Munroe: Systematics of western Atlantic Symphurus 
153 
range (1-73 m), are more commonly captured at 11 
to 45 m where approximately 90% (200/222) of the 
specimens examined in this study were collected. 
Adult S. civitatium rarely occur in deeper or shal- 
lower habitats. Little is known concerning early life 
history stages of S. civitatium. Few studies have iden- 
tified juveniles of this species, and those studies re- 
porting juveniles (Allen and Baltz, 1997) indicate 
these were taken at inshore locations. Occurrence of 
early life history stages in nearshore waters suggests 
a life history pattern similar to that of S. tessellatus 
(Munroe, 1991), where adults occur in deeper waters 
on the inner continental shelf and where juveniles 
inhabit estuarine or nearshore nurseries. 
Along the southeastern coast of the United States, 
S. civitatium occurs sympatrically with S. urospilus 
and at depths similar to those for S. urospilus, but 
these two species are completely allotopic with re- 
spect to substrate preferences. Symphurus civitatium 
is usually found on terrigenous sand substrates, 
whereas S. urospilus occurs on live-bottom sub- 
strates. In fact, differences in geographic occurrences 
for the species largely reflect their different substrate 
requirements. Symphurus urospilus occurs more or 
less continuously along the southeastern coast of the 
United States from about Cape Hatteras, North Caro- 
lina, south and around the Florida Peninsula, as far 
as approximately Apalachee Bay. It has a disjunct 
distribution in the western Gulf of Mexico off Gal- 
veston, Texas, and on the Yucatan Banks. Through 
its range, this species is found on live-bottom habi- 
tats usually between 5 and 40 m. It is generally ab- 
sent from central and western regions of the Gulf of 
Mexico where predominant substrates are composed 
of mud, silt, or quartzite sands. In contrast, along 
the southeast coast of the United States to southern 
Florida, S. civitatium is also taken commonly on the 
inner continental shelf, but unlike S. urospilus, this 
species is found predominantly on terrigenous sand 
substrates, not live-bottom substrates. Symphurus 
civitatium is almost completely absent along live- 
bottom areas of the west Florida coast (only one ci- 
tation for St. Joseph Bay, Ginsburg, 1951; and a few 
specimens from the south Florida shelf, this study). 
However, west of the Mississippi River to the Yucatan 
region, S. civitatium is one of the most abundant 
tonguefishes on the inner continental shelf (Hilde- 
brand, 1954). 
Symphurus diomedeanus, one of the most widely 
distributed species of Atlantic tonguefish, ranges 
from the region of Cape Hatteras, North Carolina, 
to Uruguay. The center of abundance for this species 
is north of northeastern Brazil. Throughout its range, 
S. diomedeanus is taken commonly and abundantly 
on diverse inner continental shelf substrates includ- 
ing those composed of calcareous mud, shell hash, 
and calcareous sands at depths ranging from 18 to 
100 m, but usually deeper than 20 m. At these depths, 
it usually does not co-occur with S. plagiusa, the only 
other western North Atlantic Symphurus with the 
combination of 10 caudal-fin rays and a 1-4-3 ID pat- 
tern. The latter has its center of abundance occur- 
ring in nearshore embayments and estuaries and 
only rarely extends into deeper waters commonly 
inhabited by S. diomedeanus . In the western Gulf of 
Mexico, S. diomedeanus is taken occasionally with 
S. civitatium , whereas off Central America it co-oc- 
curs in collections with S. tessellatus taken on soft 
mud bottoms. Symphurus diomedeanus also occurs 
sympatrically with S. urospilus on the continental 
shelf off Florida, and some collections examined in 
this study contained both species. 
Atlantic members of the S. plagusia complex 
(Munroe, 1991) are generally shallow-water species, 
inhabiting nearshore and coastal seas usually shal- 
lower than 80 m. Only rarely have individuals been 
collected deeper than 80 m, and none at depths 
greater than 110 m. Three of the five Atlantic spe- 
cies of the S. plagusia complex have overlapping geo- 
graphic ranges, but these species do not occur 
syntopically at all life history stages, especially with 
respect to bathymetric occurrences. Three of the five 
Atlantic members of the S. plagusia complex, S. 
plagusia, S. tessellatus, and S. carihbeanus, occur 
syntopically at some stage in their life history in shal- 
low waters of the Caribbean. Juveniles of all three 
species have been taken exclusively in beach-seine 
and otter-trawl collections in shallow-water (<10 m) 
estuarine and mudflat habitats. However, striking 
differences are apparent in how these species use 
inshore habitats. In these habitats, juvenile S. 
tessellatus are collected with all life history stages of 
S. plagusia and S. caribbeanus. Symphurus tessel- 
latus, however, apparently undergoes an ontogenetic 
migration from shallow, nearshore habitats to deeper 
waters farther offshore (11-80 m) on the continental 
shelf. In contrast, although small numbers of S. 
caribbeanus and S. plagusia have been taken as deep 
as 30-50 m on the continental shelf, these were iso- 
lated captures of large adults (>110 mm SL). The 
majority of S. plagusia and S. caribbeanus (80% and 
83%, respectively), including all juveniles examined, 
were collected in waters shallower than 20 m, with 
most taken by beach seine and small otter trawls in 
less than 10 m on nearshore mudflats, in mangrove 
habitats, and other estuarine locations. 
Symphurus oculellus, although occurring sympat- 
rically with S. plagusia and S. tessellatus (see Figs. 
59, 61, and 63), apparently has a different life his- 
tory than these other species. Symphurus oculellus 
