Munroe: Systematics of western Atlantic Symphurus 
33 
ters adjacent to coral reefs at depths of 6-39 m, most 
between 6 and 30 m (Table 10). Only three speci- 
mens were taken deeper than 30 m (one each at 31, 
34, and 39 m). Little else is known concerning the 
life history of this diminutive flatfish. 
Remarks Robins and Randall (1965) tentatively 
proposed that S. arawak and S. minor are a north- 
south species pair occurring in tropical and warm 
temperate regions of the western Atlantic that may 
have differentiated because of repeated latitudinal 
fluctuations in the fish fauna during glacial and in- 
terglacial periods in the western Atlantic. This hy- 
pothesis is not supported by information presented 
in Munroe (1987; 1992), who has hypothesized that 
S. arawak and S. minor belong to different species 
groups within the genus. Symphurus arawak is a 
member of the species group characterized by a 1-3-2 
ID pattern, 12 caudal-fin rays, lack of a pupillary 
operculum, and lack of ostia in basal portions of the 
dorsal- and anal-fin membranes. Symphurus minor , 
in turn, belongs to the species group characterized 
by a 1-4-2 ID pattern, 10 caudal-fin rays, and pos- 
sessing a well-developed pupillary operculum and 
membrane ostia. Similarities between S. arawak and 
S. m inor in meristic features and in small adult sizes 
do not appear to be synapomorphies that reflect a 
common ancestry but, rather, are probably con- 
vergently evolved traits. 
Comparisons Symphurus arawak has the lowest 
counts for any species in the genus (Munroe, 1992). 
Among tonguefishes, only the western Atlantic S. 
minor and the sympatrically occurring S. ommas- 
pilus approach the ranges in meristic features and 
small size of S. arawak. However, S. arawak differs 
significantly from these species in caudal-fin ray 
counts (12 vs. 10 in the others), absence of a pupil- 
lary operculum and membrane ostia (both present 
in S. minor and S. ommaspilus), a pepper-dot pat- 
tern of melanophores on the blind side of the body 
(absent in S. minor and S. ommaspilus ), and S. 
arawak has modally fewer vertebrae (40-42 vs. 41- 
43 in S. minor and 43-44 in S. ommaspilus), and a 
different ID pattern (1-3-2 vs. 1-4-2 in S. minor and 
S. ommaspilus, respectively). Symphurus arawak 
differs further from S. ommaspilus in having body 
crossbands or a darkly pigmented blotch on the ocu- 
lar side and no spots on the dorsal and anal fins (vs. 
uniformly whitish body without crossbands or pig- 
mented blotch but having a single ocellated spot on 
dorsal and anal fins of S. ommaspilus). 
Symphurus arawak is similar to three other At- 
lantic dwarf species, the sympatric S. rhytisma and 
two dwarf species, S. lubbocki Munroe and S. 
reticulatus Munroe, occurring on shallow-water sub- 
strates at midocean and eastern Atlantic islands. 
Symphurus arawak is easily separated from these 
others because of its lower counts (dorsal-fin rays 
70-76 vs. 82-89; anal-fin rays 55-61 vs. 68-75, and 
total vertebrae 39-42 vs. 46-49 in these others). 
Symphurus arawak also has considerably larger and 
fewer (55-65) scales in a longitudinal series com- 
pared with those of S. rhytisma (91-97), S. lubbocki 
( 107-109), and S. reticulatus ( 101-109). None of the 
other dwarf Symphurus have pepper-dot pigmenta- 
tion on the blind side, and for each of these other 
species the pattern of pigmentation on the ocular 
surface also differs significantly from that of S. 
arawak. In S. rhytisma, ocular-side pigmentation 
consists of crossbands on the trunk, with usually the 
two posteriormost crossbands coalesced and forming 
a heavily pigmented caudal patch. Symphurus 
lubbocki has a cream-colored ocular surface with sev- 
eral, mostly incomplete, crossbands, whereas the 
ocular-side pattern of S. reticulatus is dark, choco- 
late-brown with alternating X- and Y-shaped mark- 
ings, and in this species the dorsal and anal fins also 
have an alternating series of blotches and unpigmented 
areas (vs. uniformly pigmented areas and intensified 
pigmentation in caudal region in S. arawak). 
Symphurus pelicanus is a diminutive ( usually <70 
mm), relatively deepwater, western Atlantic tongue- 
fish that, reminiscent of S. arawak, also has a pep- 
per-dot pattern of melanophores on the blind side of 
the body, 12 caudal-fin rays, and a 1-3-2 ID pattern. 
Symphurus arawak is easily distinguished from S. 
pelicanus by its unpigmented peritoneum (vs. black 
in S. pelicanus), lower meristic features (vs. dorsal- 
fin rays 77-85, anal-fin rays 64-70, and total verte- 
brae 43-46 in S. pelicanus), in having unpigmented 
inner opercular linings and isthmus (vs. inner oper- 
cular linings and isthmus sprinkled with melano- 
phores in S. pelicanus), and S. pelicanus lacks the 
pigmented blotch on the ocular side of the body that 
is present on some adult S. arawak. 
