Cryptonanus guahybae (Tate, 1931)

Russell A. Mittermeier & Don E. Wilson, 2015, Didelphidae, Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona: Lynx Edicions, pp. 129-186 : 170

68.

Guaiba Mouse Opossum

Cryptonanus guahybae

French: Opossum de Guaiba / German: Guahiba-Zwergbeutelratte / Spanish: Marmosa gracil del Guaiba

Other common names: Guahiba Gracile Opossum, Guaiba Mouse Opossum, Guahyba Mouse Opossum

Taxonomy. Marmosa microtarsus guahybae Tate, 1931 ,

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“Island of Guahyba near Porto Alegre, Rio Grande do Sul, Brazil.”

This species is monotypic.

Distribution. S Brazil (Rio Grande do Sul).

Descriptive notes. Head-body 7-10.2 cm, tail 9.6-13.5 cm; weight 14-25 g. Dorsal fur of the Guaiba Mouse Opossum is reddishbrown and paler on face. Narrow eye-rings contrasting with cheeks and crown surround black eyes, extending toward nose but not reaching bases of ears; rings may be very narrow or absent beneath eye. Tail length is ¢.120% of head-body length, and tail is slightly bicolored. Ventral fur is mostly gray-based buffy on chest and throat and whitish on chin. Fur is long. Feet are small and pale brownish-buff, and carpal tubercles are present in old males. Ears are small. Females lack a pouch and have 15 mammae, seven on each side and a medial mamma. The Guaiba Mouse Opossum has a 2n = 14, FN = 24 karyotype, with all biarmed autosomes, and with a biarmed X-chromosome and an acrocentric Y-chromosome.

Habitat. Pampas biome in open areas such as restinga vegetation in coastal areas. Guaiba Mouse Opossums have been captured in sandy riparian forests, gaps in flooded forest, and deciduous forests north of Rio Grande do Sul.

Food and Feeding. There is no information available for this species.

Breeding. There is no information available for this species.

Activity patterns. There is no information available for this species.

Movements, Home range and Social organization. The Guaiba Mouse Opossum appears to be mostly terrestrial. The majority of specimens have been captured in pitfall traps or in traps set on the ground, but a few were captured in understory on branches or logs at heights of 0-5-1-5 m.

Status and Conservation. Classified as Data Deficient on The IUCN Red List. There is very little information on distribution of the Guaiba Mouse Opossum. New locality records been published only recently, mostly because techniques are now available for properidentification. As with several small species of opossums,it is probable that there are misidentified specimens in mammalian collections. Virtually nothing is known about ecological requirements of the Guaiba Mouse Opossum and its possible conservation threats. It has been collected in at least one protected area, Parque Estadual do Turvo, Perrubadas, Rio Grande do Sul.

Bibliography. Caceres et al. (2013), Gardner (2005, 2007¢), Martinelli et al. (2011), Melo et al. (2011), Quintela, Santos, Christoff & Gava (2012), Quintela, Santos, Gava & Christoff (2011), Sponchiado et al. (2012), Tate (1931, 1933), Voss et al. (2005).

Figures

65. Pygmy Opossum (Chacodelphys formosa), 66. Agricola’s Opossum (Cryptonanus agricola), 67. Chacoan Mouse Opossum (Cryptonanus chacoensis), 68. Guaiba Mouse Opossum (Cryptonanus guahybae), 69. Unduavi Mouse Opossum (Cryptonanus unduaviensis), 70. . Emilie’s. 9 Opossum.. Gracilinanus. (null), 71. Aceramarca Opossum (Gracilinanus aceramarcae), 72. Agile Opossum (Gracilinanus agilis), 73. Wood Sprite Opossum (Gracilinanus dryas), 74. Northern Gracile Opossum (Gracilinanus marica), 75. Brazilian Gracile Opossum (Gracilinanus microtarsus)

Distribution. S Brazil (Rio Grande do Sul).