Myotis nigricans (Schinz, 1821)

Novaes, Roberto Leonan M., Claudio, Vinicius C., Diaz, M. Monica, Wilson, Don E., Weksler, Marcelo & Moratelli, Ricardo, 2022, Argentinean Myotis (Chiroptera, Vespertilionidae), including the description of a new species from the Yungas, Vertebrate Zoology 72, pp. 1187-1216 : 1187

Myotis nigricans (Schinz, 1821)

Comments.

Recent studies have indicated that M. nigricans is a complex of allopatric species ( Moratelli et al. 2011a, 2016, 2017, 2019b). The name Myotis nigricans applies to populations from the Atlantic Forest in Southeastern Brazil to northern Argentina. Forms from northern South America previously identified as M. nigricans have received new names, or their subspecies have been raised to the species level (Moratelli and Wilson, 2011; Moratelli et al. 2013, 2017). Argentinean populations are small-sized (FA 33.0-35.1 mm; body mass 3.5-6.0 g; Table 4 , Fig. 7 ); with silky, moderately long fur (LDH 6-8 mm, LVH 5-6 mm). Ears comparatively short (length 13-15 mm). Dorsal fur without contrast between bases and tips or slightly bicolor, with blackish bases and Mummy Brown tips. Ventral fur strongly bicolored, with blackish bases (1/2 hair length) and tips ranging from Buffy Brown to Citrine Drab (1/2 hair length). Membranes and ears are Mummy Brown or darker. Legs and dorsal surface of uropatagium naked. Fringe of hairs along the trailing edge of the uropatagium absent. The plagiopatagium is attached to feet on the level of the base of the toes by a wide band of membrane. Skull delicate and small in size (GLS 12.4-14.2 mm, BCB 6.2-6.6 mm); rostrum comparatively elongated; the mastoid process is weakly-developed. The P3 is smaller than P2 and usually aligned to the toothrow. Sagittal crest usually absent or, when present, very low; lambdoidal crests usually present and ranging from medium to high. Parietal straight or slightly inclined forward; occipital region rounded and generally projected much beyond the posterior limit of the occipital condyles; braincase elongated in dorsal view; the postorbital and interorbital constrictions are comparatively broad.

In Argentina, they occur in ombrophilous tropical forests from Humid Chaco (Provinces of Chaco and Corrientes) and moist Atlantic Forest (Misiones Province), in an altitudinal range from 40 to 400 m. The distribution of this species still needs to be reviewed considering the recent taxonomic changes in populations originally identified as M. nigricans . Thus, records for other Argentinean provinces (e.g., Barquez and Díaz 2020) should be revised in light of new knowledge about Myotis systematics.

Figures

Figure 7. Adult male of Myotis nigricans (MACN 18487) from Misiones, Argentina.