SUBTERRANEAN AJVIPHIPOD STYGONECTES 123 



of pereopods 5-7, structure of abdominal side plates, and structure of 

 telson. 



Distribution and ecology. — The hadenoecus group is presently- 

 known only on the basis of a single, rather unique species, S. haden- 

 oecus, which has not been found outside of its type locality in Edwards 

 Co., Tex. 



Stygonectes hadenoecus Holsinger 



Stygonectes species. — Reddell, 1965, p. 160 (in part). 



Stygonectes hadenoecus Holsinger, 1966, pp. 111-113, figs. 43-63 [Type locality: 

 Devils Sinkhole, Edwards Co., Tex.]. 



Material examined 



TEXAS.— Edwards Co.: Devils Sinkhole Cave, female holotype (USNM 112359), 

 8 female and 1 male paratypes, R. Norton, June 15, 1964; male allotype (USNM 

 112360), 5 female and 1 male paratypes, J. Reddell and J. Porter, Oct. 26, 1963 

 (JRH). 



Diagnosis. — Medium-sized troglobitic species distinguished by 

 strongly convex gnathopodal palmar margins, large coxal plate of 

 pereopod 4, broadly expanded bases of pereopods 5-7, produced 

 posterior margins of abdominal side plates, and by a shallow, apical 

 excavation often present in the female telson. Largest male, 9.75 mm ; 

 largest females, 11.25 mm. 



Corresponding to the recent description by Holsinger (1966) with 

 the f ollomng additions and modifications : 



Antenna 1 of female up to 55 or 60 percent as long as body, about 

 50 to 55 percent longer than antenna 2. Antenna 1 of male 60 to 75 

 percent as long as body, about 50 to 60 percent longer than antenna 2. 

 Mandible well developed; palpal segment 3 ^^dth 10 to 12 long setae, 

 segment 2 ^^^th 10 to 13 setae. Maxilla 1, inner plate with. 6 or 7 

 apical, plumose setae. Maxilla 2, inner plate with 5 to 9 long, 

 obliquely placed, plumose setae. Maxilliped, inner plate with 4 to 6 

 thick, apical spines. Lower lip, inner lobes moderately broad. 

 Pereopod 7 between 50 and 60 percent as long as body, slightly longer 

 than pereopod 6 and 20 to 30 percent longer than pereopod 5. Median 

 sternal and pleonite sternal gills absent. Abdominal side plates: 

 posterior margins somewhat produced posteriorly, with 5, 7, and 3 or 

 4 setae, respectively; posterior corners of plates 1 and 2 slightly re- 

 cessed and possessing 1 seta each, that of plate 3 distinct and without 

 a seta. Pleopod 1, inner ramus 20 to 30 percent longer than peduncle. 



Remarks. — For a description of the type locality and general 

 remarks on ecology see Holsinger (1966). 



242-803—67- 



