74 
Fishery Bulletin 96(1 ), 1998 
and Benvegnu, 1976). Even the smallest specimens 
of S. trewavasae are found in relatively deep waters 
(12-38 m). In comparison, S. plagiusa is a shallow- 
water species commonly found in estuarine areas and 
shallow coastal waters at depths usually less than 
40 m, with the smallest individuals commonly taken 
in tidal creeks and coastal embayments rather than 
open waters on the inner continental shelf (see below). 
Menezes and Benvegnu were convinced, on the 
basis of material they had studied (and I agree), that 
S. plagiusa is absent along the Brazilian coast and 
that the many references to this species from this area 
and farther south are probably based on specimens of 
S. trewavasae. Reports of S. plagiusa from southern 
Brazil (Roux, 1973:176) and Argentina (Lazzaro, 1973) 
are, in all probability, those of S. trewavasae. 
Comparisons Among Atlantic tongueflshes, meris- 
tic features of S. trewavasae overlap those of several 
western Atlantic species including S. piger, S. 
pusillus, S. ginsburgi, S. billykrietei, S. stigmosus, 
and the eastern Atlantic S. nigrescens. Symphurus 
trewavasae is readily distinguished from these spe- 
cies by its unpigmented peritoneum (vs. black in the 
others), by having 10 caudal-fin rays (vs. 12), and by 
its 1-3-3 ID pattern (vs. 1-3-2 in the others). 
Counts of caudal-fin rays and total vertebrae for 
S. trewavasae partially overlap those of the western 
South Atlantic S. kyaropterygium , but these sympa- 
tric species are easily distinguished because S. 
trewavasae lacks a pupillary operculum and mem- 
brane ostia (both well developed in S. kyarop- 
terygium); the ocular surface of S. trewavasae has 
strong crossbanding without a dark brown caudal 
blotch, whereas that of S. kyaropterygium usually 
lacks crossbands and has a well-developed, dark 
brown blotch on the ocular-side caudal region. 
Symphurus trewavasae differs further in having 
more dorsal- and anal-fin rays (80-87 and 67-72, 
respectively, in S. kyaropterygium), and a different 
predominant ID pattern ( 1-4-2 in S. kyaropterygium). 
Meristic features of S. trewavasae also overlap 
those of iS. diomedeanus, S. plagiusa, S. caribbeanus, 
S. civitatium, and S. plagusia, but the ID pattern in 
S. trewavasae differs from these species (usually 1-4-3 
in the others), and S. trewavasae has fewer caudal- 
fin rays ( 10 vs. 12) than do S. civitatium, S. plagusia, 
and S. caribbeanus . Symphurus trewavasae is fur- 
ther distinguished from S. diomedeanus in lacking 
both a pupillary operculum and pigmented spots on 
the dorsal and anal fins (both features present in S. 
diomedeanus), and in having fewer longitudinal 
scales (67-77 vs. 79-96 in S. diomedeanus). 
Symphurus trewavasae , historically, has often been 
confused with the western North Atlantic S. plagiusa. 
Differences between these species are listed above 
in the “Remarks” section. Symphurus trewavasae dif- 
fers further from S. plagusia, S. civitatium, and S. 
caribbeanus in its much larger eye (114-162 HL vs. 
110 HL or smaller in these other species) and in hav- 
ing an unpigmented isthmus and a lightly pigmented 
inner opercular lining on the ocular side (vs. heavily 
pigmented ocular-side isthmus and inner opercular 
lining in these other species). From S. plagusia and 
S. civitatium, S. trewavasae is further distinguished 
in lacking the fleshy ridge on the ocular-side dentary, 
characteristic of the others, and the dorsal-fin origin 
in S. trewavasae is usually positioned at a vertical 
equal with the midregion of the upper eye, whereas 
in these others the dorsal-fin origin is situated more 
anteriorly, usually at a point anterior to the vertical 
through the anterior margin of the upper eye. 
Symphurus trewavasae has fewer longitudinal scales 
than does S. caribbeanus (67-77 vs. 78-89). 
From other species with a 1-3-3 ID pattern (S. 
varius, S. atramentatus , and S. normani), S. 
trewavasae is readily distinguished in having only 
10 caudal-fin rays (vs. 12 in these others). Symphurus 
trewavasae can be further distinguished from the 
eastern Pacific S. varius in having fewer longitudi- 
nal scales (67-77 vs. 120-124) and in having four 
hypurals (vs. five). Some meristic features of S. 
trewavasae are similar to those of the tropical east- 
ern Atlantic S. normani, and S. atramentatus, which 
occurs in temperate and tropical regions of the east- 
ern Pacific. However, S. trewavasae has sharply con- 
trasting crossbands on the ocular surface, a uniformly 
pigmented blind side, and lacks an alternating se- 
ries of boldly pigmented blotches and unpigmented 
areas on the dorsal and anal fins, whereas S. normani 
has few, if any, faint crossbands on the ocular sur- 
face and a pattern of pepper-dots on the blind side of 
the body, and S. atramentatus has a bold pattern of 
pigmented blotches alternating with unpigmented 
areas on the dorsal and anal fins. Symphurus 
trewavasae lacks the small ctenoid scales on blind 
sides of dorsal- and anal-fin rays characteristic of S. 
normani. From S. atramentatus, S. trewavasae is 
further distinguished in lacking a pupillary opercu- 
lum (vs. present), and by its lower meristic features 
(dorsal-fin rays 92-96, anal-fin rays 77-81, and 50- 
52 total vertebrae in S. atramentatus). 
