LEIS: SYSTEMATICS AND ZOOGEOGRAPHY OF THE PORCUPINEFISHES 



(pers. observ.; J. E. Randall, pers. commun.). The 

 material available for descriptive purposes is lim- 

 ited, 20 eggs (Figure 10) and 7 larvae. 



The eggs of D. hystrix are similar to those of D. 

 holocanthus (see section on the latter species for 

 characters useful in distinguishing the two types 

 of eggs). Diodon hystrix eggs are pelagic, spheri- 

 cal, and 1.9-2.1 mm in diameter (.v = 2.01; 

 SD = 0.06; n = 20) with 30-50 yellowish oil drop- 

 lets of 0.03-0.15 mm in diameter. The incubation 

 period is about 5 days at 25°C, but hatching occurs 

 at the end of the late stage (i.e., there is no 'final' 

 stage as defined by Leis 1977; see section on de- 

 velopment of D. holocanthus for comparison and 

 definition of stages); otherwise, these eggs are 

 similar to D. holocanthus eggs. 



Development is generally similar to D. holocan- 

 thus and, aside from hatching at the end of the late 

 stage (i.e., before full eye pigmentation), the only 

 substantive difference is the pigment. Early in the 

 late stage, orange and, to a lesser extent, red 

 chromatophores develop on the dermal sac. The oil 

 droplets tend to be more scattered in D. hystrix 

 eggs than they are in D. holocanthus. Watson and 

 Leis (1974) illustrated a late stage D. hystrix egg 

 (figure A21, p. 115) identified as diodontid II. 



1.00 



The newly hatched larvae of D. hystrix, ca. 2.6 

 mm SL ( Figure 11), have only slight eye pigment, 

 an open but apparently nonfunctional mouth, and 

 a large amount of yolk. The eyes become fully 

 pigmented by the second day when the mouth ap- 

 parently becomes functional. The oldest Z). hystrix 

 larvae available is a 5-day-old individual of 2.60 

 mm SL. Aside from some shrinkage during the 

 first 2 days after hatching, development is similar 

 to D. holocanthus. Table 3 summarizes mor- 

 phometric data for the larvae. 



Melanophores are sparse at hatching, but soon 

 become abundant dorsally and, except for a more 

 caudad extension of melanophores on the caudal 

 peduncle, pigment is essentially the same as that 

 of D. holocanthus. The larvae are orange, rather 

 than the yellow background of D. holocanthus. 



The eggs and larvae described by Sanzo (1930) 

 and tentatively attributed by him to Crayracion 

 sp. (Tetraodontidae) closely resemble those here 

 identified as D. hystrix. These specimens were 

 clearly not tetraodontids; marine tetraodontids 

 apparently spawn demersal eggs (Breder and 

 Rosen 1966) and their larvae do not resemble 

 those illustrated by Sanzo (pers. observ.). The eggs 

 studied by Sanzo were larger (2.4 mm) and 

 hatched in a shorter period (3 days at 25°C) than 

 D. hystrix eggs, but in all other respects they were 

 similar. It is not known how many species of 



Figure lO.— Egg tentatively identified as Diodon hystrix just 

 prior to hatching. After Watson and Leis (1974), scale in mil- 

 limeters. 



Figure ll.— Reared larvae tentatively identified as Diodon 

 hystrix: (top) newly hatched larva, 2.57 mm SL, and (bottom) 

 5-dav-old larva, 2.60 mm SL. Hawaiian material. 



547 



