Octodon ricardojeda was formally described in an article first published online in December 2020, subsequently appearing in the 2021 volume of the Journal of Mammalogy. It belongs to the genus Octodon, in the family Octodontidae. Guillermo D’ElĂa, Pablo Teta, Diego H. Verzi, Richard Cadenillas and James L. Patton recognised it after examining museum specimens and other evidence.2
The description highlighted the need to reassess diversity within the genus. A separate 2021 analysis by Richard Cadenillas and Guillermo D’ElĂa delimited between seven and eleven candidate species, depending on the method. These analytical results should not be confused with the number of formally named species.1 The name honours Ricardo Ojeda, a founder of SAREM, the Argentine Society for the Study of Mammals.3
Characteristics
The coat is brownish with black and yellow tones, and the underside is paler, yellowish grey. Long dark hairs, approximately 15–20 mm, occur particularly on the back. The body is short and robust. The relatively short tail lacks a prominent terminal tuft. The whiskers are long and may be black or white; the moderately long ears have a fine covering of grey fur. Reported measurements reach approximately 32.6 cm in total length, including a 13.4 cm tail, with a body mass around 200 g.
Geographical distribution
The species is known principally from western NeuquĂ©n Province in Argentina, with eight localities reported in the original description, at approximately 500–1,100 m above sea level. It is also recorded from Malalcahuello National Reserve in Chile’s AraucanĂa Region.2 Fossil material attributed to this form suggests a wider distribution during the last 10,000 years; these historical identifications should be interpreted in light of the recent taxonomic revision.5
Behaviour and ecology
Diet
Like its relatives, O. ricardojeda is herbivorous, with leaves and other vegetation, seeds and bark among the foods described for it. Detailed species-specific dietary information remains limited.
Habitat
It has been captured in semi-open areas of humid forest and in burrows in sandy hillocks. It is not yet established whether it excavates these burrows or occupies those of other animals. Records also include shrubland, clearings and steppe, often with substantial shrub cover.
Plants reported in its surroundings include Nothofagus, Chusquea, Baccharis, Berberis buxifolia, Mulinum spinosum, Nothofagus antarctica, Nothofagus dombeyi, Stipa, Colletia spinosissima, Schinus molle and the monkey puzzle tree (Araucaria araucana). The original article also listed “M. spinosum”; its expansion to Macledium spinosum was inconsistent with the geographical context and should not be treated as a confirmed identification. Although mainly terrestrial, the species can climb shrubs and small trees.
Predators
Predators include the black-chested buzzard-eagle (Geranoaetus melanoleucus) and Magellanic horned owl (Bubo magellanicus), alongside other terrestrial and aerial predators.
Other mammals in the same habitat
Associated small mammals include Abrothrix hirta, Irenomys tarsalis, Loxodontomys micropus, Oligoryzomys longicaudatus, Aconaemys porteri and Dromiciops bozinovici.
Conservation
Known populations occur in LanĂn National Park in Argentina and Malalcahuello National Reserve in Chile, and the species may also occur in other protected areas. Its restricted known distribution—less than 20,000 km² and fewer than ten reported localities—led the describing authors to recommend consideration as Vulnerable. This was a recommendation, rather than a completed IUCN Red List assessment: the Mammal Diversity Database currently records the species as Not Evaluated.6 Habitat loss and forest fragmentation are important concerns, particularly given evidence of a wider distribution in the recent past.
Sources
Cadenillas, R. & D'ElĂa, G. (2021). The number of species of degus (genus Octodon) is currently underestimated: An appraisal of species limits and their phylogenetic relationships (Rodentia: Hystricomorpha: Octodontidae). Molecular Phylogenetics and Evolution, 159, 107111. https://doi.org/10.1016/j.ympev.2021.107111
D’ElĂa, G., et al. (2021). A new living species of degu, genus
Octodon
(Hystricomorpha: Octodontidae). Journal of Mammalogy, 102(1), 139-154. https://doi.org/10.1093/jmammal/gyaa143
SAREM (n.d.). Ricardo A. Ojeda. Original SAREM attribution retained; the cited author page is no longer available.
Las Ăšltimas Noticias (2021). Report on Octodon ricardojeda. Social media post accompanying the original illustration. https://twitter.com/lun/status/1349763363388141581
Tammone, M. N., Lacey, E. A. & Pardiñas, U. F. (2020). Dramatic recent changes in small mammal assemblages from Northern Patagonia: A caution for paleoenvironmental reconstructions. The Holocene, 30(11), 1579-1590. https://doi.org/10.1177/0959683620941096
American Society of Mammalogists (n.d.). Octodon ricardojeda. Mammal Diversity Database. https://www.mammaldiversity.org/taxon/1006516/