long, nearly 70 percent of total body length. Free 

 thoracic segments, each succeeding one narrower 

 than the one anterior to it. Grenital segment (fig. 2) 

 slightly wider than long (96 /x by 88 ^) ; rows of 

 spinules on ventral surface as indicated in figure. 

 Abdomen 3-segmented; each segment somewhat 

 narrower than preceding one; terminal segment 

 divided nearly entire length along medial antero- 

 posterial line. Caudal rami nearly square (23 fx. by 

 23 /i), with four tenninal setae; imiermost seta 

 longest (190 /t) with base about half as wide as 

 ramus. 



First antenna (fig. 3) 6-segmented ; all segments 

 of nearly equal length, second sliglitly longer thai: 

 others. Second antenna (fig. 4) in form of a claw; 

 segments measure 89 /k, 221 /i, 118 /n, and 110 ^, 

 respectively, devoid of ornamentation. Mouth 

 parts (fig. 5) small and like other species of genus. 

 Maxilliped absent. 



Legs 1 to 4 biramose. I^eg 1 (fig. 6) rami 3-seg- 

 mented; two outer spines on endopod last segment 

 spatulate. T^g 2 (fig. 7) rami 3-segmented: row of 

 blunt spinules along outer edge, of endopod fii'st 

 segment; spinelike process near inner edge of 

 exopod on coxopod. T^eg 3 (fig. 8) rami 3-s6g- 

 mented; coxopod with rows of spinules as indi- 

 cated in figure. Leg 4 (fig. 9) exoixxl 2-segment6d; 

 endopod 3-segmented. Spine and seta fonnulas for 

 legs 1 to 4 follow : 



Leg 5 (fig. 2) a well-developed free segment 

 bearing two terminal setae, one shorter subteniii- 

 nal seta, and one seta near base. Leg 6 absent. 



Egg sacs long (640 jn), containing 50 to 60 eggs. 



Color in life unknown. 



Male. — Unknown. 



Etymology. — The specific name spatuliis is 

 Latin for "a broad, flat tool" and refers to the na- 

 ture of the endopod spiiies of leg 1. 



Remarks. — This species may be separated from 

 the other species of the genus by the row of 

 spatulate spinules on the first endoix)d segment of 

 leg 2 and by the broad spines on the last endopod 

 segment of leg 1. This sjjecies appears to be very 

 close to Ergasihis arthrosis Roberts. 



Ergasilus argulus Cressey, New Species 



Figures 10 to 16 



Specimens studied. — Three collections contain- 

 ing 106 females from the Dagua River in Colom- 

 bia, South America. The first collection contain- 

 ing the holotype female (USNTVI 125677) and 57 

 paratype females (USKM 125678) removed 

 from the outer surface of the gill filaments of 5 

 Strongylura fluviatUis (CAS 11606). The other 

 two collections from the gill filaments of S. scapu- 

 laris caught in the mouth of the same river, 44 

 from 5 specimens (FMHSfH 59434-8) and 4 from 

 1 specimen (USNTVI 203520). 



Fcm-dJc. — Body form as in figure 10. Total length 

 660 IX and greatest width 413 ix.. Cephalon some- 

 what longer tlian wide (472 /n by 413 fx) with 

 anterior portion subdivided. First thoracic seg- 

 ment fused with head. Width of free thoracic 

 segments 218 ,x, 160 /i, and 112 ^, respectively. 

 Grenital segment (fig. 11) 94 /j, long and 106 ^ wide 

 with irregular row of spinules along posterior ven- 

 tral border. Abdomen 3-segmented, each segment 

 with row of spinules along posterior ventral 

 border. Caudal rami nearly square, with four 

 setae; longest seta 235 fx. long; all setae sparsely 

 phunose; sliort row of spinules on posterior ven- 

 tral inner corner. 



First antenna (fig. 12) 6-segm6nted; each seg- 

 ment with naked setae as in figure; segments 

 measure 22 jn, 36 fi, 20 m, 15 ix, 22 /*, and 18 /i in 

 length, respectively. Second antenna (fig. 13) 

 4-segmented and in form of a claw; segments 

 measure 195 ix, 384 (x, 295 /x, and 177 fx in length, re- 

 spectively. Other mouth parts as in previous 

 species. Maxillipeds absent. 



Legs 1 to 4 biramose. Leg 1 (fig. 14) exopod 

 3-segmented; endopod 2-segmented; rami armed 

 as in figure. Leg 2 (fig. 15) botli rami 3-seg- 

 mented, interpodal plate with row of prominent 

 spinules along posterior border ; both rami armed 

 as in figure. Leg 3 same as leg 2. Leg 4 (fig. 16) 

 exopod 2-segmented ; endopod 3-s6gmented ; rami 

 armed as in figure; interpodal plate with spinules 

 but less prominent than in legs 2 and 3. All setae 

 on rami of legs 1 to 4 plumose. Spine and seta 

 formulas for legs 1 to 4 follow : 



352 



U.S. FISH AND WILDLIFE SERVICE 



