Some Polyclad Flatworms from the Hawaiian Islands 
Libbie H. Hyman^ 
One may suppose that a rich polyclad fauna 
exists along the shores of the Hawaiian Is- 
lands, but our knowledge of Hawaiian poly- 
dads is, in fact, very limited. As far as I can 
ascertain, only the following species are re- 
corded from the Hawaiian Islands in the 
literature; Planocera hawaiiensis Heath, 1907; 
Taenioplana teredini Hyman, 1944; and Sty- 
lochoplana inquilina Hyman, 1950. The first 
merits further examination, but the specimens 
cannot be located. Three further species from 
Hawaii have been received for identification, 
from the United States National Museum, 
and furnish the material for the present article, 
which thus adds something to our small 
knowledge of the polyclad fauna of these 
islands. All three species belong to the Aco- 
tylea and to the section Schematommata. As 
the taxonomic categories that concern these 
three species have been carefully defined in 
a recent publication (Hyman, 1953^), there 
appears no need for repetition of these def- 
initions here. 
Family LEPTOPLANIDAE 
Euplana tropicalis n. sp. 
Fig. 1 
The species is based on one specimen that 
was collected near Kapoho, Hawaii, Septem- 
ber 25, 1929 . The species is rather large, of 
elongated oval form, 38 millimeters long by 
17 millimeters wide (Fig. la), but, as it is 
evidently contracted, it presumably reaches 
a much greater length. The specimen had 
acquired the usual dark-brown color typical 
of museum specimens but in life was prob- 
ably tan with dark-brown spots. The tenta- 
cular eyes form small but conspicuous clusters 
of about 10 eyes on one side and 15 on the 
other, but the cerebral eyes could not be made 
out satisfactorily. They appeared to be very 
few in number and were seen chiefly on one 
side. The form of the pharynx as far as seen 
and the locations of mouth and gonopores 
appear in Figure la. 
The posterior half was removed and the 
region of the copulatory complexes sectioned 
sagittally. The histological condition is poor, 
but the parts of the complexes were followed 
satisfactorily and are represented in schematic 
sagittal view in Figure lb. Both complexes 
appear unusually sinuous, much more so than 
as represented in the figure, but whether this 
is natural or the result of the contraction of 
the specimen is uncertain. The complexes 
occur shortly behind the pharynx as is usual 
in the Leptoplanidae. The gonopores are 
widely separated. The male gonopore leads 
into a somewhat expanded male antrum lined 
with a sinuous epithelium and bearing at its 
inner end a small penis sheath. From this a 
long penis pocket proceeds anteriorly, sur- 
1 American Museum of Natural History. Manuscript 
received June 19, 1953. 
331 
