Zaedyus Research Articles

Effect of conifer afforestation on the occurrence and food availability for Zaedyus pichiy (Xenarthra: Chlamyphoridae) in the north-western Patagonian steppe of Argentina

Abstract The grasslands and shrub areas of the Patagonian steppe are the most frequent habitat for the “Near Threatened” armadillo, known as pichi (Zaedyus pichiy). Dense exotic conifer plantations are replacing the steppe in Argentinean northern Patagonia. This study aimed to evaluate the effect of conifer afforestation on the occurrence and food availability in a Z. pichiy population in north-western Patagonia. Fifteen sites in the native steppe and 50 in exotic pine plantations were sampled. We recorded the number of signs of pichi’s presence and the diversity of invertebrates. Signs of Z. pichiy presence decreased in pine afforestation compared to the native steppe. Additionally, we found a decrease in the abundance, richness, diversity, and biomass of arthropods in pine plantations. Therefore, the presence of pine plantations in the steppe reduces the main food items of Z. pichiy and also eliminates the native steppe vegetation structure that provides preferred places to dig burrows. Pine monocultures do not provide a suitable habitat for Z. pichiy and may exacerbate the degradation of an already disturbed environment.

Non-ingested vertebrate prey remains accumulated by the Chaco eagle (Buteogallus coronatus): neo-taphonomy to evaluate open-air faunal records in central western Argentina

The Chaco eagle (Buteogallus coronatus) is a large, endangered, and little-known bird of prey distributed throughout southern South America. This bird of prey accumulates large amounts of prey remains around its nests in open landscapes. To present a reliable pattern to distinguish the action of the Chaco Eagle as a potential accumulator of faunal remains in open-air archaeological contexts, we conducted a neo-taphonomic study in an area of the eastern plains of the CWA, analyzing modern remains accumulated around a nest of the Chaco eagle. Our taxonomic analysis allowed us to identify the presence of different taxa belonging to two classes: mammals and reptiles. Most of the specimens identified were non-ingested remains. The armadillo Zaedyus pichiy was the most conspicuous prey species, represented by osteoderms and skulls. We registered several endoskeletal remains and osteoderms of the Chaco tortoise (Chelonoidis chilensis), as well as bone and tooth remains of two little-known and reported species in the study area: the red tegu (Salvator rufescens) and the Patagonian weasel (Lyncodon patagonicus). In addition, we found remains corresponding to two species of small-sized rodents. We also discovered strongly digested vertebrae of an indeterminate small Ophidia preserved in the only recovered pellet. The proportion of weathering was high, with stages 1 and 2 identified as the most dominant degrees. Notably, specimens with two stages of weathering were detected based on the side grounded to the floor. The proportions of breakage, on the other hand, were low. We hope this work contributes to the distinction of accumulating agents in the region's archaeological sites, especially considering the high importance that armadillos have had for the past human populations of the area.

Zaedyus pichiy (Desmarest, 1804) is part of the collections of the Šariš Museum in Bardejov (Slovakia)

Abstract In this study are presented data of individuals belonging to armadillos (Cingulata, Chlamyphoridae, Zaedyus) from unknow locality of South America (probably from the Chubut region of Argentina). Totally, three voucher specimens and two skulls are in the SMB collection. Specimens presented in this study highlighted the importance of SMB’s collection.

High Trypanosoma cruzi prevalence in armadillo (Zaedyus pichiy; Xenarthra: Chlamyphoridae) populations from Mendoza, Argentina.

Armadillos are considered important reservoir hosts for Trypanosoma cruzi, the causative agent of Chagas disease. The first report of T. cruzi infection in pichis (Zaedyus pichiy), a small armadillo species endemic to central Argentina and Chile, dates back to 1935. However, more recent reports on T. cruzi in this species are scarce. The objective of this study was to assess T. cruzi infection and parasite load in Z. pichiy from Mendoza Province, an area endemic to human Chagas disease. Blood samples were obtained in 2014-2016 from pichis from Lavalle (low Monte), Malargüe (Patagonian steppe), and San Carlos (ecotone) departments, Mendoza Province, Argentina. The detection and quantification of T. cruzi was performed through qPCR amplification using satellite primers. Of the 265 analyzed samples, 201 (76%) were positive for T. cruzi. Parasite loads varied between < 0.1-55.8 parasite-equivalents/mL (par-eq/mL), with a median of 1.1 par-eq/mL in quantifiable samples. The prevalence was similar in Malargüe and Lavalle (85-94%), but significantly lower in pichis from San Carlos (50%). Animals from Lavalle captured after hibernation had significantly higher parasite loads (median 2.0 par-eq/mL). In Malargüe, T. cruzi infection and parasite loads were significantly lower before than after hibernation in 2016. The high prevalence and low median parasite load suggest a chronic and persistent infection of T. cruzi in pichis. Regional differences and a marked increase in precipitation during 2015-2016 could have influenced annual and seasonal infection rates of this vector-borne disease.

Trypanosoma cruzi Survey in Poached Pichis (Zaedyus pichiy; Mammalia, Cingulata) from Mendoza, Argentina.

The transmission cycles of Trypanosoma cruzi, the causative agent of Chagas disease, include a wide variety of mammals and hematophagous triatomine insects. Infection with this blood parasite has been confirmed in many armadillo species; however, information on infection in Zaedyus pichiy, a small armadillo that inhabits areas endemic to Chagas disease, is scarce. Our objective was to determine the infection frequency and parasite load of T. cruzi in 49 wild Z. pichiy confiscated dead from poachers in Mendoza, Argentina, 2010-2017. We detected T. cruzi DNA in 32 of 49 armadillos (65%) using real-time PCR, confirming infection with T. cruzi in a high proportion of confiscated pichis. No differences were found related to sex, age, or ecoregion origin of the assessed pichis. Parasite loads ranged between <0.1 and 8.88 parasite equivalents/microgram cardiac tissue. Additional studies on the infection status of Z. pichiy are needed to determine their role in the maintenance of the sylvatic transmission cycle and the potential zoonotic risk from hunted pichis.

NEOICHNOLOGY OF ARMADILLOS: KEYS FOR THE PALEOECOLOGICAL AND BEHAVIORAL INTERPRETATION OF FOSSIL TETRAPOD BURROWS

ABSTRACTThis study is based on the analysis of burrow casts of three species of armadillos from central Argentina: Chaetophractus villosus, Chaetophractus vellerosus, and Zaedyus pichiy (Chlamyphoridae: Euphractinae). The aim of this work was to identify key ichnologic signatures of Euphractinae armadillo burrows for application to the paleoecological and behavioral interpretation of fossil examples. A total of 15 active burrows from different biogeographic provinces were casted with polyurethane foam and then excavated. About two hundred uncasted burrows and foraging pits were also measured at the same localities. Euphractinae burrows are clearly distinguished from Chlamyphorinae burrows by its filling, surface ornamentation, and size. It is suggested that fossil armadillo (Euphractinae) burrows would be characterized by a single ramp with one entrance and massive or laminated fill, horizontal diameter larger than 100 mm, strongly marked sets of three claw traces that are arranged oblique to the ramp axis, and absence of feces or plant remains. The distinctive surface ornamentation present in the casted burrows is tentatively linked to a particular excavation mechanism involving rotation of the body along the antero-posterior axis. Burrow systems with a chamber are interpreted as permanent burrows, whereas those lacking chamber are considered as temporary/shelter burrows. Armadillo burrow systems (either temporary or permanent) are longer, less inclined, and have lower relative diameter indices (RDI) than armadillo foraging pits. Euphractinae burrows are linked to producers with solitary, fossorial, opportunistic omnivorous habits that excavate several burrows during their lives. They are left open after abandonment, and preferably located in xeric shrub lands and grasslands. The described morphological features of the burrows systems can be useful for the interpretation of fossil (post-Eocene) burrows.

Neo-taphonomy of prey bones ingested by pumas in central western Argentina

Pumas are American top predators that commonly frequent places that may also be inhabited by humans. With the aim of contributing to the evaluation of the accumulating processes and agents of vertebrate remains of archaeological and paleontological sites, we analyzed a modern puma scat-derived vertebrate bone assemblage from an area of the central Monte Desert, one of the most arid regions of South America. We evaluated the taphonomic signature of vertebrate remains recovered in such scats without discriminating among the different types of fauna, which strengthens this taphonomic contribution. Despite the high availability of domestic and exotic fauna from livestock fields in the surroundings of the area, the assemblage was dominated by typical native small and medium-sized fauna from xeric environments of the Monte biome. The armadillo Zaedyus pichiy was the most frequent taxon, followed by the caviid rodents Microcavia maenas and Galea leucoblephara, and the Tinamidae Eudromia elegans. The most remarkable taphonomic signatures are high breakage; a high proportion and degree of elements with evidence of digestion; and a low number of tooth marks. We find a good proportion of identifiable specimens, considering the previous assumptions on the extreme destruction of felid scat-derived vertebrate bone assemblages. A first assessment was made of specimens little known from a regional taphonomic perspective, such as armadillo osteoderms or bird remains. The taphonomic analysis of this multi-taxa accumulation enables a solid evaluation of vertebrate bone assemblages from archaeological and paleontological sites.

Fleas and ticks in armadillos from Argentinean Patagonia: Diversity, abundance and distribution

In Argentina, quantitative information on the composition and structure of assemblages of arthropod parasites in Xenarthra is scarce. The aim of this study was to describe and compare the community of arthropod parasites of Chaetophractus villosus and Zaedyus pichiy in the Argentinean Patagonia. A total of 1300 ectoparasites (1224 fleas and 76 ticks) were collected from both host species. Seven different species were found, namely Phthiropsylla agenoris, Malacopsylla grossiventris, Hectopsylla broscus, Tunga penetrans, Tunga perforans (Siphonaptera), Amblyomma pseudoconcolor and Amblyomma auricularium s.l. (Ixodida). Four species were present in both host armadillos (P. agenoris, M. grossiventris, H. broscus and A. pseudoconcolor). Phthiropsylla agenoris was the most prevalent and abundant ectoparasite showing significant differences in prevalences, mean intensities and mean abundance. Malacopsylla grossiventris only showed significant differences in mean intensity. The structure and composition of the ectoparasite assemblage and the high values of ectoparasites aggregation recorded in the Patagonian armadillos strongly suggest that these associations are stable throughout their geographical distribution.

New records of fleas and ticks in armadillos (Xenarthra: Chlamyphoridae) br /from the Espinal and Monte ecoregions of La Pampa province, Argentina.

La Pampa province is divided into two clearly distinguishable fractions: a small northeastern humid sector corresponding to the Pampas ecoregion and a drier western sector, represented by the Monte de Llanuras y Mesetas (termed Monte region in this paper) and Espinal ecoregions (sensu Brown et al. 2006). These three ecoregions are visibly distinguishable from an edaphological and phytogeographic point of view, while the mammalian fauna composition is homogeneous. The study area was located in the central part of the province, comprising the Monte and Espinal ecoregions (Fig. 1). In that area three species of armadillos are recorded (Soibelzon et al. 2015). Two of these (Zaedyus pichiy Desmarest, 1804 and Chaetophractus villosus Desmarest, 1804) (Xenarthra: Chlamyphoridae) are the most common and widely distributed armadillos both in the province and in the country, while the third species, Chlamyphorus truncatus Harlan, 1825, has a more restricted distribution and is one of the most cryptic and least known armadillos in the country. For this reason, in our fieldwork ectoparasites were obtained only from the first two species mentioned.

Helminth-fauna of Patagonian armadillos: comparative analysis of parasites geographical variation.

The similarity between parasites communities' decay with distance and its analysis may explain important ecological process such host dispersion. Patagonia is inhabited by two armadillo species, Chaetophractus villosus and Zaedyus pichiy. In this study we describe and analyze the variation on helminth fauna of these armadillos in Patagonia compared with northern localities described in previous studies. A total of 49 armadillos were collected in Patagonia. Quantitative descriptors of parasite ecology were calculated and community structure of helminths was analyzed following the central-satellite species hypothesis. The parasite richness in Patagonia decreases almost 50% in both armadillos. Zaedyus pichiy present the same central species in Patagonia as in northern localities. For C. villosus central-satellite species analysis could not be applied. The loss of some helminths in Z. pichiy could be the result of lower temperatures or the absence of intermediate arthropods hosts. But in C. villosus the absence of some helminths with Patagonian distribution could be explained by its recent dispersion in Patagonia. Trichohelix tuberculata still being the only helminth in C. villosus introduced population of Tierra del Fuego.

Carrying offspring: An unknown behavior of armadillos

Los armadillos son los únicos mamíferos que poseen regiones acorazadas que protegen su cabeza, cuerpo y cola. Se distribuyen exclusivamente en América. La reproducción es estacional y ocurre entre el fin del invierno y durante toda la primavera y verano del hemisferio sur (septiembre a marzo). Durante la época reproductiva es común que dos a cuatro machos persigan una hembra e intenten copular con ella, luego de esto la hembra es la que se encarga de cuidar a las crías. El conocimiento sobre cuidados parentales en armadillos es prácticamente nulo. En esta contribución se describe por primera vez, a través de registros fotográficos y de video, el acarreo de crías por parte de adultos de Chaetophractus villosus y Zaedyus pichiy en diferentes regiones de Argentina y Chile, obtenidas mayormente a través de ciencia ciudadana. En todos los casos las crías fueron tomadas con la boca del adulto y del brazo derecho o izquierdo (húmero) o del borde del escudo pectoral. El hecho de que estos casos se encuentran separados temporal y geográficamente, sumado a que ha sido observado en diferentes especies, permite suponer que se trata de un comportamiento reproductivo usual en armadillos. Finalmente, es importante realzar la importancia de la ciencia ciudadana como base para la obtención de información biológica, especialmente sobre especies raras o sobre comportamientos desconocidos.

Forelimb myology of armadillos (Xenarthra: Cingulata, Chlamyphoridae): Anatomical correlates with fossorial ability.

Descriptions of myology reflect adaptations of the post-cranium and are essential for understanding the functional morphology of animal limbs. Armadillos (Cingulata) are the most species-rich group of the basal superorder Xenarthra, which is evident by their various lifestyles (subterranean vs. terrestrial) and levels of fossoriality (fossorial vs. semi-fossorial). While there have been several studies on limb bone proportions in numerous armadillos, limb myology has been reported for a limited number of species. Many of these descriptions need updating, and detailed quantitative muscle data are available only for nine-banded armadillos. The main objective of this study is to assess the forelimb myology of the pichi (Zaedyus pichiy), screaming hairy (Chaetophractus vellerosus), large hairy (Chaetophractus villosus), and pink fairy (Chlamyphorus truncatus) armadillos with comparisons to previous observations to specify muscle traits that indicate scratch-digging specializations in cingulates. Several myological features are variable among the species studied, including the origin of m. trapezius pars cervicalis, presence of a distinct m. rhomboideus profundus and m. omotransversarius, and number of heads present for m. triceps brachii and m. flexor digitorum profundus, all of which can be associated with variability in their respective habitats and functional habits. These traits are consistently observed in the members of the Euphractinae, whereas they are slightly divergent (i.e., reduced complexity) in the pink fairy armadillo despite a similar distribution of muscle mass in the limb retractors, elbow extensors, and carpal/digital flexors across species. The ecomorphology observed here among cingulates also confirms their recent reorganization into separate families and subfamilies.

A new pygmy armadillo (Cingulata, Euphractinae) from the late Miocene of Andean Argentina reveals an unexpected evolutionary history of the singular Prozaedyus lineage

The extinct euphractine Prozaedyus was recognized remarking the evident morphological resemblance of the dorsal carapace with the extant piche or pygmy armadillo Zaedyus pichiy. From a phylogenetic viewpoint, Prozaedyus has been interpreted as an early diverging Euphractinae restricted, at the moment, to the late Oligocene and early mid Miocene levels (Deseadan to Laventan SALMAs) of southern South America (Argentina, Chile, and Bolivia). We report here a specimen (MSJ-317) coming from the late Miocene (Loma de Las Tapias Formation; ~9 Ma, Chasicoan Stage/Age) of western Argentina (San Juan Province), which represents a new species of Prozaedyus. The specimen includes an almost complete skull with complete dental series, some articulated fragments of the dorsal carapace and several isolated fixed and mobile osteoderms. Absence of teeth in the premaxillae, ornamentation pattern of fixed osteoderms, and presence of small foramina in the posterior and lateral margins of both mobile and fixed osteoderms, are characters that allow its inclusion within the genus Prozaedyus. Differences with the other known species of this genus include smaller size (~35–40%), cranial characters (e.g. position of the infraorbital foramen, palatine suture, morphology of the occipital condyles), and ornamentation pattern of mobile osteoderms. The phylogenetic analysis carried out support its relation as a sister group of the other Prozaedyus species, revealing an ancient divergence for the new taxon, occurred before that of the late Oligocene-early mid Miocene forms, and a distant phylogenetic position from Zaedyus pichiy. This new finding represents the youngest record of the genus, extending its biochron several millions of years, and provides novel information on the poorly know post-Santacrucian forms. Additionally, the cranial anatomy of the new species suggests a carnivore/omnivore habit, similar to extant euphractine armadillos but contrary to the insectivore habit proposed for the other Prozaedyus species.

Effect of host and environment-related factors on fleas of the pichi, an armadillo from Argentina.

The pichi (Zaedyus pichiy; Cingulata: Chlamyphoridae) is an armadillo whose ectoparasite fauna is composed of ticks and fleas. Fleas were collected from 218 pichis in southern Mendoza, Argentina, in summer and winter of 2015 and 2016. Prevalences were analyzed and differences in the intensities of the total number of fleas related to host (age, sex, weight, size and physical condition) and environment-related (seasonality and year) factors evaluated. Phthiropsylla agenoris was the only species found. Intensities of fleas were higher in 2015, in juveniles, and in males. Individuals with poor physical condition were more parasitized than those with good or normal body condition. The main explanatory variable was sampling year. This factor was directly associated with precipitation. The extreme conditions and heavy rains during the El Niño event in 2015/2016 led to environmental changes that seem to have severely affected the life cycle of fleas.

Aboveground activity, reproduction, body temperature and weight of armadillos (Xenarthra, Chlamyphoridae) according to atmospheric conditions in the central Monte (Argentina)

Hairy armadillos are generalist species widely distributed in South America. Three of these species, Chaetophractus vellerosus, C. villosus and Zaedyus pichiy, are sympatric in the arid central Monte. The objective of this study is to make a contribution to current knowledge about these species, the ecological interactions among them and their responses to arid environments. Aboveground activity, rectal temperature, body weight and reproductive status were measured in wild populations. The influence of seasonal and daily atmospheric conditions were estimated through generalized linear models. Seasonality affected the Z. pichiy reproduction cycle, body weight and aboveground frequency of occurrence. There was a higher frequency of animals with low body weight in late winter and spring, mostly breeding animals. Armadillos regained body weight in autumn, but their aboveground frequency decreased. Females showed higher weight variability than males in autumn. Daily atmospheric temperature proved to be the most relevant weather condition for Z. pichiy, with a positive influence on aboveground activities and body temperature. This species had the broadest range of body temperature, without relation to body weight. Typical dry and clear days of the central Monte were favorable conditions for Z. pichiy activity. Its diurnal activity had a higher probability of occurrence at twilight, and nocturnal activity occurred during summer. Presence of C. vellerosus was positively influenced by atmospheric temperature, whereas presence of C. villosus was not influenced by any weather condition. Differences in the use of solar radiation could represent a partial temporal segregation, promoting the coexistence of these sympatric species.

A New Rictulariid (Nematoda: Spirurida) in Xenarthrans from Argentina and New Morphological Data of Pterygodermatites ( Paucipectines) Chaetophracti.

Pterygodermatites is a cosmopolitan genus of nematodes from mammals, and it is frequently encountered in the parasite fauna of armadillos (Mammalia, Xenarthra, Cingulata). In this work, a new species, Pterygodermatites ( Paucipectines) argentinensis, is described, and new morphometric data, new host records, and the geographical distribution of Pterygodermatites ( Paucipectines) chaetophracti are provided. We examined 109 hosts belonging to Chaetophractus vellerosus, Chaetophractus villosus, Cabassous chacoensis, Dasypus hybridus, Tolypeutes matacus, and Zaedyus pichiy, from several regions of Argentina. Pterygodermatites ( Paucipectines) argentinensis can be distinguished from P. ( P.) chaetophracti by the morphology and size of esophageal teeth of both sexes, by subequal and longer spicules, by having only 1 precloacal cuticular semicircular fan in males, and by a greater number of cuticular processes in females. Cabassous chacoensis and Zaedyus pichiy are new hosts for Pterygodermatites ( P.) chaetophracti.

Hábitos alimenticios de poblaciones periféricas de Zaedyus pichiy y Chaetophractus villosus (Cingulata, Chlamyphoridae) en la Patagonia chilena

RESUMEN En Chile los armadillos Zaedyus pichiy (Desmarest, 1804) y Chaetophractus villosus (Desmarest, 1804) tienen poblaciones periféricas restringidas a planicies de altura y estepa patagónica en la vertiente occidental de la Cordillera de los Andes, donde además han sido escasamente estudiadas. En este trabajo entregamos información sobre los hábitos alimenticios de ambas especies de armadillos, obtenida mediante el análisis de heces colectadas en dos áreas de la región de Aysén, Patagonia chilena. En 38 heces de Z. pichiy identificamos dos taxones de plantas, seis de invertebrados y cuatro de vertebrados, mientras que en 72 heces C. villosus identificamos tres, nueve y cuatro taxones de las mismas categorías. En ambas especies de armadillos los invertebrados fueron la categoría más diversa y con mayor frecuencia de ocurrencia, siendo Coleoptera, Orthoptera y Hemiptera los grupos mejor representados en términos de abundancia. Entre los vertebrados se observó mayor frecuencia de restos del camélido Lama guanicoe (Müller, 1776) y el lagomorfo Lepus europaeus (Pallas, 1778). El análisis de rarefacción muestra que la riqueza de taxones fue mayor en C. villosus que en Z. pichiy, y el índice de Pianka indica que no existió un solapamiento trófico significativo entre especies de armadillos. Nuestras observaciones indican que poblaciones periféricas de ambas especies de armadillos muestran dietas omnívoras oportunistas, con un mayor consumo de invertebrados y plantas; además, sugieren que C. villosus se desarrolla en un rango ambiental más amplio, con una dieta más diversa y mayor presencia de esta especie en ambas áreas de estudio.

Effects of climatic oscillations on the faunas. The Holocene Thermal Maximum and the displacement of armadillos in Argentina: Anatomical features and conservation

The Dasypodidae (commonly known as armadillos) are exclusively from the Americas and have a long evolutionary history on the continents. They were frequently consumed by hunter-gatherers in the past and they are consumed by native people in the modern age along their distributional area. Both paleontological and archaeological records show that they inhabited areas in which they do not inhabit in the present-day. The study conducted on faunal remains at the Alfar site (southeast Buenos Aires Province, Argentina) allowed the determination of two different species (Zaedyus pichiy and Tolypeutes matacus) based on the ornamentation of the osteoderms that compose the animal's carapace. Radiocarbon dating of Unit II (fossil bearing level, 5700yBP) locates the human exploitation during a warm and arid climate period known as the Holocene Thermal Maximum. The armadillos found at Alfar site are absent in the area nowadays. Instead, they are distributed in arid/semiarid environments of the Patagonia and Central regions of Argentina, where the association is characteristic of the Monte ecoregion, 1000km northwest far from Alfar site. The results here presented serve to support the hypothesis of the Dasypodidae as paleoenvironmental proxies and also to confirm the importance of paleozoology studies to apply in conservation biology.

Environmental factors affecting the distribution of three armadillo species (Xenarthra, Dasypodidae) in Argentina

Abstract Environmental temperature, rainfall, vegetation structure, soil composition and land use were recognized as relevant factors limiting the distribution of armadillos. The aim of this study was to identify environmental and spatial factors influencing the geographical distribution of the most widespread armadillos occurring in Argentina (Chaetophractus vellerosus, Chaetophractus villosus and Zaedyus pichiy), through the most simple and accurate explanatory modeling. General linear models (GLMs), partitioning analyses of variance and hierarchical partitioning analyses were applied to estimate the species-environment relationships. Climatic variables were recognized as the most relevant factors influencing the three species distribution, consistent with that expected from the hierarchical structure theory in ecological systems. Optimal conditions were mainly arranged in a longitudinal geographic gradient for Chaetophractus species and in a latitudinal-longitudinal gradient for Z. pichiy. The optimal habitat identified for C. vellerosus, larger than previously documented, was characterized by warm, rainy summers and moderately cold, dry winters. The distribution of C. villosus was mainly influenced by temperate conditions of temperature and isothermality, scarcity of rainfall with high seasonality and low aridity conditions, and prevalence of sandy soils. Optimal habitat of Z. pichiy was affected by low temperatures with high seasonality, scarcity of rainfall with aridity conditions and sandy soils.

Comparative histology and ontogenetic change in the carapace of armadillos (Mammalia: Dasypodidae)

Among extant mammals, the presence of osteoderms is limited to armadillos (Xenarthra, Dasypodidae), being one of its distinctive features. The osteoderms are articulated to form a carapace that covers their body dorsally. In this paper we study the integumentary structures of the armadillos Chaetophractus vellerosus, Chaetophractus villosus, Euphractus sexcinctus, and Zaedyus pichiy (Euphractinae), Dasypus hybridus, and Dasypus novemcinctus (Dasypodinae) within a comparative framework, aiming to identify patterns common to the family and to the subfamilies Dasypodinae and Euphractinae, as well as peculiarities of each species. Differences between the two subfamilies were observed in the dorsal integument, related to the production of blood cells and the mobility of the carapace. The Euphractinae present more numerous and larger cavities filled with adipose tissue in the osteoderms, as well as more marginal follicles than the Dasypodinae. These provide thermal insulation that could be related to their distribution in cooler climates. The sebaceous glands associated with surface follicles are also more developed in the Euphractinae and could be related to preventing the desiccation of the cornified scales in arid climates.