Munroe: Western Atlantic tonguefishes of the Symphurus plagusia complex 



261 



uniformly pigmented with only slight evidence of band- 

 ing on the body, and with vertical fins of both sexes 

 uniformly colored with no darkening in the posterior 

 portion of the body. In contrast, in S. civitatium there 

 is considerably more pronounced sexual dimorphism in 

 pigmentation. Females tend to have well-developed 

 crossbands on the body whereas in males the cross- 

 bands are less conspicuous. In male S. civitatium, 

 posterior portions of the dorsal and anal fins are 

 noticeably darkened with black pigment (black pigment 

 absent in females). 



Symphurus plagusia of all sizes are usually collected 

 with juveniles and small adults of S. tessellatus. Despite 

 overall similarities in meristic features, the two species 

 are quite distinctive. Symphurus plagusia is uniform- 

 ly colored with only faint, narrow crossbands in some 

 individuals, has a well-developed fleshy ridge on the 

 ocular-side lower jaw (Fig. 4a), and this species lacks 

 a striking black pigment spot on the outer opercle 

 (some individuals have a diffuse blotch on the inner 

 opercle where the pigmentation on the inner surface 

 of the ocular-side opercle shows through). In S. tessel- 

 latus, in contrast, all individuals have a bold pattern 

 of wide crossbands, a prominent black spot on the outer 

 surface of the opercle, and lack a fleshy ridge on the 

 ocular-side lower jaw (Fig. 4c). Symphurus plagusia 

 also has a smaller eye (6.4-9.5, * 8.2% HL vs. 7.9- 

 11.4, x 9.5% HL in S. tessellatus) and lacks the small 

 ctenoid scales on the posterior fin rays on the blind side 

 of the dorsal and anal fins that are present in S. tessel- 

 latus larger than about 70 mm SL. Symphurus plagusia 

 also has modally lower meristic values (total vertebrae 

 49-50 vs. 50-53 in 5. tessellatus; dorsal fin rays 89-97 

 vs. 91-102 (usually 93-101); anal fin rays 73-81 vs. 

 77-86 in S. tessellatus). 



Symphurus plagusia differs further from S. tessella- 

 tus in the almost squarish snout of S. plagusia, which 

 contrasts with the more pointed snout of 5. tessellatus 

 (compare Figs. 4a and 4c). Also, in S. plagusia the 

 dorsal fin origin is usually anterior to the vertical 

 through the eye, while in <S. tessellatus the dorsal fin 

 originates slightly more posteriorly, usually above the 

 anterior margin of the pupil of the upper eye, or even 

 as far back posteriorly as the mid-eye region. Viewed 

 from the blind side, the more posterior location of the 

 dorsal fin origin in 5. tessellatus is apparent in the 

 number of rays occurring along the dorsal margin of 

 the body immediately above the space between the two 

 nostrils. In S. tessellatus usually only the first dorsal 

 fin ray occurs above the space between the nostrils, 

 while the second dorsal fin ray lies immediately above 

 the posterior nostril or the second dorsal fin ray is 

 placed even slightly posterior to the rear nostril. In 

 S. plagusia, usually the first two dorsal fin rays occur 

 along the dorsal margin in the space between the 



nostrils, and in many specimens the first dorsal fin ray 

 is actually situated anterior to the vertical equal with 

 the anterior nostril. In S. plagusia, the jaws usually 

 extend to the posterior margin of the lower eye or, in 

 some cases, actually extend slightly posterior to the 

 rear margin of the lower eye, while in S. tessellatus the 

 jaws usually reach only to the middle, rarely to the 

 posterior margin, of the lower eye. 



These two species also differ significantly in overall 

 body size and size at sexual maturation. Symphurus 

 plagusia is a medium-sized tonguefish reaching a max- 

 imum known body size of about 130 mm SL and attain- 

 ing sexual maturity as small as 80 mm SL. Symphurus 

 tessellatus is a much larger species attaining maximum 

 known lengths of 220 mm SL and does not attain sex- 

 ual maturity until reaching approximately 120mm SL. 



Meristic values of S. plagusia overlap almost com- 

 pletely those of S. caribbeanus. The two species can 

 be distinguished, however, by the absence in 5. carib- 

 beanus of the fleshy ridge on the ocular-side lower jaw 

 (present in S. plagusia; see Figures 4a and 4e). Sym- 

 phurus plagusia is generally uniformly colored with 

 only slight evidence of crossbanding, and the fins are 

 uniformly colored. In contrast, S. caribbeanus usually 

 has numerous, prominent crossbands on the body, and 

 the vertical fins have an alternating series of blotches 

 and unpigmented areas, which are especially well devel- 

 oped posteriorly. Symphurus caribbeanus has a more 

 pointed snout with a distance between upper eye and 

 dorsal fin base usually slightly less than twice the eye 

 diameter, versus a squarish snout with distance from 

 upper eye to dorsal fin base usually larger than twice 

 the eye diameter in S. plagusia (compare Figures 4a 

 and 4e). The body shape of S. caribbeanus is rounded 

 with a pronounced taper posterior to dorsal fin rays 

 25-35 (versus somewhat elongate in S. plagusia with 

 a more gradual taper). Additionally, S. caribbeanus has 

 a slightly larger eye (8.2-11.0% HL, usually 9.0-10.0% 

 HL) when compared with that of 5. plagusia (usually 

 7.0-9.0% HL). 



Symphurus plagusia is also similar to 5. oculellus 

 with respect to small eye size and presence of a fleshy 

 ridge on the ocular-side lower jaw. It differs from this 

 species, however, in its much lower counts (47-51 total 

 vertebrae vs. 52-55 in S. oculellus; dorsal fin rays 

 89-97 vs. 99-104; anal fin rays 73-81 vs. 82-88) and 

 pigmentation pattern. Symphurus plagusia has a 

 relatively uniform body color with faint crossbands, 

 uniformly pigmented fins without blotches, and no pig- 

 ment spot on the outer opercle (versus sharply con- 

 trasting crossbands, pigmented blotches alternating 

 with unpigmented areas in the dorsal and anal fins, and 

 a black spot on the outer opercle in S. oculellus). Fur- 

 thermore, in S. plagusia the first, and occasionally the 

 second, rays of the dorsal fin are usually located along 



