Oxymycterus nasutus (Waterhouse, 1837)

Don E. Wilson, Russell A. Mittermeier & Thomas E. Lacher, Jr, 2017, Cricetidae, Handbook of the Mammals of the World – Volume 7 Rodents II, Barcelona: Lynx Edicions, pp. 204-535 : 467

537.

Darwin’s Hocicudo

Oxymycterus nasutus

French: Hocicudo a nez long / German: Darwin-Grabmaus / Spanish: Ratén hocicudo de Darwin

Other common names: Long-nosed Hocicudo

Taxonomy. Mus nasutus Waterhouse, 1837 , Maldonado, Maldonado, Uruguay.

Oxymycterus nasutus is the type species of the genus. Monotypic.

Distribution. S Brazil (Parana, Santa Catarina, and Rio Grande do Sul states) and Uruguay.

Descriptive notes. Head-body 123-131 mm, tail 87-97 mm, ear 17-18 mm, hindfoot 27-28 mm; weight 50-90 g. See general characters of the genus under the Anazonian Hocicudo ( O. amazonicus ) account. Darwin’s Hocicudo is a small species of Oxymycterus . Dorsum can be vivid dark orange, with head and mid-dorsum lined with black, or much darker and duller, without black lining, or intermediate between two chromatic extremes. Sides and venter are paler in both extremes. Forefeet and hindfeet are well-haired, light to more strongly brown above. Tailis slightly bicolored to unicolored.

Habitat. Wet grasslands and steppes, coastal sandbanks, pasture lands, and edges of streams.

Food and Feeding. Darwin's Hocicudo mainly eats insects. Frequencies of occurrence in contents of twelve stomachs were: Coleoptera ( Tenebrionidae , Scarabaeidae , Lampyridae , Chrysomelidae , Carabidae , Pselaphidae , Dytiscidae ) 100%; Hymenoptera (Formicidae) 83-3%; Diptera ( Sciaridae , Bibionidae , Chironomidae , Tipalidae) 83-3%; Hemiptera (Timgidae, Pentatomidae ) 41-6%; Oligochaeta (earthworms) 33-3%; Lepidoptera ( Noctuidae , unidentified families) 25-5%; Orthoptera ( Gryllidae , Acrididae , Gryllacrididae ) 25%; Chilopoda (centipedes) 25%; Homoptera ( Cicadellidae , Fulgoridae ) 16-6%; Gastropoda (slugs) 16-6%; Aranea 16-6%; and plants (unidentified fragments) 16-6%.

Breeding. Reproduction of Darwin’s Hocicudo occurs year-round, mostly in September—April. Pregnant females had 1-4 embryos, usually two.

Activity patterns. Darwin’s Hocicudo is diurnal and crepuscular, varying according to photoperiod and temperature.

Movements, Home range and Social organization. Darwin’s Hocicudo commonly use trails of species of Cavia (guinea pigs) and Hydrochoerus (capybaras) as pathways through tall grass.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Barlow (1969), D'Elia & Teta (2016), Goncalves & Oliveira (2004), Gonzalez (2001), Gonzalez & Martinez (2010), Hershkovitz (1994), Hoffmann et al. (2002), Massoia & Fornes (1969), Oliveira (1998), Oliveira & Goncalves (2015), Paise & Vieira (2006), Pecanha (2015).

Figures

523. Huanchaca Burrowing Mouse (Juscelinomys huanchacae), 524. Candango Burrowing Mouse (Juscelinomys candango), 525. Amazonian Hocicudo (Oxymycterus amazonicus), 526. Spy Hocicudo (Oxymycterus delator), 527. Atlantic Forest Hocicudo (Oxymycterus dosytrichos), 528. Quaestor Hocicudo (Oxymycterus quaestor), 529. Inca Hocicudo (Oxymycterus inca), 530. Paramo Hocicudo (Oxymycterus paramensis), 531. Elfin Forest Hocicudo (Oxymycterus nigrifrons), 532. Upper Yungas Inca Hocicudo (Oxymycterus juliacae), 533. Small Yungas Hocicudo (Oxymycterus hiska), 534. Quechuan Hocicudo (Oxymycterus hucucha), 535. Mount Caparao Hocicudo (Oxymycterus caparoae), 536. Red Hocicudo (Oxymycterus rufus), 537. Darwin’s Hocicudo (Oxymycterus nasutus), 538. Ravine Hocicudo (Oxymycterus wayku), 539. Cook’s Hocicudo (Oxymycterus joser), 540. Common Cerrado Mouse (Thalpomys cerradensis), 541. Hairy-eared Cerrado Mouse (Thalpomys lasiotis), 542. Roraima Mouse (Podoxymys roraimae), 543. Blackish Grass Mouse (Thaptomys nigrita), 544. Ecuadorean Akodont (Necromys punctulatus), 545. Northern Akodont (Necromys urichi), 546. Hairy-tailled Akodont (Necromys lasiurus), 547. Pleasant Akodont (Necromys amoenus), 548. White-chinned Akodont (Necromys lactens), 549. Lillo’s Akodont (Necromys lilloi), 550. Dark-furred Akodont (Necromys obscurus), 551. Kemp's Grass Mouse (Deltamys kempi), 552. Araucaria Grass Mouse (Deltamys araucaria), 553. Serra do Mar Grass Mouse (Castoria angustidens)

Distribution. S Brazil (Parana, Santa Catarina, and Rio Grande do Sul states) and Uruguay.