BADCOCK and BAIRD: SYSTEMATTCS OF STERNOPTY'X 



Figure 6— Scattergram of ratio of 

 SAN photophore depth/SL and SL (mil- 

 limeters) for three species of Stemoptyx . 



• S. p&eudobscu'o IATl.) 



n s. p.-.eudodijphono lAiL.*PaC.) 



AAA 



ODD 

 1 D D 



Figure 7— Scattergram of ratio of 

 trunk depth (TD)/SAN photophore 

 height and SL (millimeters) for three 

 species of Sternoptyx. 



A S Oiopftono (ATl , 



• s . paejaoa'Joha^g I fl T L , i 



O 5, OS&uaodigphQno ( N. PACJ 



□ S piauOoblCurO fflTL.l 



(S o 



D D 



O O 

 D O O O 



diagnostic while small individuals of the two 

 species may be separated on the basis of pectoral 

 fin ray pigment present in S. pseudodiaphana . 

 The young of S. obscura are uniformly pigmented 

 and have the characteristically narrow trunk at 

 quite small sizes. 



The sequence of numbered "stages" in which 

 photophore groups appear and are completed is 

 listed in Table 1 for S. pseudodiaphana and S. 

 diaphana. The sequential pattern is identical in 

 both species, and limited data suggest S. 

 pseudobscura also conforms to this pattern though 

 the early-metamorphic forms of these species are 

 as yet undescribed. For ease of reference a se- 

 quence of stages based on the order of appearance 

 of photophores during development is presented in 

 Table 1. The brief account given below is intended 

 primarily to outline the major anatomical land- 



marks during metamorphosis and to indicate 

 some of the distinctions among species during 

 postlarval development. 



Sternoptyx pseudodiaphana 



The least developed specimen observed of S. 

 pseudodiaphana from the Atlantic (10.2 mm SL) is 

 elongate, with the head about 25% of SL. Dorsal 

 and pelvic fins are undeveloped, while the pectoral 

 fin has six and the anal seven rays developing. The 

 caudal has 19 rays. The postlarva is relatively 

 transparent and pigment is restricted to certain 

 areas: a symphysial pair of spots, two isthmus 

 spots, the pectoral fin, and a caudal peduncle spot. 

 Internally, the swim bladder is pigmented dorsad, 

 as is the posterior part of the stomach. Meningeal 

 pigment is present both as a melanophore in the 



811 



