BERRIEN: EGGS AND LARVAE OF SCOMBER 



HATCH 4 t. 8 10 12 



FORE 

 BRAIN 



HIND 

 BRAIN 



CLEITHRAL 

 SYMPHYSIS 



LOWER 

 JAW 



GUT 

 VENTRUM 



TRUNK 

 DORSUM 



FLANK 

 MIDLATERAL 



TRUNK 

 VENTRUM 



No S. joponicus pigmenfed at cleithfot symphyjii. 



STANDARD LENGTH (MMi 



Figure 4. — Acquisition of pigmentation of larval Scomber 

 scombrus and S. japonicus. Dashed lines indicate some speci- 

 mens have pigmentation; solid lines indicate all specimens have 

 pigmentation. The upper of each pair of lines refers to S. scom- 

 brus, the lower to S. japonicus. 



mm the dorsal edge of the trunk is pigmented from 

 nape to caudal fin. With further growth 

 melanophores form on the flanks, and spread 

 downward from the dorsal row; this happens first 

 in the abdominal area, then posteriorly. 



Scomber Japonicus larvae develop this pigmen- 

 tation at larger sizes than S. scombrus. Only one 

 S. japonicus (4.1 mm) <5.2 mm long possessed 

 dorsal melanophores. Subsequent percent occur- 

 rences of S. japonicus larvae possessing this pig- 

 mentation were: 24'7f at 5.0 to 5.9 mm, 597c at 6.0 

 to 6.9 mm, and lOO'/f at 7.0 mm and greater. The 

 largest S. japonicus lacking dorsal melanophores 

 was 6.9 mm long. As in S. scombrus this pigmen- 

 tation develops from a single median series into a 

 double row and increases to extend from the nape 

 to the caudal fin by a length of about 11.0 mm. 



Thus at sizes smaller than about 11 or 12 mm 

 there is a difference in dorsal pigmentation be- 

 tween the two species. While S. scombrus possess 

 dorsal pigmentation many S. japonicus either 

 lack melanophores in this location or have consid- 

 erably less than comparably sized S. scombrus. 

 This conclusion is in general agreement with ear- 

 lier published statements. Padoa (1956) men- 

 tioned that postanal pigmentation of S. japonicus 

 is less intense than that of S. scombrus, but he did 



not specify whether he was referring to dorsal or 

 ventral postanal pigment. Dekhnik (1959) re- 

 ported that, between yolk absorption and a length 

 of 6.18 mm TL, larval S. japonicus lack 

 melanophores on the dorsal edge of the trunk 

 while larval S. scombrus have melanophores in 

 this area. 



Fry (1936a, figure 12G) illustrated a late yolk- 

 sac stage S. japonicus with a small dorsal patch of 

 melanophores near the 23d myomere, but did not 

 comment in the text on the occurrence of this pig- 

 mentation. Uchida et al. (1958) and Kramer 

 (1960) referred to a similar dorsal patch of 

 melanophores in some of their late yolk-sac stage 

 S. japonicus. Watanabe (1970) did not illustrate 

 such dorsal pigment in his paper on this species. 

 None of the S. japonicus larvae in my study had 

 this dorsal patch; however, I identified only two 

 larvae <3.0 mm long. 



Flank 



A longitudinal row of melanophores develops 

 along the midline of the lateral trunk surface in 

 Scomber larvae. This row begins forming in S. 

 japonicus at 8.3 to 9.6 mm long and in S. scombrus 

 at 9.6 to 11.1 mm long. The pigment in this row, 

 first observable as a few distinct melanophores in 

 the postanal region, increases to form a line 

 flanked by scattered melanophores. These scat- 

 tered melanophores tend to occur along the 

 myosepta; this tendency is more pronounced in S. 

 scombrus than in S. japonicus. 



Postanus Ventral Pigmentation 



Both species possess postanus ventral pigmen- 

 tation, at all sizes examined. This pigmentation 

 occurs in the smallest larvae as a median row of 15 

 to 20 melanophores. This series occurs first near 

 the dermal surface and becomes internally 

 situated along the median ventral septum as the 

 anal fin develops. A second, double series of 

 melanophores forms on the dermal surface, on 

 either side of the developing anal fin base. This 

 second series appears first at lengths of 7.0 to 7.9 

 mm in both species and increases in number of 

 melanophores, so that by a length of about 15 mm 

 there is a line of melanophores along either side of 

 the anal fin, continuous with a median group of 

 melanophores between the anal and caudal fin. 



The initial median series of melanophores 

 gradually becomes obscured by overlying tissue 



103 



