LEIS: SYSTEMATICS AND ZOOGEOGRAPHY OF THE PORCrPlNEFISHES 



Figure 22. — Reared larvae ofDiodon holocanthus: (top) newly 

 hatched larva 2.0 mm, (middle) 10-day-old larva 2.4 mm, and 

 (bottom) dorsal view of 10-day-old larva with pigment omitted. 



day-10 larvae and appeared emaciated. There 

 are incipient fin rays and bases visible in the 

 fins of the 16-day-old larva, but it otherwise is 

 not obviously advanced over the 10-day-old 

 specimen. There is no sign of development of 

 the caudal fin complex. The largest larva avail- 

 able is a 2.7-mm field-collected specimen which 

 is no more advanced than the day- 16 larva. The 

 dermal sac is inflated in young larvae (Figure 

 22), but the subdermal space is virtually gone 

 by day 10 (Figure 22). 



The larvae are more or less uniformly pig- 

 mented with scattered melanophores on the 

 dorsal surfaces at all stages. The pigment 

 spreads laterally, but there is little below the 

 level of the pectoral fin and the ventral surfaces 

 remain devoid of melanophores until metamor- 

 phosis. The newly hatched larvae have no 

 melanophores posterior to the anus (Figure 22), 

 but by day 10 postanal pigment has spread to 



the middle of the dorsal fin anlage. In life, the 

 newly hatched larva is covered with widely 

 scattered red chromatophores on the dermal 

 sac and fins. The red pigment persists through 

 the larval stage and on about day 2 it is 

 supplemented by a yellow background pigment 

 covering all the body surfaces (not the dermal 

 sac), but being most obvious ventrally due to a 

 lack of melanophores there. 



A 2.0-mm field-collected specimen was 

 cleared and stained. The only ossified struc- 

 tures were the cleithrum, coracoid, and six 

 branchiostegals. 



Juvenile Development: Metamorphosis appar- 

 ently occurs at ca. 3 mm at an age of about 3 

 wk. The smallest juvenile available is 3.8 mm 

 and resembles Mito's (1966) illustration of a 

 3.7-mm juvenile except that Mito's fish had 

 smaller eyes. The caudal, dorsal, anal, and pec- 

 toral fins are all formed as are the teeth, and 

 the body is covered with small spines. The 

 spines do not appear to be erectile, but the fish 

 is capable of inflation. The spines are covered 

 with a sheathlike tissue. They elongate rapidly 

 with growth and by 4.8 mm SL (Figure 23) they 

 are obviously erectile. The nostrils are formed 

 in the 3.8-mm flsh, although the nasal tentacle 

 with two lateral openings is not formed until 

 4.8 mm SL, and in fish as large as 6.0 mm. it 

 may be open at the ends. The 4.8-mm fish is in 

 all respects a miniature adult with all external 

 structures formed and functional. External 

 changes to the adult stage involve only changes 

 in proportion; the spines in particular elongate, 

 the body becomes less rotund and the eye rela- 

 tively smaller. Morphometric and meristic data 

 are summarized in Table 3. 



A 33-day-old juvenile of 6.7 mm was cleared 

 and stained. The vertebral column and skull are 

 incompletely ossified but all other structures 

 are ossified. The vertebral formula is 

 12 + 9 = 21 and the vertebral column is 

 strongly arched. There are 1 1 dorsal and 1 1 anal 

 pterygiophores which are associated with ver- 

 tebrae 12-16 and 13-17, respectively. 



At metamorphosis, pigment changes radi- 

 cally. The background color in live material is 

 still predominantly yellow with scattered red 

 chromatophores but this does not persist. Dor- 

 sally, the melanophores are scattered fairly uni- 

 formly, with a concentration at the pectoral base 

 and very little pigment on the caudal peduncle. 



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