BUTLER and AHLSTROM: NEW SPECIES, SCOPELENGYS CLARKEl 



Larvae 



A single specimen was available, 15.4 mm SL 

 (Figure 3B). Body shape similar to that of adults 

 but with a relatively larger head — length 35.7 and 

 depth 25.0; eye 5.5; snout 12.8; body depth 23.5; 

 least depth of caudal peduncle, 14.6. Fin origins 

 farther back on body than in adults. Snout to: 

 dorsal fin origin 50.0; anal fin origin 72.8; pelvic 

 base 53.6. Pigment confined to head and nape, 

 extensively developed on the operculum and 

 lower jaw; a small pigment patch on upper jaw 

 behind eye; several melanophores on mid-brain; 

 body pigment confined to nape and to a patch an- 

 terior to pectoral base. 



Name 



This species from the central North Pacific is 

 named in honor of Dr. Thomas A. Clarke of the 

 Hawaii Institute of Marine Biology. 



COMPARISON OF SCOPELENGYS 



CLARKEl AND SCOPELENGYS 



TRISTIS 



Scopelengys clarkei differs from S. tristis in 

 meristic counts, in some morphometric charac- 

 ters, and in larval pigmentation. 



For differences in meristic characters, refer to 

 Table 3. Most marked differences are in average 

 number of vertebrae — 34.1 (S. clarkei) vs. 30.8 

 = 3.3; average pectoral-fin ray count — 12.9 {S. 

 clarkei) vs. 15.4 =2.5; and average dorsal-fin ray 

 count — 13.0 vs. 11.5 =1.5. As regards morphomet- 

 ric characters, S. clarkei has a deeper caudal 

 peduncle, a narrower maxillary, and a more 

 fusiform body. Several distinctive adult charac- 

 ters also can be recognized in larger larvae of the 

 two species, i.e., differences in meristic characters 

 and depth of caudal peduncle. The most striking 

 differences between larvae of the two species are 

 found in the head pigment which is restricted to 

 an eye-bar in S. tristis, as compared with the scat- 

 tered pigment on the operculum, lower jaw, etc. of 

 S. clarkei. 



The two species are similar in general body 

 shape, head size, eye size, length of snout, and 

 position of fins on the body. Scopelengys clarkei 

 has its greatest body depth at the dorsal origin, 

 whereas S. tristis has its greatest body depth at 

 the nape. 



When an analysis of covariance was performed 

 on the morphometric characters of 7 S. clarkei 

 and 32 S. tristis from the eastern North Pacific, 

 eastern tropical Pacific, Indian, and Atlantic 

 oceans, only the least depth of caudal peduncle 



E 

 6 



z 



o 

 liJ 



< 

 O 



< 



20p 



18- 

 16- 



14 

 12 

 10 



8 



6 



4 



2 







Scopelen gys clorkei 



Scopelen gys tristis 



INDIAN OCEAN 



EASTERN TROR PAG. 

 EASTERN NORTH PAG 

 EASTERN TROP. ATL. 



ID 



20 30 



40 



50 60 



70 80 90 100 no 120 

 STANDARD LENGTH (mm) 



30 



140 150 



160 



Figure 5.— Regression of least depth of caudal peduncle on standard length of Scopelengys tristis and S. clarkei. 



149 



