aranzazu, one individual of A. lituratus with unusual tragus form was trapped. This individual had a tragus with cylindrical shape and asymmetry. The individual was collected and deposited at the Museum of Natural History of the University of Caldas (MHN-UCa). A literature review was conducted to find similar cases using searching engines, but no previous reports of the anomaly were find. Furthermore, we reviewed the tragus of vouchers at the MHN-UCa and none of these had similar malformations. We concluded that this anomaly has not previously registered in Chiroptera.

Fifteen shades of green: The evolution of Bufotes toads revisited.

The radiation of Palearctic green toads (Bufotes) holds great potential to evaluate the role of hybridization in phylogeography at multiple stages along the speciation continuum. With fifteen species representing three ploidy levels, this model system is particularly attractive to examine the causes and consequences of allopolyploidization, a prevalent yet enigmatic pathway towards hybrid speciation. Despite substantial efforts, the evolutionary history of this species complex remains largely blurred by the lack of consistency among the corresponding literature. To get a fresh, comprehensive view on Bufotes phylogeography, here we combined genome-wide multilocus analyses (RAD-seq) with an extensive compilation of mitochondrial, genome size, niche modelling, distribution and phenotypic (bioacoustics, morphometrics, toxin composition) datasets, representing hundreds of populations throughout Eurasia. We provide a fully resolved nuclear phylogeny for Bufotes and highlight exceptional cyto-nuclear discordances characteristic of complete mtDNA replacement (in 20% of species), mitochondrial surfing during post-glacial expansions, and the formation of homoploid hybrid populations. Moreover, we traced the origin of several allopolyploids down to species level, showing that all were exclusively fathered by the West Himalayan B. latastii but mothered by several diploid forms inhabiting Central Asian lowlands, an asymmetry consistent with hypotheses on mate choice and Dobzhansky-Muller incompatibilities. Their intermediate call phenotypes potentially allowed for rapid reproductive isolation, while toxin compositions converged towards the ecologically-closest parent. Across the radiation, we pinpoint a stepwise progression of reproductive isolation through time, with a threshold below which hybridizability is irrespective of divergence (<6My), above which species barely admix and eventually evolve different mating calls (6-10My), or can successfully cross-breed through allopolyploidization (>15My). Finally, we clarified the taxonomy of Bufotes (including genetic analyses of type series) and formally described two new species, B. cypriensis sp. nov. (endemic to Cyprus) and B. perrini sp. nov. (endemic to Central Asia). Embracing the genomic age, our framework marks the advent of a new exciting era for evolutionary research in these iconic amphibians.

Sarcoptic mange in wild quichua porcupines (Coendou quichua Thomas, 1899) in Colombia.

The Quichua porcupine (Coendou quichua) is a neotropical rodent with uncertain taxonomic and conservation status. Two Quichua porcupines with severe hyperkeratosis and alopecia were found in the Magdalena River Basin of Colombia. Sarcoptes scabiei, the mite causing mange, a disease carried mainly by domestic animals, was confirmed via parasitological and molecular methods. This is the first report of mange in neotropical porcupines to date. The population-level impact of mange in Coendou spp., related mammals and predators in Colombia might represent a threat and needs further investigation.

Resolving the evolution of the mammalian middle ear using Bayesian inference.

BACKGROUND: The minute, finely-tuned ear ossicles of mammals arose through a spectacular evolutionary transformation from their origins as a load-bearing jaw joint. This involved detachment from the postdentary trough of the mandible, and final separation from the dentary through resorption of Meckel's cartilage. Recent parsimony analyses of modern and fossil mammals imply up to seven independent postdentary trough losses or even reversals, which is unexpected given the complexity of these transformations. Here we employ the first model-based, probabilistic analysis of the evolution of the definitive mammalian middle ear, supported by virtual 3D erosion simulations to assess for potential fossil preservation artifacts. RESULTS: Our results support a simple, biologically plausible scenario without reversals. The middle ear bones detach from the postdentary trough only twice among mammals, once each in the ancestors of therians and monotremes. Disappearance of Meckel's cartilage occurred independently in numerous lineages from the Late Jurassic to the Late Cretaceous. This final separation is recapitulated during early development of extant mammals, while the earlier-occurring disappearance of a postdentary trough is not. CONCLUSIONS: Our results therefore suggest a developmentally congruent and directional two-step scenario, in which the parallel uncoupling of the auditory and feeding systems in northern and southern hemisphere mammals underpinned further specialization in both lineages. Until ~168 Ma, all known mammals retained attached middle ear bones, yet all groups that diversified from ~163 Ma onwards had lost the postdentary trough, emphasizing the adaptive significance of this transformation.

Mammalian development does not recapitulate suspected key transformations in the evolutionary detachment of the mammalian middle ear.

The ectotympanic, malleus and incus of the developing mammalian middle ear (ME) are initially attached to the dentary via Meckel's cartilage, betraying their origins from the primary jaw joint of land vertebrates. This recapitulation has prompted mostly unquantified suggestions that several suspected--but similarly unquantified--key evolutionary transformations leading to the mammalian ME are recapitulated in development, through negative allometry and posterior/medial displacement of ME bones relative to the jaw joint. Here we show, using µCT reconstructions, that neither allometric nor topological change is quantifiable in the pre-detachment ME development of six marsupials and two monotremes. Also, differential ME positioning in the two monotreme species is not recapitulated. This challenges the developmental prerequisites of widely cited evolutionary scenarios of definitive mammalian middle ear (DMME) evolution, highlighting the requirement for further fossil evidence to test these hypotheses. Possible association between rear molar eruption, full ME ossification and ME detachment in marsupials suggests functional divergence between dentary and ME as a trigger for developmental, and possibly also evolutionary, ME detachment. The stable positioning of the dentary and ME supports suggestions that a 'partial mammalian middle ear' as found in many mammaliaforms--probably with a cartilaginous Meckel's cartilage--represents the only developmentally plausible evolutionary DMME precursor.

Especímenes tip de mamíferos en la colección dl instituto de ciencias naturalles, universidad nacional de Colombia / Type Specimens of Mammals in the Colections of the Instituto de Ciencias Naturales, Universidad Nacional de Colombia

Se presenta una lista anotada de los especímenes tipo de mamíferos depositados en la colección del Instituto de Ciencias Naturales, Universidad Nacional de Colombia (ICN). Este trabajo adiciona nueve holotipos y 33 paratipos al catálogo de los tipos nomenclaturales depositados en la colección de mamíferos del ICN publicado por Cadena y Muñoz-Saba, 2007. A la fecha, la colección de mamíferos del ICN cuenta con 15 holotipos y 44 paratipos pertenecientes a 18 taxones.

An annotated list of type specimens of Mammalia at Instituto de Ciencias Naturales, Universidad Nacional de Colombia (ICN) is given. This work adds nine holotypes and 33 paratypes to the catalogue of nomenclatural type specimens of mammals deposited in the ICN collections presented by Cadena and Muñoz-Saba, 2007. At the date, the ICN mammal collections housed 15 holotypes, and 44 paratypes for 18 taxa.