WING: ELLOBIOPSIDAE FROM NORTH PACIFIC 



eggs of the host species. An infected amphipod 

 carries one, rarely two, parasites. The mature 

 parasites may completely fill the marsupium of 

 small amphipods and occasionally protrude 

 beyond the marsupium of an immature host. In 

 large or heavily pigmented amphipods, T. mar- 

 supii is easily overlooked unless specifically 

 searched for. On male amphipods, T. marsupii 

 are more easily noticed although they are often 

 obscured by the thoracic legs and coxal plates 

 of the host. 



Thalassomyces marsupii parasitizes both 

 pelagic and benthic amphipods and appears to 

 have a worldwide distribution. The recorded 

 pelagic hosts are hyperiids of the genus Parathe- 

 misto: P. gaudichaudii (Guerin) in the North 

 Atlantic, Benguela Current, and Southern Ocean 

 (Kane 1964); P. abyssorum Boeck in the North 

 Atlantic (Vader and Kane 1968) and Arctic 

 (Tencati and Geiger 1968); P. gracilipes Norman 

 in the North Sea (R. A. McHardy, Department 

 of Oceanography, The University, Southampton, 

 England, pers. commun.); andP.pacifica Stebbing 

 in Puget Sound (Gait and Whisler 1970). A similar 

 parasite has been observed on Cystisoma sp., a 

 hyperiid, in the North Pacific (T. H. Bowman, 

 Division of Crustacea, Smithsonian Institution, 

 U.S. National Museum, Washington, DC 20560, 

 pers. commun.). The recorded epibenthic gam- 

 marid hosts of T. marsupii are: Eusirus lepto- 

 carpus G. O. Sars, E. longipes Boeck, Rhacho- 

 tropis aculeata (Lepechin), R. macropus G. O. 

 Sars, and R. helleri Boeck, all family Eusiridae, 

 from several North Atlantic locales (Vader and 

 Kane 1968). 



I have observed T. marsupii on three species 

 of amphipods in southeastern Alaska: the 

 hyperiids Parathemisto pacifica and P. libellula 

 (Lichtenstein) and the pelagic gammarid Cypho- 

 caris challengeri Stebbing (family Lysianissidae). 

 Parathemisto libellula and C. challengeri are new 

 host records as well as geographic range exten- 

 sions for T. marsupii. The parasitized amphipods 

 were collected with a 1.8-m Isaacs-Kidd mid- water 

 trawl by the Bureau of Commercial Fisheries 

 (now the National Marine Fisheries Service) in 

 Lynn Canal and Chatham Strait. The sampling 

 program continued from March 1964 to February 

 ]967; each year eight stations (Figure 5) were 

 sampled quarterly at depths of 15 and 100 m. 

 Beginning with the August 1965 samples, I kept 

 records of the occurrence of T. marsupii on 



POINT SHERMAN 



POINT RETREAT 

 'AUKE BAY 



• JUNEAU 



KATLIAN BAY 



LITTLE PORT WALTER 



Figure 5. — Locations in southeastern Alaska where ello- 

 biopsids were collected. 



Alaska amphipods. The parasitized amphipods 

 were found mostly in the 15-m samples. Cypho- 

 caris challengeri was the most frequent host, 

 and the highest incidence of parasitism occurred 

 in the August samples (Table 5). 



The internal portions of the parasite were 

 not examined, but the external morphology, size, 

 and site of attachment correspond closely to 

 Kane's original description. Most of the speci- 

 mens I examined were forming gonomeres. A few 

 gonomeres had begun cleavage to form spores. 

 The sporulating gonomeres were not as deeply 

 sculptured nor as dark as those described by 

 Kane (1964). 



Thalassomyces fagei (Boschma 1948) 



Thalassomyces fagei — Hoffman and Yancey 

 (1966), Komaki (1970), Vader (1973b). 



The euphausiid Thysanoessa raschii (M. Sars) 

 is the most common host of Thalassomyces fagei 

 in Alaska waters. I have examined parasitized 



179 



