6 
cephala were Notropis whipplet, N. spilopterus, N. stra- 
mineus, Pimephales vigilax, Ericymba buccata, Percina 
sciera, Hypentelium nigricans, Micro pterus punctulatus, 
and Phenacobius mirabilis. 
REPRODUCTION 
The Reproductive Cycle of the Male 
Males were sexually mature and ready to spawn 
during the first spring following their hatching. The 
smallest male captured in spring was a 40-mm specimen 
collected on May 27, 1969; although breeding pigmenta- 
tion was absent in this fish, its testes were large (6 x 
1.5 mm) and it apparently was capable of spawning, 
as were all of the larger males collected in the spring and 
examined for sexual maturity. 
The larger the male, the earlier the breeding pigmen- 
tation began to develop and the more intense it became 
by spawning time. Males 2 years old collected on May 
97, 1969 were considerably darker than females and 
somewhat darker than 1-year-old males collected at the 
same time. The brown vermiculations on the dorsum 
were darkened in males, and in contrast to females, 
the breast; belly; underside of the head; and membranes 
of the anal, soft dorsal, and pelvic fins of the males were 
covered with many expanded melanophores, giving them 
an over-all dusky appearance (Fig. 3). 
Besides the duskiness of the males, there was a pro- 
nounced color difference between the sexes in the pig- 
mentation of the soft dorsal fin. In addition to increased 
melanization, the dorsal rays of males were boldly out- 
lined with yellow; the soft dorsal fins of the females had 
no visible yellow pigment. 
Although the width and color intensity of the yellow- 
orange submarginal band in the spinous dorsal fin were 
usually greatest in males, pronounced variations occurred 
in both sexes. The color varied from pale yellow to 
bright orange. 
Pigmentation changes began in April and peaked at 
spawning time. The darker color of freshly captured, 
large males taken in the spring made them easily sepa- 
rable from females. Large size and more intense color- 
ation undoubtedly enhanced sex recognition and provid- 
ed older males an advantage over younger males in at- 
tracting females. 
Breeding P. phoxocephala males did not develop 
tubercles. Collette (1965:577) found breeding tubercles 
on none of the species of Swainia. The genital papillae 
of males were small, triangular flaps which enlarged 
slightly as spawning neared (Fig. 4). 
The testes began enlarging in late summer, and con- 
tinued to enlarge until spawning time. In specimens 
collected on September 21, the length of the testes aver- 
aged 10 percent of the standard length; in a specimen 
“) 
: ey K) 
5 Ay a 
yy aS ey 
Fig. 3—Pigmentation patterns of a 63-mm breeding male (top) and a 56-mm breeding female (bottom) Percina phoxoce 
phala, both captured on May 26, 1970. 
