Mariella Superina

Molecular phylogenetics unveils the ancient evolutionary origins of the enigmatic fairy armadillos.

Fairy armadillos or pichiciegos (Xenarthra, Dasypodidae) are among the most elusive mammals. Due to their subterranean and nocturnal lifestyle, their basic biology and evolutionary history remain virtually unknown. Two distinct species with allopatric distributions are recognized: Chlamyphorus truncatus is restricted to central Argentina, while Calyptophractus retusus occurs in the Gran Chaco of Argentina, Paraguay, and Bolivia. To test their monophyly and resolve their phylogenetic affinities within armadillos, we obtained sequence data from modern and museum specimens for two mitochondrial genes (12S RNA [MT-RNR1] and NADH dehydrogenase 1 [MT-ND1]) and two nuclear exons (breast cancer 1 early onset exon 11 [BRCA1] and von Willebrand factor exon 28 [VWF]). Phylogenetic analyses provided a reference phylogeny and timescale for living xenarthran genera. Our results reveal monophyletic pichiciegos as members of a major armadillo subfamily (Chlamyphorinae). Their strictly fossorial lifestyle probably evolved as a response to the Oligocene aridification that occurred in South America after their divergence from Tolypeutinae around 32 million years ago (Mya). The ancient divergence date (∼17Mya) for separation between the two species supports their taxonomic classification into distinct genera. The synchronicity with Middle Miocene marine incursions along the Paraná river basin suggests a vicariant origin for pichiciegos by the disruption of their ancestral range. Their phylogenetic distinctiveness and rarity in the wild argue in favor of high conservation priority.

The 2009/2010 Armadillo Red List Assessment

Abstract The conservation status of the 21 extant armadillo species was re-assessed by specialists of the IUCN/SSC Anteater, Sloth and Armadillo Specialist Group between December 2009 and May 2010. Information on their geographic range, population size and status, habitat and ecology, threats, and existing conservation measures was collected from the literature and personal communications. Four armadillo species were classified as Vulnerable, four as Near Threatened, and four were categorized as Data Deficient. Less than half of all armadillo species were listed as Least Concern. Virtually all assessed species are affected by hunting as well as habitat fragmentation and degradation. The populations of only two species are thought to be increasing, while those of at least seven species are in decline. Much work is still needed to ensure the long-term survival of all species. Most armadillo species occur in at least one protected area, but other conservation actions are scarce.

Shotgun Mitogenomics Provides a Reference Phylogenetic Framework and Timescale for Living Xenarthrans

Xenarthra (armadillos, sloths, and anteaters) constitutes one of the four major clades of placental mammals. Despite their phylogenetic distinctiveness in mammals, a reference phylogeny is still lacking for the 31 described species. Here we used Illumina shotgun sequencing to assemble 33 new complete mitochondrial genomes, establishing Xenarthra as the first major placental clade to be fully sequenced at the species level for mitogenomes. The resulting data set allowed the reconstruction of a robust phylogenetic framework and timescale that are consistent with previous studies conducted at the genus level using nuclear genes. Incorporating the full species diversity of extant xenarthrans points to a number of inconsistencies in xenarthran systematics and species definition. We propose to split armadillos into two distinct families Dasypodidae (dasypodines) and Chlamyphoridae (euphractines, chlamyphorines, and tolypeutines) to better reflect their ancient divergence, estimated around 42 Ma. Species delimitation within long-nosed armadillos (genus Dasypus) appeared more complex than anticipated, with the discovery of a divergent lineage in French Guiana. Diversification analyses showed Xenarthra to be an ancient clade with a constant diversification rate through time with a species turnover driven by high but constant extinction. We also detected a significant negative correlation between speciation rate and past temperature fluctuations with an increase in speciation rate corresponding to the general cooling observed during the last 15 My. Biogeographic reconstructions identified the tropical rainforest biome of Amazonia and the Guiana Shield as the cradle of xenarthran evolutionary history with subsequent dispersions into more open and dry habitats.

The 2010 Anteater Red List Assessment

Abstract The IUCN/SSC Anteater, Sloth and Armadillo Specialist Group re-assessed the conservation status of the four extant anteater species in May 2010. Three species maintained their Least Concern status. Myrmecophaga tridactyla was listed as Vulnerable due to an estimated reduction in population size of at least 30%. The isolated population of Cyclopes didactylus that inhabits the Atlantic forest of coastal northeastern Brazil was assessed separately for the first time due to its separation from the main population by over 1000 km. Although its habitat has been severely reduced, it was classified as Data Deficient due to the lack of scientific data. The main threats to the long-term survival of anteaters is habitat degradation and fragmentation, wildfires, traffic accidents, hunting, and their capture for illegal trade and maintenance as pets. Education programs are in place for three species. Basic questions on the taxonomy, population dynamics, life history, and how hunting and extraction of wild individuals affects anteater populations still remain unresolved.

Characterization of seasonal reproduction patterns in female pichis Zaedyus pichiy (Xenarthra: Dasypodidae) estimated by fecal sex steroid metabolites and ovarian histology

Reproductive strategies vary considerably among species, but most studies have focused on a very limited number of mammalian species. Knowledge of the reproductive cycle and behavior is essential for developing and implementing in situ and ex situ conservation strategies for threatened and endangered species. This study aimed at characterizing the seasonal reproductive pattern of female pichis Zaedyus pichiy, a threatened small armadillo native to arid regions of Argentina and Chile, through direct observations, histological studies, and by measuring fecal immunoreactive estrogens, progestagens and glucocorticoids in 10 wild-born, captive pichis and in free-ranging individuals. Results suggest that pichis are seasonal breeders that give birth to one yearly litter of 1-2 offspring, which do not leave the burrow until they are weaned at approximately 37 days. Ovarian follicular growth seems to occur throughout the year. Fecal progestagen, estrogen and glucocorticoid concentrations were minimal during the first half of pregnancy, increased to peak concentrations of up to 3500, 200 and 200ng/g dry feces, respectively, and decreased before parturition. Postpartum progestagen concentrations were greater in lactating females than females that aborted or did not raise their offspring (p<0.0001), which is probably related to an elevated corticosteroid synthesis that contributes to maintain lactation, given that fecal glucocorticoid concentrations were of similar pattern. Observations of a second pregnancy after late abortion or death of the newborn litter and sustained follicular growth during pregnancy and lactation suggest that female pichis can become receptive briefly after having lost their litter. Fecal estrogen and progestagen concentrations of non-pregnant, non-lactating females did not have a well-defined hormonal cyclic pattern, and corpora lutea were only observed in pregnant females.

Life on the Half-Shell: Consequences of a Carapace in the Evolution of Armadillos (Xenarthra: Cingulata)

Without doubt, the possession of an armored carapace represents one of the most conspicuous morphological features of all cingulates. Here, we review some of the many ways in which the carapace may have influenced the evolution of other features of extant armadillos (Xenarthra: Cingulata). Effects range from physiological impacts on respiration and thermoregulation, to mechanical and other constraints on reproduction. Additionally, in mammals, armor has been linked with relatively slow plantigrade locomotion, which in turn may have promoted the low metabolic rate and exploitation of a low quality diet typically observed in armadillos. Finally, this network of relationships may help to explain the lack of any obvious kin-selected altruism in the polyembryonic armadillos, such as the nine-banded armadillo (Dasypus novemcinctus), because of time and energy constraints associated with a short active period devoted almost exclusively to feeding. In mammals, there has been growing interest in describing an ecological “lifestyle” as the particular way in which each species makes its living, and how this lifestyle constrains the evolution of other phenotypic traits. Based on our review, it appears the carapace has been a major determinant of the lifestyle of armadillos and has played a central role in shaping the evolution of many other features of these animals.

Systematics of hairy armadillos and the taxonomic status of the Andean hairy armadillo (Chaetophractus nationi)

Hairy armadillos constitute an ecologically homogeneous and morphologically similar group with currently 5 species classified in the subfamily Euphractinae. Among them, the Andean hairy armadillo Chaetophractus nationi (Xenarthra, Cingulata, Dasypodidae) is a small, endangered armadillo that has long been suspected to represent a high-altitude variant of Chaetophractus vellerosus. Here, we report the 1st phylogenetic systematics assessment of hairy armadillos using morphological and molecular analyses of all described species with focus on the status of the Andean hairy armadillo. Multivariate analyses of shape variation based on 3-dimensional landmark coordinates of skulls allowed a clear differentiation of each species with the exception of C. vellerosus and C. nationi, within which only a latitudinal and/or altitudinal gradient in size was apparent. Moreover, analyses of mitochondrial DNA control region (D-loop) revealed a single C. nationi haplotype that appeared to be identical with a C. vellerosus haplotype from Argentina. Identical sequences in C. vellerosus and C. nationi were also observed for 3 of the 5 non-coding nuclear markers investigated. Based on these data, we propose that C. nationi should be considered as a synonym of C. vellerosus. However, this taxonomic change should not preclude the protection of the high-altitude Bolivian populations that are steadily declining because of their overexploitation for traditional purposes. Finally, phylogenetic analyses of euphractine armadillos based on a combination of 6 non-coding nuclear markers and 2 nuclear exons suggest the paraphyly of the genus Chaetophractus, with C. vellerosus being more closely related to Zaedyus pichiy than to C. villosus.

A Reference List of Common Names for the Edentates

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Research on armadillos: a review and prospectus

A detailed analysis of 1,039 scientific studies of extant armadillos (Xenarthra: Cingulata, Dasypodidae) published in the last 25 years (1989–2013) revealed substantial biases in coverage, including taxonomically, the locales where field studies were conducted, and in the topics investigated. Examination of the number of other publications that cited each paper revealed that 470 (45%) papers had been cited no more than 10 times, 249 (24%) had never been cited, and 112 (11%) were not even found in the Google Scholar database. The most heavily cited papers were molecular phylogenetic analyses that often used tissues from one or more species of armadillo but were not about the animals per se. Thus, it appears that research on armadillos is plagued by numerous gaps in coverage and is not reaching a wide audience. These data indicate obvious opportunities for future research. In addition, recent findings suggest that even relatively well-studied phenomena may require reexamination. Here, we review recent advances in the study of armadillos and highlight promising areas for future work. One critical need is for a thorough systematic revision of Dasypodidae to be completed. This will make it possible to prioritize those species and populations most in need of study. Additionally, more long-term field studies of populations of marked individuals are required. Although there are many important and interesting questions waiting to be answered, the small number of researchers currently conducting studies of armadillos, particularly in the wild, means that progress will be slow.

Seasonal reproduction in male pichis Zaedyus pichiy (Xenarthra: Dasypodidae) estimated by fecal androgen metabolites and testicular histology

Poaching poses a threat to a wide variety of wildlife, and basic information about the biology of hunted species needs to be collected before their populations decline to the extent that requires drastic human intervention. As the survival of a species is related to its ability to reproduce, data on its reproductive cycle are necessary for the development of management strategies. The hypothesis was tested that the reproductive season of pichis (Zaedyus pichiy), small hibernating armadillos that inhabit arid environments in Argentina and Chile, is limited to spring months. Gonadal competence of semi-captive and wild-caught male pichis of Mendoza Province, Argentina was studied, by measuring fecal immunoreactive testosterone concentrations and evaluating spermatogenic activity. Results suggest that Z. pichiy is a seasonal breeder that regulates reproduction through photoperiodic cues. Gonadal competence was limited to a period of 3-5 months in spring and early summer and was reflected in enlarged testes, increased spermatogenesis, and significantly elevated fecal immunoreactive testosterone concentrations. The reproductive season for males from southern Mendoza was almost 6 weeks shorter than in the north. This fact, along with significant morphological differences between both groups, suggests that northern and southern pichis belong to two distinct populations. It is concluded that prolonged breeding seasons and more favorable environmental conditions in northern Mendoza favor a prolongation of the reproductive season that may allow pichis to breed later in the year, thus maximizing reproductive opportunities.