What's in a Name?

Scientific Species Names and Biodiversity

Wedding portrait of Carl
Linnaeus (Carl von Linné).
Photograph taken by Mark A.
Wilson (Department of Geology,
The College of Wooster).

In last week's blog, I talked briefly about the vast number of species known to scientists today that live on our planet. You might think that it would be easy to count them all and provide a detailed list of all the names. Well, it's complicated.

Most scientists think there are between 1.7 and 1.8 million species for which we have names. It all started in 1758 when Carl von Linné, a Swedish botanist, scientifically described the first plants and animals using a binomial name with a genus and species name (see, e.g., the house sparrow Passer domesticus and view the original scientific description at BHL ). Following Linnaeus' new system, thousands of European scientists began to add species descriptions as they set out by land and by sea to discover what flora and fauna lived in other parts of the world. This is where the trouble began.

The main challenge in describing a new species is that one must compare it to all other previously known species to determine whether it is really "new" or not. Let's take the case of the Austrian scientist who obtained a specimen of a fly from the Moluccan Islands in Indonesia and described it as a new species. He probably checked all the existing descriptions of species known from this part of the world and also looked for it in Carl von Linné's Systema Naturae. This fly was not included in any of the existing literature and so in 1857, our Austrian scientist described the new species and called it Gonypes moluccanus (today Leptogaster moluccana (Doleschall, 1857)).

Image of Leptogaster moluccana.
Image Credit: Torsten Dikow.

To make this process even more complicated, a single species often has multiple names. Since 1857, our Indonesia fly has been "discovered" and named by four separate scientists in 1861 (as tarsalis from Batjan Island, Indonesia), 1872 and 1880 (as levis and varipes from Sumatra Island, Indonesia), and 1914 (as formosana from Taiwan and occlusa from Java Island, Indonesia).

Because all these names refer to the same biological species, they are now considered to be a "junior synonym". On larger scale, the catalogue of names for Diptera (mosquitoes, midges, house flies, deer flies etc.) lists 195,405 species names of which 157,845 (about 10% of all animal and plant species known today!) are actually valid. This means 37,560 species on that list have more than one scientific name. As you can see, accurately counting the actual number of species on our planet is a tremendously complex task.

In addition to sorting out the names of the species we have discovered, we are constantly on the lookout for species that haven't yet been found. Scientists can't agree on an estimate of how many undiscovered plants, animals, and microorganisms are still out there waiting to be named and categorized. An influential paper in 1982 projected there could be some 30 million species on the planet based on the number of known species of plants and estimates of host-specificity of phytophagous (plant feeding) insects. Other researchers have over the last years attempted to answer the same question, but haven't reached a consensus. Different estimation approaches yield wildly differing results ranging from 3 to 80 million species but most recent work favoring 5-10 million species. That means we are either half way there in describing biodiversity on planet Earth or still very far away. (Note that these figures only include species on Earth today, and not the millions of life forms that have lived previously and for which no fossil remains can be found. Wow!)

There are a number of initiatives working to make an exact list of all scientifically accepted species names available online such as the Catalogue of Life, Encyclopedia of Life (EOL), uBio, andGlobal Biodiversity Information Facility (GBIF).

A recent project spearheaded by EOL and GBIF is the Global Names Index, which serves some 18,323,094 names. Even when all the scientific names have been accumulated in a central database like the Global Names Index, it is still up to the thousands of taxonomists working at universities, natural history museums, and other research facilities to sort and evaluate which species have been described several times. Part of my research is doing exactly that - describing new species as well as re-examining many already known species.

In Europe or North America there are relatively few new species to be found, but when one studies flies from more exotic places, like I do, then there are still many new species waiting to be discovered.