SUBTERRANEAN AMPHIPOD STYGONECTES 91 



Corresponding to the description of Hubricht (1943) and the partial 

 redescription of Holsinger (1966) but with the following modifica- 

 tions noted for the male unless otherwise indicated: 



Antenna 1 up to 75 percent as long as body, 45 to 50 percent longer 

 than antenna 2; primary flagellum with up to 29 segments. Antenna 

 2, flagellum of 9 segments. Coxal plate of pereopod 3 with 9 marginal 

 setae, that of pereopod 4 with 10 or 11 marginal setae. Pereopod 7 

 about 45 to 50 percent as long as body, a little longer than pereopod 6 

 and approximately 40 percent longer than pereopod 5. Gill arrange- 

 ment in both sexes as follows: Median sternal, pleonite sternal, and 

 7th pereopod coxal gills absent; lateral sternal gills simple, not bi- 

 furcate. Abdominal side plates with 5 or 6 setae each on convex pos- 

 terior margms. Pleopod 1, inner ramus about 35 percent longer than 

 peduncle. Uropod 1, up to 12 spines on inner and outer rami each, 

 10 or 11 spines on peduncle. Uropod 2: inner ramus with 12 spines; 

 outer ramus with 6 spmes; peduncle with 4 or 5 spines. Telson: apex 

 with 8 to 10 spines, the outer spine on either side deflected laterally 

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

 Telson of female generally similar to that of S. alabamensis and armed 

 with about 8 apical spines. 



Distribution and ecology. — As presently understood, this species 

 is known only from the type locality and Irelands Cave, Tex., which 

 lies 25 miles north-northeast of the former. In both caves specimens 

 were taken from small drip pools containing organic debris. The col- 

 lection from Irelands Cave also contained three specimens of S. russelli. 

 Ovigerous females have not been collected to date. 



Remarks. — A critical reanalysis of the material which I recently 

 assigned to S. balconis (Holsinger, 1966) has indicated the existence 

 of three closely related species comprising a complex that occupies 

 most of the eastern half of the Edwards Plateau region in central 

 Texas. The two additional species of this complex are described be- 

 low. Moreover, it should be pointed out that the rather extreme vari- 

 ation noted for S. halconis in my recent paper (Holsinger, 1966) actu- 

 ally applied to a composite of all three species in this complex and not 

 to S. halconis as recognized herein. Figiu-es 72 and 73 in that paper 

 do not apply to S. halconis as indicated therein, but to S. bifurcatus. 

 In view of the evidence uncovered dming the present study, the range 

 of ^S. halconis must be greatly delimited as noted above. 



Ulilenhuth (1921; mentioned an amphipod species from Boyetts 

 Cave which he considered as either closely related to, or identical 

 with, S. flagellatus. The material he had reference to undoubtedly 

 belonged to S. halconis (see also ReddeH, 1965). 



242-803—67. 7 



