106 U.S. NATIONAL MUSEUM BULLETIN 259 



Type locality. — A well on the Clanton Farm, 4 miles southeast of 

 Ottawa, Franklm Co., Ivans. The vicinity of the type locality is 

 underlain by Pennsylvanian limestones of the Lansing group. Accord- 

 ing to Creaser (1934), attempts to collect this species subsequent to 

 its original discovery were unsuccessful. 



Distribution and ecology. — This species is known from only six 

 localities which constitute a broken range extending for approximately 

 250 miles as an arch from Butler County in south-central Kansas 

 northeastward to Franklin Co., Kans., and Cass Co., Mo., and then 

 southeastward to Camden Co., Mo. Populations may be expected 

 along the 100 mile gap between Butler County and Franklin County 

 and between Cass County and Camden County, but none have been 

 discovered to date. Most of the collections of this species have been 

 from wells (of unknown depth) situated in upper Paleozoic sedimentary 

 rocks which make up the northern Osage Plain section of the Central 

 Lowland Province. A large percent of the range of this species covers 

 an area apparently rich in Imiestone deposits but rather poor in cave 

 formation. The Camden County record is an exception, however, 

 being a cave developed in lower Paleozoic limestone of the cavernous 

 Hahatonka area of the northwestern Ozark Plateau region. In the 

 vicinity of Butler Co., Kans., the ground-water table appears to be 

 relatively close to the surface, and at Purity Springs S. clantoni was 

 taken in relative abundance from the covered exit basin of a small 

 spring where it was associated with subterranean isopods {Asellus 

 species) and flatworms (Sphallojilana kansensis Flyman). 



Remarks. — It has been necessary to completely redescribe this 

 species, focusing attention on several diagnostic characters which were 

 omitted in the original description by Creaser (1934). 



Dearolf's references to S. clantoni (Dearolf, 1937, 1941, 1948, 1953) 

 from Pennsylvania and elsewhere are undoubtedly based on erroneous 

 determinations and possibly involve as many as four distinct species 

 of Stygonectes. With the possible exception of southern Missouri, all 

 of Dearolf's records fall far out of the presently known range of S'. 

 clantoni. Hubricht and Mackin's earlier locality records for S^jn- 

 pleonia clantoni (Hubricht and Mackin, 1940) were later referred to 

 Synpleonia americana (= Stygonectes alabamensis as presently under- 

 stood) by Hubricht (1943). 



The range given for S. clantoni by Mackin (1941) is generally south 

 of the presently circumscribed range of this species, and more pre- 

 cisely includes the area inhabited by S. alabamensis and several other 

 species of the tenuis group. The material from a seep (2.3 miles 

 South of Bronson) in Bourbon Co., Kans., listed by Hubricht (1943) 

 as a locality for S. clantoni, was examined and found to belong to the 

 genus Bactrurus. 



