Remarks.—Some individuals of guadalupensis have characteristics that are applicable to emoryi. TNHC 12352 (Llano River) a hatchling, has conspicuous white dots confined to the posterior third of the carapace; the pale rim, however, is not widened posteriorly. TU 10156 (Guadalupe River) has a conspicuously widened pale rim on the carapace that is approximately 3.4 times wider posteriorly (8.5 mm.) than laterally (2.5 mm.).
T. s. guadalupensis more closely resembles pallidus than emoryi. Turtles living in rivers that drain into the Gulf of Mexico east of the Guadalupe-San Antonio river system successively show increasing resemblance to pallidus from west to east.
The expression of intergradation between guadalupensis and pallidus is of a clinal nature that involves parallel changes in the pattern on the snout, [521] side of head, limbs (to a lesser degree), tuberculation along the anterior edge of the carapace, size of whitish tubercles or dots, and the distinctness of the blackish ocelli that surround the whitish dots on the carapace. These characters form a well-marked gradation or cline that extends over a considerable area. There is, however, no continuous environmental gradient because the populations are relatively isolated by occupying adjacent drainage systems. The sharpest break in the gradation of characters mentioned above occurs between the Colorado River and Brazos River drainages. The population of softshells in the Colorado River drainage is actually an intergradient one, but more closely resembles guadalupensis, whereas the population in the Brazos River drainage more closely resembles pallidus. For convenience the turtles inhabiting the Colorado River drainage are referred to guadalupensis and those in the Brazos River drainage to pallidus. Some individuals from farther west than the Colorado River drainage will resemble pallidus, and a few individuals from father east than the Brazos River drainage will resemble guadalupensis.
The gradation of some of the characters mentioned above terminates in the subspecies emoryi. It, however, has characters not found in pallidus or guadalupensis, and is more distinct from either of those subspecies than either is from each other; the difference in characters as well as the break in the gradient of characters between guadalupensis in the Nueces River drainage and emoryi in the Río Grande drainage is greater than that between guadalupensis in the Colorado and pallidus in the Brazos River drainages.
I have refrained from designating individuals between these three subspecies (emoryi, guadalupensis and pallidus) as "intergrades" on the distribution maps, and only mention (in text) those individuals whose characters show a decided tendency toward the adjacent subspecies. For further comments on intergradation see the account of T. s. pallidus.
Specimens examined.—Total 97, as follows: Texas: Bandera: KU 50834, Hondo Creek, 4 mi. W Bandera; TNHC 797-98, 7 mi. SW Medina. Bexar: ANSP 13447, Helotes; MCZ 4587; USNM 10789, 71009, San Antonio. Borden: BCB 4066, 7 mi. N Vincent. Brown: TNHC 7262, 1 mi. E Brownwood. Comal: USNM 7700, New Braunfels. Dawson: TNHC 21594-95, 10 mi. E Lamesa. Frio: USNM 7747, Río Seco. Gillespie: TU 10185, 10187, 10205, Beaver Creek, "near" Doss. Hays: AMNH 29950-52, San Marcos. Kerr: SM 2553, headwaters Turtle Creek; TU 10142-45, 10147-65, 10176, 10833, Guadalupe River, 9 mi. SE Kerrville. Kimble: BCB 5052-55, 6010, 3 mi. SE Telegraph; TU 14476, South Fork Llano River, 1.5 mi. SE Telegraph; TU 14485, Llano River, 10 mi. W Junction. Lavaca: SM 2554-55, 2559, 3 mi. NNE Hope. Llano: TNHC 12352, TU 16036 (2), Llano River, 2 mi. W Llano. McMullen: TNHC 1446, 10 mi. W Simmons, Live Oak County; UMMZ 89915-27, 15 mi. NE Tilden. Matagorda: ANSP 11889, Matagorda. San Saba: SM 6106; TU 14419 (6), 14439-40, San Saba River, 11 mi. NNW San Saba. Tom Green: SM 3282, UMMZ 70348, USNM 83690, South Concho River at Christoval. Travis: SM 659-60, 8.5 mi. from mouth of Onion Creek in Colorado River near Austin; SM 4924, Onion Creek; TNHC 4975, Upper Bull Creek; TNHC 20257, Marshall Ford Dam. Victoria: CM 3118, Black Bayou; UMMZ 92752, San Antonio River, 3 mi. WSW Goliad; USNM 78515-17, Colleto Creek, Guadalupe River. County unknown: ANSP 16717; TNHC 1404.
Records in the literature.—Texas: Bandera: 24 mi. WNW Medina (Brown, 1950:250). Burnet: Colorado River (Strecker, 1909:8). Gillespie: 20 mi. N Harper (Brown, loc. cit.). Kendall: Cibolo Creek at Boerne (Strecker, 1926:8). Kerr: Guadalupe River, 3 mi. above Kerrville (TCWC 474, listed in card file). Mason: 12 mi. NE Mason (TCWC 3303, listed in card file). [522] Matagorda: Bay City (Brown, loc. cit.). Real: (Stejneger, 1944:66). Wilson: Cibolo River, 30 or 40 mi. N Sutherland Springs (Strecker, 1935:23).
Trionyx spinifer pallidus new subspecies
Pallid Spiny Softshell
Holotype.—TU 484, alcoholic adult male; obtained from Lake Caddo, Caddo Parish, Louisiana on June 27, 1947, by Fred R. Cagle and party ([Pl. 39], lower, left).