Distribution in Tamaulipas.—Probably occurs in southern and western parts of state; certainly known only from the Sierra de Tamaulipas.
Three June-taken females, all captured in mist nets, were lactating.
Hall and Jones (1961:91) assigned all Mexican specimens of the southern yellow bat to Lasiurus ega xanthinus, but remarked that specimens from western México were paler than those from the east. Of the six specimens examined from Tamaulipas, four are dark, resembling in color specimens from Veracruz, Yucatán and Costa Rica, and the other two are somewhat paler, approaching specimens from Baja California, Zacatecas and Coahuila. In measurements, Tamaulipan specimens of Lasiurus ega generally resemble specimens from the west, but differ from any other L. ega seen in having a longer tail, longer ear, and shorter maxillary tooth-row.
Records of occurrence.—Specimens examined, 6: Sierra de Tamaulipas, 10 mi. W, 2 mi. S Piedra, 1200 ft., 4; 10 mi. W, 3 mi. S. Piedra, 1200 ft., 1; 16 mi. W, 3 mi. S. Piedra, 1400 ft., 1.
Nycticeius humeralis
Evening Bat
Nycticeius humeralis has the same distributional pattern in Tamaulipas as has Lasiurus borealis in that both are represented there by two subspecies, one known only from Matamoros and the other occurring in the rest of the state. Bats of this species (N. h. mexicanus) from Ciudad Victoria and some from the Sierra de Tamaulipas were shot in flight in evening; others from the last-mentioned locality were taken in mist nets. Lactating females (22 specimens) were collected in June and July.
Nycticeius humeralis humeralis (Rafinesque)
1818. Vespertilio humeralis Rafinesque, Amer. Monthly Mag., 3(6):445, October, type from Kentucky.
1819. N[ycticeius]. humeralis Rafinesque, Jour. Phys. Chim. Hist. Nat. et Arts, Paris, 88:417, June.
Distribution in Tamaulipas.—Matamoros (Miller, 1897:120), one specimen.