Ac ant hums triostegus sandvicensis — RANDALL 
of the larger nocturnal crabs, may feed on small 
manini. Once a manini reaches adult size, it 
probably enjoys freedom from predation by most 
of these fishes in Hawaii, for the inshore marine 
fauna is peculiar in the paucity of moderately 
large carnivorous fishes. Shallow-water serranids 
and lutjanids, many of which are well adapted 
to prey on reef fishes, were almost totally lack- 
ing in the Hawaiian Islands until the recent ef- 
fort to introduce some of these fishes. The larger 
native predaceous fishes, such as adults of Ca- 
ranx , Sphyraena , and sharks, are not numerous 
at the present time, probably because of fishing 
pressure. 
PARASITES 
Seventeen species of parasites were detected 
on and within the manini. 
Seven specimens of transforming manini were 
found to be parasitized by Hydrichthys (Fig. 
2 A), probably H. mirus Fewkes. This unusual 
hydroid occurred on the head, body, and fins 
and apparently does not have a preferred attach- 
ment site. It was never seen on juveniles or 
adults. Probably it flourishes only on postlarval 
manini, for it appears to be abraded and re- 
gressing on most of the transforming fish ( Fig. 
2 B). 
Three specimens of a monogenetic fluke 
( Benedenia sp.) were discovered on the epider- 
mis of two adult manini. The flukes are small 
(less than 2 mm. in length), perfectly trans- 
parent in life, and were hidden in the slime of 
the fish. They are difficult to find and are prob- 
ably more common than the few specimens 
would indicate. Figure 2C is a photograph of a 
stained specimen. Jahn and Kuhn ( 1932 ) have 
worked out the life cycle of Benedenia melleni. 
The most common fluke of the manini is an 
unidentified species of the gyrodactylid genus 
Ancyrocephalus. Figure 2D is a. drawing of a 
living specimen, 631 micra in length, which was 
obtained from the gills of a 132 mm. manini. 
This very small species of trematode was found 
on the gills of most of the manini which were 
examined. In some of the manini the infesta- 
tions were heavy, an average of about one fluke 
per gill filament being present. It is extremely 
active and highly extensible and was observed 
to change its position on a gill filament by at- 
taching with the anterior end and looping the 
221 
posterior end over to another location where the 
hooks were dug into place. Siwak (1931) re- 
ported on the life cycle of a species of Ancyro- 
cephalus. 
Two digenetic trematodes were found in the 
digestive tract of the manini, Hapladena varia 
Linton and Haplosplanchnus ohtusus (Linton), 
previously known only from the surgeonfishes 
Acanthurus hepatus ( = chirm gus) and Acan- 
thurus coeruleus at Tortugas, Florida. Manter 
(1953: 76) included a discussion of this dis- 
tribution in a recent paper reviewing the zoo- 
geography of trematodes of marine fishes. 
Hapladena varia (Fig. 2 E) was only occa- 
sionally found in the intestine of the manini. 
A total of 22 specimens, usually less than 3 mm. 
in length, were taken from 200 manini whose 
digestive tracts were examined for parasites. The 
manini harboring the flukes ranged from 43 to 
136 mm. in standard length. 
Haplosplanchnus ohtusus was found only in 
juvenile manini, although it may have been over- 
looked in adults. It is smaller than Hapladena 
varia , usually less than 1.3 mm., and not as 
slender. Some of the juvenile manini contained 
a large number of these flukes. Seventy-one were 
counted in one 49 mm. specimen. Most of the 
flukes were in the duodenum, a few extended as 
far back as the halfway point of the intestine, 
and a few were found in the pyloric caeca. 
Four different nematodes were found in the 
manini. Two could not be identified to genus. 
One of these was a very attenuate immature 
male from suprapharyngeal tissue of the fish. 
The other was represented only by larval speci- 
mens from the pyloric caeca. A third worm, 
which was occasionally found encysted in the 
mesenteries, was considered to be the immature 
female of an unidentified species of Contracae- 
cum. 
The fourth nematode, Spiro camallanus mon- 
otaxis (Fig. 2 F), was described by Olsen (1952) 
from the sparid fish Monotaxis grandoculis , re- 
portedly a mollusk-feeder. In all probability this 
roundworm will be found in other Hawaiian 
fishes. 
Of 200 manini (mostly adults) from Oahu 
examined throughout the year for internal par- 
asites, 76 were found which harbored S. mon- 
otaxis in the intestine or pyloric caeca. The av- 
