Munroe: Systematics of western Atlantic Symphurus 
77 
Figure 39 
Geographic distribution of Symphurus kyaropterygium 
based on material examined (discussion of geographic dis- 
tribution appears in species account). 
that study, Munroe (1987) identified three additional 
species ( S . minor , S. parvus, and S. ommaspilus) that 
also possess membrane ostia. Munroe pointed out 
that these four species also have a similar ID pat- 
tern ( 1-4-2), a similar number of caudal-fin rays ( 10), 
relatively low meristic features, and all have a 
well-developed pupillary operculum. Additionally, 
three of the four (not S. ommaspilus) have a similar 
pigmentation pattern of a prominent, dark brown 
blotch on the caudal region of the ocular side of the 
body without pigmented spots on the dorsal and anal 
fins. In contrast, S. ommaspilus lacks the caudal 
blotch characteristic of these other species but has a 
single ocellated spot on the dorsal and anal fins. The 
large number of shared characters may indicate close 
relation among these four species; it is hypothesized 
that they comprise a lineage within the genus. 
Comparisons Of western Atlantic tonguefishes, S. 
kyaropterygium is most similar to the north Atlantic 
S. parvus. Symphurus kyaropterygium can be dis- 
tinguished from S. parvus by its more numerous dor- 
sal- (80-87, usually 83-87 vs. 75-86, usually 77-84, 
in S. parvus) and anal-fin rays (67-72 vs. 60-70, 
usually 62-68), and more longitudinal scales (73-81 
vs. 59-78, but usually 59-74 in S. parvus) (see Tables 
4- 7). There may be differences of frequency in ID pat- 
terns between these two species (larger sample sizes 
needed for S. kyaropterygium). Of 14 specimens of S. 
kyaropterygium, 13 (94%) had a 1-4-2 ID pattern and 
none had a 1-5-2 pattern. In contrast, only 33/82 (40%) 
of S. parvus had a 1-4-2 pattern, and 35 (43%) had a 1- 
5- 2 ID pattern. There are differences also in maximum 
sizes attained by both species. Symphurus parvus ap- 
parently is a smaller species, reaching a maximum size 
of only about 88 mm, and individuals as small as 35- 
50 mm are sexually mature. In contrast, S. kyarop- 
terygium attains larger sizes (120 mm), especially be- 
fore reaching sexual maturity (85 mm or larger). 
Meristic and size differences between S. kyarop- 
terygium and the Caribbean S. ommaspilus and 
North Atlantic S. minor are even more distinct (Tables 
4—9), with little or no overlap in most meristic features 
examined. Also, S. kyaropterygium lacks the ocellated 
spot on dorsal and anal fins characteristic of S. 
ommaspilus. Symphurus kyaropterygium is much 
larger than either of these diminutive flatfishes, reach- 
ing maximum lengths of ca. 120 mm, compared with 
60 mm in S. ommaspilus, and 78 mm in S. minor. 
Differences between S. kyaropterygium and the 
sympatrically occurring S. trewavasae are discussed 
in the “Comparisons” section in the species account 
for S. trewavasae. 
Symphurus kyaropterygium is similar to, and co- 
occurs throughout most of its geographic range with, 
S. diomedeanus. Both possess 10 caudal-fin rays and 
well-developed pupillary operculum; however, they 
differ in many characteristics. Symphurus kyarop- 
terygium has membrane ostia in the dorsal and anal 
fins, a well-developed, dark brown blotch on the ocu- 
lar-side caudal region and lacks spots on dorsal and 
anal fins (vs. membrane ostia and caudal blotch lack- 
ing, and spots usually well developed on posterior anal 
and dorsal fins in S. diomedeanus). Symphurus 
kyaropterygium has fewer dorsal- (80-87 vs. 86-96 in 
S. diomedeanus) and anal-fin rays (67-72 vs. 69-80), 
fewer longitudinal scales (73-81 vs. 79-96), and a dif- 
ferent ID pattern (1-4-2 vs. 1-4-3 in S. diomedeanus). 
Symphurus kyaropterygium differs from the west- 
ern North Atlantic S. plagiusa, which also possesses 
10-caudal-fin rays, by having a well-developed pu- 
pillary operculum and membrane ostia (both absent 
in S. plagiusa), in its blotch on the ocular-side caudal 
region, in an unpigmented isthmus and unpigmented 
inner opercular linings, in lacking a black spot on the 
outer surface of the ocular-side opercle (vs. no caudal 
blotch, heavily pigmented isthmus and inner opercu- 
lar linings, and usually with a conspicuous opercular 
spot in S. plagiusa), and in lacking both a fleshy ridge 
on the ocular-side lower jaw and scales on blind sides 
of dorsal- and anal-fin rays (both present in S. plagiusa). 
Among other species of Symphurus, only S. 
fasciolaris from the eastern Pacific has 10 caudal-fin 
rays. Symphurus kyaropterygium , however, has lower 
fin-ray counts (90-97 dorsal- and 77-81 anal-fin rays 
in S. fasciolaris), and also lacks a caudal-fin spot and 
the combination of crossbands and rounded spots on 
the ocular surface, features characterizing S. fasciolaris. 
