84 
John E. Cooper and Martha Riser Cooper 
contiguous or interdigitating with those of the adjacent Greater Pamlico 
River, later (probably late in the Pleistocene) to become the separate 
but twin systems now known as the Neuse and Tar-Pamlico rivers. 
Jenkins et al. (1971:45) indicated the presence of a theater of stream 
capture between the Roanoke and what are the headwaters of today’s 
Tar and Neuse rivers, which we interpret to have been in the area 
of present Person and Granville counties. It is reasonably parsimonious 
to conclude that it was through such piracies, from Teays to Greater 
Roanoke to Greater Pamlico, that the ancestor of O. carolinensis gained 
access to and became isolated in the latter system, there to evolve 
allopatrically into the present species. This dispersal, particularly between 
the contiguous Roanoke and Neuse-Tar systems where downslope differ- 
ences in elevation occurred and drainage divides were not of excessive 
magnitude, could have been abetted by the flooding that likely would 
have been prodigious during interglacial periods, and perhaps even 
by relatively minor tectonic events. 
Jenkins et al. (1971:82) postulated a generally similar dispersal 
history for the ancestor of N. furiosus. On the other hand, Sessions 
and Wiley (1985), on the basis of their karyological studies and electro- 
phoretic analyses provided by Ashton et al. (1980), considered Necturus 
lewisi to be the most primitive of the extant species of the genus 
Necturus , and the widespread western N. maculosus to be the most 
derived. They suggested that the Necturus stock initially spread south 
in the Atlantic Coastal Plain, then west through the Gulf regions and 
around the southern Appalachians, and finally north in the Ohio and 
Mississippi drainages. 
As earlier mentioned, O. carolinensis occupies the entire Tar- 
Pamlico watershed, but appears to be absent from some parts of the 
Neuse watershed, including nearly all of its Piedmont streams. If not 
a sampling deficiency, this could indicate that the initial entry of 
its ancestor into the Greater Pamlico River occurred in an extensive 
northernmost (Tar River) portion, and expansion of the species in 
the current Neuse basin is an ongoing process. If so, this stream dweller 
likely will never extend it range upriver into the Eno, Little, and 
Flat rivers, since the Neuse River has been impounded to create Falls 
Lake, which stretches for about 35 km (22 mi) from northwestern 
Wake County into Granville and Durham counties, and has converted 
most of the Neuse and its tributaries in those areas to lacustrine 
habitats. 
Etymology — Carolinensis , after North Carolina, to which the new 
species is endemic. Suggested vernacular name: North Carolina Spiny 
Crayfish. 
