Rats of Sulawesi

Prosciurillus abstrusus had not been observed since 1932
Prosciurillus abstrusus had not been observed since 1932

The island of Sulawesi hosts an extremely rich mammalian fauna, including many range-restricted montane forest endemics. Small mammals in this area are extremely poorly-known, and many had not been recorded since expeditions in the 1930s.  This is until a recent project, led by Alessio Mortelliti, enabled the re-assessment to data-sufficient categories of four rodent (Taeromys arcuatus, Taeromys microbullatus, Rattus salocco, Maxomis dollmani) and one squirrel species (Prosciurillus abstrusus) previously classified as Data Deficient on the IUCN Red List. This example illustrates the considerable potential for cost-sharing in the monitoring of Data Deficient species. Many Data Deficient species inhabit the same geographical areas, and could be monitored with identical sampling methods.

Number of Data Deficient terrestrial mammals
Number of Data Deficient terrestrial mammals
Margaretamys christinae, new species
Margaretamys christinae

The expedition also discovered a new rodent species, Margaretamys christinae, which differs from its congenerics by its craniometric characteristics, pelage colour and bicoloured tail. The discovery has both conservation and taxonomic implications. The new species has been assessed as Endangered on the Red List, a finding in line with the notion that poorly-known species may be most at risk of extinction. Indeed, Data Deficient mammals are more likely to be at threat than species of known conservation status (Bland et al. in prep), and species rediscovered after long periods of disappearance show considerably higher levels of threat than better-known species (Scheffers et al. 2011). This may be due to their small geographical range size and habitat specialization, but more research is needed to tease apart the effects of species’ traits on information availability and threat status.

From a taxonomic point of view, the discovery of a new species in the study area suggests that Data Deficient species are indicative of spatial knowledge deficiency. Knowledge of the biological world is far from complete, and even in well-known groups such as mammals, 200+ species are discovered per decade (Reeder et al. 2007). Areas containing DD species have been shown to contain more recently described amphibian species than expected by chance (Brito et al. 2010). The localization of Data Deficient species could therefore provide an efficient method for targeting surveys and inventories for species discoveries.

In short, targeting monitoring programmes to areas containing a large number of Data Deficient species may provide a cost-effective means of determining the conservation status of poorly-known species, as well as discovering species new to science.

Please have a look at Alessio Mortelliti’s project, whom I thank for access to information and photographs.

References:

Brito D (2010) Overcoming the Linnean shortfall: Data deficiency and biological survey priorities. Basic and Applied Ecology 11:709–713.

Reeder DAM, Helgen KM, Wilson DE (2007) Global trends and biases in new mammal species discoveries. Occasional papers of the Museum of Texas Tech University

Scheffers BR, Yong DL, Harris JBC, Giam X, Sodhi NS (2011) The world’s rediscovered species: back from the brink? PloS One 6:e22531.

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