It isn’t easy to determine whether or not a species is different from those already described and named. Imagine the expertise to differentiate among species from large taxonomic groups like birds (10,000 species) and ants (>12,000 species). But in tropical regions, scientists often come across a species they don’t recognize and can’t identify – “undescribed” (or “unnamed”) species that are considered “potentially new to science. “
To verify that a discovery is undescribed, scientists collect a specimen and compare its characteristics to specimens of described species in their collections. They consult the literature and other colleagues to make sure that it is not the same as other species already named. They compare many different features, including things like the number of hairs or spines on the legs, the texture of the body, the shape of the bones, or the number of scales on the head.
Characteristics that define a species new to science vary from group to group, but are generally grouped around a few key morphological characters, often related to procreation. Unique features – like the shape of reproductive organs or coloration of body parts used in a courtship display – not only prevent species from unsuccessful mating, but also provide useful traits for scientific differentiation.
Similarly, behavioral traits, such as vocalizations or courtship display, provide very good clues to a species’ identity. This principle is well known to ornithologists, who are often capable of instantly recognizing hundreds of different species of birds based on a single note. Entomologists also use sounds produced by such insects as cicadas, crickets, or katydids to tell species apart, and sometimes describe new discoveries based solely on the characteristics of the song.
The pattern of flashes produced by lightning bugs, the rhythm of claw waving in mud crabs, or the shape of an orb spun by a spider are other examples of behavioral characters that can be used to identify species, and pinpoint those that are different. During RAP surveys scientists often make sound or video recordings of animal behavior, and these data help confirm the new status of documented species. For example, the first indication that a katydid found during a RAP survey in Guinea in 2003 was potentially new to science was its song, very different from that of any other species known from Africa.
A different behavior is a very good indication of a species’ distinctness, but additional proof is often needed to declare a species new to science. These can be found among either morphological or molecular characteristics of an organism. Molecular and other genetic characters, such as certain DNA sequences or shapes and numbers of chromosomes, often provide very reliable indicators of a species’ uniqueness.
Genetic barcoding, a fast and easy genetic screening process that allows scientists to compare a key fragment of mitochondrial DNA among thousands of species at once, has recently begun to play an important role in identifying both known and as yet unnamed species. RAP scientists routinely collect DNA samples of species, which in some cases lead to the discovery of new species, like new species of frogs described in West Africa in 2005.