no. 3646 DINEUTUS* — WOOD 5 



The range then drops south along the Tennessee River and into 

 Colbert County, Ala., where the Tennessee River Valley is a finger 

 projecting eastward into northern Alabama. In southern Alabama 

 and western Florida the range is narrowed to a width of about 125 

 miles by the Appalachian Mountains. Here, in this restricted area, 

 occur intermediates in which the color of the venter changes from 

 dark to light. Half of the specimens in series from Santa Rosa County, 

 Fla., and from Houston County, Ala., have characteristic piceous 

 venters (fig. 5). Along the Chattahoochee River in Alabama, specimens 

 with light castaneous venters appear, but west of that area, in the 

 same county (Houston), specimens are taken with piceous venters. 

 In the finger of the Chattahoochee projecting north along the Alabama- 

 Georgia border, specimens from Lee County, Ala., have light cas- 

 taneous abdominal sterna. 



Specimens from Houston County, Ala., collected by Mr. George 

 Folkerts of Auburn University, suggest distribution patterns worthy of 

 special note. These specimens are from two localities in Houston 

 County. One site is the Chattahoochee State Park in the very south- 

 eastern corner of the county, where D. s. serrulatus was collected. 

 The other is Bazemore Grocery, the location of a small spring from 

 which D. s. analis was taken. This location is only 10-12 miles west 

 of Chattahoochee State Park in the south-central part of the county. 



The Bazemore Grocery spring flows into Cowarts Creek, a small 

 tributary of the Chipola River, which merges with the Apalachicola 

 River in Florida. Small streams in the Chattahoochee State Park 

 from which D. s. serrulatus was collected drain into the Chattahoochee 

 River, which in turn meets the Apalachicola River at the southwestern 

 corner of Georgia. 



During the Pleistocene, the Chipola River formed a distinct, sep- 

 arate drainage that flowed into the Gulf of Mexico. This situation 

 precluded any fresh water connection with the Apalachicola River 

 (Folkerts, 1966, in litt.) and may well have produced isolation 

 that resulted in subspeciation. Young (1954, pp. 25-27) has discussed 

 this area, its various plant refuges, and other instances of isolation. 



Two collections of D. serrulatus lie outside the projected range of 

 this species — one female of D. s. analis from El Paso, Tex. "AMNH 

 Ace. 4858," and two males of D. s. serrulatus from Medora, Reno 

 County, Kans. The latter most likely are mislabeled. 



The boundary of D. s. serrulatus extends from Santa Rosa County, 

 Fla., and Houston County, Ala., north to Lee Count}^, Ala., eastward 

 to Bibb County, Ga., and northeast to Baldwin County, Ga., where 

 forms with slightly darker venters occur. The northern limit of the 

 range of D. s. serrulatus is Richmond County, Ga. It then extends 



277-S99— 6S 2 



