The hidden anatomy of paranasal sinuses reveals biogeographically distinct morphotypes in the nine-banded armadillos (Dasypus novemcinctus)
- Published
- Accepted
- Subject Areas
- Evolutionary Studies, Taxonomy, Zoology
- Keywords
- anatomy, Xenarthra, skull, Mammalia, systematics, Cingulata, Biogeography, cranial pneumatization
- Copyright
- © 2017 Billet et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2017. The hidden anatomy of paranasal sinuses reveals biogeographically distinct morphotypes in the nine-banded armadillos (Dasypus novemcinctus) PeerJ Preprints 5:e2923v1 https://doi.org/10.7287/peerj.preprints.2923v1
Abstract
Background. With their Pan-American distribution, long-nosed armadillos (genus Dasypus) constitute an understudied model for Neotropical biogeography. This genus currently comprises seven recognized species, the nine-banded armadillo (D. novemcinctus) having the widest distribution ranging from Northern Argentina to the South-Eastern US. With their broad diversity of habitats, nine-banded armadillos provide a useful model to explore the effects of climatic and biogeographic events on morphological diversity at a continental scale.
Methods. Based on a sample of 136 skulls of Dasypus spp., including 112 specimens identified as D. novemcinctus, we studied the diversity and pattern of variation of internal paranasal cavities, which were reconstructed virtually using µCT-scanning or observed through bone transparency.
Results. Our qualitative analyses of paranasal sinuses and recesses successfully retrieved a taxonomic differentiation between the traditional species D. kappleri, D. pilosus and D. novemcinctus but failed to recover diagnostic features between the disputed and morphologically similar D. septemcinctus and D. hybridus. Most interestingly, the high variation detected in our large sample of D. novemcinctus showed a clear geographical patterning, with the recognition of three well-separated morphotypes: one ranging from North and Central America and parts of northern South America west of the Andes, one distributed across the Amazonian Basin and central South America, and one restricted to the Guiana Shield.
Discussion. The question as to whether these paranasal morphotypes may represent previously unrecognized species is to be evaluated through a thorough revision of the Dasypus species complex integrating molecular and morphological data. Remarkably, our recognition of a distinct morphotype in the Guiana Shield area is congruent with the recent discovery of a divergent mitogenomic lineage in French Guiana. The inflation of the second medialmost pair of caudal frontal sinuses constitutes an unexpected morphological diagnostic feature for this potentially distinct species. Our results demonstrate the benefits of studying overlooked internal morphological structures in supposedly cryptic species revealed by molecular data. It also illustrates the under-exploited potential of the highly variable paranasal sinuses of armadillos for systematic studies.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Table with information on investigated specimens
Supplemental Table S1. Table with information on investigated specimens: taxa, geographical origins, collection number, scan details, sinus morphotypes.
llustration of the paranasal sinuses and recesses in different specimens of Dasypus kappleri
Supplemental Figure S2. Illustration of the paranasal sinuses and recesses in different specimens of Dasypus kappleri, with geographical information. Skulls not to scale.
Raw Data
Raw data: images of all virtually reconstructed paranasal sinuses in our dataset.