Diogenichthys atlanticus 



(Taning, 1928) 



Fig. 42 — Diogenichthys atlanticus, male. From Bolin (1939. p. 22, fig. 16) (as D, 



scofieldi n. sp.i. 



Description 



D. 11 (10-12); A. 16 (14-17); P. 11 (10-12); AO 6 (5-7) + 3 (2-4), total 9 (8-10): gill rakers 2 -I- 

 1 + 11 (10-12), total 14 (13-15); vertebrae 33 (31-34). 



Upper jaw barely reaches to a vertical from hind margin of orbit. VLO usually nearer 

 lateral line than to ventral profile of body. SAOi over or slightly before VO^; SAO series in a 

 straight line on 30 of 41 sides, SAO;, behind a line through SAO,. j on 11 of 41 sides. Dn of males 

 larger than in females, but contrast in size is much less than that between the sexes in D. 

 laternatus. 



Supracaudal luminous glands of males small, undivided, covering less than half the dorsal 

 surface of caudal peduncle; infracaudal glands of females very similar to those of D. laternatus. 



Size: To about 25 mm. 



Least depth of capture: To 100 m at night, 600-650 m in daylight. 



Distribution: D. atlanticus, unlike its congener D. laternatus, has a disjunct distribution 

 in the eastern Pacific Ocean (Fig. 43). Although at the extremes of their ranges the two species 

 are found together, D. atlanticus is absent from the vast eastern area wherein D. laternatus 

 occurs commonly (Fig. 41). This hiatus in distribution coincides roughly with the area of low 

 oxygen (1.0 ml/1 and less) that dominates the subsurface waters of the eastern tropical Pacific, 

 as delineated by Wyrtki (1967) for the area east of 140° W and by Austin (1960) for the central 

 area. 



Off Chile, D. atlanticus was not taken quite as close to shore as D. laternatus, except off 

 Valparaiso; in this area Craddock and Mead ( 1970) reported the capture of 87 specimens from 

 18 stations between about 33°-34° S, 73° -90° W. 

 Discussion 



The disjunct distribution of Z). atlanticus suggests the possibility of a racial or population 

 structure, but superficial examination of specimens from each of the three areas of occurrence 

 (Fig. 43) indicated no obvious differentiation. A more detailed comparative study should be 

 made. 



Symbolophorus 



Bolin and Wisner (In: Bolin, 1959) 



SAO markedly angulate. One Pol; 2 Pre, about a photophore diameter apart, the last 

 slightly elevated. Five PO, only the last slightly elevated. Four VO, none elevated. 



The genus Symbolophorus is difficult taxonomically. Although species groups are readily 

 separable, species within a group often show a remarkable degree of similarity in counts, body 



48 



