SUBTERRANEAN AMPHIPOD STYGONECTES HI 



cent as long as pereopod 6, and by the proportionately short dactyl 

 claw of the same appendage. Distinguished from other species of the 

 tenuis group by smaller size of sexually mature females and specifically 

 from S. ozarkensis, \vi\h. which it occurs syntopically, by absence of 

 lateral spines on the telson and fewer spine teeth on the gnathopodal 

 propods. Kno^^Tl only from females, the largest of which are 6.75 mm. 



Antenna 1 up to 65 percent as long as body, about 50 percent longer 

 than antenna 2; primary flagellum of 23 segments; accessor}^ fiagellum 

 shghtly longer than 1st primary flagellar segment. Antenna 2, 

 fiagellum with 9 segments. INIandibular palpal segment 3 with 6 or 

 7 long setae, 2nd segment with 6 setae. Maxilla 1, inner plate with 

 5 apical, plumose setae. Maxilla 2, inner plate with 7 long, obUquely 

 placed, plumose setae. Maxilhped: inner plate with 3 or 4 thick, 

 apical spines; outer plate not reaching to apex of 1st palpal segment. 

 Lower Up, inner lobes small. 



Gnathopod 1 : propod palmar margin oblique, relatively straight, 

 armed with a double row of about 9 spine teeth; posterior angle with 



1 large spine and 3 smaller spines on outside, 3 or 4 small spines on 

 inside; posterior margin with 4 sets of setae; lateral setae few in 

 number; claw of dactyl long. Gnathopod 2: ])ropod palmar margin 

 less obUque, generally straight, armed with a double row of about 9 

 spine teeth; posterior angle with 1 large spine, 2 smaller spines and 



2 long setae on outside, 2 small spines on inside; posterior margin 

 with 4 sets of setae; superior lateral setae mostly doubly inserted, 

 inferior lateral setae singly inserted; dactyl claw long. Coxal plates 

 of pereopods 2 and 3 up to 15 percent longer than broad, ventral mar- 

 gins with 6 setae. Coxal plate of pereopod 4 about as broad as long, 

 with 6 ventral marginal setae. Pereopod 7 only about 35 to 40 percent 

 as long as body, about 80 percent as long as pereopod 6 and up to 15 

 percent longer than pereopod 5. Basis of pereopod 5 a httle broader 

 proximally than distally, distoposterior lobe free but not much 

 produced ventrally; basis of pereopod 6 broad, distoposterior lobe a 

 Uttle more produced; basis of pereopod 7 less broad, about as broad 

 proximally as distally, posterior margin evenly convex, distoposterior 

 lobe ventrally produced. Dactyl of pereopod 5 about 1/4 as long as 

 corresponding propod; dactyls of 6 and 7 a httle less than 1/3 as long 

 as corrasponding propods; dact}'! claw of pereopod 7 very short. 

 Pleonite sternal and 7th pereopod coxal gills absent; all other gills 

 present. 



Abdominal side plates: posterior margins broadly rounded, with 

 4 to 6 setae each; posterior corners rounded, poorly defined; ventral 

 margins of plates 2 and 3 with 3 or 4 spines each. Pleopod 1, inner 

 ramus about 40 percent longer than peduncle. Uropod 1 : outer 

 ramus about 90 percent as long as inner ramus, about 60 percent as 



