RTLGenomics scientists describe new species of rare South American rodent.

For many people the only good mouse is a dead mouse; however for RTL researcher Dr. John Hanson that is definitely not the case.  In a new article in Zoological Studies (PDF) Dr. Hanson and an international team of collaborators demonstrated the existence of an undescribed species of fish-eating rat, and named it after an expert in the group.

The new species, Neusticomys vossi, is part of a very specialized group of South and Central American rodents called the Ichthyomyini (fish rats).  Despite their name most of the species in this group are small (mouse sized), rodents that live in and around fast moving streams – usually near small waterfalls and rapids.  They are very rare in collections due to this unique lifestyle.  Generally, when field biologists are trying to catch rats and mice, they use traps baited with grain and/or fruit or peanut butter.  These tend to be irresistible to most rodents.  However, the Ichthyomyini are generally uninterested in this form of bait.  This is because they tend to be more carnivorous or insectivorous.  According co-author Dr. Thomas Lee of Abilene Christian University – the researcher who caught the new species – the best way to catch these mice is to “find a stream and put the trap in the middle of the water”.  It seems the rodents are more attracted to the insects that wash into the trap or come in to it for the regular bait than they are to the actual bait.

The interesting thing about this new species is its existence was first suggested by the scientist it was named after, Dr. Robert Voss, Curator of Mammals at the American Museum of Natural History.  In a 1988 monograph Dr. Voss noted a difference in size of mice from the eastern slopes of the Andes in Ecuador – but didn’t feel there was enough evidence to separate them.  However, after Dr. Lee caught the fresh samples, Dr. Hanson was able to use molecular techniques to sequence part of the genomes of both eastern and western Andes mice.  The genetic evidence clearly separated them into two groups.

With the rapid rate of change we find in all areas of the world’s biosphere, but especially in areas of South America’s highlands, documenting and cataloging biodiversity is critical.  Knowing that Neusticomys vossi is a different species from similar mice on the western slopes of the Andes provides land managers in Ecuador and Colombia more data for planning, but also provides a data point that future scientists can look back to as they try to describe the change in biodiversity over time.