511.

Torres’s Pink-lipped Mouse

Bibimys torresi

French: Bibimys de Torres / German: Torres-Pinknasenmaus / Spanish: Raton de labios rosados de Torres

Other common names: Torres's Akodont, Torres’'s Crimson-nosed Rat, Torres's Swollen-nosed Mouse

Taxonomy. Bibimys torres: Massoia, 1979, Estacion Experimental del INTA Delta del Parana, Campana, Buenos Aires, Argentina.

Bibimys torresi is the type species of the genus. Monotypic.

Distribution. N Buenos Aires and extreme S Entre Rios provinces in EC Argentina .

Descriptive notes. Head-body 90-110 mm, tail 72-80 mm, ear 17-17-4 mm, hindfoot 21-8-22-9 mm; weight 32-42 g.

Torres’s Pink-lipped Mouse is the largest species of Bibimys, characterized by usually a more than 4mm upper toothrow. As in the other species of Bibimys, labial area between nostrils and oral margins is covered with densely distributed, short, white hair, forming round, white, velvety area, turgent and pinkish in color in live specimens, suggesting high degree of vascularization. Pelage is long and silky; back hairs are graybased, with ocherous tips, giving general agouti appearance, especially yellowish on flanks and cheeks; venter is cream, with gray-based hair; tail is bicolored, brown above and pale orange below; mystacial vibrissae are short, not reaching pinna when laid backward; and ungual tufts are shorter than claws. Manual claws are 1-5 mm, and pedal claws are 2-2 mm. Skull is robust, with large gnatic process (a paired acute bony plate produced forward the anterior face of upper incisors) and expanded zygomatic arches. Chromosomal complement is 2n = 70, FNa = 76.

Habitat. Flooded grasslands and riparian communities in margins of Parana Delta.

Food and Feeding. Little is known, but because Torres’s Pink-lipped Mouse is rarely trapped with usual baits, it probably has a specific diet including vegetation and invertebrates.

Breeding. No information.

Activity patterns. Torres’s Pink-lipped Mouse is moderately preyed on by nocturnal owls (e.g. great horned owl, Bubo virginianus, and common barn-owl, Tyto alba), and therefore it is probably active at night. Capture rates are extremely low compared with sympatric sigmodontines, suggesting more than natural rarity and probably involving avoidance of traditional baits and mechanical traps.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Near Threatened on The IUCN Red List. Although Torres’s Pink-lipped Mouse is locally abundant in its small distribution,its occurs in less than 5000 km? at less than ten locations. A current record from southern Entre Rios province suggests it is distributed along right margin of Parana River for c.50 km. Late Holocene records indicate that Torres’s Pink-lipped Mouse suffered a very recent distributional contraction, disappearing from most of southern and central Pampean ecoregion, including coastal and hilly wet environments.

Bibliography. Bianchini & Delupi (1993), Castro & Gonzalez (2003), D'Elia et al. (2005), Dyzenchauz & Massarini (1999), Massoia (1978, 1979, 1980a, 1983), Massoia, Tiranti & Torres (1989), Pardinas (1995b, 1996, 1999a, 1999b, 2000), Pardinas & Tonni (2000), Pardinas, Teta & D'Elia (2010), Pardinas, Voglino & Galliari (2017), Scheifler et al. (2012), Teta, Pardinas etal. (2013).