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Octodontomys Palmer, 1903 Octodon: P. Gervais and d’Orbigny, 1844:22. Part (description of gliroides); not Octodon Bennett, 1832. Neoctodon Thomas, 1902:114. Type species Neoctodon simonsi Thomas (= Octodon gliroides P. Gervais and d’Orbigny) by original designation; preoccupied by Neoctodon Bedel, 1892 (Insecta: Coleoptera). Octodontomys Palmer, 1903:873. Replacement name for Neoctodon Thomas. CONTEXT AND CONTENT. Order Rodentia, suborder Hystricomorpha, infraorder Hystricognathi, family Octodontidae. This species was originally placed within the genus Octodon but later raised to generic status by Thomas (1902) as Neoctodon. The name Neoctodon Thomas was preoccupied by Neoctodon Bedel, 1892, a genus of beetle, Palmer (1903) assigned Octodontomys as a substitute name. Octodontomys is monotypic., Published as part of Pérez, M. Julieta & Díaz, M. Mónica, 2018, Octodontomys gliroides (Rodentia: Octodontidae), pp. 74-83 in Mammalian Species 50 (963) on page 74, DOI: 10.1093/mspecies/sey010, http://zenodo.org/record/4573547, {"references":["PALMER, T. S. 1903. Some new generic names of mammals. Science, n. s. 17: 873.","BENNETT, E. T. 1832. Characters of a new genus of rodent Mammalia, presented by Mr. Cuming. Proceedings of the Committee of Science and Correspondence of the Zoological Society of London, Part 2: 46 - 48.","THOMAS, O. 1902. On two new genera and rodents from the highlands of Bolivia. Proceedings of the Zoological Society of London 1: 114 - 117.","BEDEL, L. 1892. Revision des Scarabaeus palearctiques. L'Abeille; journal d'entomologie 27: 281 - 288."]}

Pérez, M. Julieta, Díaz, M. Mónica (2018): Octodontomys gliroides (Rodentia: Octodontidae). Mammalian Species 50 (963): 74-83, DOI: 10.1093/mspecies/sey010, URL: http://dx.doi.org/10.1093/mspecies/sey010

Octodontomys gliroides (P. Gervais and d’Orbigny, 1844) Mountain Degu Octodon gliroides P. Gervais and d’Orbigny, 1844:22. Type locality “des Andes boliviennes, à Lapaz;” La Paz, Bolivia. Neoctodon simonsi Thomas, 1902:115. Type locality “Mountainous region south and south- east of the Titicaca- Poopo basin. Potosí, 4400 metres,” Bolivia. Octodontomys gliroides: Thomas, 1913:143. First use of current name combination. CONTEXT AND CONTENT. Context as for genus. Octodontomys gliroides is monotypic (Verzi et al. 2015a). Mountain Degu Octodon gliroides P. Gervais and d’Orbigny, 1844:22. Type locality “des Andes boliviennes, à Lapaz;” La Paz, Bolivia. Neoctodon simonsi Thomas, 1902:115. Type locality “Mountainous region south and south- east of the Titicaca- Poopo basin. Potosí, 4400 metres,” Bolivia. Octodontomys gliroides: Thomas, 1913:143. First use of current name combination. CONTEXT AND CONTENT. Context as for genus. Octodontomys gliroides is monotypic (Verzi et al. 2015a). DIAGNOSIS Octodontomys gliroides (Fig. 1) resembles other members of the family Octodontidae, being most similar to the mountain viscacha rat Octomys mimax and species of the genus Tympanoctomys; however, O. gliroides has upper and lower molariforms with an asymmetrical occlusal pattern (Octomys and Tympanoctomys have a figure-8 occlusal pattern—Reig and Quintana 1991; Hutterer 1994; Kramarz 2005). Other distinctive features of the teeth and skull of O. gliroides (Fig. 2) include: the alveolar portion of the 1st molariform tooth (DP4) is slightly inclined anteriorly, medial to the incisor; as a result, an anterior extension of the maxillaries into the posterior margins of the incisive foramina, where DP4 is inserted, is scarcely developed to nearly absent (Verzi 2001; Verzi et al. 2015a). The molariform teeth have folds (flexi or flexids) that are shallow or absent; the maxillary cheek teeth have the anterior lobe protruding as in Octodon, but without a penetrating lingual fold (hypoflexus— Verzi and Carrín Iglesias 1999; Verzi 2001; Verzi et al. 2015a). The auditory bullae are of medium size (14.6 ± 0.7 mm) and slightly inflated compared with other desert-adapted octodontids such as Octomys (15.8 ± 0.3 mm) and Tympanoctomys (17.2 ± 0.9 mm—Mares et al. 2000). GENERAL CHARACTERS Octodontomys gliroides is a medium- to large-sized octodontid, with a body mass ranging from 100–200 g; total length, 200–380 mm; length of tail, 100–190 mm; length of hind foot, 33–40 mm; length of ear, 24–35 mm (Díaz 1999; Mares et al. 2000; Díaz and Barquez 2002; Verzi et al. 2015a). It is a semisubterranean genus of the family Octodontidae and, like Octodon and Tympanoctomys, has large eyes, ears, and hind feet (Lacey and Ebensperger 2007). The pelage is relatively long and silky; dorsal coloration is grayish drab streaked with black; tail has a reddish buffy brush; the venter has white hairs with gray bases, except on the chin and throat where they are pure white, which contrasts sharply with the dorsum (Thomas 1902; Ipinza et al. 1971; Mares et al. 2000; Verzi et al. 2015a). The ears are large, finely covered by short grayish hairs, with white tufts on the anterior ends (Ipinza et al. 1971; Díaz and Barquez 2002). Feet are hairy with the claw covered by hair, the plantar surfaces bear fine granulations (Thomas 1902; Contreras et al. 1987; Díaz and Barquez 2002), and plantar pads are prominent (Ipinza et al. 1971). The tail is nearly 80% of the head and body length; it is bicolored, with an elongated, brown or ochraceous brush extending from the tip. Juveniles are darker with a grayer venter and have an essentially unicolored tail that terminates in a short, black or dark drab brush (Díaz and Barquez 2002; Verzi et al. 2015a). The rostrum is relatively long and narrow; postorbital processes are absent or reduced; interorbital region is relatively broad and divergent with breadth slightly less than the breadth of the rostrum (9.23 mm versus 7.41 mm); lacrimal is large and triangular; palate is short, and the mesopterygoid fossa has an inverted “V” shape, not extending beyond M1; pterygoids leaning on the bullae (Díaz 1999; Mares et al. 2000). Incisive foramina are large with the posterior most ends behind the premaxillary-maxillary suture; the lateral edges of the posterior bor- der of the incisive foramina are not raised (Mares et al. 2000). The lateral flange of the canal for the infraorbital nerve is well developed and has the dorsal end free, not joined to the maxillary (Glanz and Anderson 1990; Verzi et al. 2015a). Masseteric crest and the tubercle for the insertion of the M. masseter medialis pars infraorbitalis are discontinuous (Verzi et al. 1999, 2001; Kramarz 2005). The zygomatic arches are little expanded, with a low and slightly deep jugal fossa for the posterior masseter muscle; shape of suture of jugal and zygomatic process of squamosal squared or rounded (Mares et al. 2000; Verzi et al. 2015a). The lateral supraoccipital processes show greatest development, with the long process extending to the squamosal process and then turning conspicuously downward (Glanz and Anderson 1990). Woods (1984:424, 428) mentioned a “slight lateral supraoccipital process” in both Ctenomyidae and Octodontidae, but Glanz and Anderson (1990) considered this description slightly misleading because the supraoccipital process is well developed in O. gliroides. The paraoccipital processes are small, thick, and incompletely joined to the bullae, with each root directed medially due to the development of the mastoid bullae (Mares et al. 2000; Verzi et al. 2015a). The mandible is slender, low, and moderately hystricognathous; the coronoid process is small; the condylar process is broad and slightly behind the angular process, the latter being short, slender, and slightly flattened; the lunar notch is shallow (Díaz 1999; Mares et al. 2000; Verzi et al. 2015a); the masseteric crest is not prominent (Verzi 2002). Mean cranial measurements (mm, ± SD, sample size in parentheses—Mares et al. 2000, specimens from Argentina and Bolivia) were: greatest length of skull, 45.3 ± 1.3 (25); basal length, 39.6 ± 1.3 (22); zygomatic breadth, 23.3 ± 0.7 (26); mastoid breadth, 22.1 ± 0.7 (21); least interorbital breadth, 9.4 ± 0.4 (29); length of nasals, 16.6 ± 0.9 (26); breadth of rostrum, 8.2 ± 0.3 (26); length of diastema, 11.5 ± 0.5 (28); length of maxillary toothrow, 8.1 ± 0.6 (28); length of bulla, 14.6 ± 0.7 (23); width of bulla, 11.3 ± 0.3 (23); width of zygomatic plate, 1.9 ± 0.2 (26); length of mandibular toothrow, 8.5 ± 0.6 (27); length of mandible, 27.5 ± 0.9 (28). Mean cranial measurements (mm, ± SD, sample size in parentheses—Díaz 1999, specimens from Argentina) were: condyle incisive length, 42.2 ± 1.2 (11); occipitonasal length, 43.8 ± 1.5 (10); braincase breadth, 17.9 ± 0.5 (11); zygomatic breadth, 23.0 ± 0.8 (10); mastoid breadth, 14.2 ± 2.1 (9); least interorbital breadth, 9.3 ± 0.4 (11); length of rostrum, 17.9 ± 0.7 (9); breadth of rostrum, 7.8 ± 0.5 (10); length of nasals, 15.9 ± 0.9 (4); length of diastema, 11.5 ± 0.4 (11); length of maxillary toothrow, 8.7 ± 0.5 (11); greatest alveolar length of M1, 2.7 ± 0.2 (10); alveolar width of M1, 2.08 ± 0.11 (6; please note this was original reported incorrectly as 4 ± 5.7 (10)); greatest length of incisive foramina, 4.07 ± 0.7 (10); palate length, 16.8 ± 0.7 (11); maxima distance between the external border of M3, 7.5 ± 0.5 (11); length of bulla, 14.0 ± 0.9 (10); length of mandibular toothrow, 9.2 ± 0.5 (11); length of mandible, 25.8 ± 1.2 (11). These 2 cited publications differ in mastoid breadth; it is possible that Mares et al. (2000) included part of the bulla in their measurement. The upper incisors are orthodont or slightly proodont, orange, narrow, and short; the lower incisors are orange, high, narrow, with a suboval section, straight lingual enamel edge, and curved labial edge; on the labial side, the enamel extends beyond one-half of the tooth face (Verzi et al. 1999; Verzi 2002). Like all octodontids, O. gliroides is characterized by ever-growing (hypsodont) molar teeth. In the upper molariforms, the folds (flexi) are absent in the adult and the posterior lobe is not extended labially. The molariforms are asymmetrical with no reentrant folds (Hutterer 1994), except in juveniles, which have flexids and fossettids (Verzi 1994; Verzi et al. 2016). Lower molariform teeth have an asymmetrical occlusal pattern, nearly figure-8 shaped, with slightly oblique and rounded lobes and shallow traces of folds; deciduous dp4 with mesoflexid reduced or absent and hypoflexid barely visible (Verzi 1994; Verzi et al. 2015a); the mesoflexid of m1 and m2 remains open in advanced stages of wear (Kramarz 2005); with mesoflexid less evident than hypoflexid (Verzi 1994); last upper and lower molars (M3/m3) reduced in size (Verzi 2002; Verzi et al. 2015a). O. gliroides has oblique, posterolabial-anterolingual, unilateral chewing (anterolingual jaw displacement and alternate occlusion); according to phylogenetic analyses, this is primitive for octodontids (Verzi 2001; Olivares et al. 2004). The masticatory direction (in molariform teeth, defined as asymmetry in dentine wear relative to the sagittal plane) is 58° in Octodontomys (Vassallo and Verzi 2001). Hutterer (1994) considered the occlusal pattern of Octodontomys to be plesiomorphic, because it matches with the molars of the Oligocene Platypittamys, a putative octodontid. The similarities in the cranial morphology of O. gliroides and the basal octodontoid rodent Prospaniomys make O. gliroides an optimal species for reconstructing masticatory muscle origins and insertions of this extinct species (Álvarez and Arnal 2015). The data matrix of Olivares et al. (2012) and Verzi et al. (2016) should be consulted for additional cranial and dental characters for O. gliroides. Álvarez et al. (2011) and Álvarez et al. (2015) examined 2- and 3-dimensional craniomandibular geometric morphometric characters in an evolutionary context. DISTRIBUTION Octodontomys gliroides has a disjunct distribution (Fig. 3) in the Andean and Sub-Andean areas of southwestern Bolivia (from La Paz Department to Tarija Department), northern Chile (Arica- Parinacota and Tarapacá regions), and northwestern Argentina (several localities in Salta and Jujuy provinces, one in La Rioja Province, being highly probably in Catamarca Province—Cabrera 1961; Mann Fischer 1978; Pine et al. 1979; Contreras et al. 1987; Mares et al. 2000; Muñoz-Pedreros 2000; Díaz and Barquez 2002; Díaz and Verzi 2006; Díaz and Barquez 2007; Verzi et al. 2015a; Rivera et al. 2016). In Argentina, this species occupies the High Andes, Monte Desert of Mountains and Isolated Valleys, and Puna ecoregions (Díaz and Verzi 2006). Ojeda et al. (2011) mentioned that O. gliroides is restricted to northern Monte of Mountains and Isolated Valleys. It is found on both sides of the Andes, a distribution marked by an east to west gradient of decreasing rainfall that results in east and west (from theAndes) populations with contrasting differences in the abundance and patchiness of vegetation cover (Rivera et al. 2014, 2016). This species has an elevation range from about 1,200 m at Villa Union in La Rioja Province, Argentina to about 4,400 m in Potosí, Bolivia. Verzi et al. (2015a) indicated that the lowest altitude for the distribution of this species is 200– 300 m. However, this information is incorrect because the data taken from Diaz and Ojeda (1999) correspond to measurements of precipitation (200–300 mm), and this information was misinterpreted by editors during the final process of editing the book Mammals of South America (Patton et al. 2015). FOSSIL RECORD Although Octodontomys gliroides has no fossil record, it is the most primitive extant octodontid. Its cranial and dental anatomy resemble some species from the Miocene and Pliocene of Argentina (Verzi and Carrín Iglesias 1999; Verzi et al. 1999; Verzi 2002; Verzi et al. 2014), suggesting that it may be an early octodontid offshoot (Verzi et al. 2015b). Gallardo and Kirsch (2001) mentioned that Verzi (1994) considered hypsodonty in Ctenomys and Octodontomys to be indicative of common ancestry and re-erected the subfamily Ctenomyinae to include these 2 genera; however, their interpretation of Verzi’s conclusion was erroneous because Verzi stated “hypsodonty has originated independently several times in rodents” (see Verzi 1994:92) and thus does not support the idea of common ancestry. Opazo (2005) estimated the divergence of Octodontomys from its sister clade (Octodon + Spalacopus + Aconaemys) at 6.07 ± 1.34 million years ago, near the end of the Miocene. This value agrees with the results of both Gallardo and Kirsch (2001), who used DNA hybridization data, and Verzi et al. (2016), using morphological and molecular data, to obtain an estimated divergence of 5–7 million years ago; but it is older than the estimate of Honeycutt et al. (2003; 2.9–4.1 million years ago) based on molecular data (nucleotide sequence data from nuclear receptor and mitochondrial genes nucleotide sequence). The morphology of the lower incisor is shared with the extinct octodontid Neophanomys, but whether this character state is primitive or derived is difficult to determine (Verzi et al. 1999). Octodontomys has been recorded in the archaeological site Inca Cueva 5 site, Jujuy Province, Argentina (2,120 ± 120 to 780 ± 100 years before present) based on 3 left mandibular rami; the area corresponds to the oriental border of the Puna steppe (Teta and Ortiz 2002). Octodontomys gliroides produces middens (amalgamations of plant remains, bones, insects, feathers, and rodent feces, glued together within a crystallized matrix of rodent urine), which have proven to be important sources of paleontological evidence (Betancourt and Saavedra 2002; Latorre et al. 2005). In the Atacama (Chile), middens have been recorded from possibly the Quaternary for O. gliroides as well as other families of rodents (e.g., Chinchillidae, Abrocomidae, and Muridae—Latorre et al. 2005). Arnal and Vucetich (2015a, 2015b) used extant species of the family Octodontidae, including O. gliroides, to revise the taxonomy of the fossil rodent Acaremys (Hystricognathi, Octodontoidea, Acaremyidae) and to analyze phylogenetic relationships of the Pan-Octodontoidea group. FORM AND FUNCTION Dental formula for Octodontomys gliroides is i 1/1, c 0/0, p 1/1, m 3/3, total 20. Buccal surfaces of the upper teeth are progressively rotated more distally from the distal to the mesial ends of the arches, with DP4 being nearly transverse to the line of the arch (Miles and Grigson 1990). O. gliroides has simplified teeth without reentrant angles or cement (Glanz and Anderson 1990). In hypsodont rodents, the enamel of the molariforms typically has a different structure on the side of first contact (leading edge) and the opposite face (trailing edge); O. gliroides is more primitive compared to Ctenomys in this regard, with Hunter– Schreger bands limited to some areas. In a study of ultrastructure of the incisor enamel and delineated morphofunctional traits among octodontoid genera with disparate digging adaptations, O. gliroides had an enamel thickness more than double that of the other taxa studied (e.g., Ctenomys, Octodon, Dactylomys — Vieytes et al. 2007). The relative thickness of external index showed the lowest values in the fossorial O. gliroides and the arboreal Bolivian bamboo rat Dactylomys boliviensis than the other species studied, and this has been interpreted by Vieytes et al. (2007) as indicative of low wear resistance. The middle ear of O. gliroides has 3 cavities: bulla, anterior, and posterior recesses. The bulla is divided into 8–10 large pneumatized air cells, and the cochlea protrudes into the tympanic cavity medially (Heller et al. 1976). In the normal ear, these structures have fairly uniform radiolucency without evidence of thickening of the septae of the bulla or areas of bony sclerosis (Heller et al. 1976). In extant species of fossorial rodents, the degree of reduction in size of the eye indicates the adaptation level to the subterranean lifestyle (Pearson 1984). The size of the orbital cavity provides information about the size of the eye and can be estimated using the zygomatic index (see Verzi 2002:316). The comparative analysis of Verzi (2008) showed that echyimid rodents have relatively larger orbits than octodontids (for O. gliroides, mean index value of 1.22, range 1.13–1.38). The eyes of O. gliroides are much larger than those of Octodon, matching the inferred crepuscular or nocturnal habits of this species (Rowlands 1974, not seen cited in Wilson and Kleiman 1974) compared to the apparently diurnal habits of Octodon (Wilson and Kleiman 1974). Vasallo and Mora (2007) included O. gliroides in an allometric analysis of the effect of size on skull attributes (development of the mandibular angle and masseteric crest, and the robustness of incisors) in ctenomyid and octodontid rodents. They concluded that in Octodontomys, as in other octodontids and in ctenomyids, mandibular width and cross-sectional shape of the incisors show a significant and positive association with basicranium length. They also noted that O. gliroides clearly differs from Ctenomys by the intensification of the hystricognath condition (lateral expansion of the mandibular angle and masseteric crest) in Ctenomys. The glans penis of Octodontomys has 2 long spines on each side of the intromittent sac (2-2 pattern), although some specimens show a 2-3 pattern (Spotorno 1979; Contreras et al. 1993); these spines are the longest among octodontids (average length 5.6 mm—Contreras et al. 1993). These features indicate that O. gliroides is more closely related to generalist and subterranean species than to Octomys or Tympanoctomys, as the 1-1 pattern is interpreted to be ancestral and the 2-2 pattern derived in extant octodontid rodents (Contreras et al. 1993). O. gliroides shows the longest baculum among octodontids, which gradually tapers from the base to the tip (Contreras et al. 1993). The vaginal wall of O. gliroides shows a hardened surface and does not have a complementary space to hold the spikes in a distal or lateral position, suggesting that they can be accommodated only when pointing backwards (Contreras et al. 1993). Cummin, Published as part of Pérez, M. Julieta & Díaz, M. Mónica, 2018, Octodontomys gliroides (Rodentia: Octodontidae), pp. 74-83 in Mammalian Species 50 (963) on pages 75-80, DOI: 10.1093/mspecies/sey010, http://zenodo.org/record/4573547, {"references":["THOMAS, O. 1902. On two new genera and rodents from the highlands of Bolivia. Proceedings of the Zoological Society of London 1: 114 - 117.","THOMAS, O. 1913. On small mammals collected in Jujuy by Senor E. Budin. Annals and Magazine of Natural History, Including Zoology, Botany and Geology, London 8: 136 - 143.","VERZI, D. H., M. M. DiAZ, AND R. M. BARQUEZ. 2015 a. Genus Octodontomys. Pp. 1043 - 1048 in Mammals of South America. Vol. 2, rodents (J. L. Patton, U. F. J. Pardinas, and G. 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Bulletin of the American Museum of Natural History 231: 1 - 652.","WALKER, E. P. 1964. Mammals of the world. Vol. 2. Johns Hopkins Press, Baltimore, Maryland.","RIVERA, D. S. 2013. Organizacion social de Octodontomys gliroides (Gervais y d'Orbigny, 1844) y las implicaciones sobre el origen y evolucion de la sociabilidad en roedores octodontidos. Ph. D. dissertation, Pontificia Universidad Catolica de Chile, Santiago, Chile.","REPPUCCI, J. I. 2012. Ecologia y abundancia poblacional del gato andino (Leopardus jacobita) y gato del pajonal (L. colocolo) en los altos Andes Argentinos. Ph. D. dissertation, Departamento de Biologia Bioquimica y Farmacia, Universidad Nacional del Sur, Bahia Blanca, Argentina.","SCHWEIGMANN, N. J., ET AL. 1992. A new host of Tripanozoma cruzi from Jujuy, Argentina: Octodontomys gliroides (Gervais & d'Orbigny, 1844) (Rodentia: Octodontidae). Memorias do Instituto Oswaldo Cruz 87: 217 - 220.","BUITRAGO, R., ET AL. 2016. Blood meal sources of wild and domestic Triatoma infestans (Hemiptera: Reduviidae) in Bolivia: connectivity between cycles of transmission of Trypanosoma cruzi. Parasites and Vectors 9: 214.","SMIT, F. G. A. M. 1987. An illustrated catalogue of the Rothschild collection of fleas (Siphonaptera) in the Bristish Museum (Natural History). Oxford University Press, Brittish Museum (Natural History), London, United Kingdom.","BEAUCOURNU, J. C., S. BELAZ, S. MUnOZ- LeAL, AND D. GONZALEZ- ACUnA. 2013. A new flea, Ectinorus (Ectinorus) insignis n. sp. (Siphonaptera, Rhopalopsyllidae, Parapsyllinae), with notes on the subgenus Ectinorus in Chile and comments on unciform sclerotization in the superfamily Malacopsylloidea. Parasite 20: 1 - 12.","BEAUCOURNU, J. C., L. MORENO, AND D. GONZALEZ- ACUnA. 2014. Fleas (Insecta-Siphonaptera) of Chile: a review. Zootaxa 3900: 151 - 203.","MORENO SALAS, L., D. DEL C. CASTRO, J. C. TORRES- MURA, AND D. GONZALEZ- ACUnA. 2005. Phthiraptera (Amblycera andAnoplura) parasites of the family Octodontidae, Ctenomyidae and Abrocomidae (Mammalia: Rodentia) from Chile. Rudolstadter Naturhistorische Schriften 13: 115 - 118.","EISENBERG, J. F. 1974. The function and motivational basis of hystricomorph vocalizations. Symposia of the Zoological Society of London 34: 211 - 247.","SCHLEICH, C. E., S. VEITL, E. KNOTKOVA, AND S. BEGALL. 2007. Acoustic communication in subterranean rodents. Pp. 113 - 128 in Subterranean rodents: news from underground (S. Begall, H. Burda, and C. E. Schleich, eds.). Springer, Heidelberg, Germany.","CONTRERAS, L. C., J. C. TORRES- MURA, A. E. SPOTORNO, AND L. I. WALKER. 1994. Chromosomes of Octomys mimax and Octodontomys gliroides and relationships of octodontid rodents. Journal of Mammalogy 75: 768 - 774.","CONTRERAS, L. C., J. C. TORRES- MURA, AND A. E. SPOTORNO. 1990. The largest known chromosome number for a mammal in a South American desert rodent. Experientia 46: 506 - 509.","GALLARDO, M. H. 1992. Karyotypic evolution in octodontid rodents based on C-band analysis. Journal of Mammalogy 73: 89 - 98.","SPOTORNO, A. E., ET AL. 1995. Chromosome divergence of Octodon lunatus and Abrocoma bennetti and the origins of Octodontoidea (Rodentia, Hystricognathi). Revista Chilena de Historia Natural 68: 227 - 239.","SPOTORNO, A. E., L. I. WALKER, L. C. CONTRERAS, J. PINCHEIRA, AND R. FERNANDEZ DONOSO. 1988. Cromosomas ancestrales en Octodontidae y Abrocomidae. Archivos de Biologia y Medicina Experimentales 21: 527.","GALLARDO, M. H. 1997. A saltation model of karyotypic evolution in the Octodontoidea (Mammalia, Rodentia). Pp. 347 - 365 in Chromosomes today (H. Henriques-Gil, J. S. Parker, and M. J. Puertas, eds.). Vol. 12. Chapman & Hall, London, United Kingdom.","ROSSI, M. S., O. A. REIG, AND J. ZORZoPULOS. 1990. Evidence for rollingcircle replication in a major satellite DNA from the South American rodents of the genus Ctenomys. Molecular Biology and Evolution 7: 340 - 350.","GALLARDO, M. H., R. A. OJEDA, C. GONZALEZ, AND C. RiOS. 2007. The Octodontidae revisited. Pp. 695 - 719 in The quintessential naturalist: honoring the life and legacy of Oliver Pearson (D. A. Kelt, E. P. Lessa, J. A. Salazar-Bravo, and J. L. Patton, eds.). University of California Publications in Zoology, Berkeley.","GALLARDO, M. H., J. W. BICKHAM, G. KAUSEL, N. KoHLER, AND R. L. HONEYCUTT. 2003. Gradual and quantum genome size shifts in the hystricognath rodents. Journal of Evolutionary Biology 16: 163 - 169.","MELEN, G. J., C. G. PESCE, M. S. ROSSI, AND A. R. KORNBLIHTT. 1999. Novel processing in a mammalian nuclear 28 S pre-rRNA: tissue-specific elimination of an ' intron' bearing a hidden break site. The EMBO Journal 18: 3107 - 3118.","TIRIRA, D., C. BOADA, WEKSLER, M., ANDERSON, R. P., AND GoMEZ- LAVERDE, M. 2008. Octodontomys gliroides. The IUCN Red List of Threatened Species 2008: e. T 15091 A 4493577. http: // dx. doi. org / 10.2305 / IUCN. UK. 2008. RLTS. T 15091 A 4493577. in. Accessed 24 November 2015.","OJEDA, R. A. 2012. Family Octodontidae. Pp. 189 - 191 in Libro rojo, mamiferos amenazados de la Argentina (R. A. Ojeda, V. Chillo, and G. B. Diaz Isenrath, eds.). Sociedad Argentina para el Estudio de los Mamiferos (SAREM), Buenos Aires, Argentina."]}

Don E. Wilson, Thomas E. Lacher, Jr, Russell A. Mittermeier (2016): Octodontidae. In: Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I. Barcelona: Lynx Edicions: 536-541, ISBN: 978-84-941892-3-4, DOI: http://doi.org/10.5281/zenodo.6615351

2. Kirchners’ Viscacha Rat Tympanoctomys kirchnerorum French: Octodon des Kirchner / German: KirchnerViscacharatte / Spanish: Rata vizcacha de Patagonia Taxonomy. Tympanoctomys kirchnerorum Teta et al, 2014, “ Argentina, Province of Chubut, department of Gastre, 18 km NNE by road of Los Adobes, conjunction between Ruta Provincial 58 and Zanjon El Colorado (43°13'51.6", 68°38'49.1", 517m).” This species is monotypic. Distribution. S Argentina, known distribution limited to the type locality and surrounding areas in Chubut Province. Descriptive notes. Head-body 111-136 mm, tail 111-120 mm, ear 14-15 mm, hindfoot 29-35 mm; weight 50-80 g. Kirchners’ Viscacha Rat is slightly smaller than the Red Viscacha Rat (T. barrerae). Its skull is more bowed in dorsal profile than the Red Viscacha Rat. Color of Kirchners’ Viscacha Rat is pale brown dorsally and whitish to white ventrally. Tail is relatively long (43-50% of head-body length), with a medium terminal brush. Short, thick, and whitish hairs cover forefeet and hindfeet. Oral bristle bundles are well developed. Kirchners’ Viscacha Rat has 2n = 102, similar to that of Red Viscacha Rat. Karyotype has 32 pairs of metacentric to submetecentric chromosomes and 18 pairs of subtelocentric chromosomes. Sex chromosomes could not be discriminated but probably resembled those of the Red Viscacha Rat. Sperm morphology of Kirchners’ Viscacha Rat is smaller in size but similar in shape to that of the Red Viscacha Rat. Habitat. Sandy terrain in a general badland landscape within the Chuquiraga avellanedae (Asteraceae) steppe of the Patagonian Ecoregion at an elevation of 500 m. Burrows of Kirchners’ Viscacha Rat have typical semicircular entrances c.10 cm high, are well curved above and flat below, and are usually placed under Atriplex (Amaranthaceae) bushes. Plant cover near burrows is sparse, consisting mostly of low shrubs, such as Atriplex, C. avellanedae, Prosopis sp. and Prosopidastrum sp. (both Fabaceae), and Schinus johnstonii (Anacardiaceae). Food and Feeding. There is no specific information for this species, but Kirchners’ Viscacha Rat probably feeds mainly on halophytic vegetation (e.g. Atriplex). Breeding. There is no information available for this species. Activity patterns. There is no specific information available for this species, but Kirchners’ Viscacha Rat is apparently nocturnal. Movements, Home range and Social organization. There is no specific information available for this species, but Kirchners’ Viscacha Rat is probably solitary. Status and Conservation. As a newly described species, Kirchners’ Viscacha Rat has not been assessed on The IUCN Red List. No information is available aboutits conservation status, but its very limited distribution (restricted to the type locality) together with its recent extirpation (Late Holocene) from the Chubut River Valley and potential impact of mining in central Patagonia suggest that Kirchners’ Viscacha Rat has a high risk of extinction in the short term. Bibliography. Gallardo et al. (2009), Leon et al. (1998), Ojeda et al. (2007), Pardinas et al. (2012), Sauthier et al. (2009), Teta et al. (2014).

9. Coastal Degu Octodon lunatus French: Octodon a dents de lune / German: Kistendegu / Spanish: Degu de costa Other common names: Moon-toothed Degu Taxonomy. Octodon lunatus Osgood, 1943, “Olmue, Province of Valparaiso, Chile.” M. Tamayo and D. Frassinetti in 1980 included O. lunatus in O. bridgesii. The two are very similar and hard to distinguish, but O. lunatus has a karyotype distinct from O. bridgesii. Monotypic. Distribution. Chile’s Coastal Mountain Range W of the Central Valley, from Bosque Fray Jorge National Park (Coquimbo Region) to Quilpué (Valparaiso Region). Descriptive notes. Head—body 167-221 mm, tail length 152-161 mm; weight averaging 233 g. Proportions and color of the Coastal Degu are similar to Bridges’s Degu (O. bridgesii). Tail of the Coastal Degu is straight and shorter than head-body length (45% ofits total length), with a terminal brush. Ears are large. Pelage is dense and is a uniform ocher-brown, with white spots under axillary and inguinal parts. Chromosome complement is 2n = 78, FN = 114. Habitat. Rocky areas with dense scrublands and small forests along the coast from sea level to 1200 m. Food and Feeding. The Coastal Degu is mainly herbivorous and eats leaves, seeds, grass, and small amount of insects. In Tiltil (Santiago Metropolitan Region), diet is 75% plant tissue, 23% seeds, and 2% insects. Breeding. There is no information available for this species. Activity patterns. Apparently the Coastal Degu has variable activity patterns. Some authors reported crepuscular-nocturnalactivity, while others studies suggested diurnal activity. Movements, Home range and Social organization. There is no information available for this species. Status and Conservation. Classified as Near Threatened on The IUCN Red List. The Coastal Degu was classified as Vulnerable in 2008. Major threat is loss of habitat from agricultural expansion and livestock grazing. Bibliography. Iriarte (2008), Lessa et al. (2010), Munoz-Pedreros (2000), Munoz-Pedreros & Yanez (2009), Osgood (1943), Spotorno et al. (1995), Tamayo & Frassinetti (1980), Woods & Kilpatrick (2005)., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Octodontidae, pp. 536-541 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on pages 540-541, DOI: 10.5281/zenodo.6615351

3. Golden Viscacha Rat Pipanacoctomys aureus French: Octodon doré / German: Goldene Viscacharatte / Spanish: Rata vizcacha dorada Taxonomy. Pipanacoctomys aureus Mares et al., 2000, “28 km S, 9-3 km W Andalgala; Departamento Poman, Catamarca Province, Argentina, 27° 50’ 03” 8° 66’ 15” 59” W; elevation 680 m,” Salar de Pipanaco, Saujil Department. R. M. Barquez and colleagues in 2002 treated it as Tympanoctomys based on morphological characteristics, howeverit lacks of a formal description. C. A. Woods and C. W. Kilpatrick in 2005 and M. H. Gallardo and colleagues in 2007 have continued to recognize Pipanacoctomys as a valid genus. This last revision has been followed here. Morphological data suggest a sister taxon relationship with Salinoctomys and very close relationship with Tympanoctomys. Monotypic. Distribution. NW Argentina, known only from the type locality in the Salar de Pipanaco, S Catamarca Province. Descriptive notes. Head—body 166-178 mm,tail 127-145 mm, ear 19-22 mm, hindfoot 32-40 mm. The Golden Viscacha Rat is medium-sized to large-sized. It has large and inflated auditory bullae. Dorsal pelage is golden blond, and venteris white to pale cream. Tail is long (76-85% ofits head-body length), with well-developed terminal rufous brush. Whitish hairs cover forefeet and hindfeet. Buccal bristles are present but not as developed as in the Red Viscacha Rat (7. barrerae). The Golden Viscacha Rat has a karyotype of 2n = 92, with 44-45 pairs of biarmed chromosomes and a biarmed X-chromosome and uniarmed Y-chromosome. Habitat. Edge ofsalt pans associated with peri-saline shrublands of Heterostachys sp., Atriplex lampa, and Suaeda divaricata (all Amaranthaceae). The Golden Viscacha Rat lives in a restricted, narrow band of halophytic plants that lays between bare salt flats and more typical Monte Desert habitats of Prosopis (Fabaceae), Larrea (Zygophyllaceae), and other shrubs of the Monte. Complex burrow systems are shallow and have several openings. Food and Feeding. The Golden Viscacha Rat is herbivorous and specializes on halophytic plants. It forages on Heterostachysritteriana, which has compressed leaves that form small, salt-filled balls. High salt content of these leaves cannot be reduced via mechanical means (as can leaves of Atriplex) and buccal brushes of Pipanacoctomys seem to be less well developed than those of Tympanoctomys. Breeding. Birth of a Golden Viscacha Rat was observed in October. Newborn was well haired, and eyes and ears were open within a few hours after birth. Activity patterns. There is no specific information for this species, but the Golden Viscacha Rat is considered to be nocturnal. Movements, Home range and Social organization. The Golden Viscacha Ratis ground dwelling, and apparently more than one individual can inhabit a single mound—different from the Red Viscacha Rat. Status and Conservation. Classified as Critically Endangered on The IUCN Red List. Extent of occurrence of the Golden Viscacha Rat is less than 100 km?, and its area of occupancy is less than 10 km®. All individuals occurin a single location, and extent and quality of habitat continues to decline there. Major threat to the Golden Viscacha Rat is loss of habitat to expanding olive plantations. Bibliography. Barquez et al. (2002), Gallardo et al. (2007), Mares, Braun et al. (2000), Mares, Morello & Goldstein (1985), Ojeda & Bidau (2013g), Woods & Kilpatrick (2005).

12. Chilean Rock Rat Aconaemys fuscus French: Tunduco du Chili / German: Stidamerikanische Felsenratte / Spanish: Tunduco de Chile Other common names: Great Rock Rat Taxonomy. Schizodon fuscus Waterhouse, 1842, “from Chile.” Modified by G. R. Waterhouse in 1848 to the Valle de las Cuevas near the Volcano of Peteroa, Argentina. G. R. Waterhouse in 1842 described A. fuscus based on two specimens collected by T. Bridges but never designated a type specimen, which was formally designed by O. Thomas in 1927. O. P. Pearson in 1984 summarized taxonomic history of A. fuscus. Monotypic. Distribution. Andean areas of C Chile, between Curic6 (Maule Region) and Temuco (Araucania Region) and CW Argentina (Mendoza Province), between 33° S and 41°S. Descriptive notes. Head-body 150-170 mm,tail 55-78 mm, ear 8-12 mm; weight 80-230 g. The Chilean Rock Ratis small-sized to medium-sized. Tail is relatively short (31% of its total length), without a terminal tuff, unlike other species of octodontids. Ears are small. Forelegs are strong, with long claws. Pelage is dark brown dorsally, and venteris lighter brownish yellow. Hands and feet are grayish. Karyotype is 2n = 56, FN = 108. Habitat. Rocky outcrops in highland forests of Araucaria araucana (Araucariaceae) to above Andean tree and shrub lines and flat, sandy areas covered with xerophytic shrubs and grasses such as Poa lanuginosus (Poaceae), Acacia caven (Fabaceae), Ephedra (Ephedraceae), Rosa, and Rubus (both Rosaceae), at elevations of 1000-4000 m. Food and Feeding. The Chilean Rock Rat is herbivorous and eats mainly grasses, seeds, bulbs, and roots. It also feeds on pine nuts and roots of A. aracucana and subterranean bulbs of Amarylidaceae and Alstromeriaceae. It can accumulate and store food in chambers in their burrows. Breeding. Newborn young and pregnant female Chilean Rock Rats have been recorded in spring (October-November). Activity patterns. The Chilean Rock Rat is mainly nocturnal, although daytime activity has also been reported. They only leave their burrows during the day, searching for food or to take short excursions. They have high frequency vocalizations., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Octodontidae, pp. 536-541 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on page 541, DOI: 10.5281/zenodo.6615351

7. Bridges’s Degu Octodon bridgesii French: Octodon de Bridges / German: Walddegu / Spanish: Degu de Bridges Other common names: Bridges's Octodon Taxonomy. Octodon bridgesii Waterhouse, 1845, “Chile.” Restricted by O. Thomas in 1927 to “Rio Teno, Colchagua,” O’Higgins, Chile. This species is monotypic. Distribution. Chile’s Coastal Mountain Range in Cauquenes (Maule Region), Tomé (Bio Bio Region), and Nahuelbuta National Park (L.a Araucania Region) W of the Central Valley, and through the Chilean Andes from Banos de Cauquenes (O’Higgins Region) to Banos del Rio Blanco (La Araucania Region) and adjacent Argentina (Lanin National Park, Neuquén Province). Latitudinal range 34-40° S. Descriptive notes Head-body 150-200 mm, tail length 102-167 mm; weight averaging 92 g. Bridges’s Degu is medium-sized. Ears are large. Tail is short (44-46% ofits total length) and straight, with a terminal brush of black hairs. Pelage is soft and is ocherbrown, with white spots underaxillary and inguinal parts. Karyotype is 2n = 58, FN = 116. Habitat. Rocky and dense scrublands in Chile and dense forests, especially of Nothofagus (Nothofagaceae), in Argentina, at elevations from sea level to 1200 m. Bridges’s Degu prefers low densities oftrees, bare ground, and dead branches. It is scansorial but can climb and build nests in vegetation. In Chile, habitats are dominated by Baccharis sp. and Podanthus mitiqui (both Asteraceae); Aristotelia chilensis (Elaeocarpaceae); Eupatorium salvia (Asteraceae); Lithraea caustic and Schinus latifolius (both Anacardiaceae); Adesmia arborea (Fabaceae); and Beilschmiedia miersii (Lauraceae). Food and Feeding. Bridges’s Degu is herbivorous and eats leaves, seeds, and grasses. The most important item on the diet is Pinus radiata (Pinaceae). Breeding. Reproductive activity of Bridges’s Degu occurs in April-December. Litter sizes are 2-3 young. Activity patterns. Bridges’s Degu is nocturnal. It can climb with help from its straight tail that rests on the ground. It is rarely seen, but its presence can be detected by its noisy alarm calls. Movements, Home range and Social organization. Average home range of the Bridges’s Degu is estimated to be 1242 m*. Status and Conservation. Classified as Vulnerable on The IUCN Red List. Major threat to Bridges’s Degu is deforestation from forestry and agricultural activities. It disappeared from the Andean range in central Chile due to habitat clearing for horticultural development, and it was extirpated in the coastal range by local intensification of agriculture in areas previously unused by local farmers. Bibliography. Gallardo (1992), Gallardo et al. (2007), Iriarte (2008), Munoz & Murua (1987), Munoz-Pedreros (2000), Mufoz-Pedreros & Yanez (2009), Ojeda & Bidau (2013c), Pearson (1995), Podesta et al. (2000), Redford & Eisenberg (1992), Saavedra (2003), Simonetti (1989a, 1994), Simonetti & Saavedra (1998), Thomas (1927a), Verzi & Alcover (1990), Waterhouse (1845)., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Octodontidae, pp. 536-541 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on page 540, DOI: 10.5281/zenodo.6615351

4. Chalchalero Viscacha Rat Salinoctomys loschalchalerosorum French: Octodon des Chalchaleros / German: Chalchaleros-Viscacharatte / Spanish: Rata vizcacha de Los Chalchaleros Taxonomy. Salinoctomys loschalchalerosorum Mareset al., 2000, “26 km SW Quimilo, Departamento Chamical, La Rioja Province, Argentina, (30° 02’ 43.4” S, 65° 31’ 13.4” W; elevation 581 m. ” R. M. Barquez and colleagues in 2002 treated it as Tympanoctomys based on morphological characteristics, howeverit lacks of a formal description. C. A. Woods and C. W. Kilpatrick in 2005 and M. H. Gallardo and colleagues in 2007 have continued to recognize Salinoctomys as a valid genus. This last revision has been followed here. Morphological analyses suggest that Salinoctomys, which is not represented in any molecular analysis, is member of the desert-adapted clade (Octomys [Tympanoctomys + Pipanacoctomys]), with a sister relationship with Pipanacoctomys. Monotypic. Distribution. W Argentina, known only from the type locality in NE La Rioja Province. Descriptive notes. Head-body 144-156 mm, tail 111-119 mm, ear 17 mm, hindfoot 28-30 mm. The Chalchalero Viscacha Rat is medium-sized. It has large and inflated auditory bullae. Pelage is brownish black dorsally and white ventrally. Tail is long (more than 75% of head-body length) with black tuft. Whitish to pale brownish hairs cover forefeet and hindfeet. Buccal bristles are present, but they are not well developed. Karyotype is unknown. Habitat. Peri-saline shrublands associated with the Salinas Grandes salt flat at elevations of 500-600 m. The Chalchalero Viscacha Ratlives in a burrow system restricted to a narrow band of halophytic plants thatlies between bare salt flat and dense thornscrub of cacti, trees, and shrubs, typical of the Gran Chaco. Food and Feeding. The Chalchalero Viscacha Rat specializes on halophytic vegetation and seems to forage mainly on Heterostachys ritteriana (Amaranthaceae)—often most abundant in the immediate vicinity of its burrow system. It has been found in food stores in burrows. Breeding. A pregnant Chalchalero Viscacha Rat with two embryos was collected in July. Activity patterns. There is no information available for this species. Movements, Home range and Social organization. There is no information available for this species. Status and Conservation. Classified as Critically Endangered on The IUCN Red List. Extent of occurrence of the Chalchalero Viscacha Rat is less than 100 km?, and its area of occupancy is less than 10 km? All known individuals are in a single location, and extent and quality of its habitat continues to decline. Bibliography. Barquez et al. (2002), Gallardo et al. (2007), Mares et al. (2000), Ojeda & Bidau (2013h), Woods & Kilpatrick (2005).

2. Kirchners’ Viscacha Rat Tympanoctomys kirchnerorum French: Octodon des Kirchner / German: KirchnerViscacharatte / Spanish: Rata vizcacha de Patagonia Taxonomy. Tympanoctomys kirchnerorum Teta et al, 2014, “ Argentina, Province of Chubut, department of Gastre, 18 km NNE by road of Los Adobes, conjunction between Ruta Provincial 58 and Zanjon El Colorado (43°13'51.6", 68°38'49.1", 517m).” This species is monotypic. Distribution. S Argentina, known distribution limited to the type locality and surrounding areas in Chubut Province. Descriptive notes. Head-body 111-136 mm, tail 111-120 mm, ear 14-15 mm, hindfoot 29-35 mm; weight 50-80 g. Kirchners’ Viscacha Rat is slightly smaller than the Red Viscacha Rat (T. barrerae). Its skull is more bowed in dorsal profile than the Red Viscacha Rat. Color of Kirchners’ Viscacha Rat is pale brown dorsally and whitish to white ventrally. Tail is relatively long (43-50% of head-body length), with a medium terminal brush. Short, thick, and whitish hairs cover forefeet and hindfeet. Oral bristle bundles are well developed. Kirchners’ Viscacha Rat has 2n = 102, similar to that of Red Viscacha Rat. Karyotype has 32 pairs of metacentric to submetecentric chromosomes and 18 pairs of subtelocentric chromosomes. Sex chromosomes could not be discriminated but probably resembled those of the Red Viscacha Rat. Sperm morphology of Kirchners’ Viscacha Rat is smaller in size but similar in shape to that of the Red Viscacha Rat. Habitat. Sandy terrain in a general badland landscape within the Chuquiraga avellanedae (Asteraceae) steppe of the Patagonian Ecoregion at an elevation of 500 m. Burrows of Kirchners’ Viscacha Rat have typical semicircular entrances c.10 cm high, are well curved above and flat below, and are usually placed under Atriplex (Amaranthaceae) bushes. Plant cover near burrows is sparse, consisting mostly of low shrubs, such as Atriplex, C. avellanedae, Prosopis sp. and Prosopidastrum sp. (both Fabaceae), and Schinus johnstonii (Anacardiaceae). Food and Feeding. There is no specific information for this species, but Kirchners’ Viscacha Rat probably feeds mainly on halophytic vegetation (e.g. Atriplex). Breeding. There is no information available for this species. Activity patterns. There is no specific information available for this species, but Kirchners’ Viscacha Rat is apparently nocturnal. Movements, Home range and Social organization. There is no specific information available for this species, but Kirchners’ Viscacha Rat is probably solitary. Status and Conservation. As a newly described species, Kirchners’ Viscacha Rat has not been assessed on The IUCN Red List. No information is available aboutits conservation status, but its very limited distribution (restricted to the type locality) together with its recent extirpation (Late Holocene) from the Chubut River Valley and potential impact of mining in central Patagonia suggest that Kirchners’ Viscacha Rat has a high risk of extinction in the short term. Bibliography. Gallardo et al. (2009), Leon et al. (1998), Ojeda et al. (2007), Pardinas et al. (2012), Sauthier et al. (2009), Teta et al. (2014)., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Octodontidae, pp. 536-541 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on page 538, DOI: 10.5281/zenodo.6615351

4. Chalchalero Viscacha Rat Salinoctomys loschalchalerosorum French: Octodon des Chalchaleros / German: Chalchaleros-Viscacharatte / Spanish: Rata vizcacha de Los Chalchaleros Taxonomy. Salinoctomys loschalchalerosorum Mareset al., 2000, “26 km SW Quimilo, Departamento Chamical, La Rioja Province, Argentina, (30° 02’ 43.4” S, 65° 31’ 13.4” W; elevation 581 m. ” R. M. Barquez and colleagues in 2002 treated it as Tympanoctomys based on morphological characteristics, howeverit lacks of a formal description. C. A. Woods and C. W. Kilpatrick in 2005 and M. H. Gallardo and colleagues in 2007 have continued to recognize Salinoctomys as a valid genus. This last revision has been followed here. Morphological analyses suggest that Salinoctomys, which is not represented in any molecular analysis, is member of the desert-adapted clade (Octomys [Tympanoctomys + Pipanacoctomys]), with a sister relationship with Pipanacoctomys. Monotypic. Distribution. W Argentina, known only from the type locality in NE La Rioja Province. Descriptive notes. Head-body 144-156 mm, tail 111-119 mm, ear 17 mm, hindfoot 28-30 mm. The Chalchalero Viscacha Rat is medium-sized. It has large and inflated auditory bullae. Pelage is brownish black dorsally and white ventrally. Tail is long (more than 75% of head-body length) with black tuft. Whitish to pale brownish hairs cover forefeet and hindfeet. Buccal bristles are present, but they are not well developed. Karyotype is unknown. Habitat. Peri-saline shrublands associated with the Salinas Grandes salt flat at elevations of 500-600 m. The Chalchalero Viscacha Ratlives in a burrow system restricted to a narrow band of halophytic plants thatlies between bare salt flat and dense thornscrub of cacti, trees, and shrubs, typical of the Gran Chaco. Food and Feeding. The Chalchalero Viscacha Rat specializes on halophytic vegetation and seems to forage mainly on Heterostachys ritteriana (Amaranthaceae)—often most abundant in the immediate vicinity of its burrow system. It has been found in food stores in burrows. Breeding. A pregnant Chalchalero Viscacha Rat with two embryos was collected in July. Activity patterns. There is no information available for this species. Movements, Home range and Social organization. There is no information available for this species. Status and Conservation. Classified as Critically Endangered on The IUCN Red List. Extent of occurrence of the Chalchalero Viscacha Rat is less than 100 km?, and its area of occupancy is less than 10 km? All known individuals are in a single location, and extent and quality of its habitat continues to decline. Bibliography. Barquez et al. (2002), Gallardo et al. (2007), Mares et al. (2000), Ojeda & Bidau (2013h), Woods & Kilpatrick (2005)., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Octodontidae, pp. 536-541 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on page 539, DOI: 10.5281/zenodo.6615351

6. Mountain Degu Octodontomys gliroides French: Octodon a longue queue / German: Pinselschwanzratte / Spanish: Degu del Monte Other common names: Chozchori, Long-tailed Octodon Taxonomy. Octodon gliroides P. Gervais & d’Orbigny, 1844, “des Andes boliviennes, a Lapaz,” La Paz, Bolivia. Phylogenetic position of Octodontomys remains uncertain. Most molecular studies support a sister relationship with the Chilean clade (Octodon [Aconaemys + Spalacopus]), while others place it basal to the desert-adapted Argentinean clade (Octomys [Tympanoctomys + Pipanacoctomys]). Monotypic. Distribution. Andean and sub-Andean zones of SW Bolivia, N Chile, and NW Argentina. Descriptive notes. Head-body 161-182 mm, tail 100-190 mm; weight 100-200 g. The Mountain Degu is mediumsized to large-sized. Skull is nearly similar to that of species of Octomys. Rostrum is relatively long and narrow. Tympanic bullae are large and well developed, like other desert-adapted octodontids. Pelage is long and silky. Dorsal fur is grayish brown, and venteris white, with gray bases to hairs. Chin and throat are pure white. Ears are large and covered with short grayish hairs. Tail is long (c.80% of head-body length) and bicolored, with well-developed, brown-ocher brush extending from tip. Chromosome complement is 2n = 38, FN = 64. Habitat. Open, xeric, and rocky areas of the Puna, dominated by columniform cacti (Browningia, Cereus, Trichocereus, and Opuntia, Cactaceae), shrubs, and herbaceous plants, at elevations of 2000-5000 m. The Mountain Degu is a scansorial species, but it can make superficial burrows in patches of columnar and ground-level cacti or shrubs, where they feed on vegetation, hide from predators, and rear offspring. Tail is used for substrate support when climbing. Food and Feeding. The Mountain Degu is herbivorous and eats on cacti and pods and seeds of acacia (Acacia, Fabaceae). Individuals feed on acacia sheaths in winter and cactus fruits in summer; they also eat leaves and bark of resinous shrubs and can use cactus tissues to satisfy water requirements. Breeding. Gestation of the Mountain Degu is 100-109 days, with litter sizes of 1-3 offspring. Precocial young are born completely furred and with open eyes. Juveniles in various stages of development have been found in November, and pregnant females and young in January and May. Activity patterns. The Mountain Degu is nocturnal. Its activity is highest after sunset and decreases after sunrise. Movements, Home range and Social organization. The Mountain Degu is social and communicates with gurgles, twitters, and squeaks in low, mid-, and high frequencies. A recent study of two populations of Mountain Degus identified social groups of 2-3 or 2—4 individuals. Mountain Degus from the same social group always used one burrow system for resting and hiding. Males have larger home ranges than females. Status and Conservation. Classified as Least Concern on The IUCN Red List. The Mountain Degu has no apparent conservation threats, and it can live in areas of high human densities. It has a wide distribution and presumably a large overall population. Bibliography. Contreras, Torres-Mura, Spotorno & Walker (1994), Contreras, Torres-Mura & Yanez (1987), Diaz, G.B. & Ojeda (2000), Diaz, M.M. (1999), Gallardo (1992), Gallardo & Kirsch (2001), George & Weir (1972b), Honeycutt et al. (2003), Iriarte (2008), Mann (1978), Munoz-Pedreros (2000), Opazo (2005), Pine et al. (1979), Reig (1986), Rivera (2013), Rivera et al. (2014), Rowe etal. (2010), Tirira, Boada, Weksler et al. (2008a), Upham & Patterson (2012), Weir (1974)., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Octodontidae, pp. 536-541 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on pages 539-540, DOI: 10.5281/zenodo.6615351

1. Red Viscacha Rat Tympanoctomys barrerae French: Octodon de Barrera / German: Rote Viscacharatte / Spanish: Rata vizcacha colorada Other common names: Plains Viscacha Rat, Red Viscacha-rat Taxonomy. Octomys barrerae Lawrence, 1941, “La Paz, Mendoza Province, Argentina.” This species is monotypic. Distribution. Patchily in arid regions of W & C Argentina, known only from 13 localities in San Juan, Mendoza, La Pampa, and Neuquén provinces (between 29° S and 38° 8S). Descriptive notes. Head-body 125-160 mm, tail 93-147 mm, ear 13-19 mm, hindfoot 30-36 mm; weight 52-104 g. Males tend to be larger than females. The Red Viscacha Rat has a relatively large head; cranial width is greater than cranial length due to extremely developed auditory bullae that are more than 45% of greatest length of skull. Dorsal pelage is reddish brown; ventral pelage is white. Tail is long (82% ofits head-body length) and terminates in a black brush. Whitish hairs cover forefeet and hindfeet. It has a specialized oral bundle of rigid hairs behind upper incisors. Kidneys are specialized with an elongated renal papilla able to concentrate urine at a maximum of 7080 mOsm/liter, similar to other desert rodents that forage on halophytic vegetation. The Red Viscacha Rat has a 2n = 102, FN = 200 karyotype, the largest in both diploid and fundamental number among mammals. Karyotype is composed of completely biarmed chromosomes that include 36 pairs of metacentric to submetacentric chromosomes, 14 pairs of subtelocentric autosomes, and a XY sex chromosome system. Sperm morphology is peculiar with a paddle-like sperm head, and sperm lengths are the largest reported for rodents. The Red Viscacha Rat was proposed to be the first tetraploid mammal known, but other studies presented evidence that its genomeis diploid rather than polyploid. Habitat. Salt basins and sand dunes in the lowland habitats of Monte and Patagonian deserts at elevations of 300-1400 m. The Red Viscacha Rat lives in complex burrow systems built in soft soil associated with sand dunes and salty environments. Each burrow system has several entry holes that connect with internal tunnels and galleries. Orientation of holes changes seasonally; in winter, holes are mostly oriented toward sunlight, and galleries are constructed so that they receive direct sunlight in winter and indirect sunlight in summer. Food and Feeding. The Red Viscacha Rat has a strictly and highly specialized herbivorous diet and feeds mainly on halophytic vegetation (e.g. Atriplex, Allenrolfea, Heterostachys, and Suaeda, all Amaranthaceae). Low proportions of species of true grasses (Poaceae) are detected in diets and are eaten in lower proportions than available. The Red Viscacha Rat scrapes surfaces of Atriplex leaves with lower incisors and oral bundle of rigid hairs behind upper incisors before consumption, which helps remove and discard salt excess on leaves and reduces salt ingestion. Breeding. On average, captive female Red Viscacha Rats have four litters per year. Neonates have closed eyes and weigh 4 g at birth. At five days of age, they weighed 8 g and opened their eyes after six days. Juveniles start to consume plants at c.10 days old, although weaning is not complete. Juveniles scrape Atriplex leaves as their mothers do. Activity patterns. The Red Viscacha Rat is normally considered to be nocturnal, but it is sometimes active during the day. Movements, Home range and Social organization. The Red Viscacha Rat is a grounddwelling solitary species and occurs at low densities. One individual lives in each burrow system. Anecdotal reports indicate that a male and a female occupy the same burrow system, probably during mating; in another case, two males were trapped in the same burrow. Isolated, patchy populations of Red Viscacha Rats are, in some cases, separated by hundreds of kilometers. Status and Conservation. Classified as Near Threatened on The IUCN Red List. Several attributes of the Red Viscacha Rat (e.g. patchy distribution, habitat and trophic specialization, and low densities) increase its vulnerability. Change from Vulnerable to Near Threatened since the last assessment reflected a better understanding of its biology within its distribution. In particular, occurrence and area of occupancy (new population records) were extended. Recent studies have detected genetic distinctiveness in some populations that could have important implications for conservation and management of the Red Viscacha Rat. Bibliography. Berman (2003), Diaz & Ojeda (1999), Diaz et al. (2000), Gallardo, Bickham et al. (1999), Gallardo, Gonzalez & Cebrian (2006), Gallardo, Kausel et al. (2004), Gallardo, Sauthier et al. (2009), Giannoni et al. (2000), Grzimek (2004), Lawrence (1941), Mares, Braun & Channell (1997), Mares, Ojeda et al. (1997), Ojeda, A.A. (2010), Ojeda, A.A. et al. (2007), Ojeda, R.A. & Bidau (2013j), Ojeda, R.A. & Diaz (1997), Ojeda, R.A., Gonnet et al. (1996), Ojeda, R.A., Roig et al. (1989), Reca et al. (1996), Sauthier et al. (2009), Svartman et al. (2005), Torres et al. (2003), Torres-Mura et al. (1989), Verzi et al. (2002), Woods & Kilpatrick (2005), Yepes (1942)., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Octodontidae, pp. 536-541 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on page 538, DOI: 10.5281/zenodo.6615351

11. Porter’s Rock Rat Aconaemys porter French: Tunduco de Porter / German: PorterFelsenratte / Spanish: Tunduco de Porter Taxonomy. Aconaemys porteri Thomas, 1917, “Osorno, S. Chile,” slopes of Volcan Osorno, Los Lagos Region. O. P. Pearson in 1984 synonymized A. porteri with A. fuscus, but M. H. Gallardo and D. Reise in 1992 confirmed that the two were morphologically and chromosomally distinct species. Based on molecular data, A. porteri is clearly distinct from the other two species of Aconaemys and has a basal phylogenetic position to the sister pair of A. fuscus and A. sagei. Monotypic. Distribution. Andes of Argentina and Chile, in Chile it occurs from Villarica to Puyehue volcanoes (Los Lagos Region) and in Argentina it extends from Lanin to Nahuel Huapi national parks (Neuquén Province). Descriptive notes. Head-body 148-192 mm, tail 68-85 mm, ear 20-22 mm, hindfoot 30-37 mm; weight 105-160 g. Ears are small. Forelegs have long claws. Pelage is dark brown dorsally and bright rufous on ventral parts. Main feature of dentition is long and wide incisors. Karyotype is 2n = 58, FN= 112. Habitat. Mountain plains with gentle slopes, occurring in dense bamboo and southern beech forests (Nothofagus dombeyi, Nothofagaceae) at elevations of 900-2000 m. Food and Feeding. Porter’s Rock Rat is herbivorous and feed on leaves, sprouts,little branches of bamboo, and pine nuts of araucarias. Breeding. There is no specific information for this species, but an anecdotal report indicated that one female Porter’s Rock Rat had three embryos at the end of October. Activity patterns. Porter’s Rock Rat is mainly nocturnal, but it can be active during the day. During winter,it is active under snow. Movements, Home range and Social organization. Porter’s Rock Ratis colonial and fossorial. It builds networks of interconnected superficial tunnels, with entrances 1 m from each other. It lives in small groups of up to seven individuals in communal burrow systems. In some burrows, thin bamboo stems and aggregations offeces are found. Porter’s Rock Rat makes a very strong group squeak. Status and Conservation. Classified as Data Deficient on The IUCN Red List. There is an absence of information about recent extent of occurrence, conservation threats, and ecological requirements. Porter’s Rock Rat is considered rare in the Los Lagos Region of Chile. Bibliography. Chapman (2008), Gallardo & Reise (1992), Honeycutt et al. (2003), Ipinza et al. (1971), Iriarte (2008), Munoz-Pedreros (2000), Opazo (2005), Pearson (1983, 1984), Thomas (1917a), Woods & Kilpatrick (2005)., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Octodontidae, pp. 536-541 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on page 541, DOI: 10.5281/zenodo.6615351

10. Common Degu Octodon degus French: Octodon du Chili / German: Degu / Spanish: Degli comun Other common names: Degu Taxonomy. Sciurus degus Molina, 1782, “St. Jago.” Clarified by W. H. Osgood in 1943 to “Santiago, Chile.” This species is monotypic. Distribution. NC Chile, in the lower slopes of the Andes between Atacama and Valparaiso regions (from 28° S to 35° S). Descriptive notes. Head-body 169-212 mm, tail 81-138 mm; weight 200-300 g. The Common Degu is the smallest species of Octodon. Males tend to be larger than females. Ears and eyes are large. Tail is long (40% ofthe total length) and curved and terminates in well-developed tuft with black tip. Fur is soft but coarser than in other members of the genus. Dorsal color is yellowish brown, and ventral parts are cream. Albino individuals are occasionally observed. Karyotype is 2n = 58, FN = 116. Habitat. Semiarid and Mediterranean scrubland habitats (“matorral”) on western slopes of the Andes in central Chile from sea level to 2000 m. The Common Degu occurs in open areas with limited vegetation cover, characteristic of zones with steppes dominated by Acacia caven (Fabaceae). Food and Feeding. The Common Degu is herbivorous and feeds on grasses, seeds, fruits, roots, and bark of plants such as Stipa plumosa (Poaceae), Cestrum parqui (Solanaceae), Mimosa cavenia (Fabaceae), Erodium cicutarium (Geraniaceae), Chenopodium petiolare (Amaranthaceae), Proustia cuneifolia (Asteraceae), Atriplex repanda (Amaranthaceae), and A. caven. Common Degus choose food items that reduce fiber and increase nitrogen and moisture in their diets (e.g. young leaves). They feed exclusively aboveground and have been observed climbing low shrubs while foraging. They can spend 5-6 hours/day foraging. Common Degus perform coprophagy, usually at night, which allows them to maximize their digestive efficiency. It has also been reported that Common Degus collect food and storesit in their burrows for winter consumption. Breeding. Reproduction of the Common Degu occurs in July-October. Gestation is ¢.90 days. Four to six offspring are born mainly in spring (September—October) and summer (December—January). Young are precocial, with open eyes and fur and ability to eat vegetation at c.6—10 days of age. Young are weaned at 4-5 weeks and become sexually mature at 12-16 weeks of age. In captivity, Common Degus reproduced very easily. Activity patterns. The Common Degu exhibits diurnal activity, although they are most active in morning and evening. They construct underground burrows and nest in subterranean chambers; they spend part of the time aboveground. Movements, Home range and Social organization. Common Degus are highly social and live in groups of 2-5 adult females with their young. Number of adult males per group is unclear; some authors indicate there is only one adult male per group, while others report groups with several adult males. Common Degus dig extensive communal burrow systems where members of a social group share the same burrow system, including a communal nest site. Within social groups, individuals seem to cooperate. Some individuals contribute to excavation of tunnels; in this way, they reduce per capita energetic cost of tunnel construction allowing them to construct more extensive tunnels than would be possible for one individual. They also provide communal care of young within groups. They are highly vocal and use various calls to communicate with one another, including alarm calls, mating calls, and communication between parents and young. Young Common Degus reportedly make high ultrasonic calls to elicit care from an adult. Dust bathing plays an important role in social communication among unfamiliar, same-sex conspecifics. Home ranges are small (0-04-0-71 ha). Food availability influences seasonal variation in size and location of adult homes ranges. Males and females have similar home range areas independent of season, suggesting that home ranges are influenced more by availability of food than breeding activity. Densities are c.123 ind/ha in winter and ¢.210 ind/ha in summer. Status and Conservation. Classified as a Least Concern species on The IUCN Red List. There are no major conservation threats facing the Common Degu. Bibliography. Aglero & Simonetti (1988), Contreras et al. (1987), Ebensperger (2000), Ebensperger & Bozinovic (2000a, 2000b), Ebensperger & Caiozzi (2002), Ebensperger & Hurtado (2005), Ebensperger, Hurtado et al. (2004), Ebensperger, Sobrero et al. (2008), Fernandez (1968), Fulk (1976), Iriarte (2008), Kenagy et al. (2002), Lacey & Ebensperger (2007), Lee (2004), Long (2007 2009), Mann (1978), Mella et al. (2002), Mufoz-Pedreros (2000), Ojeda & Bidau (2013e), Osgood (1943), Quirici et al. (2010), Soto-Gamboa (2004), Woods & Boraker (1975), Yanez (1976), Zunino et al. (1992)., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Octodontidae, pp. 536-541 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on page 541, DOI: 10.5281/zenodo.6615351

Don E. Wilson, Thomas E. Lacher, Jr, Russell A. Mittermeier (2016): Octodontidae. In: Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I. Barcelona: Lynx Edicions: 536-541, ISBN: 978-84-941892-3-4, DOI: http://doi.org/10.5281/zenodo.6615351

5. Common Viscacha Rat Octomys mimax French: Octodon vizcacha / German: Viscacharatte / Spanish: Rata vizcacha del Monte Other common names: Mountain Viscacha Rat, Viscacha Rat Taxonomy. Octomys mimax Thomas, 1920, “La Puntilla, near Tinogasta...a few miles | out from Tinogasta toward Copacabana, at an altitude of about 1000 metres,” Catamarca Province, Argentina. No fossils of O. mimax are known. Monotypic. Distribution. W Argentina, in Catamarca, La Rioja, San Juan, San Luis, and Mendoza provinces. Descriptive notes. Head-body 140-330 mm,tail 105-179 mm, ear 21-4-27-4 mm, hindfoot 32:3-36-6 mm; weight averaging 95-8 g. No sexual dimorphism in body weight. The Common Viscacha Rat is mediumsized. Skull is long and slender, with large and well-developed tympanic bullae butless developed than in species of Tympanoctomys. Dorsal fur is light brown and venteris white. Tail is long (c.50% ofits total length), bicolored, and hairy, with conspicuous terminal tuft. Oral vibrissae are present, but function is unknown. Chromosome complement is 2n = 56, FN = 108. Karyotype is composed of five small submetacentric chromosomes, 21 small metacentric chromosomes, and one small subtelocentric chromosome. Xand Y-chromosomes are a small subtelocentric and medium-sized metacentric, respectively. Habitat. [Lowland deserts with abundant rocks, foothills, low scrub areas, ravines, and gorges at elevations up to 800 m. The Common Viscacha Ratis a saxicolous and surface-dwelling rodent; it is a habitat specialist that lives and constructs burrows in rock formations. It also occurs in rocky macrohabitats with creosote bush (Larrea, Zygophyllaceae), “chical” (rocky substrate dominated by Ramorinoa girolae, Fabaceae, a species endemic to the temperate Monte Desert), and columnar cactus slopes. Food and Feeding. The Common Viscacha Ratis strictly herbivorous. Diets are mainly leaves of shrubs and trees but include cacti throughout the year and seeds and fruits, principally Prosopis (Fabaceae), in the wet season. They also include Larrea, cacti, species of Amaranthaceae, and drupe-type fruits (e.g. Lycium, Solanaceae) from which it may obtain preformed water. Diet also includes seedsrich in carbohydrates, a potential source of metabolic water (e.g. Prosopis). Breeding. Most observations regarding breeding of Common Viscacha Rats are anecdotal from captured young individuals in the same trap in November at Valle de la Luna, San Juan Province; they suggest that breeding occurs at the end of winter (August) or beginning of spring (September). Activity patterns. Common Viscacha Rats are nocturnal and most active after sunset; activity decreases substantially after sunrise. They are good thermoregulators, enabling nocturnal activity. Ambient temperatures can drop below freezing at nightin the Monte Desert. Individuals use rock crevices for refuge and resting sites because they provide thermally stable environments (especially in summer). Movements, Home range and Social organization. The Common Viscacha Rat ranges over large areas and exhibits low spatial overlap; overlap among conspecificsis similar for both sexes. Average home ranges (males and females combined) are 12,370 m? however, male Common Viscacha Rats have larger home ranges than females. Common Viscacha Rats are solitary and do not share resting sites during the day. Status and Conservation. Classified as a Least Concern on The IUCN Red List. Updated information on status of populations of the Common Viscacha Rat is needed, and if current agricultural trends persist, it may qualify for a Near Threatened status. It was considered as Vulnerable in a regional IUCN assessment of threatened mammals in Argentina. Bibliography. Berman (2003), Bozinovic & Contreras (1990), Campos & Giannoni (2013), Campos, Andino et al. (2013), Campos, Giannoni et al. (2015), Contreras et al. (1994), Ebensperger et al. (2008), Gallardo (1992), Gallardo et al. (2007), Mares (1980), Mares et al. (2000), Ojeda, A.A. et al. (2013), Ojeda, R.A. & Bidau (2013f), Ojeda, R.A., Borghi & Roig (2002), Ojeda, R.A., Gonnet et al. (1996), Oyarce et al. (2003), Redford & Eisenberg (1992), Sobrero et al. (2010), Woods & Kilpatrick (2005)., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Octodontidae, pp. 536-541 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on page 539, DOI: 10.5281/zenodo.6615351

Rivera, Daniela S., Vianna, Juliana A., Ebensperger, Luis A., Palma, R. Eduardo (2016): Phylogeography and demographic history of the Andean degu, Octodontomys gliroides (Rodentia: Octodontidae). Zoological Journal of the Linnean Society 178 (2): 410-430, DOI: 10.1111/zoj.12412, URL: http://dx.doi.org/10.1111/zoj.12412

Rodents are important components of nearly every terrestrial ecosystem and display considerable ecological diversity. Nevertheless, a lack of data on the ecomorphology of rodents has led to them being largely overlooked in palaeoecological reconstructions. Here, geometric and linear morphometrics are used to examine how cranial and dental shapes reflect the diets of living rodent species. Although most rodents are omnivores or generalist herbivores, some species have evolved highly specialized carnivorous, insectivorous, and herbivorous diets. Results show that living rodents with similar diets display convergent morphology, despite their independent evolutionary histories. Carnivores have relatively elongate incisors, elongate and narrow incisor blades, orthodont incisor angles, reduced cheek tooth areas, and enlarged temporal fossae. Insectivores display relatively degenerate dentition, elongate rostra, narrow and thin zygomatic arches, and smaller temporal fossae. Herbivores are characterized by relatively broader incisor blades, longer molar tooth rows, larger cheek tooth areas, wider skull and rostrum, thicker and broader zygomatic arches, and larger temporal fossae. These results suggest that cranial and dental morphology can be used to accurately infer extinct rodent diets regardless of ancestry. Application to extinct beavers suggests that most had highly specialized herbivorous diets.

Sciamys Ameghino, 1887 Included species. Sciamys principalis Ameghino, 1887, Santacrucian; Sciamys varians Ameghino, 1887, Santacrucian; Sciamys robustus Ameghino, 1894, Santacrucian; Sciamys rostratus Scott, 1905, Santacrucian; Sciamys latidens Scott, 1905, Santacrucian., Published as part of Arnal, Michelle & P��rez, Mar��a E., 2013, A new acaremyid rodent (Hystricognathi: Octodontoidea) from the middle Miocene of Patagonia (South America) and considerations on the early evolution of Octodontoidea, pp. 119-134 in Zootaxa 3616 (2) on page 123, DOI: 10.11646/zootaxa.3616.2.2, http://zenodo.org/record/222757

Sciamys petisensis sp. nov. (Figures 2 A, 3 A, 4) Holotype. MPEF-PV 3560, right mandibular fragment with p 4 -m 3. Referred material. MPEF-PV 3561, right mandibular fragment with dp 4 -m 1; MPEF-PV 3562, left mandibular fragment with p 4 -m 3; MPEF-PV 3563, left mandibular fragment with m 1 -m 3; MPEF-PV 3564, right mandibular fragment with i, posterior lobe of m 1, and m 2; MPEF-PV 3565, right mandibular fragment with i, posterior lobe of m 1, and m 2; MPEF-PV 3566, left mandibular fragment with i, dp 4 -m 2. Diagnosis. Medium size octodontoid, somewhat larger and higher crowned than Sciamys principalis, Galileomys antelucanus, and Acaremys murinus; dp 4 with the posterolabial corner of the protoconid forming a right angle; p 4 with an ephemeral or without a flexid on the anterior face of the tooth separating protoconid from metaconid unlike other acaremyids, mesolophid? more developed than in S. principalis, and rudimentary hypolophid. Molars with metalophulid II longer and extending from the ectolophid in a more posterior position, near the hypolophid, delimiting a broader anterofossettid than in others acaremyids. Mandible with the notch for the insertion of the tendon of the masseter medialis pars infraorbitalis muscle oblique anterodorsal���posteroventrally and aligned with the masseteric crest, unlike S. principalis. Anterior portion of the masseteric fossa shallower than in A. murinus. Locality and horizon. Materials were found in the locality El Petiso, Northwestern of Chubut Province, central Patagonia, Argentina (Fig. 1; Villafa��e et al. 2008; P��rez 2010). The faunal assemblage found at this locality indicates a middle Miocene age, probably post-Colloncuran (early���middle Miocene; Villafa��e et al. 2008). Precise coordinates of the fossiliferous locality of the type material are housed at the MPEF-PV collections and can be obtained from one of the author (MEP) upon request. Etymology. The specific epithet refers to the locality name "El Petiso" (Chubut Province, Argentina). Description and comparison. The cheek teeth of Sciamys petisensis are higher crowned than in other acaremyids (Table 1). Cusps are strongly embedded within crests, unlike the species of Galileomys, Acaremys, and S. latidens. Lower deciduous premolar. The dp 4 morphology is in general terms as in S. principalis and A. murinus, and unlike G. eurygnathus (dp 4 of the type species of Galileomys, G. antelucanus, are unknown), since it has a well developed metalophulid II, and a reduced mesolophid. The dp 4 present a metalophulid I and a mesolophid delimiting an anterior lobe, as in other acaremyids. The ectolophid is very oblique and extends from the protoconid to the anterior arm of the hypoconid (Fig. 2 A). The mesolophid is long, unlike G. eurygnathus, and extends from the ectolophid near the hypolophid in a more posterior position than in S. principalis and A. murinus (Fig. 2 A���B). In juvenile specimens the anterofossettid is divided by an anterior-posterior oriented crest of uncertain homologies (neolophid?, Candela 2002; metalophulid II?, Arnal 2012), because it is not possible to distinguish if this crest is an anterior extension of the mesolophid as in S. principalis (Fig. 2 B) and A. murinus, or a posterior extension of the metalophulid I. The lingual fossettid is shallower than the labial one, and disappears with little wear (in Fig. 2 A this fossetid is nearly unnoticeable), while in S. principalis it is evident in the same stage of wear. Unlike other acaremyids, the posterolabial corner of the protocone forms a right angle (Fig. 2 A). The hypolophid extends lingually from the point where the ectolophid contacts the anterior arm of the hypocone, and reaches the lingual margin of the tooth. The posterolophid is anteriorly concave and is as long (transversally) as the hypolophid. The mesoflexid penetrates half of the crown, and is more posteriorly oriented and narrower than S. principalis (Fig. 2 A���B). The posteroflexid is transverse, and is as deep and penetrating as the mesoflexid, like G. eurygnathus and unlike S. principalis and A. murinus. The hypoflexid is the deepest and broadest of all flexids. Lower permanent premolar. The p 4 is more complex than in most acaremyids, except for some specimens of S. principalis, and has the typical acaremyid morphology (Vucetich & Ribeiro 2003). In the holotype of S. petisensis (MPEF-PV 3560) the metalophulid I is complete and there is no a flexid separating protoconid and metaconid (Fig. 3 A). Nevertheless, this could be by the presence of a minute flexid that disappears rapidly with wear, or by the absence of such a flexid. Regardless the case, it differs from the species of Galileomys, Acaremys and most specimens of Sciamys, where this flexid is conspicuous. From the posterior border of the protoconid extends the ectolophid that is oblique and reaches the posterolophid. A second crest in position, anterolingually oriented, extends from the ectolophid to the metaconid, delimiting a subcircular anterofossettid (Fig. 3 A). This crest seems to correspond to the mesolophid of some specimens assigned to S. principalis (Fig. 3 B) and S. varians, and its identification is based on its more posterior origin in the ectolophid (the metalophulid II, or the posterior arm of the protoconid, would has an anterior origin). An anteriorly concave posterolophid delimits the posterior rim of the tooth, as in other acaremyids. S. petisensis has a small hypolophid (Fig. 3 A) as in S. principalis and S. varians, and unlike S. latidens, that is separated from the posterolophid by a minute flexid. Lower molars. Molar morphology of S. petisensis is similar to other acaremyids, with a few differences (Fig. 2 and 3). Metalophulid I unites protoconid and metaconid and is straight, unlike S. latidens where this crest is oblique. Metalophulid II is long; unlike other acaremyids, it contacts the ectolophid in a posterior position, near the hypolophid, and extends to the metaconid delimiting a broader anterofossettid than in the species of Sciamys (Fig. 2 A���B). This anterofossettid disappears with little wear (Fig. 3 A). This is the most important character that differentiate the molars of this new species from others acaremyids; nevertheless, it is only evident in teeth without or with little wear. The posterolophid is long, reaching the lingual margin of the tooth, as in the species of Sciamys and Acaremys, and unlike species of Galileomys and Platypittamys brachyodon. As in the dp 4, the mesoflexid is little more penetrating and deeper than the posteroflexid. Hypoflexid is little posteriorly oblique and is the broadest and deepest of all flexids. As is usual in octodontoids, m 3 is labio-lingually shorter in its posterior half. This is due to a shorter posterolophid and the lingual position of the hypocone respect the protocone (Fig. 3 A). Incisors. In most specimens of S. petisensis, incisors are broken near the outer border of their alveolus. In the specimen MPEF-PV 3566 the incisor is oval in section (the tooth is broken off above m 1 alveolus). The anterior face of the tooth forms a straight medial angle, being the lateral one curved. The incisors are long and extend below the tooth row as far as m 3, where they rise up to the coronoid process, as is usual in acaremyids. Mandible. Available dentaries have some damage, and the posterior part is not preserved in any specimen. The body of the mandible, the tooth bearing horizontal part, is high and broad. Anterior to the tooth row the diastema is concave and not very deep (Fig. 3 C). The mental foramen is well developed and is located slightly in front of the deepest point of the diastema, far from the p 4 (Fig. 3 C). The notch for the insertion of the tendon of the masseter medialis pars infraorbitalis muscle (sensu Woods & Howland 1979) is long anteroposteriorly, and lies beneath p 4 - m 1 (Fig. 3 D); it is oblique unlike in species of Sciamys, and is continuously aligned with the masseteric crest (Fig. 3 D). The masseteric fossa extends forward beneath the anterior lobe of the m 1 and its anterior portion is shallower than in A. murinus, G. antelucanus, and G. eurygnathus. In the posterodorsal portion of the fossa is a rounded prominence that corresponds to the base of the incisor. The coronoid process rises at the m 3 level, and the retromolar fossa (sensu Woods & Howland 1979) is mostly posterior to the tooth row. Dental Ontogeny. The availability of specimens with different stages of wear enables us to study the ontogenetic sequences of flexid closure, as well the formation and disappearance of fossettids (Fig. 4). The MPEF-PV 3561 and MPEF-PV 3563 (Fig. 4 A���B) represent the most juvenile available specimens, since both retain the dp 4. Of the two fossettids present in the anterofossettid of the dp 4, the lingual one is shallower and disappears with little wear (Fig. 4 A). With a little more wear the labial fossetid disappears (Fig. 4 B). In MPEF-PV 3561 (an almost unworn specimen) the posteroflexid is broad and more penetrating than the mesoflexid, while in MPEF-PV 3563, which is little more-worn, the posteroflexid is narrower and less penetrating than the mesoflexid. In MPEF-PV 3561 the hypoflexid is wide, with its anterior border nearly C shaped (Fig. 4 A), while in MPEF-PV 3563 it is much narrower and U shape (Fig. 4 B). The holotype (MPEF-PV 3560) and the specimen MPEF-PV 3562 had replaced the deciduous premolars by permanent ones. Little-worn p 4 s have conspicuous anterofossettid and a distinct hypolophid (Fig. 4 C), while in more-worn premolars the anterofossettid is entirely worn away and the hypolophid is fused with the posterolophid, resulting in a simplified occlusal surface (Fig. 4 E). Unworn molars have a broad and shallow anterofossettid (Fig. 4 A) that disappears with little wear (Fig. 4 B-C). The posterolophid is long and seems to reach the lingual border of the tooth. The posteroflexid is broad and deep in unworn specimens, but with little wear it becomes narrower and less penetrating in the occlusal surface (Fig. 4 B), and in adult specimens it is transformed into an ephemeral posterofossettid (Fig. 4 C) that rapidly disappears (Fig. 4 D-E). In worn molars (Fig. 4 D) a temporary octodontiform occlusal pattern is observable, as in other acaremyids, which has led many authors to propose the acaremyids as being octodontids, or the ancestors of modern octodontids (Wood & Patterson 1959; Pascual 1967; Patterson & Wood 1982). Nevertheless, the octodontiform pattern present in acaremyids and octodontids is not homologous; in acaremyids the lingual flexid corresponds to the mesoflexid while in octodontids it is the mesoflexid+anteroflexid (the metalophulid II is reduced or absent in the latter). In most-worn specimens (Fig. 4 E) the mesoflexid is transformed into mesofossettid, except in m 3, where an octodontiform molar pattern is still present (Fig. 4 E). The hypoflexid is the deepest flexid; in most-worn specimens it remains open, and becomes more straight and transverse (Fig. 4 E). Phylogenetic analysis. The parsimony analysis resulted in one most parsimonious tree (MPT) of 40.178 steps (CI=0.600 RI= 0.727). The decimal values in the Tree lengths correspond to the use of a continuous character for the character on the degree of hypdodonty (see above). The MPT is shown in Figure 5. The only most parsimonious hypothesis of this analysis found Acaremyidae to be a monophyletic group (Fig. 5), and placed Sciamys petisensis in a sister relationship with S. principalis (Fig. 5, node 7), thereby justifying the generic assignment of the new taxon. One unambiguous synapomorphy supports this clade in the MPT: cusps not distinguishable from their respective crests (character 2 [1]). Galileomys antelucanus is the sister group of Sciamys (Fig. 5, node 6), and one unambiguous synapomorphy supports its position: degree of hypsodonty larger than 0.9 (character 1 [0.941]). Acaremys murinus is the basalmost species of Acaremyidae, and four unambiguous synapomorphies support this clade in the MPT: 1) hypoflexus in the upper premolar poorly developed (character 5 [1]); 2) presence of the figure-eight-shaped in the upper cheek teeth (character 7 [1]); 3) presence of the figure-eight-shaped in the lower cheek teeth (character 13 [1]); and, 4) presence of a conspicuous anterodorsal limit of the mandibular masseteric fossa (character 19 [1]). The topology obtained in this analysis coincides with the results of Vucetich & Kramarz (2003), in retrieving a monophyletic Acaremyidae, which is supported by the same unambiguous synapomorphies (see Appendix 3). Here, we decided to consider the figure-eight-shaped occlusal surface of the lower and upper cheek teeth as two separated characters (character 7, and 13), given that Massoiamys obliquus presents a different condition in the upper and lower toothrow [lower tooth presents an octodontiform molar pattern (MLP 76 -VIII- 30 - 2), but the upper tooth does not (MPL 91 -V- 1 -36)], demonstrating that these two characters varied independently in the evolutionary history of the group. On the other hand, unlike the results of Vucetich & Kramarz (2003), Sciamys is depicted in our analysis as more closely related to Galileomys, whereas Acaremys is the basalmost taxa of this clade. The grouping of G. antelucanus and Sciamys is supported by their more developed degree of hypsodonty (c. 1), as reflected by the hypsodonty index that here we treated as a continuous character. The support values in the strict consensus are low, but Acaremyidae is the node with the highest support values (Bremer = 1.602; jackknife absolute frequency = 69; jackknife GC frequency = 66; see fig. 5, node 5). The relationships within Acaremyidae are not strongly supported within the context of this dataset, and the treatment of the hypsodonty index as a continuous character provides information to resolve their relationships in absence of other phylogenetically informative discrete characters. It has been noted that the use of continuous characters avoids making arbitrary character state delimitations (Goloboff et al. 2006) but also their use allows using subtle morphological variations at low taxonomic levels (Escapa & Pol 2011). This is reflected in the support values of the groups within Acaremyidae. For instance the clade of Galileomys + Sciamys has lower support values (Bremer = 0.348; jackknife absolute frequency Sciamys clade (i.e., S. petisensis + S. principalis) where nodal support is low (Bremer = 0.348; jackknife absolute frequency S. petisensis were located elsewhere within the clade Acaremyidae, it would imply that the high hypsodonty of this taxon was acquired independently from that of S. principalis (or that this character had a reversal in other members of the family). Previous cladistic analyses (Vucetich & Kramarz 2003; P��rez 2010; P��rez & Pol 2012) treated the degree of hypsodonty as a discrete character, building arbitrary characters states (generally poorly defined). Nevertheless, the results obtained by Vucetich & Kramarz (2003) showed the internal relationships of Acaremyidae totally resolved using the hypsodont index as a discrete character. Our use of a continuous character to describe degree of hypsodonty is a first in studies of fossil rodents. While all measurements should ideally be taken in specimens without wear, we have taken the measurements in juvenile specimens with the least possible wear., Published as part of Arnal, Michelle & P��rez, Mar��a E., 2013, A new acaremyid rodent (Hystricognathi: Octodontoidea) from the middle Miocene of Patagonia (South America) and considerations on the early evolution of Octodontoidea, pp. 119-134 in Zootaxa 3616 (2) on pages 123-128, DOI: 10.11646/zootaxa.3616.2.2, http://zenodo.org/record/222757

Arnal, Michelle, Pérez, María E. (2013): A new acaremyid rodent (Hystricognathi: Octodontoidea) from the middle Miocene of Patagonia (South America) and considerations on the early evolution of Octodontoidea. Zootaxa 3616 (2): 119-134, DOI: http://dx.doi.org/10.11646/zootaxa.3616.2.2

We present new cytogenetic, morphometric, and sperm morphology data of eight populations belonging to the C. pundti complex from Southern Córdoba and Eastern La Pampa Provinces in Argentina. The diploid numbers ranged from 2n = 44 to 2n = 50, and C- bands revealed a pattern of centromeric and pericentromeric heterochromatin. Comparisons of G-banded karyotypes revealed that the 2n = 44 (Holmberg, Santa Catalina, Sampacho), 2n = 46 (Realicó), 2n = 48 (El Guanaco, Guatraché), 2n = 46-48 (Vicuña Mackenna), and 2n = 50 (Puente Olmos) karyotypes, are closely related. In addition, these karyotypes show a high degree of homology (95%) with C. talarum talarum, despite the fact that five chromosomal rearrangements differentiate both taxa. Discriminant Function Analysis of morphometric data allows to distinguish three clusters: i) the C. mendocinus species group, ii) C. t. talarum, and iii) populations of the C. pundti complex proposed herein. The close phylogenetic relationship between C. talarum and the C. pundti complex, which undoubtedly belong to the same evolutionary lineage, is well supported by two different kinds of evidence: the extensive chromosomal homology and the same symmetric type of sperm. The morphological and chromosomal differences show that these two forms have diverged recently. © Publications Scientifiques du Muséum national d'Histoire naturelle. Fil:Hasson, E.R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Massarini, A.I. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

STATUS OF ALTERODON MAJOR The dubious notion that Jamaica supported an endemic octodontid during the late Quaternary may be traced to Anthony’s (1920) exceedingly brief description of the holotype of Alterodon major, a species based on a single, apparently hypsodont cheektooth (AMNHP 17638) from Wallingford Roadside Cave (Manchester Parish) in central Jamaica (figs. 3, 4; see MacPhee [1984] for description and dating of faunule). In light of the new fossils described elsewhere in this paper, it is appropriate to briefly reconsider the status of Alterodon, with special reference to Spencer’s (1987) arguments in favor of an octodontid affiliation for this genus. Anthony (1920) was impressed by the fact that the holotype of Alterodon bore, in his view, a certain resemblance to the cheekteeth of Octodontidae, which are characteristically bilobate or dumbbell­shaped in cross­section. However, Anthony’s remarks amount to no more than the mere recognition of vague similarity: in his only other published remarks on the matter, Anthony (1926: 206) simply noted that Alterodon may have unspecified ‘‘affinities to Octodontidae?’’. Reference to Octodontidae was enough to get Alterodon into the biogeographical literature as an insular member of that family (e.g., Darlington, 1957), but not enough to get anyone interested in re­examining the holotype in print until MacPhee et al. (1983) did so. These authors concluded that Anthony’s interpretation was fundamentally flawed, because the holotype tooth of Alterodon is incomplete: AMNHP 17638 as preserved (fig. 3) has a fracture surface on the cementum lining its apparent distal aspect, which in our view is secure evidence that the tooth originally possessed at least one more lamella. This would make it unlike any accepted octodontid but suggestively like Clidomys, abundant remains of which occur in Wallingford Roadside Cave (MacPhee, 1984). However, as the partial tooth pattern of the Alterodon holotype did not precisely match that of any teeth assigned to Clidomys (cf. fig. 4), MacPhee et al. (1983) concluded that Alterodon might represent a different but closely related species of clidomyine. In a subsequent revision, MacPhee (1984) reconsidered this point and placed Alterodon major in synonymy with C. osborni, arguing that despite its shape the former was just another dental variant of the latter. Spencer (1987) disagreed with each of these actions, arguing that MacPhee et al. (1983) misinterpreted the amount of damage to the Alterodon holotype. Far from being extensively damaged, he argued, the tooth has lost nothing but the greater part of a thick outer covering of cementum. That is, it is nearly complete as preserved, and therefore cannot have been multilamellar. Spencer (1987: 108–109) went on to note that thick cementum sheathing is characteristic of the cheekteeth of the capromyid Isolobodon and ‘‘many octodontids’’, and that therefore ‘‘ Alterodon major could as easily be a capromyid like Isolobodon ’’ or ‘‘a remnant octodontid as maintained by Anthony.’’ Although there have been several new Clidomys discoveries in the past few years (e.g., McFarlane et al., 1998; Morgan and Wilkins, 2003), investigators have not turned up any more teeth with an Alterodon ­like morphology. Spencer’s (1987) argument must therefore be analyzed on the basis of the existing fossil evidence. While it is true that cementum sheaths covering the cheekteeth of extant octodontids and their unquestioned relatives vary in thickness, none displays a substantial local thickening of the sort seen in the Alterodon holotype —situated exactly where the interlamellar plaque of cementum ought to be if the tooth belonged to a clidomyine, as MacPhee et al. (1983) originally contended. There is an additional aspect to this. On re­examining the few intact isolated cheekteeth of Clidomys in the AMNHP collection, we noticed that, disregarding the interlamellar plaques, the cementum covering is actually very thin or absent on all surfaces. Indeed, on most teeth in the collection cementum is not present at all on free surfaces, apparently because of overly vigorous preparation on Anthony’s part. Nevertheless, it is evident that the cementum covering on the Alterodon holotype could never have been of substantial, even thickness. On this analysis the type of Alterodon actually looks very much like other teeth in the Clidomys hypodigm, and we see no reason to infer that it once had a much thicker circumferential coating of cementum. The other feature that Spencer (1987) em­ phasized is tooth pattern. Numerous examples of ‘‘unusual’’ occlusal­surface patterns in isolated cheekteeth from the Clidomys type site show that clidomyines were dentally variable (fig. 4A–J; MacPhee, 1984), a point which Morgan and Wilkins (2003) have additionally documented. To this we add the further observation that in Clidomys cheekteeth the enamel sheath of the mesialmost or distalmost lamella is occasionally interrupted or much thinner on one side than the other. In the holotype of Alterodon there are two interruptions that define a tiny splint of enamel (fig. 3B). One’s initial impression is that the interruptions are simply artifacts, but they lack fracture surfaces and can be traced continuously to the root end, where it is clear that they are developmental in origin. Such a minor, variable feature does not show beyond doubt that Alterodon is a clidomyine, but it is one more way in which its holotype fits within accepted variation in that group. How this variability ought to be reflected at lower taxonomic levels is possibly still an issue in need of resolution (see table 1), but at present there is no warrant to infer the presence of a family otherwise unrepresented in the Jamaican fossil record., Published as part of MacPhee, R. D. E. & Flemming, Clare, 2003, A Possible Heptaxodontine and Other Caviidan Rodents from the Quaternary of Jamaica, pp. 1-43 in American Museum Novitates 3422 on pages 8-11, DOI: 10.1206/0003-0082(2003)4222.0.co;2, http://zenodo.org/record/5056742, {"references":["Anthony, H. E. 1920. New mammals from Jamaica. Bulletin of the American Museum of Natural History 42: 469 - 475.","MacPhee, R. D. E. 1984. Quaternary mammal localities and heptaxodontid rodents of Jamaica. American Museum Novitates 2803: 1 - 34.","Spencer, L. 1987. Fossil Abracomidae and Octodontidae (Rodentia: Hystricina), a phylogenetic analysis. Ph. D. dissertation, Loma Linda University, California.","Anthony, H. E. 1926. Mammals of Porto Rico, living and extinct - Rodentia and Edentata. Scientific Survey of Porto Rico and the Virgin Islands 9 (2): 97 - 241. New York: New York Academy of Sciences.","Darlington, P. J. 1957. Zoogeography: the geographical distribution of animals. New York: Wiley & Sons.","MacPhee, R. D. E., C. A. Woods, and G. S. Morgan. 1983. The Pleistocene rodent Alterodon major and the mammalian biogeography of Jamaica. Palaeontology 26: 831 - 837.","McFarlane, D. A., J. Lundberg, C. Flemming, R. D. E. MacPhee, and S. - E. Lauritzen. 1998. A second pre-Wisconsinan locality for the extinct Jamaican rodent Clidomys (Rodentia: Heptaxodontidae). Caribbean Journal of Science 34: 315 - 317.","Morgan, G. S., and L. Wilkins. 2003. The extinct rodent Clidomys (Mammalia: Rodentia: Hep- taxodontidae) from a Pleistocene cave deposit in Jamaica. Caribbean Journal of Science 39: 34 - 41."]}

MacPhee, R. D. E., Flemming, Clare (2003): A Possible Heptaxodontine and Other Caviidan Rodents from the Quaternary of Jamaica. American Museum Novitates 3422: 1-43, DOI: 10.1206/0003-0082(2003)4222.0.co;2, URL: http://dx.doi.org/10.1206/0003-0082(2003)4192.0.co;2

Aconaemys fuscus (Waterhouse, 1842). Proc. Zool. Soc. Lond., 1841:91 [1842]. TYPE LOCALITY: Argentina, Mendoza Prov., Valle de las Cuevas; see comments. DISTRIBUTION: High Andes of Chile and Argentina (between 33° and 41°S). STATUS: Locally abundant. SYNONYMS: porteri. COMMENTS: Waterhouse never designated a type species, which was finally designated as a lectotype by Thomas (1917a). Waterhouse's original type locality was "from Chile ", but in 1848 he added that the locality was from the Valle de las Cuevas near the Volcano of Peteroa, which would make the locality in Argentina (Pearson, 1984). These complications make it difficult to evaluate the status of the following species. The chromosome no. is 2n=56., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 787, DOI: 10.5281/zenodo.7353083, {"references":["Thomas, O. 1917 a. A new species of Aconaemys from southern Chile. Annals and Magazine of Natural History, ser. 8, 19: 281 - 282.","Pearson, O. P. 1984. Taxonomy and natural history of some fossorial rodents of Patagonia, southern Argentina. Journal of Zoology, London, 202: 225 - 237."]}

Octomys Thomas, 1920. Ann. Mag. Nat. Hist., ser. 9, 6:117. TYPE SPECIES: Octomys mimax Thomas, 1920. COMMENTS: Formerly included Octomys barrerae, which is now separated as Tympanoctomys., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 788, DOI: 10.5281/zenodo.7353083

Aconaemys sagei Pearson, 1984. Jour. Zool. (London), 202:229. TYPE LOCALITY: Argentina, Neuquén Prov. 2 km S Cerro Quillén at Pampa de Hui Hui (1050 m). DISTRIBUTION: Known only from near Lago Quillén and Lago Hui Hui in Neuquén Prov. of Argentina, but reports suggest it might also occur in Malleco Prov. of Chile. STATUS: Locally abundant, but may have very limited distribution. COMMENTS: Much smaller than A. fuscus., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 788, DOI: 10.5281/zenodo.7353083

Octodon bridgesi Waterhouse, 1845. Proc. Zool. Soc. Lond., 1844:155 [1845]. TYPE LOCALITY: Chile, Curico Prov., Rio Teno. DISTRIBUTION: Chilean Andes from 34°15' to at least 40°S (Redford and Eisenberg, 1992). STATUS: Once common, but now quite rare (Redford and Eisenberg, 1992). COMMENTS: Massoia (1979:36) reported Octodon, perhaps bridgesi, from S Argentina. The chromosome no. is 2n=58., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 788, DOI: 10.5281/zenodo.7353083, {"references":["Redford, K. H., and J. Eisenberg. 1992. Mammals of the Neotropics, 2. The southern cone. University of Chicago Press, Chicago, IL, 430 pp."]}

Octodon degus (Molina, 1782). Sagg. Stor. Nat. Chile, p. 303. TYPE LOCALITY: Chile, Santiago Prov., Santiago. DISTRIBUTION: Chile, west slope of the Andes between Vallenar and Curico, to 1,200 m. STATUS: Common. SYNONYMS: alba, clivorum, cumingii, getulus, kutnmingii, pallidus, peruana. COMMENTS: Reviewed by Woods and Boraker (1975, Mammalian Species, 67). The chromosome no. is 2n=58., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 788, DOI: 10.5281/zenodo.7353083, {"references":["Woods, C. A., and D. Boraker. 1975. Octodon degus. Mammalian Species, 67: 1 - 5."]}

Octodon lunatus Osgood, 1943. Field Mus. Nat. Hist. Pubi., Zool. Ser., 30:110. TYPE LOCALITY: Chile, Valparaiso Prov., Olmue. DISTRIBUTION: Coastal mountains of Valparaiso, Aconcagua, and Coquimbo Provs. (Chile) between 31°30' and 35°S. STATUS: Common. COMMENTS: Included in Octodon bridgesi by Tamayo and Frassinetti (1980:354). The chromosome no. is 2n=78 (Spotorno et al., 1988)., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 788, DOI: 10.5281/zenodo.7353083, {"references":["Tamayo H., M., and D. Frassinetti C. 1980. Catalogo de los mamiferos fosiles y vivientes de Chile. Boletin de Museo Nacional de Historia Natural Chile (Santiago), 37: 323 - 399.","Spotorno O., A. E., L. Walker, L. Contreras, J. Pincheira, and R. Fernandez-Donoso. 1988. Cromosomas ancestrales en Octodontidae y Abrocomyidae. Sociedad Genetica Chilensis, resumen no. R- 65, not paginated."]}

Octodon Bennett, 1832. Proc. Zool. Soc. Lond., 1832:46. TYPE SPECIES: Octodon cumingi Bennett, 1832 (= Sciurus degus Molina, 1782). SYNONYMS: Dendrobius., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 788, DOI: 10.5281/zenodo.7353083, {"references":["Molina, G. I. 1782. Saggio sulla storia naturale del Chili. Stamperia di S. Tommaso d'Aquino, Bologna."]}

Tympanoctomys barrerae (Lawrence, 1941). Proc. New England Zool. Club, 18:43. TYPE LOCALITY: Argentina, Mendoza Prov., La Paz. DISTRIBUTION: Arid plains of Mendoza Province. STATUS: IUCN - Vulnerable; rare. COMMENTS: The chromosome no. is 2n=102 (Contreras and Tores-Mura, 1987)., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 789, DOI: 10.5281/zenodo.7353083

Spalacopus cyanus (Molina, 1782). Sagg. Stor. Nat. Chile, p. 300. TYPE LOCALITY: Chile, Valparaiso Prov. DISTRIBUTION: Chile, west of the Andes between 27° and 36°S. STATUS: Locally common, very fossorial. SYNONYMS: ater, maulinus, noctivagus, poeppigii, tabanus. COMMENTS: Includes tabanus (Cabrera, 1961:517; Corbet and Hill, 1991:203). Chromosome no. is 2n = 58., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 789, DOI: 10.5281/zenodo.7353083, {"references":["Corbet, G. B., and J. E. Hill. 1991. A world list of mammalian species. Third ed. British Museum (Natural History) Publications, London, 243 pp."]}

Octodontomys gliroides (Gervais and d'Orbigny, 1844). Bull. Sci. Soc. Philom. Paris, p. 22. TYPE LOCALITY: Bolivia, La Paz Dept., near La Paz. DISTRIBUTION: Andes of N Chile, SW Bolivia, and NW Argentina; occurs between 2,000 and 5,000 m in xeric habitats. STATUS: Common. SYNONYMS: simonsi. COMMENTS: The chromosome no. is 2n=38., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 788, DOI: 10.5281/zenodo.7353083, {"references":["Helgen, K. M., and D. E. Wilson. in press. A systematic and zoogeographic overview of the raccoons of Mexico and Central America. Instituto de Biologia, UNAM, Mexico."]}

Family Octodontidae Waterhouse, 1840. Proc. Zool. Soc. Lond., 1839:172 [1840]. SYNONYMS: Spalacopidae. COMMENTS: Includes Spalacopidae Lilljeborg, 1866. Sometimes considered the most primitive group of South American hystricognaths with numerous fossil genera from Oligocene on, but Reig (1986:418) reserved this distinction for the Echimyidae. Ctenomys is often placed here as subfamily, and is closely related to octodontids (see comments under Ctenomyidae and in Cook et al., 1990:22-23). Chromosomal variation is not as conservative as previously thought, and is 2n=38-102., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 787, DOI: 10.5281/zenodo.7353083, {"references":["Reig, O. A. 1986. Diversity patterns and differentiation of high Andean rodents. Pp. 404 - 440, in High altitude tropical biogeography (F. Vuilleumier and M. Monasterio, eds.). Oxford University Press, New York, 649 pp.","Cook, J. A., S. Anderson, and T. L. Yates. 1990. Notes on Bolivian mammals. 6. The genus Ctenomys (Rodentia, Ctenomyidae) in the highlands. American Museum Novitates, 2980: 1 - 27."]}

Aconaemys Ameghino, 1891. Rev. Argent. Hist. Nat., 1:245. TYPE SPECIES: Schizodon fuscus Waterhouse, 1842. COMMENTS: Reig (1986:408) noted that Aconaemys is not separable from the Pliocene/ Pleistocene form Pithanotomys Ameghino, 1887 at the generic level. If indeed the two are not separable, Pithanotomys would have priority as a name over Acomaemys., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 787, DOI: 10.5281/zenodo.7353083, {"references":["Waterhouse, G. R. 1842 [1843]. Descriptions of a new species of quadrupeds collected by Mr. Fraser at Fernando Po. Proceedings of the Zoological Society of London, 1842: 124 - 130.","Reig, O. A. 1986. Diversity patterns and differentiation of high Andean rodents. Pp. 404 - 440, in High altitude tropical biogeography (F. Vuilleumier and M. Monasterio, eds.). Oxford University Press, New York, 649 pp."]}

Ctenomys bonettoi Contrerras and Berry, 1982 Historia Natural (Argentina), 2(14):123. TYPE LOCALITY: Argentina, Chaco Prov., Dept. Sargento Cabral, 7.5 km SE of Capitân Solari (26°48'S, 59°33'W). DISTRIBUTION: Argentina, Chaco Prov., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 784, DOI: 10.5281/zenodo.7353083

Octomys mimax Thomas, 1920. Ann. Mag. Nat. Hist., ser. 9, 6:118. TYPE LOCALITY: Argentina, Catamarca Prov., La Puntilia. DISTRIBUTION: Foothills and lower montane slopes of the Andes, and portions of the Monte desert of Catamarca, La Rioja, San Juan, and N Mendoza Provs. (Argentina). SYNONYMS: joannius. COMMENTS: Occurs at high elevations in Andes, and is similar in habits to the North American Woodrat (Redford and Eisenberg, 1992)., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 788, DOI: 10.5281/zenodo.7353083, {"references":["Redford, K. H., and J. Eisenberg. 1992. Mammals of the Neotropics, 2. The southern cone. University of Chicago Press, Chicago, IL, 430 pp."]}

Charles A. Woods (1993): Order Rodentia - Suborder Hystricognathi. In: Don E. Wilson, DeeAnn M. Reeder (Eds): Mammal Species of the World (2nd Edition). Washington and London: Smithsonian Institution Press: 771-806, ISBN: 1-56098-217-9, DOI: http://doi.org/10.5281/zenodo.7353083

Tympanoctomys Yepes, 1941. Rev. Inst. Bact., 9, 1940 [1941]:569. TYPE SPECIES: Octomys barrerae Lawrence, 1941. COMMENTS: Widely considered a synonym of Octomys (see Reig, 1986:408; Corbet and Hill, 1991:204), but Cabrera (1961:516), and Redford and Eisenberg (1992) considered it a separate genus based on very enlarged tympanic bullae., Published as part of Charles A. Woods, 1993, Order Rodentia - Suborder Hystricognathi, pp. 771-806 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 789, DOI: 10.5281/zenodo.7353083, {"references":["Lawrence, B. 1941. Neacomys from northwestern South America. Journal of Mammalogy, 22: 418 - 427.","Reig, O. A. 1986. Diversity patterns and differentiation of high Andean rodents. Pp. 404 - 440, in High altitude tropical biogeography (F. Vuilleumier and M. Monasterio, eds.). Oxford University Press, New York, 649 pp.","Corbet, G. B., and J. E. Hill. 1991. A world list of mammalian species. Third ed. British Museum (Natural History) Publications, London, 243 pp.","Redford, K. H., and J. Eisenberg. 1992. Mammals of the Neotropics, 2. The southern cone. University of Chicago Press, Chicago, IL, 430 pp."]}

Spalacopus cyanus (Molina, 1782). Sagg. Stor. Nat. Chile, p. 300. TYPE LOCALITY: Chile, Valparaiso Prov. DISTRIBUTION: Chile, west of the Andes. COMMENT: Includes tabanus; see Cabrera, 1961:517. ISIS NUMBER: 5301410026005002001 as S. cyanus. 5301410026005001001 as S. tabanus., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 582, DOI: 10.5281/zenodo.7353039

Octodon bridgesi Waterhouse, 1845. Proc. Zool. Soc. Lond., 1844:155. TYPE LOCALITY: Chile, Curico Prov., Rio Teno. DISTRIBUTION: Andes, in Colchagua, Curico, and Concepcion Provs. (Chile). COMMENT: Massoia, 1979, Neotropica, 25:36, reported Octodon, perhaps bridgesi, from S. Argentina. ISIS NUMBER: 5301410026002001001., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 581, DOI: 10.5281/zenodo.7353039

Family Octodontidae REVIEWED BY: M. A. Mares (MAM); C. A. Woods (CAW). ISIS NUMBER: 5301410026000000000., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 581, DOI: 10.5281/zenodo.7353039

Octomys mimax Thomas, 1920. Ann. Mag. Nat. Hist., ser. 9, 6: 118. TYPE LOCALITY: Argentina, Catamarca Prov., La Puntilia. DISTRIBUTION: Foothills and lower montane slopes of the Andes, and portions of the Monte desert of Catamarca, La Rioja, San Juan, and N. Mendoza Provs. (W. Argentina). ISIS NUMBER: 5301410026004002001., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 582, DOI: 10.5281/zenodo.7353039

Octodon lunatus Osgood, 1943. Field Mus. Nat. Hist. Publ. Zool. Ser., 30: 110. TYPE LOCALITY: Chile, Valparaiso Prov., Olmue. DISTRIBUTION: Coastal mountains of Valparaiso, Aconcagua, and Coquimbo Provs. (Chile). COMMENT: Probably a subspecies of bridgesi (CAW). ISIS NUMBER: 5301410026002003001., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 581, DOI: 10.5281/zenodo.7353039

James H. Honacki, Kenneth E. Kinman, James W. Koeppl (1982): Order Rodentia (Part 6). In: James H. Honacki, Kenneth E. Kinman, James W. Koeppl (Eds): Mammal Species of the World (1st Edition). Lawrence, Kansas, USA: Alien Press, Inc. & The Association of Systematics Collections: 560-594, ISBN: 0-89327-235-3, DOI: http://doi.org/10.5281/zenodo.7353039

Octodontomys gliroides (Gervais and d'Orbigny, 1844). Bull. Sei. Soc. Philom. Paris, p. 22. TYPE LOCALITY: Bolivia, La Paz Dept., near La Paz. DISTRIBUTION: Andes of N. Chile, S.W. Bolivia, and N.W. Argentina. ISIS NUMBER: 5301410026003001001., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 582, DOI: 10.5281/zenodo.7353039