Subfamily Sergestinae 



Carapace moderately compressed. Inferior an- 

 tennular flagella present ; with prehensile organ in 

 male. Second and third pair of legs, at least, 

 terminated by a pincer. Gills present. Sixth 

 abdominal segment and telson without sexual dif- 

 ferences; without protuberances or ventral pro- 

 cesses in males. Petasma with a short base. No 

 protuberance on peduncle of first pleopod (after 

 Hansen, 1922). 



Genus Acetes Milne Edwards, 1830 



Burkenroad, 1934a, p. 99. — 1934b, p. 126. 

 Acetes americanus carolinae Hansen 



Figures 30-31 



Acetes americanus Ortmann, 1893, p. 39. pi. 2, fig. 2. 

 Acetes carolinae Hansen, 1933, p. 31, figs. 1-8. 

 Acetes americanus carolinae: Holthuis, 1959, p. 49, fig. 1, a-c 

 (rev.). 



Recognition characters. — Body small. Integu- 

 ment thin, smooth, polished. Carapace with 

 rostrum elevated, short; a single tooth behind 

 acute tip. A prominent spine on rounded ridge 

 behind eye; hepatic spine small. Eyes prominent, 

 stalk conical, cornea large. Antennules with pe- 

 duncle long, third article more than twice length 

 of second article, lower flagellum much shorter 

 and more slender than upper, upper hairy ventral- 

 ly near base; in males, curved lower flagellum 

 forming clasping organ, basal four annulations 

 thicker than distal annuli, third and fourth armed 

 dorsally with a short row of spines, distal one 

 strongest. Antennal scale reaching end of second 

 article of antennular peduncle in males, beyond 

 end of second article in females. 



Figure 30. — Acetes americanus carolinae Hansen, 

 in lateral view, X 4.8. 



Female 



Figure 31. — Acetes americanus carolinae Hansen. 



A, clasping organ on antennule of male X 50; 



B, petasma of male, right side in posterior view 

 X 90; C, tip of petasma, anterior view of right 

 side X 90. 



Sixth segment of abdomen with convex ventral 

 margin bifurcated caudally. Exopod of uropod 

 about 4.5 times longer than broad ; proximal three- 

 fifths of outer margin smooth, ending in a minute 

 tooth, remainder of margin hairy. 



Petasma of male with membranous, triangular- 

 tipped external portion exceeded by slender 

 median part; median portion ending in compli- 

 cated capitulum, a distomedian crooked lobe 

 tipped with four thick, short spines, and three 

 other shorter lateral lobes each produced into 

 an acute point. Lobes behind base of last pair 

 of legs greatly enlarged in males forming genital 

 coxae broader than long. Coxae of third legs 

 in females with posteromedian corner produced 

 into a protuberance; sternite immediately behind 

 third legs bearing two curved projections forming 

 a U-shaped thelycum. 



Measurements. — Length of body : 15 to 26 mm. 



Variations.— Holthuis (1948, 1959) followed 

 Burkenroad (1934a) in considering the known 

 species of Acetes from the western Atlantic with 

 one tooth behind the tip of the rostrum to be all 



MARINE DECAPOD CRUSTACEAN'S OF THE CAROLINAS 



39 



