Distribution in Tamaulipas.—From Jaumave and Llera to north.
This subspecies is distinguished from S. h. toltecus by larger size and paler, grayish coloration.
Table 3.—Data on Reproduction.
| Locality | Date | Embryos | Size in mm. |
|---|---|---|---|
| 4 mi. N La Pesca | May 26 | 4 | 30 |
| Sierra de Tamaulipas | June 10 | 3 | 10 |
| Sierra de Tamaulipas | June 11 | 4 | 10 |
| Sierra de Tamaulipas | June 20 | 2 | 20 |
| Ciudad Victoria | July 12 | 5 | 5 |
| Jaumave | July 28 | 4 | 14 |
| Jaumave | July 29 | 6 | 25 |
| San Fernando | August 30 | 7 | 20 |
| San Fernando | August 31 | 8 | 11 |
| Vicinity of Nuevo Laredo | November 15 | 3 | 5 |
| Vicinity of Nuevo Laredo | November 16 | 5 | 2 |
Baker (1951:216) reported a specimen from 35 kilometers north and 10 kilometers west of Ciudad Victoria (= 1 km. E El Barretal) as S. h. toltecus. Comparison of its skull with those from the vicinity of Altamira (S. h. toltecus) and those from Jaumave (S. h. berlandieri) shows that the skull from El Barretal closely resembles those from Jaumave, in having the zygomatic arches more nearly parallel and the braincase more rounded than in skulls from Altamira. Therefore the specimen from the vicinity of El Barretal is here assigned to S. h. berlandieri.
Records of occurrence.—Specimens examined, 64: 4-1/2 mi. S Nuevo Laredo, 600 ft., 1; 10 mi. S, 11 mi. E Nuevo Laredo, 8; San Fernando, 180 ft., 8; 4 mi. N La Pesca, 10; 3 mi. N La Pesca, 1; 1 mi. E La Pesca, 3; Soto la Marina, 500 ft., 1; 36 km. N, 10 km. W Cd. Victoria, 1 km. E El Barretal, Río Purificación, 1; Cd. Victoria, 1; 2 km. W Pan-American Highway (12 km. S Llera), Ejido Santa Isabel, 2000 ft., 1; Jaumave, 2400 ft., 29.
Additional records: Matamoros (Baird, 1858:506); Sierra San Carlos (El Mulato, Tamaulipeca, San Miguel) (Dice, 1937:254); Mesa de Llera (Hooper, 1953:9); Tamaulipas [state?] (Baird, 1858:506).
Sigmodon hispidus solus Hall
1951. Sigmodon hispidus solus Hall, Univ. Kansas Publ., Mus. Nat. Hist., 5:42, October 1, type from island 88 mi. S, 10 mi. W Matamoros, Tamaulipas.
Distribution in Tamaulipas.—Known only from two specimens from the type locality.