Thursday, 5 September 2013

Hunting the lost Opossum.

The One-striped Opossum, Monodelphis unistriata, was described as a species by JA Wagner from a skin and skull of an adult male animal, brought back from Brazil by the explorer Johann Natterer in 1821, which had apparently been obtained near Itararé in São Paulo State, Brazil. The material was deposited in the Vienna Museum, and is now in the collection of the Naturhistorisches Museum Wien, though at some point the skull has been lost. In a purported second specimen of Monodelphis unistriata is in the collection of the Museo Argentino de Ciencias Naturales in  Buenos Aires, Argentina. This was captured by the explorer Luis Boccard in April 1899, somewhere in what is now northeastern Argentina, and also comprises a skin and skull (which in this case has not been lost) of an adult male Opossum.

In a paper published in the journal Zootaxa on 18 April 2013, Ronald Pine of the Biodiversity Institute at the University of Kansas and the Division of Mammals at the Field Museum in Chicago, David Flores of the Museo Argentino de Ciencias Naturales and Kurt Bauer of the Naturhistorisches Museum Wien, redescribe the two specimens, and discuss the results of an DNA analysis carried out in order to determine that the two specimens were in fact the same species.

The One-striped Opossum, Monodelphis unistriata; (A) Austrian specimen and (B) Argentinean specimen. Scale bares are 20 mm. Pine et al. (2013). 

The DNA analysis confirmed that the two specimens are members of the same species, and do not belong to the same species as any other known specimen. The distribution and habitat of the One Striped Opossum remains a mystery, and it is unclear if the species still exists. The study suggests that its closest relative is Ihering's Three-striped Opossum, which is known from the southeast of Brazil.

Lateral (above, left), ventral (above, right), and dorsal (below, left) views of incomplete cranium, and lateral (below, right) view of incomplete right dentary of the only known extant skull of Monodelphis unistriata. A distinctive combination of characters is shown, i.e., first upper premolar separated from canine and P2; infraorbital foramen placed at level of P3; posterior tips of nasals projecting between frontals, being not manifestly widest at frontomaxillary suture; and anterior tip of lacrimal at level of P3. Scale bar is 5 mm. Pine et al. (2013). 

The approximate locations of the two sites where Monodelphis unistriata specimens were collected. ICUN Red List.

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