Phylogeny, evolution, and systematics of theGalea musteloidescomplex (Rodentia: Caviidae)

Structural and Ultrastructural Characteristics of the Spix's Yellow-Toothed Cavy (Galea spixii, Wagler, 1831) Tongue

The tongue is a fundamental organ in feeding, vocalization, and grooming. It is characterized by evolutionary adaptations reflected by diet, habitat, and function. Rodents are a very diverse mammalian order and the tongue's morphology varies in size, form, and presence of papillae. This work aimed to describe the morphological and ultrastructural aspects of the tongue of Spix's yellow-toothed cavy (Galea spixii, Wagler, 1831). Tongues of Spix's yellow-toothed cavies were analyzed with light microscopy, scanning, and transmission electron microscopy. The results showed that the tongue was divided into apex, body, and root. There were different types of papillae, such as vallate, foliate, laterally placed fungiform, fungiform, filiform, and robust filiform. The epithelium was organized into layers, including keratinized, granulous, spinous, and basal, below were lamina propria, and musculature, which evolved mucous and serous gland clusters. The tongue of Spix's yellow-toothed cavy was structurally and ultrastructurally similar to other rodents and had papillae with similar morphologies to other Caviidae species. However, the presence of robust filiform papillary lines and laterally placed fungiform papillae showed the main differences from other species. This was the first description of the tongue of Spix's yellow-toothed cavy.

Morphology and postnatal ontogeny of the cranial endocast and paranasal sinuses of capybara (Hydrochoerus hydrochaeris), the largest living rodent

Recent studies have analyzed and described the endocranial cavities of caviomorph rodents. However, no study has documented the changes in the morphology and relative size of such cavities during ontogeny. Expecting to contribute to the discussion of the endocranial spaces of extinct caviomorphs, we aimed to characterize the cranial endocast morphology and paranasal sinuses of the largest living rodent, Hydrochoerus hydrochaeris, by focusing on its ontogenetic growth patterns. We analyzed 12 specimens of different ontogenetic stages and provided a comparison with other cavioids. Our study demonstrates that the adult cranial endocast of H. hydrochaeris is characterized by olfactory bulbs with an irregular shape, showing an elongated olfactory tract without a clear circular fissure, a marked temporal region that makes the endocast with rhombus outline, and gyrencephaly. Some of these traits change as the brain grows. The cranial pneumatization is present in the frontal and lacrimal bones. We identified two recesses (frontal and lacrimal) and one sinus (frontal). These pneumatic cavities increase their volume as the cranium grows, covering the cranial region of the cranial endocast. The encephalization quotient was calculated for each specimen, demonstrating that it decreases as the individual grows, being much higher in younger specimens than in adults. Our results show that the ontogenetic stage can be a confounding factor when it comes to the general patterns of encephalization of extinct rodents, reinforcing the need for paleobiologists to take the age of the specimens into account in future studies on this subject to avoid age-related biases.

Integrative taxonomy of extant maras supports the recognition of the genera Pediolagus and Dolichotis within the Dolichotinae (Rodentia, Caviidae)

The subfamily Dolichotinae (Rodentia, Caviidae) includes two living species (Dolichotis patagonum and D. salinicola) of cursorial, long-legged rodents that inhabit semiarid thorn scrubs and shrublands in southern South America. Some authors consider that the morphological differences between D. patagonum and D. salinicola warrant circumscription of the latter in its own genus, Pediolagus. Based on a phylogeny and divergence times grounded on molecular data, as well as a qualitative and quantitative assessment of morphological differences, the distinction between Dolichotis and Pediolagus is equal to or greater than differences seen for other intergeneric comparisons within Cavioidea. Based on these results, we argue that the taxonomic designations of Dolichotis and Pediolagus should be retained.

Morphological reassessment and new locality records for Galea comes Thomas, 1919 (Rodentia, Caviidae)

The genus Galea Meyen, 1833 includes at least five species of terrestrial, diurnal and herbivorous cavies that occupy grasslands and rocky scrub areas at both high and low elevations in South America. According to the available molecular and morphological data, Galea comes Thomas, 1919 is restricted to highland areas above 2000 m in southern Bolivia and northwestern Argentina. Its distributional range as well as its morphological distinctiveness from other closely related species (Galea leucoblephara and Galea musteloides) is poorly documented. Using both qualitative and quantitative morphological traits, we provided an emended diagnosis for G. comes. In addition, we added six new locality records to its known distribution.

The mammalian faunas endemic to the Cerrado and the Caatinga

We undertook a comprehensive, critical review of literature concerning the distribution, conservation status, and taxonomy of species of mammals endemic to the Cerrado and the Caatinga, the two largest biomes of the South American Dry-Diagonal. We present species accounts and lists of species, which we built with criteria that, in our opinion, yielded results with increased scientific rigor relative to previously published lists - e.g., excluding nominal taxa whose statuses as species have been claimed only on the basis of unpublished data, incomplete taxonomic work, or weak evidence. For various taxa, we provided arguments regarding species distributions, conservation and taxonomic statuses previously lacking in the literature. Two major findings are worth highlighting. First, we unveil the existence of a group of species endemic to both the Cerrado and the Caatinga (i.e., present in both biomes and absent in all other biomes). From the biogeographic point of view, this group, herein referred to as Caatinga-Cerrado endemics, deserves attention as a unit - just as in case of the Caatinga-only and the Cerrado-only endemics. We present preliminary hypotheses on the origin of these three endemic faunas (Cerrado-only, Caatinga-only, and Caatinga-Cerrado endemics). Secondly, we discovered that a substantial portion of the endemic mammalian faunas of the Caatinga and the Cerrado faces risks of extinction that are unrecognized in the highly influential Red List of Threatened Species published by the International Union for Conservation of Nature (IUCN). "Data deficient" is a category that misrepresents the real risks of extinction of these species considering that (a) some of these species are known only from a handful of specimens collected in a single or a few localities long ago; (b) the Cerrado and the Caatinga have been sufficiently sampled to guarantee collection of additional specimens of these species if they were abundant; (c) natural habitats of the Cerrado and the Caatinga have been substantially altered or lost in recent decades. Failures either in the design of the IUCN criteria or in their application to assign categories of extinction risks represent an additional important threat to these endemic faunas because their real risks of extinctions become hidden. It is imperative to correct this situation, particularly considering that these species are associated to habitats that are experiencing fast transformation into areas for agriculture, at an unbearable cost for biodiversity.

Blood meal sources of wild and domestic Triatoma infestans (Hemiptera: Reduviidae) in Bolivia: connectivity between cycles of transmission of Trypanosoma cruzi

Background

Chagas disease is a major public health problem in Latin America. Its etiologic agent, Trypanosoma cruzi, is mainly transmitted through the contaminated faeces of blood-sucking insects called triatomines. Triatoma infestans is the main vector in various countries in South America and recently, several foci of wild populations of this species have been described in Bolivia and other countries. These wild populations are suspected of affecting the success of insecticide control campaigns being carried out in South America. To assess the risk that these T. infestans populations pose to human health, it is helpful to determine blood meal sources.

Methods

In the present work, blood meals were identified in various Bolivian wild T. infestans populations and in three specific areas, in both wild and intra-peridomestic populations to assess the links between wild and domestic cycles of T. cruzi transmission. PCR-HDA and sequencing of Cytb gene were used to identify these blood meal sources.

Results and discussion

Fourteen vertebrate species were identified as wild blood meal sources. Of those, the most prevalent species were two Andean endemic rodents, Octodontomys gliroides (36 %) and Galea musteloides (30 %), while humans were the third most prevalent source (18.7 %). Of 163 blood meals from peridomestic areas, more than half were chickens, and the others were generally domestic animals or humans. Interestingly, blood from wild animals was identified in triatomines captured in the peridomestic and domestic environment, and blood from domestic animals was found in triatomines captured in the wild, revealing links between wild and domestic cycles of T. cruzi transmission.

Conclusion

The current study suggests that wild T. infestans attack humans in the wild, but is also able to bite humans in domestic settings before going back to its natural environment. These results support the risk to human health posed by wild populations of T. infestans.

Dense sampling provides a reevaluation of the southern geographic distribution of the cavies Galea and Microcavia (Rodentia)

The southern distribution of the small cavies

Description of Karyotype of Kerodon acrobata, an endemic rodent in Brazilian Cerrado

Kerodon acrobata is a caviidae rodent endemic from Brazilian Cerrado. It was described only in 1997 and the data about it is very scarce. The aim of this work was to characterize the karyotype of K. acrobata. Giemsa staining, nucleolar organizer region (NOR) banding, C-positive heterochromatin banding and DAPI fluorescence were used in N metaphases of a specimen collected in Asa Branca Farm, in Aurora do Tocantins municipality, Tocantins state, Brazil. K. acrobata showed the same diploid number, fundamental number and chromosome morphology as Kerodon rupestris. But its NOR location and heterochromatin distribution patterns indicated a unique cytogenetic profile when compared to its sister species, emphasizing the evolutionary uniqueness of this relatively new and unknown species. This record also extends the distribution of this species northward.

The ticks (Acari: Ixodida: Argasidae, Ixodidae) of Bolivia

The tick species reported in Bolivia are reviewed here as (1) endemic or established: Ornithodoros echimys, O. guaporensis, O. hasei, O. kohlsi, O. mimon, O. peropteryx, O. rostratus, Otobius megnini, Amblyomma auricularium, A. cajennense, A. calcaratum, A. coelebs, A. dubitatum, A. humerale, A. incisum, A. longirostre, A. naponense, A. nodosum, A. oblongoguttatum, A. ovale, A. parvitarsum, A. parvum, A. pecarium, A. pseudoconcolor, A. rotundatum, A. scalpturatum, A. tigrinum, A. triste, Dermacentor nitens, Haemaphysalis juxtakochi, H. leporispalustris, I. boliviensis, I. cooleyi, I. luciae, Rhipicephalus microplus, R. sanguineus, and (2) erroneously reported: Ornithodoros puertoricensis, O. talaje, O. turicata, Amblyomma americanum, A. maculatum, A. multipunctum, Ixodes ricinus, I. scapularis, Rhipicephalus annulatus. Many of these records are lacking locality and/or host, and some of them need new findings for confirmation. Some of the species recorded may represent a threat for human and animal health, therefore would be of great value to make a countrywide survey of ticks in order to update the information presented in this work.

Major radiations in the evolution of Caviid rodents: reconciling fossils, ghost lineages, and relaxed molecular clocks

BACKGROUND

Caviidae is a diverse group of caviomorph rodents that is broadly distributed in South America and is divided into three highly divergent extant lineages: Caviinae (cavies), Dolichotinae (maras), and Hydrochoerinae (capybaras). The fossil record of Caviidae is only abundant and diverse since the late Miocene. Caviids belongs to Cavioidea sensu stricto (Cavioidea s.s.) that also includes a diverse assemblage of extinct taxa recorded from the late Oligocene to the middle Miocene of South America ("eocardiids").

RESULTS

A phylogenetic analysis combining morphological and molecular data is presented here, evaluating the time of diversification of selected nodes based on the calibration of phylogenetic trees with fossil taxa and the use of relaxed molecular clocks. This analysis reveals three major phases of diversification in the evolutionary history of Cavioidea s.s. The first two phases involve two successive radiations of extinct lineages that occurred during the late Oligocene and the early Miocene. The third phase consists of the diversification of Caviidae. The initial split of caviids is dated as middle Miocene by the fossil record. This date falls within the 95% higher probability distribution estimated by the relaxed Bayesian molecular clock, although the mean age estimate ages are 3.5 to 7 Myr older. The initial split of caviids is followed by an obscure period of poor fossil record (referred here as the Mayoan gap) and then by the appearance of highly differentiated modern lineages of caviids, which evidentially occurred at the late Miocene as indicated by both the fossil record and molecular clock estimates.

CONCLUSIONS

The integrated approach used here allowed us identifying the agreements and discrepancies of the fossil record and molecular clock estimates on the timing of the major events in cavioid evolution, revealing evolutionary patterns that would not have been possible to gather using only molecular or paleontological data alone.

Combination of cytochrome b heteroduplex-assay and sequencing for identification of triatomine blood meals

The identification of blood meals in vectors contributes greatly to the understanding of interactions between vectors, microorganisms and hosts. The aim of the current work was to complement the validation of cytochrome b (Cytb) heteroduplex assay (HDA) previously described, and to add the sequencing of the Cytb gene of some samples for the identification of blood meals in triatomines. Experimental feedings of reared triatomines helped to clarify the sensitivity of the HDA. Moreover, the sequencing coupled with the HDA, allowed the assessment of the technique's taxonomic level of discrimination. The primers used to produce DNA fragments of Cytb genes for HDA had a very high sensitivity for vertebrate DNAs, rather similar for mammals, birds and reptiles. However, the formation of heteroduplex depended on blood meal's quality rather than its quantity; a correlation was observed between blood meals' color and the positivity of HDA. HDA electrophoresis profiles were reproducible, and allowed the discrimination of blood origins at the species level. However, in some cases, intraspecific variability of Cytb gene generated different HDA profiles. The HDA based on comparison of electrophoresis profiles is a very useful tool for screening large samples to determine blood origins; the subsequent sequencing of PCR products of Cytb corresponding to different HDA profiles allowed the identification of species whatever the biotope in which the vectors were captured.