Munroe: Systematics of western Atlantic Symphurus 
65 
as part of the type series and therefore does not com- 
promise the original concept of Aphoristia marginata. 
Metzelaar’s reference (1919:134) to S. marginatus 
from Saint Eustatius is based on a misidentified 
specimen (ZMA 119.422) of S. ommaspilus. 
Comparisons Symphurus marginatus has some- 
what similar geographic and bathymetric distribu- 
tions throughout the Caribbean Sea and Gulf of 
Mexico as those reported for S. piger (see below), and 
these are the only western Atlantic species with a 
combination of a 1-3-2 ID pattern, black peritoneum, 
and five hypurals (although five hypurals occur much 
less frequently in S. marginatus — only 28% of 57 
specimens of this species had this count vs. 99% of 
136 specimens of S. piger). However, these distinctive 
species are not usually collected syntopically and the 
two species can be readily identified (compare Figs. 32 
and 34). Symphurus marginatus lacks crossbands on 
the ocular surface and has a prominent blotch on the 
ocular-side caudal region, whereas S. piger usually has 
prominent crossbands and lacks any blotch on the ocu- 
lar-side caudal region. The isthmus and inner opercu- 
lar linings of S. marginatus are unpigmented, whereas 
those of S. piger are lightly sprinkled with melano- 
phores, and basal margins of the dorsal and anal fins 
in S. marginatus have a dark brown stripe that is ab- 
sent in S. piger. Symphurus marginatus also differs 
from S. piger by its much higher and nonoverlapping 
meristic features (93-104 dorsal-fin rays vs. 80-88 in 
S. piger; 80-89 anal-fin rays vs. 68-74; 86-99 scales in 
a longitudinal series vs. 62-75; and 51-56 total verte- 
brae vs. 45^9 in S. piger). In addition, S. marginatus 
has a more elongate body (BD 200-315, x =250) with a 
relatively narrow head ( 147-227 SL, x =191) compared 
with that of S. piger (wide body 244—350 SL, x=322 
and wide head 242-313 SL, x=277). 
The relatively elongate body of S. marginatus is 
reminiscent of other Atlantic slender-bodied, 
deepwater species, namely the western Atlantic S. 
nebulosus, and S. ligulatus and S. uanmelleae from 
the eastern Atlantic. Symphurus marginatus is 
readily distinguished from S. nebulosus and S. 
ligulatus by its fewer caudal-fin rays (12 vs. 14 in 
these others), from all three species by differences 
in ID pattern (1-3-2-2-2 in S. marginatus vs. 1-2-2- 
2-2 in S. nebulosus and S. ligulatus and 1-2-2-1-2 in 
S. uanmelleae), and its generally lower meristic fea- 
tures (93-104 dorsal-fin rays in S. marginatus vs. 
105-113 in S. nebulosus , 101-108 in S. uanmelleae, 
and 102-113 in S. ligulatus', 80-89 anal-fin rays in 
S. marginatus vs. 91-98 in S. nebulosus , 86-93 in S. 
uanmelleae, and 90-102 in S. ligulatus', 51-56 total 
vertebrae in S. marginatus vs. 57-60 in S. nebulosus, 
55-59 in S. uanmelleae, and 56-61 in S. ligulatus', 
86-99 scales in a longitudinal series in S. marginatus 
vs. 120-135 in S. nebulosus, 107-124 in S. uan- 
melleae, and 115-135 in S. ligulatus). In addition, 
all three species lack the dark brown ocular-side cau- 
dal blotch present in S. marginatus . From S. 
uanmelleae, S. marginatus differs further in having 
only nine abdominal vertebrae (vs. 10 or 11). 
Differences between S. marginatus and S. 
billykrietei, S. ginsburgi, and S. stigmosus, three 
other western Atlantic members of this species group, 
are discussed in the “Comparisons” section of each 
species account, respectively. 
Symphurus marginatus is similar in some meris- 
tic features to the western Atlantic, shallow-water 
species, S. tessellatus, S. oculellus, and S. carib- 
beanus, but is easily recognized from all three by its 
black peritoneum (unpigmented in these other spe- 
cies), well-developed dentition on ocular-side jaws (vs. 
absent or reduced dentition on ocular-side jaws), and 
differences in pigmentation patterns. The ocular sur- 
face in S. marginatus is uniformly pigmented with a 
single dark brown blotch in the caudal region, the isth- 
mus and inner opercular linings are unpigmented, and 
spots or blotches are lacking on the ocular-side opercle. 
In contrast, the ocular surface of these other species 
usually has well-developed crossbands, the ocular-side 
isthmus and inner opercular linings are heavily pig- 
mented, and all lack the dark brown caudal blotch char- 
acteristic of S. marginatus. Both S. tessellatus and S. 
oculellus also differ in having a dark blotch on the outer 
surface of the ocular-side opercle. Symphurus margi- 
natus has a different ID pattern (1-3-2) than that in 
these others (1-4-3 ID pattern). 
Approximately 28% (16/57) of the S. marginatus ex- 
amined had five hypurals (the remainder had four). 
Four other species in the genus, the western Atlantic 
S. piger and eastern Pacific S. microlepis, S. diabolicus, 
and S. oligomerus, also have the combination of a 1-3- 
2 ID pattern, 12 caudal-fin rays, black peritoneum, and 
five hypurals. Differences between S. marginatus and 
S. piger were discussed above. Symphurus marginatus 
is easily distinguished from the eastern Pacific species 
because they lack the large dark brown blotch on the 
ocular-side caudal region. From S. oligomerus, S. 
marginatus differs further in having dorsal and anal 
fins with a dark brown stripe along the basal margins 
(vs. an alternating series of rectilinear pigmented 
blotches and unpigmented regions on the dorsal and 
anal fins and no basal stripe in S. oligomerus). Meris- 
tic features of S. marginatus are distinctly lower than 
those of S. microlepis and S. diabolicus (less than 105 
dorsal-fin rays, 90 or fewer anal-fin rays, and 56 or 
fewer vertebrae in S. marginatus vs. more than 105 
dorsal-fin rays and 91 anal-fin rays, and more than 56 
total vertebrae in these other species). 
