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| Thomasomys pardignasi Brito, Vaca-Puente, Koch & Tinoco, 2021 |
Abstract
A new species of the cricetid rodent genus Thomasomys is described from the montane forests of the Cordilleras del Cóndor and Kutukú, southeastern Ecuador, at elevations between 1,770 and 2,215 m. The species has a large body size (head and body length 137–147 mm) in comparison with other species in the genus, and also is distinguished from its congeners by presenting a tail longer than the head–body length, presence of genal vibrissae 1 and 2, wide presphenoid, first and second lower molars with ectolophid, and third lower molar slightly shorter than the second. A molecular phylogeny based on mitochondrial genes resolved the new species a member of the “aureus” group, most closely related to Thomasomys aureus sensu stricto (genetic distance 8.57%) and as well as an additional undescribed species from southeastern Ecuador. This finding increases the diversity of Thomasomys to 46 species, of which 17 species are present in Ecuador. In addition, the species described herein is the first Thomasomys from the Amazonian basin, a genus that up to now was thought to be restricted to Andean ranges.
montane forest, Rodentia, Thomasomyini, Thomasomys aureus
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| Thomasomys pardignasi sp. nov. (MECN 5852, holotype) external appearance of the adult female alive in its natural habitat in the Cordillera de Kutukú, Ecuador |
Family Cricetidae Fischer, 1817
Subfamily Sigmodontinae Wagner, 1843
Tribe Thomasomyini Steadman and Ray, 1982
Genus Thomasomys Coues, 1884
Thomasomys pardignasi sp. nov.
Pardiñas’ Andean Mouse
Ratón andino de Pardiñas (in Spanish)
Diagnosis: A species of Thomasomys that can be recognized by the following combination of characters: head and body length of 137–145 mm; tail longer than the head and body length, measuring 210–226 mm; tail with 12 rows of scales per cm on the axis; genal vibrissae 1 and 2 present; wide presphenoid; upper maxillary row 6.4–6.6 mm; M1 with shallow anteroflexus; M3 with reduced paracone; m1–m2 with ectolophids and without ectostylids; m3 slightly shorter than m2.
Etymology: This species is named in honor of Ulyses F. J. Pardiñas (Argentina, b. 18 May 1969), a prominent paleontologist who has dedicated his academic life to the study of sigmodontine rodents. The epithet of the species is formed from the surname “Pardiñas,” taken as a noun in the genitive case (replacing “ñ” with “gn” as per article 27 of ICZN), with the Latin Suffix “i” (ICZN 31.1.2).
Jorge Brito, Sarah Vaca-Puente, Claudia Koch and Nicolás Tinoco. 2021. Discovery of the First Amazonian Thomasomys (Rodentia, Cricetidae, Sigmodontinae): A New Species from the remote Cordilleras del Cóndor and Kutukú in Ecuador. Journal of Mammalogy. gyaa183. DOI: 10.1093/jmammal/gyaa183
Describimos una nueva especie de roedor cricétido del género Thomasomys proveniente de los bosques montanos de las Cordilleras del Cóndor y Kutukú, sureste de Ecuador, a una altura comprendida entre 1,770–2,215 m. Se trata de una especie de tamaño corporal grande (longitud cabeza-cuerpo 137–147 mm) con respecto a las demás especies del género, que se distingue de sus congéneres por presentar una cola más larga que la longitud cabeza-cuerpo, presencia de vibrisas genales 1 y 2, presfenoide ancho, primer y segundo molar inferiores con ectolófido y tercer molar inferior ligeramente más corto que el segundo. Una filogenia molecular derivada a partir de los genes mitocondriales muestra que la nueva especie forma parte del grupo “aureus,” cercanamente relacionada con Thomasomys aureus sensu stricto (distancia genética de 8.57%) y con otra especie de Thomasomys aún no descrita del sudeste ecuatoriano. Este hallazgo aumenta la riqueza de Thomasomys a 46 especies, de las cuales 17 están presentes en Ecuador. Adicionalmente, la especie descrita aquí es el primer Thomasomys de la cuenca amazónica, un género que hasta ahora había estado restringido a ambientes andinos.
bosque montano, Rodentia, Thomasomyini, Thomasomys aureus
