FISHERY BULLETIN: VOL. 73, NO. 1 



join the primary stalk makes it difficult to deter- 

 mine the number of trophomeres in a dense tuft, 

 or the number that may be developing, or those 

 that may have been lost. Counts of trophomeres 

 on 21 T. boschmai from southeastern Alaska 

 ranged from 13 to 46 (mean 28.6). Hoffman and 

 Yancey (1966) examined six parasites which had 

 7 to 20 trophomeres each. Nouvel and Hoenigman 

 (1955) found a maximum of 32 (mode 16) tropho- 

 meres for 21 Mediterranean T. boschmai from 

 Cabo do Palos, Spain. 



The number of gonomeres on a mature tropho- 

 mere of 7". boschmai is usually three, rarely four. 

 Trophomeres having no gonomeres or up to two 

 are immature, damaged, or are degenerating after 

 sporulation. Degenerating trophomeres may be 

 recognized by the small rudiments of protoplasm 

 left after sporulation (Nouvel and Hoenigman 

 1955). 



The size and shape of the gonomeres, especially 

 the distal gonomere (Figure 1), are used as 

 taxonomic characters, but most descriptions give 

 little information on the variability of gonomere 

 characters. I measured gonomere lengths and 

 diameters and computed length-diameter ratios 

 for 10 T. boschmai from each of two sites in south- 

 eastern Alaska and one in Puget Sound for 

 comparison with data from central Alaska 

 (Hoffman and Yancey 1966) and the western 

 Mediterranean (Nouvel and Hoenigman 1955) 

 (Table 2). The ranges of lengths and diameters 

 were greater in specimens from southeastern 

 Alaska and Puget Sound than in those from cen- 

 tral Alaska or the Mediterranean, although the 

 mean sizes were similar. A weighted ^-test (Ostle 

 1963) confirmed (95% level) that ellobiopsids from 

 different host species of mysids but within the 

 same collection belong to the same statistical 

 population; that is, all the ellobiopsids within 

 each collection may be considered as one species. 

 Tests for significant differences between means 

 indicated that T. boschmai from the three col- 

 lections were from different populations, but the 

 broad overlap of gonomere size ranges, especially 

 the length-diameter ratios (Figure 2), makes 

 specific distinction unwarranted. 



Occasionally an ellobiopsid will form more than 

 one primary stalk by internal budding. This 

 produces two or more stalks which separately 

 penetrate the host's cuticle. The stalks are usually 

 less than 1 mm apart. Budding described for 

 T. boschmai and T. nouueli in the Mediterranean 



(Hoenigman 1954) is rare in the North Pacific 

 T. boschmai. I examined 130 ellobiopsids from 

 the North Pacific and found only one instance 

 of apparent budding — a T. boschmai on an 

 A. pseudomacropsis from Katlian Bay, Alaska. 



On mysids, T. boschmai usually occur either 

 on the dorsal surface of the host's carapace or 

 on the last thoracic segment, although some are 

 found on the dorsal, lateral, or ventral surface 

 of the abdomen. In contrast, the most frequent 

 sites of attachment on L. gracilis are the frontal 

 plaque and rostral areas (Hoenigman 1954; 

 Nouvel 1954; Nouvel and Hoenigman 1955). 



Less than 10% of the parasitized mysids I 

 examined had more than one T. boschmai. In 

 one case a mysid had four ellobiopsids, and 

 another mysid bore scars from four ellobiopsids. 

 Hoenigman (1954) observed one L. gracilis with 

 seven T. boschmai. When two or more ellobiop- 

 sids occur on a mysid, they usually are widely 

 separated; one ellobiopsid may be on the thorax 

 and the other(s) may be on various parts of the 

 abdomen or rostrum. Two of the three hosts 

 described by Hoffman and Yancey ( 1966) had both 

 ellobiopsids on the carapace; in the third, the 

 second ellobiopsid was on the abdomen. 



Observations of Living T. boschmai 



Collard (1966), Vader and Kane (1968), and 

 Gait and Whisler (1970) have described living 

 Thalassomyces spp. I briefly observed three liv- 

 ing T. boschmai on A. pseudomacropsis from the 

 first Auke Bay collection (AB65-108). In the live 

 T. boschmai, the external portions were trans- 

 parent and colorless except for a slight yellow 

 tint at the base of the primary stalk. Perhaps 

 the tinting is caused by the same melanic pig- 

 ment deposited by the host at the margin of the 

 pore through the host's cuticle. Deposition of pig- 

 ments at the site of injury or parasitism is a 

 frequent occurrence among crustaceans. The 

 parasites stand out from the host's carapace, 

 which gives the appearance of a flexible cluster 

 of grapes that twist and turn slightly as the host 

 swims. The live ellobiopsids I observed had about 

 40 trophomeres each with one to four gonomeres 

 per trophomere. Many distal gonomeres were 

 pebbled as described by Collard (1966) and Gait 

 and Whisler (1970). I observed that some gono- 

 meres had the amorphous drop of protoplasm 

 described by Collard, but I did not find the 



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