SUBTERRANEAN AMPHIPOD STYGONECTES 87 



antenna 2, primary flagellum with up to 27 segments. Uropod 3, 

 ramus with only 2 apical spines. Telson armed apically with 10 

 unequal spines, the outer spine on either side being deflected laterally 

 from the midline and armed with 1 or 2 small, distal tines. Absence 

 or presence of sternal gills on pleonite not determinable but all other 

 gills present. 



Type locality. — Seep, 0.2 mile east of The Lodge, Magazine Mt., 

 Logan Co., Ark. Magazine Mountain is the highest point in Arkansas 

 and reaches an elevation of 2,823 feet above sea level. Geologically, 

 this area is generally underlain by sandstones of Pennsylvanian age. 



Distribution and ecology. — This species is known only from the 

 type locality and further data are not available on its ecology. 



Remarks. — The single male (allotype) may not be completely 

 mature but most diagnostic characters appear to be developed. In 

 respect to the slender spines on the fourth peduncular segment of 

 antenna 2 and the general structure of the gnathopodal propods, this 

 species bears a close resemblance to S. clantoni. In most of its other 

 characters, however, S. elatus more closely resembled S. alabamensis 

 and S. montanus. 



Stygonectes harri, new species 



Figure 21 



Synpleonia clantoni Creaser. — Hubricht and Mackin, 1940, p. 206 (in part). 

 Synpleonta americana (Mackin).— Hubricht, 1943, p. 711 (in part). 



Material examined 



MISSOURI. — Wayne Co.: seep, 0.5 mile E of Greenville, male holotype, female 

 allotype, 16 paratypes, L. Hubricht, Apr. 10, 1938 (USNM); Madison Co.: small 

 intermittent stream, tributary to Twelve Mile Creek, 7 miles S of Fredericktown, 

 27 paratypes, L. Hubricht, Apr. 21, 1938 (USNM and slide mounts of 2 paratypes 

 in JRH). 



Diagnosis. — Rather closely allied morphologically with both 

 S. alabamensis and S. tenuis but distinguished from these species by 

 having a few more spine teeth on gnathopodal propods, more sijines 

 on uropods 1 and 2, and by presence of lateral spines on the telson. 

 Further distinguished from the former by having more posterior 

 marginal setae on gnathopodal propods and straighter posterior 

 margins of pereopod bases; and from the latter by having more pos- 

 terior marginal setae on propod of gnathopod 1. Largest males, 

 12.75 mm; largest females, 8.25 mm. 



Male. — Antenna 1 up to 85 percent as long as body and up to 60 

 percent longer than antenna 2; primary flagellum with up to 37 

 segments; accessory flagellum a Uttle longer than 1st segment of 

 primary flagellum. Antenna 2 with up to 12 segments in flagellum. 

 Mouthparts similar to those of S. alabamensis. 



