FILEFISHES (MONACANTHIDAE ) OF THE WESTERN NORTH ATLANTIC 



69 



recognize the value of Fraser-Bruniier's generic 

 distinction of Siephanolepw from Monacanthus. 



The pelvic spine in Monacanthus is very similar 

 to that in Stepkanolepis (fig. 5). 



Monacanthus tuckeri Bean 1906 



(Figm-es 13 and 29) 



Although this species was described more than 

 50 years ago, it Has never been adequately dis- 

 tinguished from Monacanthus ciliatus, and many 

 museum collections we have examined contained 

 both species, usually cataloged as M. ciliatus-. 



Diagnostic characters. — Dorsal spines, 2. Dorsal 

 soft rays, 32 to 37; anal soft rays, 31 to 36 (table 

 5). Pectoral spine, 1 rudimentar}-. Pectoral soft 

 rays, 10 to 12 (table 11). Pelvic spine, large and 

 movable (as in Stephanolepis; fig. 5). GUI slit, 

 nearh' vertical with respect to horizontal body axis 

 (as in Stephanolepis; fig. 4). First dorsal spine, 

 inserted over posterior part of eye (as in Steph- 

 anolepis; fig. 4). No deep groove behind dorsal 

 spines. Body depth, 31.3 to 38.6 % S.L. (table 12; 

 fig. 36). Head length, 33.1 to 41.5 %S.L. (table 

 13). Snout length, 20.7 to 28.2 % S.L. (table 14). 

 Eye diameter, 8.7 to 14.4 % S.L. (table 15). Eye 

 to dorsal spine distance, 6.3 to 10.6 mm. S.L. (table 

 16). 



Specimens examined. — 60 of 15.3 to 56.5 mm. 

 S.L., from Bermuda, off the Carolmas, off eastern 

 Florida, in the Bahamas and the Lesser Antilles 

 (fig. 39). 



Sexual characters. — The seven largest specimens 

 available had gonads large enough to permit deter- 

 mination of sex (2 males, 56.5 and 50.5 mm. S.L.; 

 5 females, 53, 51.5, 50.5, 49, and 48 mm. S.L.). 

 The next largest specimens, 44 and 36 mm. S.L., 

 had visible gonads, but they were too smaU for the 

 sex to be interpreted. The males have a dorsal 

 and a ventral pair of enlarged recurved spines on 

 each side of the caudal peduncle, and the spmes 

 on other scales on the sides of the peduncle are 

 elongated, forming a bristlelike patch. The 

 females have similar pairs of spines on the pedmicle 

 but they are smaller and are directed posteriorly, 

 and the spines of scales on the peduncle are not 

 much, if any, larger than other bodj' scale spines. 

 These dorsal and ventral pairs of spines are dis- 

 cernible on specimens as small as 19 mm. S.L., 

 since at this size and larger the scale bases from 

 which they arise are larger (of greater diameter) 



than the bases of the other peduncle scales. The 

 larger or more expandible ventral flap of the male 

 with the dark stripe near its margin was described 

 and illustrated by Clark (1950: p. 162). Clark 

 listed males of 39, 59, and 60 mm. S.L., a female 

 of 45 mm. S.L., and immatm-e specimens of 17 to 

 30 mm. S.L. 



Monacanthus ciliatus (Mitchill) 1818 



(Figures 14, 15, 29, and 30) 



As noted before, this species has frequently been 

 confused with Monacanthus tuckeri. 



Diagnostic characters. — Dorsal spines, 2. Dorsal 

 soft rays, 29 to 37 ; anal soft rays, 28 to 36 (table 

 6). Pectoral spine, 1 rudimentary. Pectoral 

 soft rays, 9 to 13 (table 11). Pelvic spine, large 

 and movable (as in Stephanolepis; fig. 5). Gill 

 slit, nearly vertical with respect to horizontal 

 body axis (as Stephanolepis; fig. 4). Fu-st dorsal 

 spine, inserted over posterior part of eye (as in 

 Stephanolepis; fig. 4). No deep groove behind 

 dorsal spines. Body depth, 39.1 to 54.5 % S.L. 

 (table 12 ; fig. 36). Head length, 29.0 to 38.7 % S.L. 

 (table 13). Snout length, 16.4 to 25.7 % S.L. 

 (table 14). Ej-e diameter, 7.4 to 14.5 % S.L. 

 (table 15). Eye to dorsal spine distance, 6.7 to 

 10.1 % S.L. (table 16). 



Specimens examined.- — 347 of 11.0 to HI mm. 

 S.L., from Bermuda, Massachusetts, the coast of 

 the Carolinas, around Florida, in the Gulf of 

 Mexico, the Bahamas, and throughout the Carib- 

 bean (fig. 39). 



Sexual characters.— Clark (1950: p. 159) de- 

 scribed the sexual characters of this species. Im- 

 matm-e specimens have a dorsal and a ventral pair 

 of posteriorly directed spines on each side of the 

 caudal peduncle — discernible on specimens as 

 small as 20 mm. S.L. In the three largest females 

 we examined (92.5, 101, and 109 mm. S.L.) the 

 anterior spine of each pair was slightly recurved. 

 In male fish larger than about 60 mm. S.L., these 

 spines enlarge and become strongly recurved. 

 Although the original pairs of spines remain 

 distinct, additional and similar spines form with 

 growth — the largest male examined (107 mm. S.L.) 

 had 5 dorsal and 4 ventral spines on each side. 

 On males 90 nmi. S.L. and larger, the spines on 

 the other scales on the sides of the peduncle are 

 elongated, forming a bristlelike patch. 



