The range of T. s. asper overlaps that of T. ferox in Georgia and South Carolina. The two species remain distinct in the area of overlap of their geographic ranges (Crenshaw and Hopkins, 1955:16; Schwartz, op. cit.:5). Trionyx s. asper intergrades with T. s. hartwegi and T. s. spinifer in the lower Mississippi Valley (Conant and Goin, 1948:11).
However, there are few specimens available that indicate intergradation of asper with the spinifer-hartwegi complex in the lower Mississippi River drainage; this may be due to the fact that asper inhabits waterways that do not drain into the Mississippi River. Perhaps intergradation is more prevalent than the morphological basis that I have relied upon indicates; in any event, there are few specimens that have more than one dark marginal line (which is the only character that is unique for asper) from the lower Mississippi drainage. A young male (TU 11928.9) from Bayou Gauche between Paradis and Des Allemands, St. Charles Parish, Louisiana, has a pattern on the carapace resembling that of asper; several other small softshells (TU) are available from the same locality but none shows more than one dark marginal line. Another specimen (USNM 95192), a young female from a barrow pit of the Big Black River (Mississippi River drainage), Madison County, Mississippi, resembles asper in having more than one marginal ring. Of three large females from Moon Lake, an ox-bow of the Mississippi River in Coatopa County, Mississippi (AMNH 5285-86, 5289), only 5289 shows evidence of two marginal lines. USNM 73669 (Greenwood, LeFlore County, Mississippi) also indicates intergradation in that the spots tend to be linear just inside the dark marginal [508] line, but the specimen more closely resembles the hartwegi-spinifer complex rather than asper.
There seems to be little adumbration of the dark marginal lines of asper in populations from the lower Mississippi River drainage. Blackish spots and ocelli vary in size and there are many kinds of pattern on the carapace. Soft-shelled turtles inhabiting the Mississippi River and its tributaries in Louisiana and Mississippi certainly represent an intergrading population of spinifer and hartwegi, and, to a lesser extent, of asper. Soft-shelled turtles inhabiting the Pearl River drainage and rivers that drain into Lake Pontchartrain immediately adjacent to the east are predominantly asper.
Specimens having localities from the Pearl River and Lake Pontchartrain drainages are listed under the account of asper and are referred to that subspecies on the distribution map; specimens from the Mississippi drainage in Mississippi are referred to spinifer.
One specimen (UMMZ 59198, Bradley County, Tennessee), from the Tennessee River drainage where T. s. spinifer occurs, deviates markedly from spinifer and suggests intergradation. UMMZ 59198, plastral length 4.8 centimeters, has ocelli in the center of the carapace only two millimeters in diameter, a distinct but interrupted, second marginal ring consisting of spots, and the pale postlabial and postocular stripes in contact on both sides of the head.
Specimens examined.—Total 110, as follows: Alabama: Barbour: UMMZ 113038, Chattahoochee River, Eufala. Cherokee: ANSP 24592, "near" center of Terrapin Creek. Conecuh: UMMZ 70736, Murder Creek, Castleberry. Escambia: TU 15823, Escambia River, 1 mi. N Sardine; UMMZ 70734, Escambia River at Flomaton. Henry: TU 15630, 3 mi. NW jct. Echo Farm Rd. and Rt. 136 on Echo Farm Rd. Lowndes: UMMZ 67759, Pintlalla Creek. Mobile: MCZ 1608 (2), 1608A, Mobile. Sumpter: USNM 83996, 3 mi. SE Coatopa. Tuscaloosa: TU 14673 (5), Black Warrior River, 17.5 mi. SSW Tuscaloosa; UA 52-1085, Cottondale. Walker: KU 50843, 50851, TU 17137, Mulberry Fork, Black Warrior River, 9 mi. E Jasper.
Florida: Calhoun: KU 50837-38, Chipola River, 4 mi. N Scott's Ferry; TU 16689 (4), Chipola River "near" Blountstown. Escambia: TU 13474, 15869 (3), 16584, Escambia River, 1.2 mi. E Century. Okaloosa: TU 15661, Blackwater River, 4.3 mi. NW Baker on Route 4. Santa Rosa: AMNH 44621, Blackwater River, Milton. Walton: UMMZ 110421, Pond Creek, 4 mi. SW Florala, Covington County, Alabama.
Georgia: Baker: TU 15889 (3), USNM 134243-48, Flint River "near" Newton; USNM 30822. Baldwin: USNM 8708, Milledgeville. Bryan: TU 15090, Canouche River, 2.3 mi. W Groveland. Chatham: USNM 51981, 92583-84, Savannah. Chattooga: UMMZ 113037, tributary of Chattooga River, Lyerly. Decatur: KU 50839-42, Flint River, 1.5 mi. S Bainbridge. Fulton: UMMZ 53037, Roswell. Lincoln: USNM 91282-83, above Price Island, Savannah River. Murray: UMMZ 59196, 9 mi. N Spring Place. Pulaski: TU 14882, Ocmulgee River, 4.3 mi. SE Hawkinsville. Richmond: USNM 66859, Augusta. Whitfield: UMMZ 74209, Cohulla Creek, Prater's Mill "near" Dalton. County unknown: MCZ 37172; UMMZ 109864, Flint River at mouth of Dry Creek; USNM 029034.
Louisiana: East Baton Rouge: LSU 11, 1643-44, City Park Lake in Baton Rouge; TU 17237, Amite River "near" Baton Rouge. St. Tammany: TU 6356, headwater creek of Bayou Lacombe; TU 16071, USNM 66147, mouth of Tchefuncta Creek in Lake Pontchartrain. Tangipahoa: TU 13623, 3.1 mi. W Hammond; USNM 68054, Robert. Washington: KU 50840, 50846, TU 17117, Pearl River at Varnado. Parish unknown (East Baton Rouge or Tangipahoa): UMMZ 95614, Manchac.