234 FLABELLIFERA • SPHAEROMATIDAE 



morphosed. Three pairs of overlapping oostegites arising from pereonites 2- 

 4 (but S. terebrans has anterior pair rudimentary). 



REMARKS The genus Sphaeroma is one of the few sphaeromatids in which the 

 number of oostegites varies, from the diagnostic three pairs, through two 

 normal pairs (as in S. terebrans), to having the oostegites completely absent 

 (as in S. annandalei) . 



Jacobs (1987) has provided a useful reevaluation of the European, Medi- 

 terranean, and northwest African species of Sphaeroma and related genera. 



Key to species of Sphaeroma 



1. Pleotelson posteriorly bluntly triangular, with 4 strong anterior 



tubercles 



terebrans 



Pleotelson posteriorly broadly rounded 2 



2. Pleotelson dorsally smooth or with few low tubercles quadridentata 



Pleotelson dorsally with numerous strong tubercules walkeri 



Sphaeroma quadridentata Say, 1818 

 Figure lOlC 



DIAGNOSIS 6 11.0 mm, 9 8.0 mm. Pleotelson anteriorly inflated, some- 

 times with few low rounded tubercles, posteriorly flattened to concave; pos- 

 terior margin entire, broadly rounded. 



RECORDS New England to Florida; Gulf of Mexico, intertidal to 1 m, often 

 in pilings and partially submerged dead tree trunks, and commonly associ- 

 ated with barnacles. 



Sphaeroma terebrans Bate, 1866 

 Figure lOlD 



DIAGNOSIS 6 10.0 mm, 9 11.5 mm. Pereonite 7 with pair of submedian 

 and pair of lateral tubercles. Dorsal pleon densely tuberculate. Posterior 

 pleonite with pair of submedian acute tubercles. Pleotelson anteriorly with 

 submedian pair and lateral pair of tubercles, posteriorly rounded-triangular. 



