SUBTERRANEAN AMPHIPOD STYGONECTES 97 



Stowers Cave, J. Reddell and B. Bell, Mar. 20, 1965; Mason Co.: Zesch Ranch 

 Cave, J. Reddell, Nov. 8, 1964; San Saba Co.: Gorman Cave, J. Reddell and D. 

 McKenzie, Mar. 15, 1963; Harrells Cave, K. Kunath and J. Reddell, Aug. 31, 

 1963; Travis Co.: Adobe Springs Cave, W. Russell and J. Porter, Oct. 4 and 10, 

 1964; Balcones Sink Cave, W. Russell, July 31, 1964, and June 30, 1965; Cave X, 

 J. Reddell, Jan. 3, 1964; Dead Dog Cave No. 2, W. Russell, October 1963, and 

 Mar. 10, 1964; Irelands Cave, W. Russell, Mar. 14, 1964; Salamander Cave, J. 

 Reddell, spring of 1963 and K. Garrett, March 1964; Spanish Wells Cave, W. 

 Russell, Oct. 6, 1963. 



Diagnosis. — An extremely variable species ocurring sympatrically 

 with both S. balconis and S. hijurcatus but distinguished from these 

 species by proportionately longer outer plate of maxilliped, straighter 

 propod palmar margins of gnathopods, smaller and fewer spine teeth 

 on gnathopodal propods of female, smaller size of the male, and often 

 by having more elongate coxal plates of pereopods 3 and 4. Distin- 

 guished specifically from S. balconis by less rounded posterior margins 

 of abdominal side plates and from S. hijurcatus by absence of bifurcate, 

 lateral sternal gills. Largest males, 9.00 mm; largest females, 11.75 

 mm. 



Female.^ — Antenna 1 varying between 37 and 69 percent as long as 

 body, 35 to 50 percent longer than antenna 2; primary flagellum with 

 22 to 27 segments; accessory flagellum extending about the length of 

 1st 2 primary flagellar segments. Palpal segment 3 of mandible with 

 5 to 8 long setae, segment 2 with 4 to 8 setae. Maxilla 1, inner plate 

 with 5 or 6 apical, plumose setae. Maxilla 2, inner plate with 5 to 7 

 long, obliquely placed, plumose setae. Maxilliped; inner plate with 4 

 to 6 thick, apical spines; outer plate reaching to and usually just 

 beyond apex of palpal segment 1. Lower lip, inner lobes moderately 

 broad. 



Gnathopod 1 : propod palmar margin straight, armed with a double 

 row of 7 small spine teeth ; posterior angle with 1 large spine and 3 to 5 

 small spines on outside, 3 to 6 small spines on inside; posterior margin 

 with 2 to 4 (usually 3) sets of setae; superior lateral setae in transverse 

 row, singly inserted, inferior lateral setae not in transverse row, 

 singly inserted; dactyl claw rather long. Gnathopod 2: propod 

 palmar margin straight, armed with a double row of 7 or 8 small spine 

 teeth; posterior angle with 1 large spine and 3 to 6 smaller spines and 

 several setae on outside, 3 to 6 small spines on inside; posterior margin 

 with 4 to 7 sets of setae ; superior lateral setae in transverse row, triply 

 and doubly inserted; inferior lateral setae singly inserted; dactyl claw 

 rather long. Coxal plates of pereopods 2 and 3 varying from just 

 slightly longer than broad up to 25 percent longer than broad; plate 2 

 with about 6 marginal setae; that of 3 with 8 or 9 marginal setae. 

 Coxal plate of pereopod 4 varying from about as long as broad up to 

 25 percent longer than broad, ventral margin with 8 to 10 setae. 



