T. s. hartwegi differs from the subspecies asper, guadalupensis and emoryi in having a narrower head, and from emoryi in having a wider carapace. T. s. hartwegi resembles spinifer and asper but differs from the other subspecies in having the carapace widest at a plane approximately one-half way back on the carapace. T. s. hartwegi and spinifer have longer snouts than do pallidus and guadalupensis or emoryi. T. s. hartwegi differs from asper but resembles the other subspecies in having a relatively longer plastron.
Remarks.—The validity of T. s. hartwegi has never been questioned. It intergrades with spinifer over a broad area paralleling the Mississippi River. For convenience, specimens occurring west of the Mississippi River are referred to the subspecies hartwegi. [Figure 8] shows much variation in size of ocelli on different individuals from the same state. For example, UMMZ 92667, plastral length 6.7 centimeters has a uniform pale brown carapace lacking any dark marks, whereas UMMZ 92652, plastral length 5.9 centimeters has some ocelli three millimeters in diameter on the carapace. Both are from Iowa. One specimen from Kansas, KU 1954 (Doniphan County, plastral length 11.8 cm.), has ocelli four millimeters in diameter, and USNM 7648 captured farther west at Fort Laramie, Wyoming, an adult male having a plastral length of 11.0 centimeters, has some ocelli five millimeters in diameter on the carapace. TTC 1090, an adult male from the panhandle of Texas has some ocelli so much as 5.5 millimeters in diameter. The size of the ocelli seemingly varies in the same local population.
Specimens of T. spinifer in the lower Mississippi Valley are intergrades. Most individuals have small black dots on the carapace; some have small ocelli (TU 7216, 7501, 11912, 12123-24) interspersed with black dots (TU 5863), others have black dots confined to the edge of the carapace (TU 157, 4539, 7105), and still others have no pattern on the carapace (TU 7506, 13698.1, 10087.6). Two large males (TU 11580, 13025) have large ocelli (approximately five mm. in diameter) that have nearly black centers. In general, there is more dark pigmentation than farther north; some specimens have extensive pigmentation on the ventral surface of the carapace and soft parts of the body (TU 156, 5648). The dorsal surface of the limbs, especially the hind limbs, have a bold, black marbling and may be almost completely black (TU 5484, 5597). Many females, not exceeding plastral lengths of 7.0 centimeters, have a pale blotched pattern of lichenlike figures or have ill-defined black dots on the carapace (TU 10087, 13698.13, 13753.15).
Localities of specimens of T. spinifer occurring in the Mississippi River drainage in Mississippi are arbitrarily listed under the account of the subspecies spinifer, whereas those in Louisiana (excluding pallidus) are listed under the account of hartwegi.
Neither Over (1943) nor Wheeler (1947:169) record T. s. hartwegi, respectively, from South Dakota or North Dakota; records from the Missouri River drainage in Montana suggest the occurrence of the species in that drainage in North and South Dakota.
Specimens examined.—Total, 392 as follows: Arkansas: Clay: UMMZ 70735 (2), 7 mi. S St. Francis. Crawford: USNM 95352, Lee Creek, 7 mi. NW Natural Dam. Drew: CNHM 40785. Lafayette: KU 2225-29, 2944 (one of three specimens bearing last catalog number), 2963 (one of three specimens bearing this catalog number), 2964 (one of two specimens bearing this catalog number), Lewisville (see remarks under the account of the [500] subspecies pallidus). Lawrence: CNHM 8949; CNHM 12598-600, 12602-04, TU 5855, UI 2413, Imboden; UI 2412, Black River at Powhatan. Marion: TU 14591 (6), White River at Cotter. Prairie: KU 1867, 1869, 1879, 1949-51, 2280-83, 2285-91 (2 specimens bear catalog number 2287), 2307, 2761-62, 2666, 2826, 2842, 3346-47, White River at DeValls Bluff. Pulaski: UMMZ 96540, Little Rock. Saline: USNM 17823, Saline River at Benton. Searcy: UMMZ 92755, Little Red River, 1.5 mi. SE Leslie. Yell: TU 14565, Petit Jean Creek, 10 mi. N Casa. County unknown: CNHM 28566-67, Ouachita River.
Iowa: Allamakee: UMMZ 72556-58, 92642-49, Mississippi River "near" Lansing. Appanoose: UMMZ 92667, Chariton River, 4.3 mi. N. Centerville. Decatur: UMMZ 92651, Grand River, 3.5 mi. WSW Decatur. Dickinson: UMMZ 55249, Milford; UMMZ 92655, Spirit Lake Twp. Hamilton: USNM 9928, Webster City. Hardin: UMMZ 92650, Eldora. Louisa: UMMZ 92654, Muscatine Slough, 12 mi. SW Muscatine, Muscatine County. Muscatine: INHS 7675, 5.5 mi. SE Muscatine; USNM 54730-32, Fairport. Scott: CNHM 433, Davenport; UMMZ 92656, Steamboat Slough, 2 mi. N Princeton. Story: UMMZ 92653, Squaw Creek at Ames. Washington: UMMZ 92652, English River, 2 mi. E Riverside.
Kansas: Anderson: KU 52286-87, 31/4 mi. E, 1/2 mi. N Colony. Atchison: UMMZ 66939-41, Atchison. Barber: KU 17728, 4.5 mi. S Sun City; KU 41379, 41742, 6 mi. N, 3.5 mi. E Sharon; USNM 100580, Medicine River, 1 mi. S Lake City. Cherokee: KU 1323, Galena. Comanche: KU 18385, 3-4 mi. SE Arrington. Cowley: UMMZ 75963, USNM 90441-44, 91022, 100529-30, "near" Winfield. Doniphan: KU 1943, 1952-54, Doniphan Lake. Douglas: KU 1955-56, Wakarusa River; KU 40176-77, Kansas River at Lawrence. Franklin: KU 3290. Hamilton: KU 2990, Syracuse. Harper: KU 18159, 1 mi. N Harper. Kingman: USNM 95261, 2 mi. E Calista. Labette: KU 3339. Lane: KU 3738-41, Pendennis. Logan: KU 16531, Smoky Hill River, 3 mi. SW Elkader. Meade: KU 40210, Crooked Creek, 12.5 mi. S, 11/4 mi. W Meade. Montgomery: KU 3731-32, Independence; KU 50856, Cherryvale Lake. Neosho: UMMZ 69294, Caneville Creek, 32 mi. N. Parsons, Labette County. Osage: KU 3294-96, Appanoose Creek. Pratt: KU 15931-32, 15934, State Fish Hatchery "near" Pratt. Riley: KU 48239, McDowell Creek, WSW Manhattan; UMMZ 64434, "near" Manhattan. Russell: KU 3289. Sedgwick: UMMZ 95363-65, Wichita. Shawnee: USNM 123446, Kansas River at Topeka. Stafford: KU 3758, Little Salt Marsh; KU 41743, 13.5 mi. N, 6 mi. E Stafford. Trego: KU 2757, 3769, Smoky Hill River, 10 mi. N (NNE) Utica, Ness County; KU 51517, Saline River, 5 mi. N, 1/2 mi. E Wakeeney. Wilson: KU 56744-45, Verdigris River, 1 mi. S Altoona. Woodson: KU 55295, Neosho River, 1/2 mi. E, 11/2 mi. S Neosho Falls. County unknown: USNM 51529.
Louisiana: Catahoula: TU 12629, Ouachita River, 4 mi. N Harrisonburg. Claiborne: TU 13080, Caney Lake "near" Summerfield. Concordia: KU 50849, Tensas River at Clayton; TU 16524 (3), USNM 012349, Lake Concordia; USNM 99865, Red River "near" Shaw. East Carrol: TU 827-30, 905, 5644-45, Lake Providence. Grant: TU 12735, Big Creek at Fishville, "near" Pollock. Jefferson: TU 5592-98, 7184, 10741, 10171, Mahogany Pond. Lafourche: TU 7105, 7132, 7216, 7501, 7505-07, 10087 (14), 11828-29, 11912, 11983 (2), 12123-28, 13502, 13679 (8), 13753 (22), 13766.2, Bayou Lafourche at Raceland. Morehouse: USNM 11631 (2), Mer Rouge. Natchitoches: USNM 100420, Cane River "near" Natchitoches. Orleans: TU 16169 (3), Audubon Park, New Orleans; USNM 029310, "near" New Orleans. Ouachita: TU 12916, 12954, 12970-71, 13019, 13025, Bartholomew Bayou at Sterlington; TU 5988, Monroe. Pointe Coupee: TU 153, 156-59, 165, 5484, 5513, 5518-19, 5646, 5648, 5651, USNM 100202-12, False River at New Roads. Rapides: TU 14040, Red River at Rapides. Richland: OU 25082. St. Bernard: TU 16170, Delacroix Island. St. Charles: TU 4539, 4579, 5224, 5990, 11928 (12), 13698 (16), Bayou Gauche between Paradis and Des Allemands; TU 5863, 11580, Bonnet Carre Spillway at Norco. Tensas: TU 5762, Lake St. Joseph near Newellton. Union: USNM 138946, Meridian Creek, 1 mi. E Conway; USNM 138947, Ouachita River, Alabama Landing. Parish unknown: MCZ 1622, Lake St. John (Concordia or Tensas Parish); USNM 029266, Louisiana?