On the occurrence of Holochilus chacarius (Cricetidae: Sigmodontinae) in Brazil, with taxonomic notes on Holochilus species

Abstract

Currently four species of Holochilus (Cricetidae: Sigmodontinae) are recognized. According to the literature, three species are recorded for Brazil: H. sciureus, H. brasiliensis and H. chacarius. Samples from western Brazil (Mato Grosso and Mato Grosso do Sul states) are usually reported as H. sciureus and, when referring to specimens from the Pantanal, as H. chacarius. However, the taxonomic status of specimens from this region has not been properly evaluated through detailed morphological analyses or voucher specimens. About 110 specimens of Holochilus deposited in Brazilian collections were qualitatively and quantitatively analyzed (univariate and multivariate tests). Our results suggested the existence of three species (H. sciureus, H. brasiliensis and H. chacarius) in Brazil, which present significant morphological and morphometric differences, thus confirming that the Mato Grosso and Mato Grosso do Sul samples, formerly misidentified as H. sciureus, belong to H. chacarius. This species differs from H. sciureus and H. brasiliensis by a series of pelage and skull characters, such as: the coloration of pelage, light orange-brown in the dorsum, light orangish in the flanks and white in the venter; ridges of the masseteric crest confluent at the level (or slightly above) of the mental foramen and at the anterior part of m1, alternated main molar cusps, lophids compressed and with acute outer margins (rarely prismatic), anteromedian fossetid labially displaced and subcircular (small to medium), metaflexid less developed (frequently not reaching the midline of the tooth), proto and hipoconid subrectangular in outline and transversely orientated, mesoflexid transversely orientated and mesoloph absent. The updated geographic distribution of Holochilus in Brazil shows that H. sciureus is present in the northern portion of the country, being the only species present at the Amazon and at the Caatinga and with limit in the Cerrado biome at the center of Goiás state. Holochilus brasiliensis is restricted to eastern Brazil, with its northern record at the Atlantic Forest of south Bahia. Holochilus chacarius occurs in the Pantanal areas of the Mato Grosso and Mato Grosso do Sul states. A new record extends the distribution of H. chacarius to the Cerrado biome at eastern Mato Grosso, confirming its presence in this biome.

Checklist of mammals from Mato Grosso do Sul, Brazil

“…The specimens from Mato Grosso do Sul considered by Cáceres et al (2008) and Carmingnoto (2004) as Holochilus sciureus are still in need of analysis to clarify if they actually correspond to H. chacarius, as the presence of the former species in the state have been questioned by Brandão & Nascimento (2015). These specimens originated in the state and deposited elsewhere are AMNH 37077, FMNH 26758-2678, USNM 390249-39050, MN 1989-4207-4209-4205-4271, AMNH 37077, MN 1987, UFSM 266, USNM 390249, and those deposited as MCPAP 217-218-221-223 (see Table III for the institution names).…”

Niche partitioning in small mammals: interspecific and biome-level analyses using stable isotopes

“…For most specimens, we recorded body mass before death, which we used to estimate mean body mass per species. We also gathered information on locomotion (Astúa 2009;Paglia et al 2012;Brandão and Nascimento 2015;Smith and Owen 2016;Bubadué et al 2019) and diet (Paglia et al 2012;Arregoitia and D'Elía 2020;Bubadué et al 2021) from the literature for every species included in this study (Supplementary Data SD1).…”

Sigmodontine rodents (Rodentia, Cricetidae) from Quaternary cave deposits of Serra da Capivara, Northeastern Brazil

“…The majority of the Sigmodontinae taxa reported here have been found living in open environments of Caatinga and Cerrado, according to Patton et al (2015) and Carmignotto et al (2012), such as Calomys sp., Necromys lasiurus, Pseudoryzomys simplex, and Holochilus sciureus, the last two associated with flooded areas, such as riverbanks or wetlands (Voss & Myers, 1991;Voss, 2015;Brandão & Nascimento, 2015). However, despite the proposition of paleoenvironmental inferences based on extinct and extant vertebrate fauna from the Serra da Capivara region (Guérin et al, 1996;Guérin & Faure, 2008), in the absence of detailed taphonomic and chronological data, the assemblages potentially represent taxa from different habitats, which were not necessarily part of the same landscape during the Quaternary.…”