filefishes ( monacanthidae ) of the western north atlantic 63 



Key to Genera of Monacanthidae from the Western North Atlantic 



A. Pelvic bone without an external spine or with only a very small rudimentary barbed spine present in three species 

 (fig. 5). Gill slit usually very oblique (at an angle of about 45° from longitudinal body axis on specimens larger than 

 40 mm. S.L.) (fig. 4). First dorsal spine located over middle or back of eye (fig. 4). Anal-fin rays, 35 to 52 (fig. 3) 



Alutera. 



A A. Pelvic bone with a prominent external spine (fig. 5). Gill slit nearly vertical or only slightly oblique (fig. 4) B. 



B. A deep groove behind the dorsal spines (fig. 27B). Pelvic spine not movable (fusion may be broken on damaged 

 specimens) (fig. 5). First dorsal spine inserted over anterior part of eye (on specimens 30 mm. S.L. and larger) 



(fig. 4). Anal-fin rays, 29 to 32 (fig. 3) Amanses. 



BB. No deep groove behind the dorsal spines. Pelvic spine movable in anterioposterior direction (fig. 5). First 



dorsal spine inserted over posterior part of eye (fig. 4) . Anal-fin rays, 26 to 36 (fig. 3) C. 



C. Scales with 1 to 8 or more spines, each spine arising individually from the scale base, and none of the spines 

 branched; the spines usually separate but joined basally by a thin bony connection on larger specimens (95 mm. 

 S.L. and larger; fig. 8). Body relatively shallower (table 12). Caudal peduncle of specimens 20 mm. S.L. and 

 larger with 2 to 4 pairs of enlarged spines on each side (spines recurved in males). No elongated dorsal rays. 



Ventral flap relatively large (fig. 30) Monacanthus. 



CC. Scales usually with 1 spine, but with about 3 to 8 closely joined spines in larger specimens (100 mm. S.L. and 

 larger). On specimens larger than about 40 mm. S.L. the spines branched one to many times above their bases; 

 on specimens between about 19 and 40 mm. S.L. the spines of only a part of the scales are branched; and on speci- 

 mens smaller than about 19 mm. S.L. spines are not branched (fig. 8). Body relatively deeper (table 12). No 

 enlarged paired and recurved spines on caudal peduncle. Second dorsal ray elongated in mature males. Ventral 

 flap relatively small (fig. 31) Stephanolepis. 



Keys to Species of Monacanthidae from the Western North Atlantic 



Genus Alutera Cloquet 



A. Dorsal rays 43 to 50. Anal rays 46 to 52 (fig. 3). Pectoral rays modally 14 B- 



B. Caudal peduncle longer than deep; peduncle length into peduncle depth 0.65 to 0.95 times. Caudal fin relatively 

 short, about 18 to 26% S.L. Eye to dorsal spine distance relatively large, 7.0 to 8.6% S.L. Depth relatively great 

 on specimens smaller than 175 mm. S.L., 36.8 to 43.8% S.L. (fig. 35) Alulera monoceros. 



BB. Caudal peduncle deeper than long on specimens larger than 30 mm. S.L.; peduncle length into peduncle depth 

 1.24 to 1.60 times on specimens larger than 50 mm. S.L., 1.03 to 1.05 times on specimens of 31 to 46 mm. S.L., 0.86 

 on a 27-mm. specimen. Caudal fin relatively long, about 33 to 61% S.L. Eye to dorsal spine distance relatively 

 small, 5.0 to 6.7% S.L. Depth relatively shallow on specimens smaller than 175 mm. S.L., 21.5 to 33.1% S.L. 



(fig. 35) Alutera scripta. 



AA. Dorsal rays 32 to 41. Anal rays 35 to 44 (fig. 3). Pectoral rays modally 12 and 13 C. 



C. No pelvic spine. Eye to dorsal spine distance variable and relatively large on specimens larger than 100 mm. 

 S.L. (fig. 34), 7.3 to 13.5% S.L. Eye relatively small on specimens larger than 175 mm. S.L., 4.8 to 6.8% S.L. 

 Body depth relatively small in specimens smaller than 35 mm. S.L., 17.3 to 23.2%, S.L. Snout relatively short on 

 specimens smaller than 45 mm. S.L., 12.0 to 23.9 %> S.L. Body scales relatively large and sparse; spines on scales 

 relatively long and not close set (fig. 6), producing a comparatively rough feeling to the touch. Dorsal spine 

 relatively long, thin, and with small barbs (fig. 7). Ventral profile of specimens smaller than about 45 mm. S.L. 

 flatly curved, not produced into an angle (fig. 11). Pigment pattern of preserved specimens of about 70 to 200 mm. 

 S.L., usually consisting of relatively fewer rounded spots or stripes mainly present on the ventral portion of the body; 

 however, this pigmentation may be entirely absent (fig. 23) . Coloration of live specimens with few to many orange 

 spots Alutera schoepfii. 



CC. Rudimentary pelvic spine present (on specimens 30 to 135 mm. S.L.) (figs. 4 and 5). Eye to dorsal spine distance 

 relatively small on specimens larger than 100 mm. S.L. (fig. 34), 4.6 to 6.6% S.L. Eye relatively large on specimens 

 larger than 175 mm. S.L., 6.2 to 7.7% S.L. Body depth relatively great in specimens smaller than 35 mm. S.L., 

 27.6 to 30.6% S.L. Snout relatively long on specimens smaller than 45 mm. S.L., 23.8 to 26.7% S.L. Body scales 

 relatively small and numerous; spines on scales relatively short and close set (fig. 6), producing a "velvety" feeling 

 to the touch, especially on specimens larger than 70 mm. S.L. Dorsal spine relatively short with large barbs (fig. 

 7); this condition pronounced on specimens between 40 and 140 mm. S.L. Ventral profile on specimens smaller 

 than about 45 mm. S.L. produced in a convex angle by the extended pelvic bone (fig. 12). Pigment pattern of 

 preserved specimens larger than about 70 mm. S.L. consisting of rounded or elongated and rounded spots, these more 



numerous on the dorsal half of the body (fig. 25). Color markings on live specimens bluish purple 



Alutera heudelotii. 



