84 
Noel M. Burkhead, et al. 
Roanoke drainage may have allowed it to invade smaller stream habitats 
thought to be typically occupied by only I. brunneus when the two species 
are sympatric. The first life history study of I. platycephalus was conduc- 
ted by Olmstead and Cloutman (1979). 
Ictalurus punctatus. — The channel catfish is native in the Tennessee 
and Big Sandy drainages in Virginia and, based on Cope’s 1867 record 
{sQQ 1. furcatus), probably native in the New River above Kanawha Falls. 
It has been introduced in all Atlantic slope drainages in the state (Jenkins 
et al. 1972). 
Pylodictis olivaris. — The flathead catfish is native to the Tennessee, 
Big Sandy, and New drainages in Virginia. It has recently been in- 
troduced into the James and Roanoke drainages. Introduction into lower 
James River near Surry accidentally occurred in 1965 when a temporary 
holding pond at Hog Island Game Refuge washed out during a storm 
and released about 50 P. olivaris. A 20 to 30 pound P. olivaris was seen by 
Dean Estes (Virginia Electric Power Co. biologist) in 1977; it was taken 
on a trotline near Surry (J. Gourley, pers. comm.). Hart (1978) reported 
the introduction into Smith Mountain Reservoir (the most upstream 
reservoir on the Roanoke River, Fig. 1) of one specimen in 1976 and five 
in 1977. Specimens from 10 inches long to 10 pounds weight, taken from 
the Roanoke River near Brookneal below Smith Mountain Lake, were 
observed in 1978-79 by L. Hart (pers. comm.). 
DIAGNOSTIC CHARACTERS 
The following account and critique of distinguishing characters in- 
cludes summaries of our data as well as characters abstracted from the 
literature. Discussion of diagnostic features is supplemented by fre- 
quency distributions of counts for Virginia Ictalurus (Amiurus) in Tables 
1-3, comparison of eye sizes (Fig. 2), and fins (shape and pigmentation), 
as well as premaxillary teeth configurations (Fig. 3). We emphasize that 
the following discussion pertains to Virginia Ictalurus (except where sup- 
plemented; see Methods and Materials), and is limited to characters with 
known or reputed utility in identifying species. Mention of somatic and 
fin pigmentation is generally avoided, as many aspects of coloration are 
variable in all species of Ictalurus. Although the Virginia Ictalurus fauna 
is artificially enriched in species, the species are easily distinguished. To 
reduce redundancy, diagnostic features are discussed by the following 
groups: the flathead bullheads, the typical bullheads, and the Ictalurus 
with forked tails. Characters of the monotypic genus Pylodictis are listed 
only in the key at the end of this section. 
Flathead bullheads. — This group is represented in Virginia by I. brun- 
neus and I. platycephalus. The species were clearly distinguished first by 
Yerger and Relyea (1968), who recognized the flathead bullheads as a 
group but did not provide a key character for its separation from the 
