Munroe and Ross: Distribution and life history of Citharichthys gymnorhinus and C. cornutus 
337 
length was estimated at 60 mm SL as listed in Gutherz 
and Blackman (1970). Of 131 males examined in the 
present study, all but nine are mature with obvious 
discernible dimorphic characters typical of sexually 
mature individuals (Fig. 2A; and discussed above). All 
four males <25.0 mm are immature. The only male 
(29.0 mm) in the next larger size class is the smallest 
mature male in the study (Fig. 7A). Between 30 and 35 
mm, half (5 of 10) of the males examined are immature, 
whereas five others are mature and display external 
features characteristic of adult males. At 35.1 mm and 
larger, all males examined are mature. Of 58 female C. 
gymnorhinus examined, all but six (26.2, 26.5, 27.5, 27.6, 
28.0, and 30.1 mm) are mature (Fig. 7B). The smallest 
mature female was 30 mm, and eight others smaller 
than 35 mm are also mature. At sizes >35.1 mm SL, all 
females are mature. 
No published information on maturity schedules or 
size at maturity based on microscopic staging of gonads 
is available for C. gymnorhinus. Information on size at 
maturity for this species is based only on examination 
of external sexual dimorphisms for males and exter- 
nal examination of ovaries of females. For example, 
Gutherz and Blackman (1970) noted that the smallest 
mature male in their study was 42 mm SL. Small size 
at maturity compared to that of congeners was also 
noted for C. gymnorhinus in specimens taken in the 
eastern Gulf of Mexico off the west Florida shelf (Topp 
and Hoff, 1972). Among the six females examined by 
Topp and Hoff, ovaries of a 21.0-mm-SL female were 
maturing (observed macroscopically), whereas ovaries 
of a 30.2-mm-SL female were filled with ripe, spherical 
eggs. They also observed that males of the same size 
had sexually dimorphic features, indicating they were 
mature at sizes similar to those at which females reach 
maturity. 
Abundance 
Of 42 field collections containing C. gymnorhinus (Appen- 
dix 2), 16 comprised solitary specimens, 11 consisted 
of two or three specimens each, and 15 collections con- 
tained four or more specimens. The largest collections of 
C. gymnorhinus comprised 36 and 23 specimens taken in 
the Straits of Florida off Key West and off South Caro- 
lina, respectively. Other significant collections of this 
species are those containing 19, 16, and 15 specimens 
taken in single trawls in the Straits of Florida, off the 
eastern side of the Florida Peninsula, and South Caro- 
lina, respectively. Three other trawls made off North 
Carolina, South Carolina, and the British Virgin Islands 
contained eight, nine, and eight individuals, respec- 
tively. 
From the collections we examined and those listed in 
previous studies that provide detailed information on 
C. gymnorhinus (Gutherz and Blackman, 1970; Topp 
and Hoff, 1972), we believe that this species appar- 
ently is not taken anywhere in its geographic range in 
such large numbers as is C. cornutus (see above). The 
largest collections reported in Gutherz and Blackman 
(1970) and Topp and Hoff (1972) contained only 10 and 
11 individuals, respectively, for trawl catches made in 
the Straits of Florida and off Venezuela, but most of 
their collections of C. gymnorhinus contained only five 
or fewer specimens. Wenner et al. (1979b; 1979c) listed 
collections of 15 and 12 specimens taken off the east 
coast of Florida (28°50.3'N, 80°07'W and 29°50.3'N, 
80°07'W, respectively). 
General discussion 
These data represent the most comprehensive assess- 
ments of biological, ecological, and distributional infor- 
mation for C. cornutus and C. gymnorhinus. Data on 
geographic occurrences, bathymetric distributions, maxi- 
mum sizes, sizes at maturity, and depth of occurrence 
are provided for the majority of known specimens of 
both species that have been collected off the eastern 
United States. The combined information gleaned from 
a variety of mostly small collections of these species 
from this region, including data from specimens reported 
on in previously published studies and data associated 
with specimens vouchered in museum collections but 
for which no previously published information has been 
available, provides considerable insights into, and com- 
prehensive documentation of, the occurrence, distribu- 
tion, and natural history of these interesting flatfishes. 
This updated information, in turn, provides a baseline 
for evaluating any changes observed in their geographic 
and bathymetric distributions along the continental shelf 
off the eastern United States. 
In prevailing literature since the late 1960s, the 
northern extent of the geographic ranges for adult C. 
cornutus and C. gymnorhinus has been misreported, 
resulting in a long history of inaccurate distribution 
data for these species. Both species are residents on the 
continental shelf off the southeastern United States off 
North Carolina and South Carolina, and their persis- 
tent presence in this region is documented from nearly 
a century (C. gymnorhinus) to more than a century ago 
(C. cornutus). Occurrences of C. cornutus north of North 
Carolina appear to he irregular, based on the absence 
of this species in many of the fish community studies 
conducted in this region (e.g., Grosslein and Azarovitz, 
1982; Colvocoresses and Musick, 1984), and based on 
its generally low frequency of occurrence in the NMFS- 
NEFSC groundfish surveys conducted annually in this 
area (J. Galbraith, personal commun. 3 ). Gear selectiv- 
ity in most trawl surveys influences the frequency of 
occurrence of small-size species in their catches, and 
many small-size flatfishes, including C. cornutus and C. 
gymnorhinus , have often escaped capture or have been 
misidentified or overlooked in earlier surveys. These 
factors also likely contributed to the infrequency of 
reports on these species. 
3 Galbraith, John. 2009. Woods Hole Laboratory, North- 
east Fisheries Science Center, National Marine Fisheries 
Service, National Oceanic and Atmospheric Administration, 
166 Water Street, Woods Hole, MA 02543. 
