the channel, were seined, but no darters were found. 
In February a specimen was collected in the relatively 
shallow portion of the channel, but its occurrence there 
was exceptional, and other attempts to collect specimens 
in the winter months were unsuccessful. _P. phoxocepha- 
la left the raceway areas in November and returned in 
March or April. 
Besides the hiemal migration, the spring movements 
into and out of the spawning area involved a large pro- 
portion of the population and should be recognized as 
a breeding migration characteristic of the species. Wheth- 
ar P. phoxocephala migrated in and out of tributaries 
with the change in seasons as P. sciera was thought to 
Jo is unknown. 
‘erritoriality 
Mass movements of the males into the spawning 
iabitat well before the females suggested that the species 
vas territorial during the spawning season. Aquaria 
ised to observe P. phoxocephala were probably too 
mall to allow the establishment of territories although 
1ales were rather consistently belligerent toward other 
nales. 
PHYLOGENETIC RELATIONSHIPS 
In his description of Hadropterus nasutus, Bailey 
1941:1-2) suggested a close relationship with P. phoxo- 
ephala and P. oxyrhyncha. Percina squamata, the 
ourth species in the subgenus Swainia, is more general- 
ed and less closely related, but it strongly resembles 
. phoxocephala in some characteristics, most notably 
1e pigmentation pattern. 
Swainia is one of the most primitive subgenera of 
ercina. Generalized characteristics of the subgenus 
1clude the modest specialization of the midventral row 
f scales in the male, lack of pronounced sexual dimor- 
hism, highly pelagic habits, and high meristic counts. 
omparisons of data collected during this study and 
Taste 4.—Stomach contents of Percina phoxocephala of all sizes collected in the Embarras River. 
‘e numbers of stomachs examined. 
11 
during the life-history study of P. sciera indicate Swainia 
to be somewhat less evolutionarily advanced than the 
subgenus Hadropterus. 
Winn (19585: 188) suggested the degree of abate- 
ment of the gas bladder to be an indicator of phyloge- 
netic advancement of darters, Page & Smith (1970:11) 
found P. sciera to have a large bladder, averaging ap- 
proximately 16 percent of the standard length of the 
fish examined. In eight P. phoxocephala specimens 
the bladder was also large, ranging from 11 to 18 per- 
cent and averaging 15 percent of the standard length. 
DIET AND FEEDING HABITS 
Thomas (1970:8-12) examined the stomach con- 
tents of 103 P. phoxocephala from the Kaskaskia River, 
Hlinois. He found the predominant food items to be 
“baetid nymphs, chironomid larvae, and hydropsychid 
larvae,” and noted that certain organisms (e.g., stonefly 
nalads and elmid beetle adults), although abundant in 
the darter habitat, were avoided as food items by all 
four darters he studied. The young fed mainly on 
midge larvae. 
In 45 specimens of P. phoxocephala from the Embar- 
ras River study area examined for stomach contents 
(Table 4), midge larvae and pupae, black fly larvae, 
caddisfly larvae, and mayfly naiads formed over 99 per- 
cent of the food items encountered. Less frequent items 
were amphipods, fish eggs, and terrestrial insects. 
The small variety of food items found in P. phoxo- 
cephala was also found in P. sciera studied in the same 
area. In addition to a similarity in over-all diet, the 
seasonal variations in the diets of the two species were 
approximately concurrent; dipterans and mayflies_pre- 
dominated during all: seasons, and caddisflies formed a 
large portion of the diet during the summer (Fig. 9). 
The correlation between the two fish species in seasonal 
variations in diet strongly suggests that both fed on 
whatever insect immatures were available and palatable, 
Figures in parentheses 
Percent of Stomachs Examined in Which Each Food Organism Occurred 
Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. 
Food Organism (1) G25) (4) (4) (9) (9) (4) (4) (4) (4) 
idge larvae, pupae 100 100 25 50 44.4 55.6 50 100 We 50 
ack fly larvae 100 ee 100 25 Doe, 222 Pe 25 a 
addisfly larvae 100 Bere 25 25 Pot 44.4 25 50 50 a 
ayfly naiads ane 75 100 66.7 66.7 £3 50 25 50 
iscellaneous ae 25 Race D5 a aD 20 
Mean Number of Food Organisms Per Stomach 
Feb. Mar. Apr. May June July Aug. Sept. Oct Nov 
idge larvae, pupae 5.00 3.00 O25 Deis 39 S233 1.00 1B. 0S B20 0.75 
ack fly larvae 1.00 Sache 15.50 15.50 6.00 0.44 ae: 0.50 Ahi 
iddisfly larvae 1.00 ae Ms 2S D2 0.44 DSS OR25 1.50 a axis 
ayfly naiads ee e748 Po Hs 4.33 1.00 eee 0.50 2.50 0.75 
iscellaneous OR20 seas OR25 O25 
