FISHERY Bl'LLETIN: VOL. 69, NO. 4 



Table 3. — Number of spines on the telson and the pro- 

 portional measurements of the antennal scale for indi- 

 vidual male and female specimens of Pseudoynma affine 

 of various sizes. 



1 Total count of lateral spines from both sides of the telson. 



2 Measurements expressed as percentages of the antennal scale length. 



scale change as the specimens increase in size. 

 The number of lateral sjjines on the telson in- 

 creases with body length, particularly in males. 

 In both males and females the apex of the an- 

 tennal scale is proportionately longer in larger 

 specimens. 



Sexual dimorphism is rather slight in the 

 characters listed in Table 3. Females have a 

 relatively larger antennal scale apex and a 

 slightly broader antennal scale than males. 



The close affinity of P. affine with P. roseum 

 G. O. Sars necessitated considerable effort to 

 establish the identity of the specimens at hand. 

 In addition to the taxonomic characters men- 

 tioned above, sijecimens in our collection were 

 distinguished from P. i-oscum l)y: the relatively 

 broad telson and an ocular plate that has a broad, 

 gently rounded anterolateral "corner" with serra- 

 tions extending along a large portion of the later- 

 al margins. The practice of using morphological 

 characters that change with size or vary accord- 

 ing to sex or stage of maturity has led to confu- 

 sion between these species. Further taxonomic 

 studies of these two species are clearly in order. 



Pseudomma sp. 



Ten specimens of Pseudomma that do not cor- 

 respond morphologically to any known species 



are represented from three localities off southern 

 New England. A description of this species and 

 notes on its ecology is being prepared and will 

 be reported elsewhere. 



Amhlyops abbreviata (M. Sars 1869) 



This widely distributed boreal mysid occui-s 

 in both the North Atlantic and North Pacific 

 Oceans. In the Pacific it has been found off 

 Japan and off the west coast of North America 

 from Washington to Alaska. In the Atlantic it 

 ranges from the Bay of Biscay north to Scandi- 

 navia, west to Greenland and North America. 

 Previous records from the northeastern coast 

 of the United States consist of 38 specimens 

 from 7 offshore stations situated between Cape 

 Cod, Mass., and northern New Jersey. These 

 specimens were collected by the U.S. Fish Com- 

 mission between 1879 and 1881 at water depths 

 between 238 and 838 m. 



Our collection contains 34 specimens from 8 

 samples taken in the Gulf of Maine, primarily 

 in the southern part of the Gulf (Figure 9; 

 Burns and Wigley, Table 10). Water depths 

 at these localities range from 183 to 329 m. The 

 bottom sediments where these specimens were 

 taken are composed predominantly of silts, clays, 

 and fine sands; one excei)tion is a sandy gravel 

 bottom off the eastern end of Georges Bank 

 where one juvenile specimen was obtained. Body 

 length ranged from 4.7 to 15.0 mm. The size 

 of adults is 10 to 15 mm; the males tend to be 

 slightly larger (average length 12.9 mm) than 

 females (average length 12.3 mm). 



Spawning occurs during winter and possibly 

 in other seasons as well. One ovigerous female 

 collected in December (Albatross III. cruise 70, 

 station 25) had 29 eggs in the marsupium, each 

 0.4 mm in diameter. The presence of juvenile 

 specimens 4 to 6 mm in length in August and 

 an 8-mm specimen in December suggests that 

 spawning also takes place in summer and fall. 



Sex ratio of the specimens in the NMFS col- 

 lection is 0.65 male (11 specimens) to 1 female 

 (17 specimens). 



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