110 U.S. NATIONAL MUSEUM BULLETIN 2 59 



cording to Bretz (1956), it also contains an extensive stream system 

 and is one of the deepest caves in the state. 



Distribution and ecology. — This species is known only from 

 three caves and one seep, all of which are located in the southwestern 

 part of the Ozark Plateau region. The linear extent of the known 

 range (Marvel Cave southwestward across Arkansas to Mayes Co., 

 Okla.) is approximately 110 miles and covers an area underlain almost 

 exclusively by cavernous, Mississippian limestones of the Boone for- 

 mation. The range crosses a maj or drainage divide between the White 

 River to the northeast and the Arkansas River to the southwest. 

 Specimens taken from Hensons and Danfords Caves were in small 

 streams and stream pools distant from the entrance. The collection 

 made by Hubricht from a seep south of Locust Grove in Oklahoma 

 Mas probably from one of several ground-v\'ater exits A\'hich character- 

 istically open along stream-cut ravines in this area. Hubricht's 

 collection from eastern Oklahoma also contained 16 specimens (8 

 females and 8 juveniles) of a significantly smaller species, S. bowmani, 

 described below. 



None of the females of S. ozarkensis collected to date have been 

 ovigerous or had esi)ecially well-developed brood plates; thus, virtually 

 nothing is known about the biology of this species. 



Remarks. — A number of records previously cited for S. clantoni 

 actually belong to S. ozarkensis. At least three and possibly four of 

 the five localities listed as records for S. clantoni (viz., Smallins Cave, 

 Christian Co., Pine Creek or Pine Run Cave, and Marvel Cave, 

 Stone Co., Mo.; and Watsons Cave, Ark.) by Dearolf (1953) fall within 

 the range limits of S. ozarkensis and well south of the known range 

 limits of S. clantoni. I have examined one of the two collections made 

 from Marvel Cave bj^ Dearolf and have designated this material as a 

 part of the type series of S. ozarkensis (see above). Unfortunately, 

 Dearolf's other Missouri cave collections were not available for this 

 study. Watsons Cave could not be specifically pinpointed but is pre- 

 sumably located in the northwestern part of Arkansas, and if so, it 

 falls within the presently circumscribed range of S. ozarkensis. 



Stygonectes bowmani, new species 



Figure 27 



Synpleonia clantoni Creaser. — Hubricht, 1943, p. 711 (in part). 



Material examined 



OKLAHOMA. — Mayes Co.: seep at girl scout camp, 3.2 miles S of Locust Grove, 

 female holotype, 6 female and 9 juvenile paratypes, L. Hubricht, May 22, 1940 

 (USNM and slide mount of 1 paratype in JRH). 



Diagnosis. — Small subterranean species readily distinguished by 

 the proportionately short 7th pereopod, which is only about 80 per- 



