Ellobiopsidae of Alaskan Coastal Waters — Hoffman and Yancey 
77 
Ellobiopsis chattoni 
The genus Ellobiopsis contains two species, 
E. fagei Hovasse and E. chattoni Caullery. E. 
fagei was described as parasitic on the cope- 
pod Clausocalanus arcuicornis Dana by Hovasse 
( 1951 ). E. chattoni is known to be parasitic on 
the following copepods: Calanus fmmarchicus 
(Marshall et ah, 1934; Marshall and Orr, 1955; 
Jepps, 1937); Calanus helgolandicus (Boschma, 
1949); Pseudo calanus minutus (Marshall, 1949); 
and Acartia clausii (Boschma, 1956). Marshall 
et al. and Marshall and Orr state that E. chattoni 
is more common on Calanus during the summer 
than the winter. 
In our investigation Metridia longa was found 
to be a host for Ellobiopsis chattoni. This is the 
first record of a species of Metridia as host for 
ellobiopsids. M. lucens, which was present in 
the same samples, was not found to be para- 
sitized by E. chattoni. Parasites were observed 
only on Stage V males and females. M. longa 
was the only copepod taken which was host to 
a species of ellobiopsid. 
The plankton samples examined during this 
study were taken in southeastern Alaska at the 
mouth of Auke Bay (58°2TN, 134°4l'W) by 
the Oceanography Investigation of the Bureau 
of Commercial Fisheries Biological Laboratory, 
Auke Bay, Alaska. The samples were taken 
monthly during 1962 and 1963. Samples were 
taken both during the day and at night. Metridia 
longa and M. lucens were the most abundant 
copepods in the Auke Bay samples taken during 
Fig. 5. Drawing showing the anterior portion of 
the carapace of an infected Pasiphaea pacifica. 
the late fall in both 1962 and 1963. Throughout 
the other seasons Metridia are taken in con- 
siderably fewer numbers. At night both species 
of Metridia are common in the sample taken just 
beneath the surface, whereas in the daytime 
Metridia are most common in the samples taken 
from approximately 20 m. Few Metridia were 
taken in the samples from Kasitsna Bay, Alaska, 
and none of these were parasitized by E. chat- 
toni. 
E. chattoni was most abundant in the samples 
from Auke Bay taken in October and November 
of 1962 and 1963. The percentage of infection 
was established by examining 250 specimens of 
Metridia and calculating the percentage of in- 
fection in this subsample. Samples taken in the 
middle of November, 1962 showed the highest 
infection rate. The percentage of infected cope- 
pods ranged from 7.7 % in the daytime samples 
to 22.4% in the nighttime samples taken at the 
same station. No explanation of this difference 
is available. During October and November, 
1963 approximately 5% of the Metridia speci- 
mens were found to be parasitized by E. chattoni. 
The morphology and development of E. chat- 
toni is described and discussed by Jepps (1937). 
Our observations of E. chattoni on Metridia 
agree with those reported by Jepps on its para- 
sitizing Calanus fmmarchicus. An ellobiopsid in- 
dividual initially appears as a small knoblike 
structure on one of the setae of any of the 
cephalic appendages. The mature individuals are 
attached by a stalk which extends into the tissue 
of the host’s appendage. There are one or two 
gonomeres present on the mature ellobiopsid. 
The distal gonomere sometimes has an "apical 
cone’’ as described by Jepps. Although several 
immature E. chattoni may be located on a single 
host, no more than three mature parasites were 
observed on any single specimen of M. longa. 
The finding of Ellobiopsis chattoni on Metri- 
dia longa in the coastal waters of southeastern 
Alaska extends the known range of this parasite 
from the northern Atlantic Ocean to the north- 
eastern Pacific Ocean. This is the first report of 
E. chattoni taken in the Pacific. 
ACKNOWLEDGMENTS 
The authors would like to thank the follow- 
ing individuals whose work has aided this study: 
