REVIEW OF THE DEEP-SEA FISH GENUS SCOPELENGYS 



(NEOSCOPELIDAE) WITH A DESCRIPTION OF A NEW SPECIES, 



SCOPELENGYS CLARKEI, FROM THE CENTRAL PACIFIC 



John L. Butler^ and Elbert H. Ahlstrom^ 



ABSTRACT 



Scopelengys has been known previously from a few widely scattered collections. Recent collections by 

 the Scripps Institution of Oceanography in the Pacific, the RV Walther Herwig in the Atlantic, and 

 the International Indian Ocean Expedition have made possible a critical study of this genus. No 

 significant differences were found in either morphometric characters or meristic counts between 

 specimens of S. tristis Alcock from the eastern North Pacific (la 1. 16 ° to 33°N, long. 117° to 126°W) and 

 those from the eastern South Pacific (lat. 5° to 16°S, long. 77° to 90°W). When Pacific Ocean specimens 

 were compared with those from the Atlantic and Indian oceans, no significant differences were 

 found in morphometric characters, and although differences in average meristic counts were some- 

 what larger between oceans than among Pacific specimens, such differences exceed one for only one 

 meristic character (gill rakers), and the ranges for all counts from all oceans almost completely 

 overlapped. 



Scopelengys clarkei is described from the central North Pacific. It differs from S. tristis mainly in 

 pectoral ray count (2.5 average difference), average counts of vertebrae (3.3 average difference), 

 deeper caudal peduncle, narrower maxillary, and in a differently pigmented larva. 



In 1890, Alcock described a new genus and 

 species, Scopelengys tristis, from a single denuded 

 specimen collected in the Arabian Sea. Although 

 there was no evidence of photophores, Alcock 

 placed his new genus in the family Scopelidae 

 ( = Myctophidae) allowing that the "exact position 

 among the Scopelidae cannot be accurately de- 

 fined at present." Garman (1899) described S. 

 dispar from two specimens collected in the Gulf of 

 Panama. Garman distinguished S. dispar from S. 

 tristis by its lower dorsal- and anal-fin ray counts. 

 Scopelengys dispar was considered a junior 

 synonym by Parr (1928), Bolin (1939), and Nor- 

 man (1939). Until 1963, Scopelengys was known 

 only from the Indian and Pacific oceans. Its dis- 

 covery in the Caribbean Sea by Mead (1963) re- 

 sulted in the description of a third species, S. 

 whoi Mead. 



A recent survey of mid-water fishes conducted 

 by the California Cooperative Oceanic Fisheries 

 Investigations (CalCOFI) provided us with 

 specimens which indicated that two species of 

 Scopelengys were present in the Pacific Ocean. 

 Additional specimens made available to us by 

 Thomas A. Clarke of the Hawaiian Institute of 



'Smithsonian Institution, Southwest Fisheries Center, Na- 

 tional Marine Fisheries Service, NOAA, La Jolla, CA 92038. 



^Southwest Fisheries Center, National Marine Fisheries Ser- 

 vice, NOAA, La Jolla, CA 92038. 



Marine Biology (see in this regard Clarke 1973), 

 confirmed that the second form was an unde- 

 scribed species. Study of Scopelengys from the At- 

 lantic, Pacific, and Indian oceans indicates thatS. 

 dispar andS. whoi Mead are synonyms ofS. tris- 

 tis Alcock. 



METHODS AND MATERIALS 



Measurements were made following Hubbs and 

 Lagler (1958). Measurements are given in percent 

 of standard length (SL), unless indicated other- 

 wise. Only lath-shaped gill rakers on the first gill 

 arch are included in gill raker counts. Vertebral 

 counts were determined from radiographs; the 

 urostyle was included as one vertebra. 



Morphometric and meristic data were obtained 

 from 211 specimens from the Atlantic, Pacific, and 

 Indian oceans. Subsamples equal to the smallest 

 N (32 in the Atlantic) were randomly taken from 

 the Indian Ocean, the eastern North Pacific be- 

 tween lat. 16° and 33°N and long. 117° to 126°W, 

 and the eastern tropical Pacific between lat. 5° 

 and 16°S and long. 77° to 90° W. Morphometric 

 data were compared by analysis of covariance. 

 Meristic data were compared by Tukey's multiple 

 comparison procedure at the 5% level (Rothschild 

 1963). 



Material was examined from the following col- 

 lections: Scripps Institution of Oceanography 



Manuscript accepted June 1975. 



FISHERY BULLETIN: VOL. 74, NO. 1. 1976. 



142 



