236 FLABELLIFERA • TRIDENTELLIDAE 



Tridentella Richardson, 1905 



DIAGNOSIS Body dorsally often bearing spines, tubercles, or carinae, more 

 developed in 6 than in 9 . Frontal lamina narrow, pentagonal. Antennular 

 peduncle of three articles; antennal peduncle of five articles. Mandibular 

 molar weakly sclerotized. Pereopods 1-3 weakly prehensile; pereopods 4-7 

 ambulatory. Copulatory stylet of pleopod 2 rodlike, arising proximally on 

 mesial margin of endopod. Pleopod 5 endopod lacking marginal setae. 



REMARKS Delaney and Brusca (1985) provide useful taxonomic and dis- 

 tributional comments on the family Tridentellidae. 



Tridentella virginiana (Richardson, 1900b) 

 Figure 102 



DIAGNOSIS 6 9.5 mm, ovigerous 9 9.5-11.0 mm. Cephalon and pereon 

 dorsally smooth, pleon minutely granular. Uropodal rami with distal mar- 

 gins faintly dentate, apically narrowly rounded, endopod wider and slightly 

 longer than exopod. Pleotelson basally wider than middorsal length; pos- 

 terior margin broadly rounded to subtruncate. 



RECORDS Nova Scotia to Florida; off Georgia, 550 m; Gulf Stream off Key 



West, 220 m. 



Suborder Gnathiidea Leach, 1814 



DIAGNOSIS Eyes usually well developed, rarely on short lateral processes, 

 occasionally absent. Mandibles in S greatly enlarged, projecting anteriorly 

 from cephalon, not used in feeding. Mandibles lacking in 9 . Mouthparts of 

 praniza larva styliform, with acute mandibles projecting anteriorly (see Fig- 

 ure 103D). Pereopod 1 modified, forming second pair of broad opercular 

 maxillipeds covering mouthparts, referred to as pylopods. Pereopods 2-6 

 ambulatory. Pereonite 7 reduced, lacking pereopod. Pleonites separate, nar- 

 rower than pereon. Uropods lateral, rami lamellar, forming tailfan with 

 telson. Praniza larva with pereonites 4-6 enlarged, sometimes inflated. 9 

 with pereonites 4-6 greatly inflated, forming broodpouch for internally 

 brooded eggs (see Figure 103E). 



REMARKS The gnathiideans are entirely marine, most described species 

 being from shallow waters. The males and females are frequently found in 

 association with sponges and do not feed. The praniza larva is an efiicient 

 swimmer and has been recorded from shallow-water plankton, but is more 



