1941 CATALOGUE OF FISHES OF TORTUGAS ^y 



of nitidum were all female, and 16 of bifasciatum were all male, but still reserved 

 final judgment regarding the relation of the two (Zoologica, vol. 10, 1928, p. 205). 



Thirty additional specimens of bifasciatum collected in different years and at 

 different places in the Tortugas now prove to be all males, but fish in the nitidum 

 phase are not all females, as females and males in a lot of 115 number 85 and 30 

 respectively. The incomplete record of size range by sex and phase shows 50 

 nitidum females, 64 to 117 mm. long; 19 nitidum males, 84 to 114 mm. long; 

 and 8 bifasciatum males, 114 to 146 mm. long. Clearly this is a single sexually 

 dimorphic species, in which the male attains sexual maturity while still display- 

 ing that juvenile coloration which the female retains throughout life. 



In early June the females seemed scarcely mature, though the young males were 

 already producing sperm. By the first of August the breeding season appeared 

 at its height. The eggs are transparent, of the pelagic type, 0.4 to 0.46 mm. in 

 diameter, with a single oil globule varying in diameter from 0.088 to 0.096 mm. 



In the nitidum stage or phase the body is obliteratively shaded, with dorsal fin 

 dark, bordered by light blue, and covered by a dark spot to the 4th or 5th spine; 

 lobes of caudal broadly dark-margined above and below; pectorals transparent 

 except for slightly dusky tips; ventrals and anal almost transparent. The color is 

 very variable. In the darker striped phase there is a median dark stripe from 

 nape along base of dorsal, and a dark lateral band extending from snout through 

 eye to caudal. The lateral stripe, however, may be replaced by six rectangular 

 dark areas. When the light stripes separating the lateral and dorsal dark areas 

 are yellow, one has the nitidis simum phase; when they are grayish, nitidum. 

 Sometimes the dark stripes are so faint, the yellow so evident and widely spread, 

 that the fish is almost completely yellow. The striped phase is usually shown by 

 swimming, the banded one more frequently by resting fish, although bands are 

 sometimes shown by the first and not always by the second. Bermudichthys sub- 

 furcatus Nichols (see citation above) is based on a fish in the banded phase. 



The bifasciatum stage arises from the nitidum through change in color, and 

 exsertion of the angles of the caudal. The head and throat to the base of the pec- 

 torals become violet, the first two dark bars of the nitidum stage becoming almost 

 black, the space between light blue, and that behind the second green or greenish. 

 The intensification of the two black bars is perhaps the first indication of the 

 impending change. The interspace between begins to assume its definitive hue 

 while the bands on the trunk still persist. Rarely the pale bar fails to develop, 

 and the body is then crossed by a solid black bar nearly as wide as the pectoral fin 

 is long. 



The adult fish in nature was not seen to change its color, but it is changeable 

 in captivity. It is one of the many labrids that bury themselves in sand at dusk 

 and rise when the morning sky is reddening. When routed out in a laboratory 

 tank after dark, it had lost its black bars and was in a dress of simple blue. The 

 changes in the nitidum stage, on the other hand, were readily observed in the 

 field, as gray replaced yellow whenever the fish came from bottom covered with 

 algae or living coral to gather about food placed on bare gray sand. 



When fish in the juvenile pattern swim well up from the bottom they also put 



