SUBTERRANEAN AMPHIPOD STYGONECTES 81 



distinct enough to be considered a subspecies of S. alabamensis as 

 indicated herein. Collections reported from Adair Co. (spring 5 miles 

 S of Kansas, Okla.) and Mayes Co. (spring creek at Locust Grove), 

 Okla., were not available for this investigation, but both localities fall 

 within the western range of S. a. alabamensis. 



Stygonectes alabamensis occidentalism new subspecies 



Synpleonia dantoni Creaser.— Hubricht and Mackin, 1940, p. 206 (in part). — 



Mackin, 1941, p. 30 (in part). 

 Synpleonia americana (Mackin). — Hubricht, 1959, p. 878 (in part). — Nicholas, 



1960, p. 129 (in part). 

 Stygonectes americanus (Mackin). — Ilolsinger, 1966, pp. 120-122 (in part). 



Material examined 

 OKLAHOMA. — Pontotoc Co.: seeps, 2.3 miles S of Fittstown, male holotype, female 

 allotype, 141 paratypes, L. Hubricht and J. G. Mackin, May 22, 1940 (USNM 

 and slide mounts of 2 paratypes in JRH). Additional material as follows: 

 OKLAHOMA. — Pontotoc Co.'. Springs issuing from Franks Fault on tributary to 

 Sheep Creek, May 1936 (USNM); Tulsa Co.: seep at "Lost City," 1 mile S of 

 Sand Springs, collector and date not indicated (USNM). Texas. — Dallas Co.: 

 seeps. Turtle Ci'eek, L. Hubricht, Feb. 1.5, 1949 (LH). Louisiana. — Union Co.: 

 well at Farmerville, D. Haberyan, no date on label (USNM). 



Diagnosis.— Differmg from S. a. alabamensis in the absence of 

 median and pleonite sternal gills and 7th pereopod coxal gills in both 

 sexes. Largest males, 10.00 mm; largest females, 9.00 mm. 



Type locality. — Seeps, 2.3 miles south of Fittstown, Pontotoc Co., 

 Okla. The type locality is situated in Paleozoic sedimentary rock on 

 the northeastern side of the Arbuckle Mountains. This locality was 

 not visited specifically during field work in June 1964, but several 

 springs were checked in the same general vicinity. 



Distribution and ecology. — S. a. occidentalis occurs in interstitial 

 ground-water habitats of the Osage Plains and ranges from Tulsa Co., 

 Okla., southward through the Arbuckle Mountains of central Okla- 

 homa to Dallas Co., Tex., and possibly southeastward to Union Co. 

 in northern Louisiana. 



Four ovigerous females (size range=6.00 to 7.50 mm) were noted in 

 the May collection from the type locahty. The average number of 

 eggs per brood pouch was four (range, 3 to 6) . 



Remarks. — The absence of the indicated gill structures is consistent 

 in all populations within the presently circumscribed range of this 

 subspecies. The single female from Farmerville, Louisiana, is larger 

 (13.00 mm) than any other female examined in either subspecies of S. 

 alabamensis but otherwise fits the diagnosis for S. a. occidentalis. I 

 have not made it a paratype, however, and am only tentatively 

 assigning it to this subspecies. Additional material must be obtained 

 from northern Louisiana and closely examined before the exact 

 taxonomic status of populations in this area can be fully ascertained. 



