152 
Fishery Bulletin 96(1 ), 1998 
gions of the Atlantic. Several deepwater western At- 
lantic members of this species group inhabit similar 
depths but have allopatric geographic distributions 
(S. pusillus — western North Atlantic, S. ginsburgi — 
western South Atlantic, and S. nigrescens— eastern 
Atlantic; S. billykrietei on continental shelf off east- 
ern United States, S. stigmosus and S. piger on con- 
tinental shelf off southern Florida and Caribbean 
Sea). Conversely, other deepwater species in this 
group with sympatric geographic distributions, such 
as S. pusillus and S. billykrietei , and S. piger and S. 
marginatus, do not overlap extensively with respect 
to depth of occurrence. Among shallow-water mem- 
bers of this species group, S. arawak and S. rhytisma 
have sympatric distributions in the Caribbean Sea 
and both species occupy a similar range of depths 
(6-39 m, and 3-25 m, respectively). It is unknown to 
what degree, if any, these species occur syntopically. 
None of the collections I examined contained both 
species, nor have these species been reported to oc- 
cur syntopically. Symphurus rhytisma is rare in col- 
lections (only nine specimens available to this study), 
and more specimens with associated depth-of-cap- 
ture information are necessary before a detailed 
statement can be made regarding its ecological re- 
quirements. This species is very similar with respect 
to shape, meristics, size, and depth of occurrence to 
S. lubbocki and S. reticulatus (Ascension Island and 
St. Helena-Madeira, respectively; Munroe, 1990). 
Interestingly, and consistent with findings for other 
species where more information is available, all three 
species have allopatric distributions but apparently 
similar ecological requirements. 
Symphurus trewavasae, the only western Atlantic 
species with the 1-3-3 ID pattern, has been collected 
on the inner continental shelf off Brazil to Argentina 
at depths of ca. 7 to 180 m. Among other Atlantic 
species, only S. normani has a 1-3-3 ID pattern 
(Munroe, 1990). This species occurs allopatrically off 
West Africa at depths (25-80 m) approximately simi- 
lar to those inhabited by S. trewavasae. 
Similar patterns of geographical and ecological 
occurrence are also evident for the four species with 
a 1-4-2 ID pattern. Three are North Atlantic species, 
but only two, S. minor and S. parvus , occur sympat- 
rically. Symphurus ommaspilus is completely differ- 
ent, both in its preferred habitat and in its depth of 
occurrence, and is therefore completely allotopic rela- 
tive to other members of this ID pattern group. It is 
the only species in the group that occurs on shallow 
(1-20 m) sandy substrates, namely those with sub- 
merged aquatic vegetation, on or adjacent to Carib- 
bean coral reefs. Other members in this group are 
more similar phenotypically and inhabit substrates 
on the continental shelf. The geographic distribution 
of S. minor extends along the southeastern coast of 
the United States to the west coast of Florida, in- 
cluding areas extending westward into the Gulf of 
Mexico almost to the DeSoto Canyon. The pheneti- 
cally similar S. parvus, occurs from North Carolina 
to Venezuela, and throughout its geographic range, 
commonly inhabits mud substrates at depths from 
40 to 90 m. Although S. parvus occurs sympatrically 
with S', minor in the northeastern section of its geo- 
graphic range, these species are nearly always com- 
pletely allotopic with respect to depth of occurrence. 
The geographic distribution and bathymetric center 
of abundance (11-50 m) of S. minor corresponds 
closely with the occurrence of live-bottom areas. The 
abrupt change in sediments that occurs in the re- 
gion of the Mississippi River outflow and which ex- 
tends into the central and western areas of the Gulf 
may account for the absence of the species in these 
areas. The geographic distribution of S. minor off the 
southeastern United States closely parallels that of 
S. urospilus, another species inhabiting live-bottom 
substrates but belonging to the 1-4-3 ID pattern spe- 
cies group (see below). Symphurus kyaropterygium, 
which occurs off southern Brazil, is hypothesized to be 
most closely related to S. parvus. These two represent 
another example of related species with allopatric dis- 
tributions that occupy nearly identical bathymetric 
environments (36—69 m for S. kyaropterygium). 
The nine western Atlantic species characterized 
by the 1-4-3 ID pattern are the most diverse shal- 
low-water tonguefish group in this area. Many are 
sympatric, or partially sympatric, with other mem- 
bers of the group, and several species also overlap 
with respect to bathymetric occurrence. These spe- 
cies, however, do not usually occur syntopically. 
Rather, adults of sympatric species are found at dif- 
ferent depths, or if occurring at similar depths, then 
they inhabit different substrates. Along the south- 
eastern coast of the United States and in the north- 
ern Gulf of Mexico, S. plagiusa, S. civitatium, S. 
urospilus, and S. diomedeanus co-occur sympatri- 
cally. Symphurus plagiusa is unique among these 
tonguefishes in being the only species that occurs 
predominantly in nearshore shallow-water and es- 
tuarine mud and silt substrates. Although larger in- 
dividuals of S. plagiusa are occasionally found on the 
continental shelf to depths of 40 m and beyond, the 
majority of the population is found in nearshore ar- 
eas and largely allopatric to populations of other 
tonguefishes. This species sometimes co-occurs in 
collections with S. civitatium, but the majority of the 
adult population of S. civitatium is found in deeper 
water on inner continental shelf terrigenous sand 
substrates. Adult S. civitatium are very abundant in 
collections and, although inhabiting a wide depth 
