Description 



D. 13 (12-14); A. 18 (17-20); P. 13 (11-15); AO 11 (10-13) + 5 (3-6), total 16 (14-18); gill 

 rakers 5 (4-6) -I- 1 -h 10 (9-11), total 16 (14-18); vertebrae 41 (40-42). 



Basically, T. taylori is very similar in appearance to T. crenularis. It differs principally in 

 the short, bulky supracaudal and infracaudal luminous glands of males that stand well above 

 the peduncular profiles; this is in contrast to the thin, elongate band of T. crenularis, in which 

 neither of the caudal glands are raised above the peduncular profiles. Females bear no caudal 

 luminous glands. 



Size: To about 70 mm. 



Least depth of capture: At surface at night. 



Distribution: Across the North Pacific from norther Honshu, Japan, to about 45° N along 

 the North American coast. 

 Discussion 



The existence of the infracaudal luminous gland of T. cren ularis has been discussed by 

 Wisner (1959) and Becker (1963c). Wisner stated that the males of T. crenularis bore only a 

 pale, elongate area in the region usually occupied by the infracaudal gland of T. taylori. 

 Becker interpreted this pale area as an infracaudal gland and reduced T. taylori to a sub- 

 species of T. crenularis, despite the very notable differences in the appearance and size of both 

 the supracaudal and infracaudal glands of each species. Subsequent examination has shown 

 that a thin, fragile layer of apparently luminous tissue, coinciding with the pale infracaudal 

 area, is present on some but not all males of T. crenularis; the overlying scales must be 

 removed before this tissue is visible. In no way does this fragile tissue resemble in appearance 

 the bulky infracaudal gland of males of T. taylori (Fig. 70). Also, in none of hundreds of 

 specimens of T. taylori examined did the short and bulky supracaudal gland resemble the long 

 and thin one of T. crenularis. 



Although the females of the two species bear no caudal luminous glands, and they and the 

 immature forms cannot now be separated as to species by reason of very similar counts and 

 body proportions, the marked difference in the caudal glands of males appears to justify 

 retention of T. crenularis and T. taylori as separate species until more detailed studies of these 

 glands are made. 



Gonicthys 



Gistel, 1850 



Supraorbital (Suo) photophore absent. Lateral line complete, or nearly so. PLO at level of 

 origin of pectoral fin. SAO broadly angulate. Caudal peduncle long, slender, its least depth less 

 than orbital length. Two Pre on same level, very low on caudal peduncle. Luminous scales in 

 caudal glands separate or slightly overlapping. 



The four presently recognized species of Gonichthys in the eastern Pacific Ocean are 

 superficially very similar, and only the species G. tenuiculus is figured. 



Key to species of Gonichthys 



la. Lateral line complete, all scales perforated 2 



lb. Lateral line incomplete, at least a few of the posteriormost scales not perforated 3 



2a. Anal rays 18(17-20); pectoral rays 12-13; 3 to 5 AOp over anal base G. tenuiculus 



2b. Anal rays 22 (20-24); pectoral rays 16(13-18); 5 to 7 AOp over anal base G. barnesi 



3a. Only the last 3 or 4 scales of lateral line unperforated; 5 to 6 (rarely 7) AOp over anal 



base G. venetus 



3b. Last perforated scale of lateral line under or before adipose-fin base; 4 to 6 AOp over anal 



base G. cocco 



83 



