Description of Adult Female 



The total lengths of 19 adult females range 

 from 6.52 to 7.00 mm. The prosome is much 

 longer than the urosome (plate 1, fig. 16), and 

 the ratio of these two body parts is about 7.6:1. 

 The anterior region of the head (plate 2, fig. 

 1) is markedly constricted in front of the an- 

 tennules and is triangular in dorsal view; the 

 height is about two-thirds the length of the 

 base. The first metasomal segment is fused with 

 the cephalosome. The fourth and fifth meta- 

 somal segments are not completely separated, 

 but are fused in the ventrolateral regions (plate 

 2, fig. 3). The posterolateral corners of the 

 metasome are smoothly rounded. 



The urosome consists of 2 free segments and 

 the compound caudal furca. The first or genital 

 segment is composed of 2 fused segments, and 

 the caudal furca is formed of 2 segments fused 

 with the rami. The proportional lengths of the 

 segments and caudal furca, from anterior to 

 posterior, are 45:18:37. 



The genital segment (plate 2, fig. 2) is wider 

 than long (55:45) ; ventrally it projects in a 

 round swelling, bearing the genital aperture 

 (plate 2, figs. 3 and 4). The left caudal ramus 

 is slightly larger than the right. The second 

 medial terminal seta on the left ramus is 

 markedly stouter and much longer than the 

 others. 



The antennule (plate 1, fig. 17) has 23 free 

 segments; the first and second and the eighth 

 and ninth segments are fused. The" last 6 seg- 

 ments extend beyond the caudal rami. Each seg- 

 ment carries one or several strong plumose 

 setae that are often reddish. 



The exopod of the antenna (plate 2, fig. 5) 

 is 8-segmented, has 12 setae, and reaches about 

 the end of the first endopodal segment. The 

 first endopodal— segment is about 1.3 times as 

 long as the second and has 2 setae along the 

 inner edge, two-fifths the length of the segment 

 from the distal end. The second endopodal seg- 

 ment has 8 long setae and 1 short seta on the 

 internal lobe and 6 long setae and 1 short seta 

 on the external lobe. 



The mandibular palpus (plate 2, fig. 6) is 

 1.7 times as long as the mandibular blade and is 

 biramous. The basis is more or less cylindrical 

 and has 4 setae at the upper portion of the in- 

 ternal margin. The endopod arises from near 



the middle of the basis and is 2-segmented ; 

 the first segment has 2 short setae and the sec- 

 ond 1 short seta and 4 long setae. 



In the maxillule (plate 2, fig. 7), the first 

 inner lobe has 15 spines, and each of the sec- 

 ond and third inner lobes has 4 setae. The first 

 outer lobe is rather small and has 9 setae. The 

 second outer lobe is not pronounced and has a 

 single plumose seta. The basis has 5 setae along 

 the internal margin and carries laterally an 

 exopod and distally an endopod. The exopod has 

 5 setae. The endopod is 3-segmented; the first 

 2 segments are partially fu.sed and each has 4 

 setae, and the small apical segment has 5 setae. 



The maxilla (plate 2, fig. 8) is well developed. 

 The outer margin of the coxa has a round 

 swelling with hairs. Next to the swelling is a 

 markedly depressed portion from which arises 

 a long, plumose seta. The various lobes are well 

 developed. The first lobe has 6 setae and a small 

 spine, each of the second to fourth lobes has 3 

 setae, the fifth lobe carries 3 setae and a long 

 spine, and the sixth lobe has a single .seta. In 

 addition, the segments of the endopod have 

 setae as follows : 1 on the fir.st, 2 on the second, 

 and 2 on the terminal segment. 



The coxa of the maxilliped (plate 2, fig. 9) is 

 composed of 4 lobes: the proximal lobe has 1 

 seta; the second, 2 .setae; and the third and 

 fourth lobes, 3 setae each. The basis has 3 setae 

 just distad of the midpoint and 2 on the distal 

 lobe. The endopod consists of 5 segments, which 

 have 3, 4, 3, 3 + 1, and 2 -f 2 .setae, 

 respectively. 



The coxa of the first leg (plate 2, fig. 10) 

 lacks setae, but its inner margin is fringed 

 with hairs. The basis has a curved, plumose 

 seta at the internal apex. The exopod is 3-seg- 

 mented. The first and second .segments are de- 

 void of external spines, but each has 1 internal 

 .seta ; the third segment has 1 external spine at 

 the di.stal corner, a slender terminal spine, and 

 4 internal setae. The endopod is 2-segmented : 

 the fir.st segment has a single internal seta ; the 

 -second segment 2 internal and 2 terminal setae. 



The second to fourth legs (plate 2, figs. 11- 

 13) are alike. The coxa has an internal plumose 

 seta, but the basis lacks setae. Both the exopod 

 and the endopod are 3-segmented. Each of the 

 first and second exopodal segments has 1 .strong 

 external spine and 1 internal seta; the third 



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U.S. FISH AND WILDLIFE SERVICE 



