REVIEW OF GENUS ARGULUS — MEEHEAN 481 



ARGULUS ALOSAE Gould 



Figure 23 



Argulus alosae Gould, 1841, p. 340.— Wilson, 1902, p. 707, pi, 12, pi. 26, fig. 80; 

 1932, p. 17, fig. 6. 



Carapace of female elliptical, male ovate ; cephalic area very prom- 

 inent; eyes comparatively large and set wide apart. Last thoracic 

 segment is very wide and flares over the abdomen. Abdomen with 

 points flaring, sinus shallow and wide, anal fiircae minute and basal. 

 Respiratory area reaching to the base of the suction cups, anterior 

 small one slightly oblong, posterior one reniform (fig. 23, a). 



Figure 23. — Argulus alosae: a. Respiratory areas ; h, male accessory organs of third and 

 fourth legs ; c, ribs of suction cups. 



Antennae with anterior hook, weak, but lateral hook curved back 

 some distance; spine on ventral surface fairly large, a large one at 

 the base; a medium one at the base of second antennae, and a very 

 large one at the midline. Second antennae comparatively long and 

 slender. Suction cups large, ribs in rim made up of 10 to 12 imbri- 

 cate plates with an elongate one at the base; marginal lappets long 

 and narrow with setae at the ends (fig. 23, c). Second maxillae with 

 wide basal plate, short, sharp teeth, widely separated, lateral one 

 more widely separated than the others. Both pairs of postmaxillary 

 spines pointed. 



Swimming appendages without flagella, normal on the female 

 except for a posterior bilobed coxa on the fourth appendages. First 

 two pairs unmodified on male, peg merely a rounded papilla on the 

 dorsal distal edge of the basis which fits into a posterior rounded 

 cone-shaped lobe on the posterior surface of the third appendages, 

 so that the papilla appears to overlap the socket when viewed either 

 clorsally or ventrally (fig. 23, h). 



