FISHERY BULLETIN; VOL. 73, NO. 1 



described by Coutiere. Boschma also examined 

 the question of including the genus Ellobiocystis 

 within the family Ellobiopsidae and of including 

 various epibionts described by With (1915), 

 Monod (1926), and Sewell ( 1951) within the genus. 

 I follow Boschma (1959) in considering the 

 Ellobiocystis found on P. pacifica to belong to the 

 collective species E. caridarum s.l. This consti- 

 tutes the first record oiE. caridarum s.l. outside 

 of the Atlantic and Antarctic oceans. 



Ellobiocystis caridarum attach as single tropho- 

 meres directly to the mouth parts of the host. 

 There is no branching of the trophomeres, and 

 no organs of adsorption penetrate the cuticle 

 of the host. The trophomeres may occur singly 

 or in small groups attached to the labia, man- 

 dibles, maxillae, or maxillipeds. Single tropho- 

 meres on the oral appendages are usually attached 

 near the base of a seta, sometimes directly to 

 a seta. When on the mandibles, the tropho- 

 meres are located between the teeth. Groups 

 of trophomeres, each trophomere separately 

 attached to the host's cuticle, may contain 12 or 

 more individuals when on the labia but usually 

 contain less than 8 when attached to the maxilla 

 or maxillipeds. I have seen nearly 50£. caridarum 

 on a single Pas/p/iaea. 



The size and form o{ E. caridarum s.l. found 

 on P. pacifica in southeastern Alaska are as 

 variable as the size and form figured by Boschma 

 (1959) for the E. caridarum found on P. semi- 

 spinosa Holthuis. The maximum observed length 

 of trophomeres of Alaska specimens was 1.17 mm 

 and of gonomeres was 0.54 mm; the maximum 

 diameter of trophomeres was 0.56 mm and of 

 gonomeres was 0.42 mm. The shapes of the 

 gonomeres varied from ovals, slightly longer than 

 wide, to rods eight times longer than wide. 

 Each maturing trophomere carried one gonomere; 

 less than 1% of the trophomeres had two or three 

 gonomeres. 



The incidence ofE. caridarum s.l. on P. pacifica 

 is not known, primarily because the epibiont is 

 not readily noticeable in either the living or pre- 

 served state. When searched for, E. caridarum 

 have been found on P. pacifica of a wide size 

 range (30 to 80 mm total length) and during all 

 months of the year. The proportion of the P. 

 pacifica having £^. caridarum varies but is usually 

 less than 10% . In one exceptional sample (AB65- 

 15, southern Chatham Strait, May 1965), 84% 

 (263 of 314) were infested. 



Ellobiocystis species? 



Monod (1926) figured an epibiont found on the 

 mouth parts of the Antarctic amphipod Podo- 

 cerus septemcarinatus Shellenberg ( = Platophium 

 hystricoides Monod). This epibiont has been pro- 

 visionally classified as Ellobiocystis caridarum by 

 Boschma (1959). Vader and Kane (1968) reported 

 a similar epibiont on the mouth parts ofRhacho- 

 tropis macropus from western Norway. The taxo- 

 nomic status of these epibionts still is uncertain 

 (W. Vader, Zoologisk Avdeling, Troms0 Museum, 

 Troms0, Norway, pers. commun.). 



I found small epibionts like those figured by 

 Monod (1926) on the amphipod R. helleri from 

 Auke Bay, Alaska. The small bean-shaped organ- 

 isms (Figure 6) are attached to the labia, mandi- 

 bles, and maxillipeds of the host by a short stalk. 

 Lengths range from 0.10 to 0.13 mm. The separa- 

 tion of body and stalk is more distinct than in 

 the E. caridarum figured by Boschma (1959) or 

 than in material from Pasiphaea pacifica that I 

 have seen. None of the epibionts on R. helleri 

 are divided into gonomeres or spores. Although 

 these epibionts superficially resemble early stages 

 of developing £■. caridarum, their proper identi- 

 fication remains in doubt. 



SUMMARY 



1. Thalassomyces boschmai is found on the 

 mysids of the genera Acanthomysis, Neomysis, 

 and Meterythrops in the northeastern Pacific. 



2. Thalassomyces albatrossi n.sp. is described 

 as a parasite ofStilomysis major from the western 

 Pacific off Korea. 



3. Thalassomyces fasciatus is found on 

 Gnathophausia ingens and G. gracilis from Baja 

 California and southern California. 



4. Thalassomyces marsupii is found on the 

 amphipodsParathemisto pacifica, P. libellula, and 

 Cyphocaris challengeri from the inside coastal 

 waters of southeastern Alaska and P. pacifica 

 from Puget Sound. 



5. Thalassomyces fagei has been found on the 

 euphausiid Thysanoessa raschii from south- 

 eastern Alaska, the Bering Sea, and the Chukchi 

 Sea and on Euphausia pacifica from California 

 and southeastern Alaska. 



6. Thalassomyces capillosus is common on the 

 shrimp Pasiphaea pacifica in the coastal waters 



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