1980] 
Pupedis — Spongilla-fly Larvae 
309 
tergites. The setae form two parallel rows, one on either side of the 
dorsal midline, that run the length of the abdomen. On the eighth 
segment of Sisyra larvae both setae remain small with no discernible 
bases. In the same location on Climacia species each seta is enlarged 
to form a large hair on a short distinct tubercle. Poirrier and 
Arceneaux (1972) noted this setal variation in southern specimens of 
C. areolaris, C. chapini, S. vicaria, and S. apicalis. Ventrally on the 
eighth abdominal segment is a similar pair of setae; on southern 
specimens of S. vicaria and S. apicalis the setae are sessile, but on C. 
areolaris and C. chapini they arise from tubercles (Poirrier and 
Arceneaux, 1972). This condition was not developed sufficiently to 
separate my northern specimens of S. vicaria from those of C. 
areolaris; both had bases. The above indicates geographic variabil¬ 
ity of this character, possibly of a clinal nature. 
A third, but more variable feature can be seen on the large 
pronotal tergites located to either side of the prothoracic midline. 
Each tergite has six prominent, setiferous tubercles (Fig. le). 
Generic identification can usually be made from the ratio A/B: the 
distance (A) between the anterior, horizontally paired tubercles (1 
and 2) divided by the distance (B) between the longitudinally paired, 
medial tubercles (2 and 3). Table 1 shows the ratio to be close to 
Table 1. Comparison of the ratio A/B obtained from the prothoracic tergites of 
seven sisyrid species (significance of differences between ratio values was analyzed 
using a modified T-test with alpha = .05; N is composed of measurements from the 
right and left sides of individual specimens). 
SPECIES 
N 
A/B X 
S 2 
RANGE 
Sisyra vicaria' 
46 
1.3 
0.0249 
1.0 -1.75 
S. fuscata 
18 
1.0 
0.0082 
0.85-1.14 
Climacia areolaris 2 
46 
2.2 
0.1487 
1.45-3.0 
Climacia species 
16 
2.3 
0.0473 
2.0 -2.75 
C. striata 
2 
2.3 
0.0008 
2.29-2.33 
C. californica 
4 
2.0 
0.0000 
2.0 
C. chapini 
9 
2.0 
0.0398 
1.5 -2.27 
1. Sisyra vicaria and S', fuscata differ significantly from all Climacia species and 
from each other. 
2. Two significantly different groups of Climacia larvae are present with the 
members within the groups not significantly different from each other; C. areolaris, 
Climacia species, and C. striata versus C. californica and C. chapini. 
