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| Holotype of Ctenomys bidaui n. sp. (CFA-MA 11867). Skins of the holotypes of Ctenomys bidaui n. sp. (A, B), Ctenomys contrerasi n. sp. (C, D), and Ctenomys thalesi n. sp. (E, F)
Teta & D’Elía, 2020
DOI: 10.7717/peerj.9259
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Abstract
Ctenomys Blainville 1826 is one of the most diverse genera of South American caviomorph rodents. Currently, six species of this genus are reported from Patagonia, south of 42°S. In this contribution, we assessed the taxonomic status of several populations from eastern and central Chubut province, northern Patagonia. Based on phylogenetic analyses of DNA sequences, morphology assessment (qualitative and quantitative), and previously published karyological data, we describe three new species of this genus, one formed by two subspecies, endemic to northern Patagonia. In addition, we include C. coyhaiquensis Kelt and Gallardo 1994 into the synonymy of C. sericeus J.A. Allen 1903. Finally, we discussed the need for additional integrative approaches, including field collection of specimens, to better understand the diversity of this highly speciose rodent genus.
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| Figure 4: Skins of the holotypes of Ctenomys bidaui n. sp., Ctenomys contrerasi n. sp., and Ctenomys thalesi n. sp. Dorsal (A, C, E) and ventral (B, D, F) views of the skins of the holotypes of Ctenomys bidaui n. sp. (A, B; CFA-MA 11867), C. contrerasi n. sp. (C, D; CFA-MA 11853), and C. thalesi n. sp. (E, F; CFA-MA 11849). |
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| Figure 5: Holotype of Ctenomys bidaui n. sp. (CFA-MA 11867). Dorsal (A), ventral (B) and lateral (C) views of the skull and labial view of the mandible (D) and selected cranial traits (E–J) of the holotype of Ctenomys bidaui n. sp. (CFA-MA 11867). E: nasals (nl) and premaxillae (pm); F: interparietal (ip); G; lateral view of the zygomatic arch; H: incisive (fi) and interpremaxillary (fh) foramina; I: tympanic bullae (tb) in posterolateral view; J: condyloid process (clp) of the mandible in dorsal view.
Other abbreviations: fr, frontals; mr, masseteric ridge; pp, paraoccipital process; ppj, postorbital process of jugal; va, ventrolateral apophysis of the postcondyloid process. Scale = 5 mm.
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Ctenomys bidaui n. sp.
Bidau’s tuco-tuco
Tuco-Tuco de Bidau
Morphological diagnosis—A medium-sized tuco-tuco of the C. magellanicus species group with moderately differentiated dorsal and ventral colorations; dorsum Light Brownish Olive to Brownish Olive; venter Pale Olive Buff with Gray colored basal hairs. Skull strongly built; interorbital processes of frontals slightly developed; zygomatic arches robust; premaxillo-frontal suture at the level of the naso-frontal suture; interparietal broad and short; incisive foramina moderately short and broad, recessed in a common fossa of straight outer borders and incompletely separated by a bony septum; interpremaxillary foramen large; auditory bullae inflated and ovate.
Distribution—Known only from three localities near coastal areas of Península de Valdés, Chubut, Argentina (Fig. 1). Possibly, also correspond to this species the late Holocene fossil remains referred by Udrizar Sauthier & D’Agostino (2017) from this same general area.
Etymology—We named this species in honor of the late Claudio J. Bidau (1953-2018), an Argentinian biologist with an extensive and varied scientific production, of which an important fraction is aimed to elucidate the complex evolutionary history of the genus Ctenomys. Claudio was a much-appreciated member of the South American community of mammalogists where he is well remembered. The species name is a patronym in the genitive singular.
Ctenomys contrerasi n. sp.
Contreras’tuco-tuco
Tuco-Tuco de Contreras
Morphological diagnosis—A small to medium sized tuco-tuco of the C. magellanicus species group with dorsal and ventral colorations moderately differentiated; dorsum Brownish Olive to Olive or Tawny Olive; venter Pale Olive Buff with Gray colored basal hairs. Skull moderately robust, interorbital region with posteriorly divergent outer margins; premaxillo-frontal suture placed slightly to well behind from the naso-frontal suture; zygomatic arch thin to moderately robust, with slightly developed postorbital and mandibular processes of jugal and a conspicuous zygomatic depression; interparietal completely fused; incisive foramina moderately long and narrow, recessed in a common fossa of straight to slightly convex outer borders and completely separated by a thin bony septum; interpremaxillary foramen small to large; paraoccipital process fan-shaped; auditory bullae inflated, and pyrifom.
Distribution—This species has an apparently disjunct distribution, being recorded at four localities close to the Atlantic coast, between the Chubut river in the south and the Ameghino Isthmus to the north, and other two populations in west-central Chubut, south of the Chubut river (Fig. 1). Both distributional areas are about 335 km apart.
Etymology—This species of Ctenomys is named in honor of Julio R. Contreras (1933-2017), an Argentinean mammalogist and ornithologist who dedicated more than 45 years of his life to the study of the taxonomy, systematics, and biogeography of the genus Ctenomys (see Teta & Ríos, 2019). Contreras described more than a dozen of new species of tuco-tucos, both from Argentina and Paraguay. Together with C. Bidau (Contreras & Bidau, 1999), he authored one of the first attempts to summarize the complex evolutionary history of this genus, proposing a general hypothesis about its diversification. The species name is a patronym in the genitive singular.
Ctenomys contrerasi contrerasi n. subsp.
Ctenomys contrerasi navonae n. subsp.
Etymology—This subspecies of Ctenomys is named in honor of our colleague and friend Graciela T. Navone, an Argentinean parasitologist with a large career studying small mammal endoparasites. Graciela is also a prominent and active member of the Sociedad Argentina para el Estudio de los Mamíferos (SAREM). The species name is a patronym in the genitive singular.
Ctenomys thalesi n. sp.
Thales’s tuco-tuco
Tuco-Tuco de Thales
Morphological diagnosis— A small-sized tuco-tuco of the C. magellanicus species group with dorsal and ventral coloration moderately differentiated; dorsum Light Brownish Olive; venter Pale Olive Buff with gray colored basal hairs. Skull moderately robust, interorbital region with posteriorly divergent outer margins; premaxillo-frontal suture placed slightly behind the naso-frontal suture; zygomatic arch thin, with slightly developed postorbital and mandibular processes of jugal and a conspicuous zygomatic depression; interparietal completely fused; incisive foramina moderately short and narrow, recessed in a common fossa of nearly convex outer borders and completely separated by a thin bony septum; interpremaxillary foramen small to absent; paraoccipital process hook-shaped; auditory bullae inflated, and pyrifom.
Distribution— Known only from two localities on northeastern Chubut province, close to the Atlantic coast, south of Chubut river (Fig. 1).
Etymology— We name this species in honor of Thales Renato Ochotorena de Freitas, a Brazilian geneticist who leads a productive research program mostly centered on Brazilian species of Ctenomys, covering among others, aspects of taxonomy, cytogenetics, speciation, phylogeography, and conservation genetics. The species name is a patronym in the genitive singular.
Ctenomys sericeus Allen, 1903
Silky tuco-tuco
Tuco-Tuco sedoso
Morphological diagnosis—pelage short, soft, and glossy (Fig. 5S, on Data S2); general color above Olive Brown to Sepia strongly varied with Black, the hairs being Dark Gray for the basal three fourths, then banded narrowly with pale Yellowish Brown, and tipped with Black; top of nose and top of head like median dorsal region, which is darker than the sides, sometimes forming a dark median dorsal band extending from the nose to the base of the tail; flanks lighter than dorsum and venter Isabella; ears very small, blackish; upper surface of feet grayish to yellowish; tail Tawny Olive, with a median dusky stripe along the apical half of the upper surface. Skull moderately robust (Fig. 6S, on Data S2), interorbital region with posteriorly divergent outer margins; premaxillo-frontal suture placed behind from the naso-frontal suture; zygomatic arches robust, with conspicuously and moderately developed postorbital and mandibular processes of jugal, respectively, and a well-marked zygomatic depression; interparietal absent to very small; incisive foramina moderately short and broad, recessed in a common fossa of convex outer borders and completely separated by a thin bony septum; interpremaxillary foramen large to inconspicuous; paraoccipital hook-shaped; auditory bullae inflated, and pyrifom.
Distribution— C. sericeus occurs in open shrubby to herbaceous steppes from southwestern Chubut (Argentina) in the north to the northern margin of the Santa Cruz river (Santa Cruz, Argentina) in the south, and adjacent open areas of Aysen, Chile (Fig. 1).
Conclusions:
The integrative analyses of morphological, molecular, and karyotipic data of Patagonian specimens of Ctenomys allowed as to describe three new species endemics to the open areas of northern Patagonia. The three new species belong to the C. magellanicus species group. In addition, we consider the geographically restricted C. coyhaiquensis (Kelt & Gallardo, 1994) as a junior synonym of the widespread C. sericeus (Allen, 1903). Our results also shown that as currently understood, C. haigi is likely a composite of two lineages of species level; tentatively, we refer to then as C. haigi s.s. and C. cf. C. lentulus. Our findings, together with the fact that large Patagonian areas still remain unstudied, suggest that the diversity of Patagonian species of Ctenomys is only partially understood. Therefore, to fill in this gap of knowledge, it is needed to carry out additional integrative taxonomic studies, based on the field collection of additional specimens.
Pablo Teta and Guillermo D’Elía. 2020. Uncovering the Species Diversity of Subterranean Rodents at the End of the World: Three New Species of Patagonian Tuco-tucos (Rodentia, Hystricomorpha, Ctenomys). PeerJ. 8:e9259. DOI: 10.7717/peerj.9259
