42 
Fishery Bulletin 96( 1 ), 1998 
were found, the best visualized demarcation of dif- 
ferences between these species is the ratio of ED to 
TKL plotted against head length (Fig. 20). There is 
little ontogenetic change evident in this ratio for S. 
billy krietei, and a slight increase in the ratio with 
increasing head length for S. ginsburgi', however, the 
ratio is usually greater for S. ginsburgi than for S. 
billy krietei, especially in larger individuals. For S. 
ginsburgi, 87% of 54 individuals had a ratio exceed- 
ing 3.5, whereas 96% of the specimens had a ratio 
exceeding 3.4. In contrast, estimated ratios in speci- 
mens of S. billykrietei (n=6 9) were lower, with 91% 
of the specimens having a ratio of ED to TKL less 
than 3.5, whereas 94% had a ratio less than 3.6. 
Symphurus billykrietei is also a larger species than 
S. ginsburgi (compare Figs. 7B and 8A), reaching 
maximum known size of 119 mm, with most adult 
specimens (72/88) reaching lengths greater than 65 
mm, and females not reaching maturity until a mini- 
mum of 80 mm. In contrast, S. ginsburgi reach only 
ca. 90 mm, with most specimens much smaller (55/61 
specimens were smaller than 65 mm); some female S. 
ginsburgi begin maturing at sizes as small as 44 mm 
and some gravid females are as small as 51-53 mm. 
Symphurus billykrietei is similar to S. stigmosus, 
another deepwater, western North Atlantic tongue- 
fish in this species group, but differs most notice- 
ably from this species in lacking the prominent se- 
ries of pigmented blotches alternating with unpig- 
mented areas of equal or greater size on the poste- 
rior two-thirds of the dorsal and anal fins character- 
istic of S. stigmosus. Symphurus billykrietei usually 
Standard length Standard length 
Figure 18 
Comparisons of selected morphometric features of Symphurus billykrietei and S. ginsburgi (measurements in mm). (A) Trunk 
length versus standard length. (B) Head length versus standard length. (C) Snout length versus head length. (Regression equa- 
tions and P-values for differences between lines appear in Table 15.) 
