Chacodelphys formosa

Cladus: Eukaryota
Supergroup: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Mammalia
Subclassis: Theria
Infraclassis: Marsupialia
Ordo: Didelphimorphia
Familia: Didelphidae
Subfamilia: Didelphinae
Genus: Chacodelphys
Species: Chacodelphys formosa

Name

Chacodelphys formosa (Shamel, 1930)

Type locality: Argentina, Formosa, "Riacho Pilago, 10miles northwest of Kilometro 182".

Synonyms

* Gracilianus formosus (Shamel, 1930)
* Marmosa muscula Shamel, 1930

Vernacular names
Español: Marmosa pigmea de El Chaco

References
* H.H. Shamel: A new murine opossum from Argentina. Journal of the Washington Academy of Sciences 20: 83-84 (1930)
* R.S. Voss, A.L. Gardner & S.A. Jansa: On the relationships of Marmosa formosa Shamel 1930 (Marsupialia, Didelphidae), a phylogenetic puzzle from the chaco of northern Argentina. American Museum Novitates 3442: 1-18 (2004)

The Chacoan Pygmy Opossum (Chacodelphys formosa) is a recently described genus and species of didelphimorph marsupial. The only species in Chacodelphys, C. formosa, is known from only one specimen collected in 1920 in the Chaco of Formosa Province, Argentina.

Description

The Chacoan Pygmy Opossum is the smallest known species of didelphid. It has a head-body length of 68 mm, a tail of 55 mm and a hind foot of 11. It differs from the other "marmosine" genera (Marmosa, Micoureus, Monodelphis, Thylamys, Tlacuatzin, Gracilinanus, Marmosops, Lestodelphys) in having a long third manual digit, no distinctly tricolored pelage, a long fourth pedal digit, and a tail shorter than head-body. No other marmosine genera has this combination of characters.

Taxonomic history

C. formosa was originally described as Marmosa muscula Shamel (1930a); however, this name is preoccupied, so Shamel (1930b) renamed it M. formosa. Afterwards, George Tate (1933) considered it a valid member of his "Elegans group" (=Thylamys) of Marmosa, whereafter it has been variously synonymized or treated as a distinct species of Marmosa or Thylamys until 1989, when Gardner & Creighton (1989) listed it as a synonym of Gracilinanus agilis, and then later separated from this species as G. formosus. Finally, Voss et al. (2004) erected the new genus Chacodelphys for the species.

References

1. ^ Teta, P. & de la Sancha, N. (2008). Chacodelphys formosa. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 28 December 2008. Database entry includes justification for why this species is listed as vulnerable

* Gardner, A.L. & Creighton, G.K. 1989. A new generic name for Tate's microtarsus group of South American mouse opossums (Marsupialia: Didelphidae). Proceedings of the Biological Society of Washington 102:3–7.
* Shamel, H.H. 1930a. A new murine opossum from Argentina. Journal of the Washington Academy of Sciences 20:83-84.
* Shamel, H.H. 1930b. A new name for Marmosa muscula Shamel. Journal of Mammalogy 11:311.
* Tate, G.H.H. 1933. A systematic revision of the marsupial genus Marmosa with a discussion of the adaptive radiation of the murine opossums (Marmosa). Bulletin of the American Museum of Natural History 66:1–250.
* Gardner, Alfred (16 November 2005). Wilson, Don E., and Reeder, DeeAnn M., eds. ed. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3.
* Voss, R.S., Gardner, A.L. & Jansa, S.A. 2004. On the relationships of "Marmosa" formosa Shamel 1930 (Marsupialia, Didelphidae), a phylogenetic puzzle from the chaco of northern Argentina. American Museum Novitates 3442:1-18, 2 June 2004.