WIGLEY an,l BURNS: DISTRIBUTION AND BIOLOGY OF MYSIDS 



of only two young in the brood pouch. Collec- 

 tion of this specimen in August indicates a sum- 

 mei- spawning season for this sjiecies. This 

 larvigerous specimen was found in the stomach 

 of a Gulf Stream flounder, Citharkhthys arctif- 

 rons Goode. Since H. caribbaea. is found in 

 warm-temperate waters, its occurrence in the 

 Gulf of Maine may be restricted to the deeper 

 basin areas where water temperatures are ameli- 

 orated by the intrusion of relatively warm, high- 

 salinity slope water. 



Pseudomma affine G. O. Sars, 1870 

 The geographic distribution of this species 

 extends from the Bay of Biscay northward to 

 Norway, westward to Iceland, Greenland, and 

 North America. We found only two records of 

 its occurrence in North American waters. Tat- 

 tersall (1951) recorded one specimen taken by 

 the research vessel Fhh Hawk at station 999, 

 located 153 km south of Rhode Island (lat 

 39°45' N, long 71°30' W) at a depth of 487 m. 

 Klawe (1955) reported taking this species 2 km 

 off Campobello Island, New Brunswick, Canada. 



.^ 



f 



f 



Pseudomma affine 



Bathymetric range of all records from the North 

 Atlantic Ocean is 80 to 914 m. 



Our collection contain;; 119 specimens from 22 

 samples (Figure 8; Burns and VVigley, Table 9) , 

 all from the Gulf of Maine, except one from just 

 south of Georges Bank. They were collected at 

 moderate water depths: 146 to 329 m. Bottom 

 sediments at these collecting sites contain large 

 projiortions of fine particles, chiefly silts, clays, 

 and fine sands. Only two samples were taken 

 in areas having gravel or coarse sand bottom. 



Body lengths range from 4.0 to 13.1 mm; the 

 majority are between 8 and 11 mm. 



Evidence of an extended spawning season is 

 provided by the presence of ovigerous, larviger- 

 ous, and small juvenile specimens in the col- 

 lection. A 10.9-mm ovigerous specimen was 

 taken in December (Albatross III, cruise 70, 

 station 41) with 11 eggs and an average egg 

 diameter of 0.4 mm. One 11.0-mm larvigerous 

 specimen taken in August {Albatross IV, cruise 

 65-11. station 56) contains one larva 1.2 mm 

 long. Additionally, juveniles 5 mm or less in 

 length were taken in August, November, and 

 December. Spawning thus takes place during 

 summer and winter and may also occur in the 

 spring and fall. 



Sex ratio of the specimens in the NMFS col- 

 lection is 2.3 males (68 specimens) to 1 female 

 (29 specimens). 



Several morphological features in our speci- 

 mens differ slightly from published descriptions 

 of this species. In Table 3 are listed the number 

 of spines on the telson and relative length of the 

 antennal scale apex and relative width of the 

 antennal scale. Specimens in our collection have 

 fewer apical spines (nearly always 6) on the 

 telson, and a greater number of spines (9-24, 

 average 17) on the lateral margins of the telson, 

 than specimens from the eastern Atlantic. Also, 

 the antennal .scales on Gulf of Maine sjiecimens 

 have a proportionately longer apex (that portion 

 of the scale between the spine cleft and the an- 

 terior end) than eastern Atlantic specimens. 

 Spination of the telson and shape of the antennal 



Figure 8. — Geographic distribution of Psendoinma af- 

 fine based on .specimens in the collection at the NMFS 

 Biological Laboratory, Woods Hole. 



