The identification and description of life on Earth is a fundamental aspect of biology. When most people think about describing new species, they think about expeditions to remote and unexplored places. However, new species are still regularly described even from regions like the southeastern United States that have few truly wild and unexplored places remaining. There have been a variety of reptile and amphibian species described from this region over the last two decades. This is in large part because of better genetic techniques that let biologists examine differences between species in more meaningful ways, but some of the described species have also been morphologically distinct.
Sirens are fascinating animals that have remained understudied for decades. Long, eel-like salamanders with external gills and only two front legs, sirens inhabit a variety of freshwater habitats across the southeast. This group made the news several years ago when Graham et al. (2018) described the Reticulated of Leopard Siren (Siren reticulata) as a new species. This new species seemed to capture the interest of a lot of people, probably because of its large size and reticulated pattern. Leopard Sirens are known from several localities in the Gulf Coastal Plain in both Alabama and Florida. In their description of the Leopard Siren, Graham et al. (2018) indicated that their data suggested there were other undescribed siren species from around the southeast. In fact, herpetologists have known for several decades that there were likely additional undescribed siren species, but additional published data were lacking.
Recent work by Fedler at al. (2023) further examined the undescribed diversity within sirens by examining the Lesser Siren (S. intermedia) lineage using both morphological and genetic data. The author’s analyses supported the current description of the Leopard Siren and Greater Siren (S. lacertian) and indicated that there were several lineages within the currently described Lesser Siren. To resolve some of the current taxonomic issues, Fedler at al. (2023) raise the Western Siren (S. nettingi) to a full species and describe the Seepage Siren (S. sphagnicola) as a new species. As the name suggests, the Western Siren can be found west of the Mobile drainage, while the Lesser or Intermediate Siren still occupies the eastern portion of the distribution. The authors suggest that additional taxonomic revisions may occur within these two species as more data is collected.
The Seepage Siren is the smallest described siren species, reaching lengths of about 8 inches. The species can be distinguished from other sirens based on coastal groove count, black spotting on the head, and visibility of the sensory pits (beige coloration on the head). The species has a relatively small distribution in extreme western Florida and southern Alabama. The western range limit is poorly understood but likely extends into eastern Louisiana. As the name indicates, this species is a suspected microhabitat specialists, inhabiting seepage areas of headwater streams, mucky seeps, seepage bogs, shallow-water depressions with dense sphagnum moss, and other small mucky water bodies. Most other detailed natural history information is currently missing for this new species (as well as for a majority of other siren species), and more research will be needed to better understand this species role in these shallow wetland systems.
This recent taxonomic work highlights how species can go undescribed even in well-studied regions. The Gulf Coastal Plain of the southeastern United States is a global biodiversity hotspot, and new species continue to be described from this region. Habitat protection is critical to ensure that species do not go extinct before we have a chance to describe and, more importantly, understand them.
The full description of the new siren species can be found here.
Fedler, M.T., K.E. Enge, and P.E. Moler. 2023. Unraveling Siren (Caudata: Sirenidae) systematics and description of a small, seepage specialist. Zootaxa 5258:351–378.
Graham, S.P., R. Kline, D.A. Steen, and C. Kelehear. 2018. Description of an extant salamander from the Gulf Coastal Plain of North America: The Reticulated Siren, Siren reticulata. PLoS One 13:e0207460.