The genus
Chacodelphys has one species, the Chacoan Pygmy Opossum (
Chacodelphys formosa), a small didelphid marsupial (family
Didelphidae) known from only from a single specimen gathered in Linda Vista, 15km northwest of Comandante Fontana, Formosa province, Argentina. Recent reexamination of the holotype by Voss et al. (2004) concluded that formosa exhibits a unique set of character states that do not fit diagnoses of the other marmosine genera, leading to the creation of
Chacodelphys.
C. formosa was originally described by Shamel (1930a) as
Marmosa muscula, then renamed
M. formosa (Shamel 1930b) to avoid homonymy with
M. muscula Cabanis (=
M. murina Linnaeus). Voss et al. (2004) contains an account of its taxonomic history. Recently, new specimens identified in owl pellets by Teta et al. (2006) have led to the "rediscovery" of
Chacodelphys.
