 |
| Mindomys kutuku Brito, Koch, Tinoco & Pardiñas, 2022 Kutukú Rat | Rata de Kutukú || DOI: 10.3897/evolsyst.6.76879 painted by Glenda Pozo |
Abstract
The diversity of the oryzomyine rat Mindomys (Cricetidae, Sigmodontinae, Oryzomyini), is doubled here with the description of a new species from the remote Cordillera de Kutukú (Ecuador). The novel form can be easily differentiated from Mindomys hammondi –type species of the genus– by a large set of anatomical traits including, among others, larger jugals, parietal “wings” extending to zygomatic roots, larger otic capsules, well-exposed petrosals, narrow zygomatic plates almost without upper free borders, foramen magnum caudally oriented, larger molars, and accessory root of first upper molar present. Until now, the records of Mindomys were restricted to western Andean foothills. The material from Kutukú highlights an Amazonian species and reinforces the valuable biological significance of isolated mountain ranges in eastern Ecuador. Since Mindomys shows some external traits classically related to arboreal life, here we present a brief reappraisal of this poorly explored topic. A partially neglected anatomical system in sigmodontine studies, the fore feet, encloses crucial information reflecting arboreality.
Key Words: Arboreal cricetids, Ecuador, fore feet, Kutukú mountain range, Oryzomyini, Sigmodontinae
Family Cricetidae Fischer, 1817
Subfamily Sigmodontinae Wagner, 1843
Tribe Oryzomyini Vorontsov, 1959
Genus Mindomys Weksler, Percequillo & Voss, 2006
 |
| Mindomys kutuku sp. nov. (MECN 5809, holotype; Cordillera de Kutukú, Ecuador): external aspect based on museum skin in dorsal (a), ventral (b), and lateral (c) view. Scale bar: 50 mm. |
 |
| Three-dimensional reconstruction of the skull of Mindomys kutuku sp. nov. based on micro-CT data of the holotype (MECN 5809; Cordillera de Kutukú, Ecuador): cranium in dorsal, ventral, and lateral view, and left hemimandible in labial view. Scale bar: 10 mm. |
Mindomys kutuku sp. nov.
Kutukú Rat, Rata de Kutukú
Diagnosis: A species of Mindomys smaller than M. hammondi, with opisthodont upper incisors; zygomatic notch very shallow; zygomatic plate moderately narrow and almost without upper free border; zygomatic plate frontally directed; posterior margin of the zygomatic plate anterior to M1; interorbital constriction moderately posterior and narrow; molars of absolute larger size comparatively to the skull, large jugal fully separating maxillary and squamosal portions of the zygomatic arch; hamular process of pterygoid large; alisphenoid strut present; parietal lateral “wing” reaching the zygomatic root; otic capsule medium in size; undefined hamular process of the squamosal; paraoccipital process small; well-exposed petrosal; caudally directed foramen magnum; minute Hill foramen; long incisive foramen; inferior ridge of the masseteric crest not concealing the lower margin of the dentary; lateral view of m3 not hidden by the ascending ramus; angular process of the dentary shorter than condyle; M1 broad, with anterior stylar shelf, anteroposteriorly compressed procingulum and defined anterolingual conule; M1 paracone and metacone transversally compressed; M1 accessory root present; M2 mesofosette rounded; M3 posterior lobe transversally compressed with closed metaflexus.
 |
| External aspect of Mindomys kutuku sp. nov., in its natural habitat (painted by Glenda Pozo). |
Distribution and remarks: Known only from the type locality (Fig. 5). The zoogeographic terrain in which M. kutuku was collected belongs to the eastern subtropics (Albuja et al. 2012). The holotype was collected in evergreen montane forest of the Cordilleras Cóndor-Kutukú (Ministerio del Ambiente del Ecuador 2013), which is characterized by trees with abundant orchids, ferns and bromeliads. The height of the emerging vegetation reaches up to 25 m. M. kutuku was collected within a mature forest near a stream (Fig. 10). The surrounding undergrowth has a visual domain of herbaceous families such as Araceae and Melastomataceae. On the slopes, the royal palm (Dictyocaryum lamarckianun) predominates. The new species was collected in sympatry with the didelphids Marmosops caucae and Monodelphis adusta and the sigmodontine rodents Akodon aerosus, Chilomys sp., Hyaleamys yunganus, Nephelomys auriventer, Microryzomys minutus, Oecomys superans, Oreoryzomys balneator and Rhipidomys albujai.
 |
| General landscape of the Cordillera de Kutukú (Ecuador), aerial survey in east-west orientation (a, b), photographs taken on August 26, 2017; field expedition in evergreen montane forest (c, d), and stream near the trapping site (d), photographs taken on September 8, 2017. |
Etymology: The specific epithet is a noun in apposition after the type locality, Kutukú.
Jorge Brito, Claudia Koch, Nicolás Tinoco and Ulyses F. J. Pardiñas. 2022. A New Species of Mindomys (Rodentia, Cricetidae) with Remarks on External Traits as Indicators of Arboreality in Sigmodontine Rodents. Evolutionary Systematics 6(1): 35-55. DOI: 10.3897/evolsyst.6.76879
