Vespertilio: Schreber, 1774 : pl. 53; part; not Vespertilio Linnaeus, 1758 .
Eptesicus Rafinesque, 1820: 2 ; type species Eptesicus melanops Rafinesque, 1820 (= Eptesicus fuscus Palisot de Beauvois, 1796 ), by subsequent designation (Méhely 1900: 206).
Vesperugo Keyserling & Blasius, 1839: 312 ; part.
Vesperus Keyserling & Blasius, 1839: 313 ; part; proposed as a subgenus of Vesperugo Keyserling & Blasius, 1839 ; preoccupied by Vesperus Latreille, 1829 (Coleoptera, Cerambycidae).
Adelonycteris H. Allen, 1892: 466 ; part; replacement name for Vesperus Keyserling and Blasius, 1839 , preoccupied.
Type species: Vespertilio fuscus Palisot de Beauvois, 1796.
Other species: E.guadeloupensis Genoways & Baker, 1975.
Distribution: Eptesicus is widely distributed across North and Central Americas, including the West Indies, and with a few records from northern South America, where it is restricted to Colombia, Ecuador, and Venezuela.
Diagnosis: Eptesicus can be distinguished by the following characters: ears short (<21 mm) and not connected; skull very robust, wide, and short; sagittal and lambdoidal crests well developed; postorbital process of the jugal weakly developed; eyes reduced, smaller or about the same size as lower canines and nostrils; auditory bullae small, the space between auditory bullae is larger than the width of each bullae; length of dorsal fur usually long (averaging 10.1 mm); length of forearm long, ranging from 40.1–54.0 mm (averaging 46.6 mm); tragus short and rounded, smooth and broad; GLS 16.9–20.8 mm (averaging 19.1 mm); and MTL 6.2–7.7 mm (averaging 7.1 mm).
Description: Eptesicus includes medium-sized to large bats. Dorsal fur long (LDF 8.1–13.7 mm) and woolly; hairs usually strongly bicolored with blackish bases extending about 1/2 of hair length, distal 1/2 of hairs golden to orangish brown; the juncture between bands is well marked. Ventral fur long (LVF 7.1–12.0 mm, averaging 8.8 mm) and woolly; hairs bicolored with dark brown bases extending to about 2/3 of hairs length, distal 1/3 of hairs grayish yellow. Wing membranes naked, dark brown. Plagiopatagium attached to the base of the toe. Dorsal surface of the uropatagium almost naked, or with short sparse hairs that do not extend beyond the knees. Ventral surface of the uropatagium dark brown and sparsely haired along the base of the tail. Feet densely furred with short chestnut hairs.Ears well-separated, medium sized, dark brown, and with rounded tips; tragus wider at the base, straight to slightly curved, long, rounded, and broad. Muzzle broad and inflated.
Skull robust; rostrum short, wide, and flattened, and weakly sloping upwards to the braincase; braincase slightly wider than the rostrum. Posterior region of the braincase straight, slightly projected upwards.Nasal opening V-shaped. Frontal expanded laterally towards the orbit. Sagittal and lambdoidal crests well developed and connected; occipital helmet well-developed.Triangular,flattened bony plate where the sagittal and lambdoidal crests connect absent, the region where crests connect may be enlarged. Zygomatic arches thin and slightly widened medially. Basisphenoid pits absent.Palate extends well beyond molars, ending in a concave posterior edge, with a weakly- to moderately-developed medial spine.
Dental formula is I 2/3, C 1/1, P 1/2, M 3/3 (×2) = 32. I 1 separated, weakly to strongly bilobed; shape varies from narrow and long to broad and short, with outer cusps weakly to well developed. I 1 about three to four times the size of I 2. I 2 and C 1 separated by a small gap, C 1 with two slightly concave faces on the lingual region, and one slightly concave face on the labial region. P1 well developed, reaching 1/2 of C 1 in height; P 1 in contact with C 1 and molars. M 1 and M 2 about the same size, almost square shaped, with W-shaped cusps. M 3 reduced, triangular, with only 3 cusps. I 1 to I 3 reduced, trilobed, and filling all the space between canines. P 2 about three times P 1 in height. Molars have well developed cusps and decrease in size from M 1 to M 3.
See Neoeptesicus gen. nov. account and Table 3 for comparisons.