Some Trematodes of Fishes from the Central Equatorial Pacific 
Edwin S. Iversen 1 and Earl E. Hoven 2 
This report is based on a collection of 
trematodes from marine fishes captured in the 
vicinity of the Line Islands. All the trematode 
species listed are believed to constitute first 
records from this area, and some are first re- 
ports from new hosts. Collections were made 
in 1955 during exploratory tuna fishing by 
trolling and longlining. These fishing surveys 
were carried out by Pacific Oceanic Fishery 
Investigations (POFI), a branch of the U. S. 
Fish and Wildlife Service, as one phase of a 
program designed to determine the distribu- 
tion and abundance of tunas in the Pacific. 
The Line Islands from which this material 
was collected are: Christmas, Fanning, Wash- 
ington, and Palmyra islands, and Kingman 
Reef. They extend in a northwesterly direction 
from 2° N. latitude, 157° W. longitude to 
6° N. latitude, 163° W. longitude. 
All specimens, except the hemiurids, were 
identified through the kind efforts of Dr. 
Harold W. Manter, Department of Zoology, 
University of Nebraska. Unfortunately facili- 
ties were not available aboard ship for proper 
preservation of such material; as a result many 
of the specimens were identified with diffi- 
culty and some could not be accurately iden- 
tified. Dr. Donald C. Matthews, Department 
of Zoology, University of Hawaii, very kindly 
provided sections of the encysted didymo- 
cystid included herein. Thanks are extended 
to E. Dixon Stroup, POFI, for making the 
photographs used in this report. All collec- 
tions have been deposited in the U. S. Na- 
tional Museum. 
1 Formerly with Pacific Oceanic Fishery Investiga- 
tions, Honolulu, T. H., presently with Marine Labora- 
tory, University of Miami, Coral Gables, Fla. Manu- 
script received September 27, 1956. 
2 Pacific Oceanic Fishery Investigations, Honolulu, 
r. h. 
Order MONOGENEA 
Family MICROCOTYLIDAE 
Neothoracocotyle acanthocybii 
(Meserve, 1938) 
synonyms: Gotocotyla acanthocybii Meserve, 
1938. 
host: Wahoo, Acanthocybium solandri (Cu- 
vier and Valenciennes). 
location: Between gill filaments. 
locality: Kingman Reef, 6° 20' N., 162° 
30' W. 
specimens: USNM Helm. Coll. No. 38132. 
PREVIOUSLY REPORTED HOSTS AND LOCALI- 
TIES: Acanthocybium solandri from the Gala- 
pagos Islands. 
discussion: Since these parasites are lo- 
cated between the gill filaments, they are 
found only by rather close scrutiny. Other 
duties while at sea prevented a careful record 
of the number of infected fish. The number 
of worms per host is probably large and the 
rate of infestation high. Hargis (1956), who 
has erected the genus Neothoracocotyle , re- 
ported the new combination. 
Family CAPSALIDAE 
Capsala poeyi (Vigueras, 1935) Price, 1938 
synonyms: Tristomum poeyi Vigueras, 1935. 
HOST: Black marlin, Makaira ample? (Poey). 
location: Outside surface on isthmus and 
second dorsal fin. 
locality: 04° 48' N., 160° 37' W. (vicinity 
of Washington Island). 
3 Identification of the Pacific M. ampla was based on 
an unpublished key provided by Dr. William F. Royce. 
As this paper goes to press, it is apparent that there is 
considerable disagreement concerning the classification 
of the marlins. 
131 
