SUBTERRANEAN AMPHIPOD STYGONECTES 5 



while species in the latter (referring here specifically to S. flagellatus) 

 had simple lateral sternal gills. 



Dearolf (1937, 1941, 1948, 1953) pubhshed a number of new locality- 

 records for stygonectid amphipods, but unfortunately many of these 

 (especially records for S. clantoni from Pennsylvania caves) were 

 apparently based on erroneous determinations and have added httle 

 to the knowledge on species distribution in this group. Hubricht 

 and Mackin (1940) added Sijnpleonia hayi to the hst of stygonectid 

 amphipods, and in the same paper they placed S. americana in the 

 synonymy of S. clantoni. Mackin (1941), apparently still regarding 

 S. americana as a synonym of S. clantoni, included only the latter in 

 a key to the Amphipoda of Oklahoma. A year later, Shoemaker 

 (1942a), in a rather comprehensive paper on subterranean amphipods, 

 added figures and some new locahty records for S. pizzinii. Hubricht 

 (1943) recognized that S. clantoni and S. americana were in fact 

 distinct forms and resurrected the latter from its short sojourn in 

 synonymy. In the same account, Hubricht, apparently following 

 Shoemaker's earher reason for keeping Stygonectes and Synpleonia 

 apart as separate genera, described two new stygonectids, assigning 

 one {halconis) to the former genus and the other (emarginatus) to the 

 latter. 



Pennak (1953), in his compendium, "Fresh-Water Invertebrates 

 of the United States," gave a few notes on both Stygonectes and 

 Synpleonia and astutely observed that both of these genera (along 

 with Apocrangonyx and Stygobromus) were poorly defined and should 

 be studied further to determine whether or not their generic dif- 

 ferences were real. The amphipod section by Hubricht (1959) in 

 the revised edition of "Freshwater Biology" included ranges for 

 eight stygonectid species (two in Stygonectes and six in Synpleonia), 

 and in the same paper S. hayi was synonymized (incorrectly, in the 

 writer's opinion) with S. tenuis. 



No new species were added to either Stygonectes or Synpleonia 

 between 1943 and 1966, although a number of papers dealing with 

 cave fauna in general included data on the distribution of a number 

 of the previously described species (see Holsinger, 1963, 1964; Nicholas, 

 1960; Reddell, 1965). 



Next to the most recent paper on stygonectids is that of Holsinger 

 (1966), which treats five species of Stygonectes from Texas (three of 

 which are newly described) and presents reasons for sjmonymizing 

 Synpleonia with Stygonectes. The present account treats 29 species 

 and 2 subspecies of Stygonectes, 20 of which (including 2 subspecies) 

 are newly described and 5 of which are completely redescribed. 



