Description 



D. 12-13; A. 22-23; P. 16; AO 16-17; gill rakers 4 -h 1 -t- 14, total 19; vertebrae 38-39. 



SAO evenly spaced in a usually straight, oblique line that passes through VOo. SAO, 

 nearer VO;j than to VOj. Pre very close together, the last often slightly elevated. Snout obtuse, 

 not steeply rounded. 



Supracaudal glands of males described by Becker, from only two of six specimens, as a 

 muddy-gray narrow band extending the length of the caudal peduncle. The caudal glands of 

 females are unknown. 



Size: To about 35 mm. 



Least depth of capture: Recorded by Becker ( 1963a) as from 312 to 624 m. 



Distribution: The species is known only from the southern Atlantic Ocean, at about 42° S, 

 39° W. 



Subgenus Hierops 



Fraser-Brunner, 1949 



The subgenus Hierops is very similar to but differs from the subgenus Protomyctophum in 

 that the interorbital space is generally less than half as great as the widest part of the 

 expanded distal portion of the upper jaw, rather than equal to it or greater; the frontal bones 

 over the orbit are nearly parallel, or are slightly closer together posteriorly than anteriorly, 

 rather than considerably wider posteriorly and converging anteriorly, as in the subgenus 

 Protomyctophum . In correlation with this narrowing of the frontal bones the eyes are canted 

 inward toward the dorsal midline. Also, the dorsal portion of the iris is noticeably narrower 

 than the ventral portion, and the lens is often directed more dorsally than laterally — a condi- 

 tion that has been referred to as "telescopic." 



Fraser-Brunner (1949) divided the genus Electrona Goods and Bean (1896) into four 

 subgenera, Protomyctophum, Hierops, Electrona, and Elampa. Bolin (1959) raised the first 

 three to full generic status but did not discuss the subgenus Elampa; Wisner (1963b) referred 

 the latter to the genus Electrona. Since its introduction the subgenus Hierops has been alter- 

 nately accepted and rejected, both as a genus and subgenus. 



Andriashev (1962) considered but two genera as valid, Protomyctophum and Electrona, 

 and reduced Hierops to a subgenus of the first, stating that he had found at least one specimen 

 of the subgenus with an interorbital width nearly as great as the width of the expanded distal 

 portion of the upper jaw — a basic character separating Protomyctophum and Hierops. Becker 

 (1963a and b), although appearing to agree with the subgenus status oi Hierops, used only 

 Protomyctophum as a generic term in dealing with primitive electronins from the North and 

 South Pacific Oceans. More recent authors have been divided on the use of the subgeneric 

 name Hierops. Nafpaktitis and Nafpaktitis (1969) retained it, but Moser and Ahlstrom (1970) 

 at first did not and subsequently did (1974). 



In an effort to determine the limits of variation of two basic characters that distinguish 

 the subgenus Hierops (the very narrow interorbital space and asymmetrical iris), 351 speci- 

 mens of P. (H.) crockeri (15 to 47 mm) and 207 specimens of P. (H.) thompsoni (16 to 51 mm) 

 were examined. The interorbital space ranged from 21*7^ to S&'/f of greatest width of upper jaw 

 in P. (H.) thompsoni. In P. (H.) crockeri the interorbital space was half or less the greatest 

 width of upper jaw in 89% of the specimens, and half or less in 76% of P. (H.) thompsoni. Of 

 those specimens of P. (H.) crockeri with values below the 50% level 57% were in the 31%-45% 

 bracket, whereas of those of P. (H.) thompsoni 50% were in this bracket. 



In regard to the characters of asymmetrical iris and "telescopic eyes," of 270 specimens of 

 P. (H.) crockeri with the eyes intact, 97.4% had asymmetrical irises but only 27.4% had the 

 lens directed upward. Of 196 specimens of P. (H.) thompsoni with intact eyes, 79.6% had 

 asymmetrical irises and only 23.5% had lenses directed upward ("telescopic eyes"). 



It may be that the dorsal displacement of the lens is an artifact of crowding in the net 

 during capture, or of preservation: but the predominant asymmetry of the iris does not appear 



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