Munroe: Western Atlantic tonguefishes of the Symphurus plagusia complex 



265 



crossing head short distance anterior to opercular open- 

 ing. Crossbands along trunk 3-6 scale rows wide. Two 

 posteriormost bands immediately anterior to caudal fin 

 base often conjoined. Blind side off-white. Peritoneum 

 unpigmented. Dorsal margin of outer surface of ocular- 

 side opercle often with dusky blotch due to dark pig- 

 mentation of inner lining of opercle showing through 

 to outer surface. Inner lining of opercle and isthmus 

 on ocular side usually heavily pigmented; lining of blind- 

 side opercle and blind-side isthmus usually unpig- 

 mented. Band of pigmentation usually developed on 

 ocular-side upper lip; lower lip on ocular side frequently 

 spotted but usually without definite band. 



Pigmentation of dorsal and anal fins generally similar 

 in both sexes, but usually more intense in males. All 

 dorsal and anal fin rays on anterior two-thirds of body 

 streaked with brown pigment similar in shade and in- 

 tensity to body color. Fin rays completely pigmented 

 other than for extreme distal tips, which are unpig- 

 mented. Membranes of anterior three-fourths of fins 

 unpigmented. Caudal fin and dorsal and anal fins on 

 posterior one-third of body more heavily pigmented and 

 considerably darker than anterior two-thirds of fin. Fin 

 membranes on posterior quarter of body heavily pig- 

 mented. Basal one-third of caudal fin more lightly 

 pigmented than posterior two-thirds of fin. Distal tips 

 of middle caudal fin rays unpigmented, or with tips of 

 middle caudal fin rays streaked with pigment but mem- 

 brane unpigmented. 



Size and sexual maturity (Fig. 2) The largest fish ex- 

 amined, a female (152 mm SL), was only slightly larger 

 than the largest male (149 mm SL). Most specimens ex- 

 amined ranged in size from 80 to 140 mm SL. 



Females mature at sizes usually larger than 90 mm 

 SL. Of 86 females examined, only three (83-95 mm SL) 



were immature. The two smallest gravid females were 

 80-90 mm SL, whereas the majority of gravid females 

 were usually larger (91-140mm SL). 



Geographic distribution (Fig. 5) Western North 

 Atlantic from Cape Hatteras, North Carolina, to the 

 Yucatan Peninsula of Mexico. There is a single record 

 for this species from Bermuda (ANSP 137573). In the 

 Gulf of Mexico, S. civitatium occurs most commonly 

 west of Apalachicola Bay in northern Florida (Springer 

 and Bullis 1956, Chittenden and McEachran 1976, 

 McCaffrey 1981). It is one of the most commonly col- 

 lected tonguefishes on inner continental shelf regions 

 in the central and western portions of the Gulf of Mex- 

 ico from Alabama to Texas. Along northern Mexico, 

 this species occurs coastally on sandy substrates at 

 least as far south as coastal lagoons (lagunas El Carmen 

 y La Machona, Laguna de Terminos) in Tabasco and 

 Campeche, Mexico (Resendez 1979) and on the con- 

 tinental shelf of the southern Gulf of Mexico (Cabo 

 Rojo, Veracruz to Sabuncuy, Yucatan). 



Collection data for 347 specimens from this study 

 reveal a general absence of this species from the 

 western Florida shelf. Only two collections record this 

 species from the Tortugas region off southern Florida. 

 Topp and Hoff (1972) also noted the general absence 

 of this species along the west Florida shelf and found 

 just a single record for S. civitatium in the eastern Gulf 

 of Mexico (St. Joseph Bay; from Ginsburg 1951). 

 Neither their efforts during the Hourglass cruises on 

 the continental shelf off west Florida nor other studies 

 (Moe and Martin 1965, Ogren and Brusher 1977, 

 Naughton and Saloman 1978) have collected this 

 species in coastal and continental shelf habitats off west 

 Florida. Furthermore, Darcy and Gutherz (1984) 

 reported taking only a single specimen during 338 

 10-minute bottom trawls in 9-193 m on the west 

 Florida shelf. 



Symphurus civitatium occurs on sand or silt sub- 

 strates throughout its range. The geographic and 

 bathymetric distribution of this species apparently coin- 

 cides with the distribution of terrigenous, quartzite 

 sandy, and silty substrates on the inner continental 

 shelf. The scarcity of this species on the west Florida 

 shelf and Yucatan Peninsula may reflect the striking- 

 ly different substrate compositions there. Along the 

 west Florida shelf, primarily in depths of 55-92 m, Topp 

 and Hoff (1972) reported that substrates consist of 

 lithified sediments of cemented lime, including (1) near- 

 shore deposits of cemented shell beachrock, (2) lime- 

 stone, ranging from soft marl to conglomeritic and 

 foraminiferal limestone, (3) small patches of living 

 and dead coral, and (4) calcareous algae. They noted 

 that substrates off the Yucatan Peninsula are similar 

 in composition to those of the west Florida shelf. In 



