Thylamys

The fat-tailed opossum Thylamys elegans, photographed by Patt Riquelme.

Belongs within: Didelphinae.

Thylamys is a genus of opossums found in subequatorial South America.

Characters (from Creighton & Gardner 2008): Small, head plus body length 75-147 mm, tail length 65-161 mm. Colour of dorsum greyish or greyish-brown agouti, venter varying from pure white to yellowish buff. Postorbital processes normally lacking, may be developed as ridges or postorbital projections. Nasals long, slender, not laterally expanded at maxillofrontal suture. Auditory bullae relatively large, rounded, close together (ratio of bulla width to distance between bullae 1.5 or less), each buttressed by anteromedial alisphenoid process. Palate with either two or three sets of paired fenestrae. Posterolateral palatal foramina long, breadth of each equal to or exceeding width of last molar. P³ exceeding P² in height and anteroposterior length. Mammae inguinal, abdominal and pectoral, numbering up to 19. Manu and pes white-haired and small with short digits; claws on digits II-IV extending noticeably beyond terminal digital pads; digit IV longest on pes, ratio to length of hind foot less than 0.45; central palmar and plantar surfaces covered with small nodular granules to base of digits. Tail usually bicolored, seasonally becoming thickened with fat deposits; tail scales minute (35 or more rows per cm), rounded-square in outline, annular in arrangement.

<==Thylamys Gray 1943 JV05, C57
    |  i. s.: T. aceramarcae (Tate 1931) [=Marmosa (Thylamys) aceramarcae] C57
    |         T. agilis (Burmeister 1854) [=Grymaeomys agilis, Marmosa (Thylamys) agilis] C57
    |           |--T. a. agilis (see below for synonymy) C57
    |           |--T. a. beatrix (Thomas 1910) [=Marmosa agilis beatrix, Grymaeomys beatrix] C57
    |           |--T. a. buenavistae (Tate 1931) (see below for synonymy) C57
    |           `--T. a. peruanus (Tate 1931) [=Marmosa agilis peruana, M. agilia peruania] C57
    |         T. agricolai (Moojen 1943) [=Marmosa (Thylamys) agricolai] C57
    |         T. dryas (Thomas 1898) [=Marmosa (Thylamys) dryas, Grymaeomys dryas] C57
    |         T. emiliae (Thomas 1909) [=Marmosa (Thylamys) emiliae] C57
    |         T. griseus (Desmarest 1827) [=Didelphis grisea, Grymaeomys griseus, Marmosa (Thylamys) grisea] C57
    |         T. marica (Thomas 1898) [=Marmosa (Thylamys) marica, Grymaeomys marica] C57
    |         T. microtarsus (Wagner 1842) (see below for synonymy) C57
    |           |--T. m. microtarsus [incl. Marmosa herhardti Miranda Ribeiro 1936] C57
    |           `--T. m. guahybae (Tate 1931) [=Marmosa microtarsus guahybae] C57
    |         T. unduaviensis (Tate 1931) [=Marmosa (Thylamys) unduaviensis] C57
    |         T. velutinus (Wagner 1842) (see below for synonymy) C57
    |           |--T. v. velutinus [incl. Didelphys pimelura Reinhardt 1849] C57
    |           `--T. v. formosa (Shamel 1930) [=Marmosa velutina formosa] C57
    |         T. venustus (Thomas 1902) JV05, C57 (see below for synonymy)
    |--+--*T. elegans (Waterhous 1839) C57, CB-E04, C57 (see below for synonymy)
    |  |    |--T. e. elegans C57
    |  |    |--T. e. cinderella (Thomas 1902) (see below for synonymy) C57
    |  |    |--T. e. coquimbensis (Tate 1931) [=Marmosa elegans coquimbensis] C57
    |  |    `--T. e. soricina (Philippi 1894) (see below for synonymy) C57
    |  `--T. pallidior (Thomas 1902) CB-E04, C57 [=Marmosa elegans pallidior C57, M. pusilla pallidior C57]
    `--+--T. macrurus CB-E04, JV05
       `--T. pusillus (Desmarest 1804) CB-E04, C57 (see below for synonymy)
            |--T. p. pusillus (see below for synonymy) C57
            `--T. p. bruchi (Thomas 1921) (see below for synonymy) C57

Thylamys agilis agilis (Burmeister 1854) [incl. Marmosa blaseri Miranda Ribeiro 1936, M. agilis chacoensis Tate 1931] C57

Thylamys agilis buenavistae (Tate 1931) [=Marmosa agilis buenavistae; incl. T. rondoni Miranda Ribeiro 1936] C57

*Thylamys elegans (Waterhous 1839) C57, CB-E04, C57 [=Didelphis elegans C57, Marmosa (Thylamys) elegans C57; incl. D. hortensis Reid 1837 (n. n.) C57]

Thylamys elegans cinderella (Thomas 1902) [=Marmosa elegans cinderella, M. venusta cinderella; incl. M. elegans sponsoria Thomas 1921, M. venusta sponsoria] C57

Thylamys elegans soricina (Philippi 1894) [=Didelphys soricina, Di. (Paramys) soricina, Dromictops soricina, Marmosa elegans soricina] C57

Thylamys microtarsus (Wagner 1842) [=Didelphis microtarsus, Didelphys microtarsus, Grymaeomys microtarsus, Marmosa (Thylamys) microtarsus] C57

Thylamys pusillus (Desmarest 1804) CB-E04, C57 [=Didelphis pusilla C57, Grymaeomys pusilla C57, G. pusillus C57, Marmosa (Thylamys) pusilla C57, Sarigua pusilla C57]

Thylamys pusillus bruchi (Thomas 1921) [=Marmosa pusilla bruchi; incl. M. elegans fenestrae Marelli 1931, M. pulchella Cabrera 1934] C57

Thylamys pusillus pusillus (Desmarest 1804) [incl. Marmosa citella Thomas 1912, T. citella, M. marmota Thomas 1894, Didelphis nana Illiger 1815, M. verax Thomas 1921, M. marmota verax] C57

Thylamys velutinus (Wagner 1842) [=Didelphys velutina, Grymaeomys velutinus, Marmosa (Thylamys) velutina, Microdelphis velutina] C57

Thylamys venustus (Thomas 1902) JV05, C57 [=Marmosa (Thylamys) elegans venusta C57; incl. M. janetta Thomas 1926 C57]

*Type species of generic name indicated

REFERENCES

[C57] Cabrera, A. 1957. Catalogo de los mamiferos de America del Sur. I (Metatheria - Unguiculata - Carnivora). Revista del Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” e Instituto Nacional de Investigacion de Las Ciencias Naturales, Ciencias Zoológicas 4 (1): 1-307.

[CB-E04] Cardillo, M., O. R. P. Bininda-Emonds, E. Boakes & A. Purvis. 2004. A species-level phylogenetic supertree of marsupials. Journal of Zoology 264: 11-31.

Creighton, G. K., & A. L. Gardner. 2008. Genus Thylamys Gray, 1843. In: Gardner, A. L. (ed.) Mammals of South America vol. 1. Marsupials, xenarthrans, shrews, and bats pp. 107-117. University of Chicago Press.

[JV05] Jansa, S. A., & R. S. Voss. 2005. Phylogenetic relationships of the marsupial genus Hyladelphys based on nuclear gene sequences and morphology. Journal of Mammalogy 86 (5): 853-865.