SUBTERRANEAN AJMPHIPOD STYGONECTES 107 



Stygonectes ozarkensis, new species 



Figure 26 



Synpleonia clantoni Creaser. — Mackin, 1941, p. 30 (in part). — Ilubricht, 1943, p. 

 711 (in part) .— Dearolf , 1953, p. 228.— Hubricht, 1959, p. 878 (in part).— 

 Nicholas, 1960, p. 130 (in part). 



Mateeial examined 



MISSOURI. — Stone Co.: Marvel Cave, male holotype, female allotype, K. Dearolf, 

 June 27, 1938 (USNM). Paratypes as follows: Missouri. — McDonald Co.: 

 Henson Cave, J. R. Holsinger and R. Norton, June 11, 1964 (JRH). 

 ARKANSAS. — Benton Co.: Danford Cave, near Lowell, D. Martin, Oct. 14, 1963 

 (JRH). OKLAHOMA. — Maycs Co.: seep at girl scout camp, 3.2 miles S of Locust 

 Grove, L. Hubricht, May 23, 1940 (LH). 



DiAGNOSis.^ — Moderately large species rather closely allied morpho- 

 logically with S. clantoni, but distinguished from that species by 

 smaller size at maturity, greater degree of sexual dimorphism, more 

 narrow bases of pereopods 5-7, proportionately longer rami of 1st and 

 2nd uropods of the male, more apical spines on 3rd uropod of the 

 female, and by the telson which differs in having lateral spines, fewer 

 apical spmes, and being proportionately longer in the male. Largest 

 male, 13.50 mm; largest females, 12.75 mm. 



Male. — Antenna 1 up to 90 percent as long as body, about 65 

 percent longer than antenna 2 ; primary flagellum with up to 54 seg- 

 ments; accessory flagellum short as described for aS. clantoni. An- 

 tenna 2 : peduncular segments 4 and 5 with 4 or 5 sets of stiff, bristle- 

 like setae, segment 4 with a few slender spines on ventral margin; 

 flagellum with about 12 segments, most of which have a proximal 

 lateral seta imusually inserted as shown. Mouth parts similar to 

 those of S. clantoni with possible exception of maxilla 2 which has 5 

 or 6 long, obliquely placed, plumose setae. 



Gnathopod 1: propod palmar margin oblique, slightly concave 

 distally, armed with a double row of 12 or 13 spine teeth; posterior 

 angle with 1 large spine and 4 smaller spines on outside, 5 small spines 

 on inside; posterior margin with 2 or 3 sets of setae; superior lateral 

 setae few in number, inferior lateral setae singly inserted; dactyl with 

 4 outer marginal setae unusually inserted as shown in figure 25, claw 

 short. Gnathopod 2: propod palmar margin less oblique, slightly 

 convex proximally and slightly concave distally, armed with a double 

 row of 15 or 16 spine teeth; posterior angle with 1 large spine and 4 

 smaller spines on outside, 5 small spines on inside; posterior margin 

 with 6 sets of setae; superior lateral setae in transverse row, mostly 

 doubly inserted, inferior lateral setae singly and doubly inserted; 

 dactyl claw short. Coxal plates of pereopods 1-4 with a few less 

 marginal setae and spinules than S. clantoni but not otherwise appre- 

 ciably different. Pereopod 7 about 50 percent as long as body, a 



242-803—67 8 



