WIGLEV and BURNS: DISTRIBUTION AND BIOLOCV OP MVSIDS 



trates the relative scarcity of this species off- 

 shore. 



Based on NMFS samples, spawning; takes 

 place from June to September. Ovigerous or 

 larvigerous females are 5.0 to 8.0 mm long and 

 the number of young per brood is 13 to 15. The 

 average diameter of eggs is 0.4 mm; the length 

 of stage VI larvae is 1.0 mm and of stage VII 

 larvae is 1.7 mm. 



The NMFS collection contains 27 males and 

 31 females, a ratio of 0.9 male to 1 female. 



Immature specimens within the size range of 

 3.4 to 4.5 mm are present in samples from Oc- 

 tober through January. Body lengths of adults 

 range from 4.7 to 8.9 mm. 



This species was collected from a variety of 

 different bottom types (gravel, sand, coarse 

 sand, glacial till, and silty sand). Apiiarently 

 it has no special affinity for any one kind of sedi- 

 ment, but ap])ears to be more commonly associ- 

 ated with coarse-textured sediments. Members 

 of this species congregate in dead shells of bi- 

 valves such as Mercciiaria and Spwiila. 



Sizes of adult specimens from coastal areas 

 are approximately 5 to 9 mm, whereas the off- 

 shore specimens reportedly reach lengths of 

 15 mm. Owing in part to this difference in size, 

 and partly to their deepwater habitat, Tattersall 

 (1951) considered the possibility that the large 

 offshore specimens collected by the research ves- 

 sels Albatross and Fish Haivk might represent 

 a new species closely related to H. formosa. He 

 concluded, however, that both groups were sim- 

 ilar and only one species was represented. 



The deepwater specimen in the NMFS col- 

 lection is a female only 6.5 mm long. A mor- 

 ])hological comparison of this specimen with 

 inshore specimens revealed no major differences 

 that we could detect. 



SUMMARY 



GENERAL 



The princii:)al biological and ecological char- 

 acteristics for each of the 19 species in the 

 NMFS collection are summarized in abbreviated 

 form in Table 11. This tabulation provides a 

 condensed comijarison of one species with an- 



other within the NMFS collection and can be 

 used for comparing NMFS information with 

 data from other sources. 



TAXONOMIC AFFINITY AND ENDEMISM 



The taxonomic affinities of mysids in the 

 NMFS collection are most closely allied with the 

 boreal and subarctic species in the North At- 

 lantic; however, a high degree of endemism is 

 evident. 



Nine species having an amphi-Atlantic dis- 

 tribution are: Eucopia grhnaldU, Boreomysis 

 tridens, Eiythrops erythrophthalma , Metery- 

 throps robusfa, Pseudomma affine, Amhlyops 

 abhreciata, Mysis mixta, Pmunus flexuosus, and 

 Heteromysis formosa. The eight species that 

 are indigenous to the western North Atlantic 

 are: Bowmnniella portoricensis, Hypereryth- 

 rops caribbaea, Pseudomma sp., Bathymysis re- 

 noculata, Mysidopsis bigelorvi, M. furca, Mysis 

 stenolepis, and Neomysis americana. These in- 

 digenous species are all inhabitants of warm- 

 temjierate to tropical waters. Only one species 

 in the NMFS collection (Eucopia grimaldii) is 

 cosmo]Mlitan. Four species (Eucopia grimaldii. 

 Anchialina typica, Meterythrops robusta, and 

 Amhlijojis abbreviata) occur in the Pacific Ocean 

 as well as in the western Atlantic. One species 

 (Promysis atlantica) occurs in the South At- 

 lantic and North Atlantic Oceans. 



GEOGRAPHIC DISTRIBUTION 



The geographic distribution of sjjecies repre- 

 sented in the NMFS collection differs in scope 

 from .single records (of which there are three) 

 to wide-ranging multiple records. Mysidopsis 

 bigeloiri has the greatest range, extending from 

 northern Georges Bank southward to northern 

 Florida. Neo^nysis americana has a moderate 

 range, extending from northern Gulf of Maine 

 south to Chesapeake Bay. Bowmaniella portor- 

 icensis and Promysis atlantica have widespread 

 ranges in the southern area, with distributions 

 extending from Virginia to Florida. All re- 

 maining species were collected within rather 

 limited geographic areas along the eastern coast 

 of the United States, mostly off New England. 



741 



