Munroe: Systematics of western Atlantic Symphurus 
37 
Comparisons In the western Atlantic and Carib- 
bean region, only S. rhytisma and S. arawak possess 
the combination of a 1-3-2 ID pattern, 12 caudal-fin 
rays, unpigmented peritoneum, and small adult size. 
Symphurus rhytisma is readily diagnosed from S. 
arawak by differences outlined in the “Comparisons” 
section of the account for S. arawak. 
Symphurus rhytisma has some meristic features 
that overlap those of two deepwater, western Atlan- 
tic species, S. pusillus and S. piger. Although both 
have a 1-3-2 ID pattern and 12 caudal-fin rays as 
does S. rhytisma , they are easily separated from S. 
rhytisma in having a black peritoneum (unpigmented 
in S. rhytisma) and by lacking a pigmented blotch 
on the caudal region of the ocular side of the body 
(present in S. rhytisma). Symphurus rhytisma has 
much smaller and more numerous scales in a longi- 
tudinal series than does either of the other species 
(91-97 in S. rhytisma vs. 62-75 in S. piger and 77- 
87 in S. pusillus). Symphurus rhytisma also has fewer 
anal-fin rays (68—7 1 ) than does S. pusillus (71-75). 
Symphurus rhytisma differs further from S. piger in 
having an unpigmented isthmus and inner opercu- 
lar linings (vs. lightly pigmented in S. piger), 4 
hypurals (vs. 5 in S. piger), and in its much smaller 
size (45 mm vs. ca. 130 mm in S. piger). 
Other Atlantic species most closely resembling S. 
rhytisma are S. lubbocki and S. reticulatus, dwarf 
species of tonguefishes collected in shallow-water 
habitats in insular locations in the central and east- 
ern Atlantic. Symphurus rhytisma may be distin- 
guished from both species by its lower meristic fea- 
tures (dorsal-fin rays 83-87 vs. 87-89 in S. lubbocki 
and S. reticulatus', anal-fin rays 68-71 vs. 74-75; total 
vertebrae 46-48 vs. 48-49 in these other species), 
somewhat larger scales (91-97 scales in a longitudi- 
nal series vs. 101-109 in the other two species), and 
by differences in pigmentation. In S. rhytisma, all 
but the largest specimens have a dark blotch across 
the posterior one-third of the body (vs. no blotch in 
these other species), and the ocular surface of the 
body of S. rhytisma generally has a series of incom- 
plete, dark brown crossbands contrasting against a 
pallid background. This combination of features con- 
trasts with that observed in S. reticulatus, which has 
a dark, chocolate-brown body with X- and Y-mark- 
ings and a series of alternating blotches and unpig- 
mented areas in the dorsal and anal fins, and that 
observed in <S. lubbocki, which has a cream-colored 
background, lacks a caudal blotch, and which has 
dorsal and anal fins uniformly and lightly pigmented. 
