Discussion 



The species is provisionally listed as D. longleyi since it compares well with measure- 

 ments and notes made by me of the holotype (USNM 92320). Unfortunately, Fowler's unsatis- 

 factory figure and description are of little use in distinguishing his form from any closely 

 related one. The pattern of distribution suggests that the name longleyi may not apply to these 

 specimens, unless that species is widespread. However, the far western Pacific has been very 

 inadequately collected, and the one capture locality at 170° E on the equator (Fig. 124) 

 strengthens the possibility that the specimens in question may be D. longleyi. 



Diaphus theta 



A species complex 

 Eigenmann and Eigenmann, 1890 



Fig. 125 — Diaphus theta, male, 52.0 mm. 



Description 



The counts below were taken from specimens from off San Diego, California (the type 

 locality). This was done in order to confine the counts to specimens that unquestionably are D. 

 theta (see Discussion ). 



D. 13 (12-14); A. 13 (14); P. 10 (11); AO 5-6 + 6 (5); total 11 (10) (12 once in 70 sides); gill 

 rakers 6-7 + 1 -H 14 (13-15), total 21-22 (19-23); vertebrae 35 (34-36). 



PLO and VLO much nearer pectoral and pelvic bases than to lateral line. SAO, Pol, and 

 upper Pre, two to three diameters below lateral line. SAO series usually equally spaced and in 

 line with VO,,; SAO^ often a little behind a line through SAO,.:,; SA02.,i interspace in- 

 frequently slightly greater than that of SAO, .2. First AOa usually on level of adjacent ones 

 but occasionally slightly elevated, though seldom by a full diameter; last 1 or 2 AOa elevated 

 to form a curve with Pol. Pol and last AOa interspace usually a little larger than those between 

 the other AOa. 



Size: To about 90 mm. 



Least depth of capture: To 10 m at night, 400 m in daylight. 



Distribution: This species ranges into the north-central Pacific (Fig. 126), and the num- 

 bers of total gill rakers increase with increasing latitudes; also, the species appears to reach a 

 larger size in northern waters, a 50-mm specimen being uncommon off southern California. 

 Discussion 



The larger specimens from the northeastern Pacific, with higher total gill raker counts on 

 the average (aboutone raker), appear to represent the form on which Gilbert (1891) based his 

 description of Z). protoculus, herein considered a synonym of D. theta. 



140 



