SUBTERRANEAN AMPHIPOD STYGONECTES 101 



S. russelli occurs in shallow cave pools and small streams usually- 

 containing organic debris and overlaps ecologically and geographically 

 with aS'. balconis, S. bifurcatus, and S. dejectus. To date, the majority 

 of specimens collected have been females (55 vs. 15), thus indicating 

 a possible disproportionate sex ratio. Females with well-developed 

 brood plates have been collected during seven or eight months of the 

 year, but only collections from two caves (Balcones Sink and Cave X) 

 made during January, June, and July contained ovigerous specimens. 

 Six ovigerous females, ranging in length from 6.75 to 9.75 mm, were 

 observed in these collections, and on the average individuals were 

 carrying six (±1) eggs or newly hatched young. 



Remarks. — At least one of the three specimens reported by Hu- 

 bricht (1943) from Cascade Cave as S.flagellatus was conspecific with 

 S. russelli. Although I included some of the above material under 

 S. balconis in a recent paper (Holsinger, 1966), further examination, 

 aided by additional collections made since the writing of that paper, 

 clearly indicates that S. russelli should be considered a separate species. 



Attempts to correlate specific patterns of variation with populations 

 from different parts of the geographic range have not been satisfactory. 

 But even so, the possibility that several poorly defined subspecies exist 

 cannot be ruled out, and furthermore, even the possible existence of two 

 or more sibling species cannot be excluded. The absence or scarcity 

 of males in most of the available samples further obscures the picture, 

 and until larger and more numerous samples (preferably of both sexes) 

 are available, it seems taxonomically feasible to regard this form as a 

 single taxon. 



Stygonectes reddelli Holsinger 



Stygonectes species. — Reddell, 1965, p. 160. 



Stygonectes reddelliHolsinger, 1966, pp. 116-119, figs. 74-94 (in part) [Type-locality: 

 Whiteface Cave, approximately 20 miles SW of San Saba, San Saba Co., Tex.]. 



Material examined 



TEXAS. — San Saba Co.: female holotype (USNM 112358) and 5 female paratypes 

 (JRH), K. Garrett and D. McKenzie, Feb. 7, 1964. 



Diagnosis. — A somewhat abberant species apparently most closely 

 allied to the tenuis group and distinguished by the oblique and straight 

 propod palmar margins of gnathopod 1, relatively longer pereopod 5 

 which is about 75 percent as long as pereopod 7, and generally more 

 slender segments of pereopods 5, 6, and 7. Further distinguished from 

 other Texas species of the tenuis group by consistently (?) having 3 

 apical spines on uropod 3 and a few more apical spines on the telson. 

 Known only from 5 females, the largest of which is 13.50 mm long. 



