Munroe: Systematics of western Atlantic Symphurus 
29 
Comparisons Among western Atlantic tongue- 
fishes, S. nebulosus overlaps only S.jenynsi in some 
meristic features but can easily be distinguished from 
the latter by its 14 caudal-fin rays (vs. 10 in S. 
jenynsi), black peritoneum, and ocular-side pigmen- 
tation without pattern of crossbanding (vs. unpig- 
mented peritoneum and ocular surface usually with 
pattern of crossbanding in S.jenynsi), in having com- 
plete dentition on both ocular-side jaws (reduced 
dentition on ocular-side premaxilla and teeth absent 
on ocular-side dentary in S. jenynsi), more numer- 
ous scales in longitudinal series (120-135 vs. 102- 
119 in S. jenynsi), its different ID pattern (1-2-2 vs. 
1-4-3 in S. jenynsi), its larger eye (94-113 vs. 74-95 
in S. jenynsi), in having 5 hypurals (vs. 4 in S. 
jenynsi), and by its much narrower (BD 165-282 SL 
in S. nebulosus vs. 231-328 SL in S. jenynsi) and 
smaller body (maximum sizes ca. 87 mm in S. 
nebulosus vs. >300 mm in S. jenynsi). 
Body depth measurements in S. nebulosus approxi- 
mate those in juvenile and small adultS. marginatus, 
another deepwater western Atlantic species (see be- 
low). However, S. nebulosus lacks the conspicuous 
dark brown blotch on the ocular-side caudal region 
of the body and posterior dorsal and anal fins and 
also lacks the stripe along basal margins of the dor- 
sal and anal fins (both features present in S. 
marginatus). In addition, S. marginatus differs in 
having 12 caudal-fin rays, fewer total vertebrae (51- 
56), dorsal-fin rays (93-104), anal-fin rays (80-89), 
and fewer scales in a longitudinal series (86-99), its 
larger eye (125-248 HL), and ID pattern (1-3-2 in S. 
marginatus). 
Of tonguefishes occurring outside the western At- 
lantic Ocean, S. nebulosus most closely resembles two 
deepwater species: S. variegatus, known only from 
two specimens taken in the western Indian Ocean 
off South Africa; and S. ligulatus, a species in the 
eastern Atlantic and Mediterranean Sea that possi- 
bly forms an amphi-Atlantic species pair with S. 
nebulosus. All three species have similar numbers of 
caudal-fin rays, slender bodies, and possess a 1-2-2 
ID pattern. Symphurus nebulosus is distinguished 
from S. variegatus in having more vertebrae (57-60, 
usually 58-59 vs. 56 in S. variegatus). Within the 
genus, S. nebulosus is most similar to S. ligulatus. 
Comparisons of S. ligulatus and S. nebulosus re- 
vealed subtle but significant differences between 
these two species in 8 of 14 morphometric charac- 
ters examined (Munroe, 1990). According to results 
from a discriminant function analysis (DFA), notable 
differences occur in postorbital and head lengths 
(both longer in S. nebulosus), lower head lobe width 
(wider in S. nebulosus), and body depth, which is 
somewhat deeper in S. nebulosus (BD 16.5-28.2% 
SL, but usually 22.5-24.0% SL vs. 19.4-23.8%, but 
usually 21.0-22.0% SL in S. ligulatus). Symphurus 
nebulosus , despite having a more darkly pigmented 
body in general, has only a slight band of pigment, if 
any, on the ocular-side upper lip. In contrast, S. 
ligulatus specimens generally have a well-developed 
band of pigment on both ocular-side lips. The spe- 
cies also differ in modal counts of total vertebrae (58 — 
59 in S. nebulosus vs. 59-60 in S. ligulatus). 
Symphurus nebulosus is readily distinguished from 
S. vanmelleae, a deepwater tropical eastern Atlantic 
species, in caudal-fin rays (14 vs. 12 in S. vanmelleae), 
vertebrae (9 abdominal vertebrae, 57-60, modally 
58-59, total vertebrae vs. 10-11 abdominal and 56- 
58 total vertebrae in S. vanmelleae), modally higher 
meristic features (dorsal-fin rays 105-113 in S. 
nebulosus vs. 101-108 in S. vanmelleae', anal-fin rays 
91-98 vs. 86-93), and ID patterns (1-2-2-2-2 vs. 1-2- 
2-1-2 or 1-2-2-2-1 in S. vanmelleae). 
