Supracaudal luminous gland short and weak, of 2 or 3 coalesced scales; infracaudal gland 

 more robust, of 3 to 5 overlapping and coalesced scales, its length about equal to or slightly 

 greater than least depth of caudal peduncle. 



Size: To about 90 mm (see Discussion). 



Least depth of capture: To about 1000 m at night. 



Distribution: The nominal species L. niger is worldwide, but at present there is considera- 

 ble doubt as to the correctness of identification. Until a definitive study is made of all forms 

 concerned, the distribution of L. niger (sensu stricto) must remain in question. 

 Discussion 



Giinther's description oVNannobrachium nigrum ," based on a single damaged specimen, 

 applies to several lampanyctid species in that the body structures received the most discussion. 

 Photophores are described in the following terms: "The eye-like phosphorescent organs are 

 small and arranged very much in the same manner as in Scopelus engraulis, but owing to the 

 condition of the specimens no exact description of their number can be given. A long, linear, 

 glandular organ of white colour occupies the back and opposite side of the posterior half of the 

 caudal peduncle." Unfortunately, this account of the photophores is useless in defining L. 

 niger. because Sopelus engraulis belongs to the genus Diaphus, as shown by the description 

 and figure provided by Giinther (1963 reprint: p. 197, pi. LI, fig. C). 



Tuning (1928) described Lampanyctus ater as new; Bolin (1959) expressed doubt that L. 

 ater was specifically distinct from L. niger and stated that fishes of this group were variable in 

 the numbers of infracaudal glands, those from the southern hemisphere and East Indian 

 region having fewer glands than those from the North Atlantic Ocean. 



It is of interest that Bolin's figure (above) of the holotype of L. niger differs from that 

 shown by Giinther (Plate LII, fig. b, Report on the deep-sea fishes) in that Bolin shows SAO] to 

 be nearly over VOj rather than over VO.j, as shown in Giinther's and subsequent illustrations 

 of the species. (Bolin had included with the drawing the statement "no trace of pectorals left"). 

 Possibly this discrepancy was due to the poor condition of the specimen, but in his personal 

 notes Bolin has stated that in specimens from the South Atlantic Ocean VLO was more nearly 

 over VOj than over VO3. 



At least two forms of this niger-ater (?) complex are found in the eastern and central 

 Pacific Ocean. Aside from the probable difference in maximum sizes, the smaller form has 

 VLO very near lateral line and a gill raker count of 5 + 1 + 11-13; in the larger form VLO is 

 several of its diameters below lateral line, and the rakers number 4-1-1-1- 9-10. 



Much more study on specimens in good condition from all oceans, and a careful examina- 

 tion of the holotype of L. niger must be accomplished before this problem is solved. 



Lampanyctus achirus 



Andriashev, 1962 

 Species Complex 



Fig. 165 — Lampanyctus achirus, holotype, 124.0 mm. From Andriashev 

 (1962, p. 257, fig. 27). 



176 



