6 - Sphaeromatidae::“Cute As Buttons”

236 FLABELLIFERA • TRIDENTELLIDAE
Tridentella Richardson, 1905
DIAGNOSIS Body dorsally often bearing spines, tubercles, or carinae, more
developed in 8 than in 9. Frontal lamina narrow, pentagonal. Antcnnular
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 8 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 8 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 efficient
swimmer and has been recorded from shallow-water plankton, but is more