36 U-S. NATIONAL MUSEUM BULLETIN 25 9 



this pool might be flooded during periods of extremely high water, 

 it otherwise appears to be fed by seepage. In the lower level stream, 

 four small females of S. allegheniensis were also collected on the same 

 day. 



Distribution and ecology. — This species may be expected to 

 occiu" elsewhere in subterranean waters of the Nittany Valley area of 

 central Pennsylvania, but to date it is known only from the type 

 locality where it is apparently rare. S. stellmacki occurs 65 miles 

 further north than any other species in the emarginatus group. 



Remarks. — It is unfortunate that only one specimen of this rather 

 unique species is so far available, and until more material is collected 

 it will remain uncertain whether the absence of the first uropodal 

 peduncular process is an evolutionary loss or is only aberrantly 

 missing from this single male. S. stellmacki is further significant 

 because, while it appears allied rather closely to other species in the 

 emarginatus group, it is the only species of this group with setae on 

 the posterior margin of the first gnathopodal propod and with rastellate 

 setae on the gnathopods. 



Dearolf's record for ^S'. clantoni from Penns Cave, Centre Co., Pa. 

 (Dearolf, 1941) could have easUy been S. stellmacki, since super- 

 ficially these two species might be mistaken for each other. Penns 

 Cave is only 23 miles northeast of Millers Cave and falls within the 

 theoretical subterranean dispersal limits of S. stellmacki. 



It is a real pleasure to name this new species for Mr. John Stellmack, 

 a well-known Pennsylvania speleologist, who first called my attention 

 to the type locality as a potential "amphipod cave" and who later 

 materially assisted in collecting this unique animal. 



gracilipes Subgroup 



Diagnosis. — Posterior angle of 1st gnathopodal propod with 4 

 to 6 large, unequal spines on outside. Bases of pereopods 5-7 sub- 

 triangular, broader proximaUy than distally; distoposterior lobes 

 poorly developed. Telson longer than broad, gently tapering distally; 

 apical margin entire; armed with at least 4 sets of lateral spines and 

 up to 13 apical spines. 



Stygonectes gracilipes, new species 



Figure 7 



Synpleonia pizzinii Shoemaker — Hubricht, 1943, p. 709 (in part). — Holsinger, 

 1963, p. 29 (in part); 1964, p. 62 (in part). 



Material examined 



VIRGINIA. — Warren Co.: Skyline Caverns, male holotype, female allotype, 6 

 male and 14 female paratypes, J. Fowler, Jan. 12, 1941 (USNM). Additional 



