Fossil Bats 103 



Lasiurus intermedins H. Allen, 1862 



Referred material— Stratum 3-V7202, proximal two-thirds of left 

 humerus; V7203, proximal end of right radius. 



Recent distribution. — Lasiurus intermedius occurs primarily in the 

 southeastern United States, from South Carolina to Texas, and into 

 lowland tropical Middle America as far south as Honduras. The yellow 

 bat is found throughout Florida, with records from as far south as Lee 

 County on the west coast and Palm Beach, Broward, and Dade counties 

 on the Atlantic coast (Layne 1974). 



Fossil record. — Lasiurus intermedius is known as a fossil only from 

 Florida. Webb (1974) recorded this species from three late Pleistocene 

 sites in the state: Haile XIB, Alachua County; Devil's Den, Levy 

 County; and Reddick I A, Marion County. Martin (1972) also identified 

 L. intermedius from Arredondo IIA. I have recently identified a mandi- 

 ble of this species from the Glyptodont Site in Pinellas County. 



Description and comparisons. — Based on its large size, the humer- 

 us referred to Lasiurus intermedius can readily be distinguished from 

 all other Florida bats except Eumops and Eptesicus. The proximal end 

 of the humerus differs from that of Eptesicus by the elliptical humeral 

 head oriented at a 45° angle to the shaft, the more prominent greater 

 tuberosity, and the smaller lesser turberosity. It is also readily separable 

 from the humerus of Eumops by its smaller size, almost perfectly ellipti- 

 cal head, relatively longer and less expanded pectoral ridge, and lack of 

 a deep groove on the lateral surface of the greater tuberosity. The fossil 

 is identical in size and morphology to humeri of recent L. intermedius 

 from Florida (see measurements in Table 2). Although the other large 

 North American species of Lasiurus, L. cinereus, has been recorded 

 from Florida on several occasions, it occurs there only as a rare 

 migrant. The humerus of L. cinereus is larger than the fossil from Vero, 

 with a broader proximal end and relatively thicker shaft. 



As with the humerus, the proximal radius referred to Lasiurus 

 intermedius needs comparison only with Eumops and Eptesicus. It is 

 completely unlike the radius of Eptesicus, differing from that genus in 

 the more robust shaft, considerably shorter ridge extending distally 

 from the flexor fossa, lack of a deep groove in the articular surface for 

 the capitulum of the humerus, and the acutely triangular shape of the 

 proximalmost extension. The fossil radius can be distinguished from 

 Eumops by its smaller size, more laterally placed flexor fossa, more 

 slender shaft, relatively smaller articular surface that is rounded in out- 

 line rather than distinctly triangular, and lack of a deep central groove 

 on the articular surface. Although essentially identical to the radius of 

 Lasiurus cinereus, the fossil is somewhat smaller, as is the radius of L. 

 intermedius. 



