KEY FOR IDENTIFICATION OF RECOGNIZED SPECIES OF MOLOSSUS E. GEOFFROY, 1805 IN BRAZIL

1. Forearm length between 44.6 and 56.0 mm; length of maxillary toothrow between 7.5 and 8.7 mm; greatest length of skull without incisors from 18.0 to 23.5 mm; palatal length between 6.3 and 7.8 mm ................. 2

— Forearm length between 33.0 and 44.0 mm; Length of maxillary toothrow between 5.0 and 7.5 mm; greatest length of skull without incisors from 14.0 to 18.0 mm; palatal length between 4.5 and 6.3 mm ................. 3

2. Upper incisors short and spatulated, with convergent tips (Fig. 2H); depth of the basioccipital pits moderate, without formation of crest between the basioccipital and the basisphenoid (Fig. 2B); nasal process highly developed (Fig. 2B); mastoid process facing toward the foramen magnum in posterior view (Fig. 2F). Larger size, forearm between 47.7 and 55.2 mm in males and 46.7 and 54.0 mm in females. Greatest length of skull between 20.8 and 23.8 mm in males and 19.9 and 22.6 mm in females ...... ............................................................................................................................. M. rufus E. Geoffroy, 1805

— Elongated upper incisors without converging tips; deep basioccipital pits, with the formation of a crest between the basioccipital and the basisphenoid; nasal process undeveloped (Fig. 2A); mastoid process directed ventrally in posterior view (Fig. 2F). Smaller size, forearm between 44.6 and 48.5 mm in males and 45.0 and 49.0 mm in females. Greatest length of skull without incisors between 19.8 and 22.7 mm in males and 18.9 and 21.0 mm in females ................................................................................................................ M. pretiosus Miller, 1902

3. Dorsal hair with a long and pale, and usually whitish, band at the base, covering from 1/4 to 1/2 of the total length of the hair; dorsal pelage colouration varying from medium to dark brown; triangular occipital complex (Fig. 2E); elongated incisors with parallel tips (Fig. 2G) .............................................................................. 4

— Dorsal hair without a pale band at the base, if present, the basal band is incipient, usually greyish or buff, and not extending more than 1/3 of the total length of the hair; dark dorsal pelage that may vary from dark brown, grayish to blackish brown; occipital complex quadrangular in shape (Fig. 2F); small and spatulated upper incisors (Fig. 2H) .............................................................................................................................................. 5

4. Infraorbital foramen directed laterally (Fig. 2H); very well-developed sagittal and lambdoidal crests (Fig. 2F, B) ....................................................................................................... M. currentium Thomas, 1901

— Infraorbital foramen directed frontally (Fig. 2G); undeveloped sagittal and lambdoidal crests (Fig. 2A, E) ..... ............................................................................................................................... M. molossus (Pallas, 1776)

5. Infraorbital foramen opens frontally in rostral view (Fig. 2G); shallow or absent basioccipital pits (Fig. 2A). Smaller size, forearm between 36.1 and 37.9 mm in males, and 34.3 and 37.5 mm in females. Greatest length of skull between 15.7 and 16.9 mm in males and 14.9 and 16.7 mm in females ...... M. coibensis Allen, 1904

— Infraorbital foramen directed laterally in rostral view (Fig. 2G); basioccipital pits with moderate depth (Fig. 2B). Larger size, forearm between 35.9 and 41.5 mm in males, and 35.0 and 41.9 mm in females; greatest length of skull between 16.2 and 18.3 mm in males, and 16.4 and 18.6 mm in females ...... M. aztecus Saussure, 1860