Dried skin, skull, and mandible of an adult female (CML 7623; Figs 2 and 3), collected by M. D. Miotti (field number 540) on September 14, 2006. The specimen is deposited in the Colección Mamíferos Lillo (CML, Tucumán, Argentina).

Figure 2. 

Dorsal (A) and ventral (B) views of the skin of the holotype of Myotis barquezi (CML 7623).

Figure 3. 

Dorsal, ventral and lateral views of the skull, and lateral view of the mandible of the holotype of Myotis barquezi (CML 7623). Scale bar = 10 mm.

Finca Alto Verde, ca. 20 km SW San Ramón de La Nueva Orán, Orán Department, Salta Province, Argentina (23°13′S, 64°32″W; 670 m elevation).

Dried skin, skull and mandible of an adult female (CML 7622), collected by M. D. Miotti (field number 539) on September 14, 2006 at the type locality.

Myotis barquezi is known only from the type locality, in Salta Province, northern Argentina, where it inhabits lowland tropical forests inside the Southern Andean Yungas ecoregion (Fig. 4). This vegetational domain is classified as tropical and subtropical moist broadleaf forest (Olson et al. 2001) and is located between the Eastern slope of the Andes and the lowlands of the Alto Chaco ecoregion. The locality where M. barquezi was captured is close to Orán city and consists of a Premontane Forest (“selva pedemontana palo blanco and palo amarillo”) of the Upper Bermejo River Basin distributed altitudinally between 400 and 900 m, with dominance of Calycophyllum multiflorum and Phyllostilon rhamnoides (Jayat and Ortiz 2010). Some dominant species of trees in the area include pink lapacho (Tabebuia impetiginosa), pink cedar (Cedrela balansae), oak (Amburana cearensis), red cedar (Anadenanthera colubrina), cinchona (Myroxylon peruiferum), afata (Cordia tricotoma), palo lanza (Patagonula americana), and urundel (Astronium urundeuva) (Brown 1995). The area is closely related to the Eastern Cordillera and the piedmont forest reaches only 700 m, bordering extensively with the Montane Forest of Argentina and Bolivia; to the east it is bordered by areas of highly disturbed Premontane Forests and highland Chaco environments (Jayat and Ortiz 2010).

Figure 4. 

Map of part of South America with type locality of Myotis barquezi (red star).

The climate presents hot, rainy summers and cold, dry winters, and the annual mean temperature exceeds 21°C (Adámoli et al. 1972; Ojeda and Mares 1989). Summer temperatures (December to March) may approach 40°C, whereas winter minima (June to September) are near 6°C; annual rainfall mean ranges from 500 to 800 mm (Adámoli et al. 1972; Cabrera 1976; Ojeda and Mares 1989). During the cooler months, the condensed water mist that characterizes these “cloud forests” is captured and cooperates to partially compensate for the lack of rains in that season (Burkart et al. 1999).

Myotis barquezi is named in honor of Dr. Rubén M. Barquez, in recognition of his outstanding contributions to Neotropical mammalogy, especially on the bat fauna from Argentina. This species name is a noun in the genitive case formed by adding −i to the stem of the name (ICZN, 1999; 31.1.2).

Barquez’s Myotis [English]; Myotis de Barquez [Spanish].

Small to medium sized species (FA 35.1–35.2 mm; GLS 13.1–13.5 mm); sagittal crest present but low; robust and broad skull; braincase inflated and remarkably high in lateral profile; braincase roof formed by the parietal bone strongly inclined forward; frontal bone with a slight slope towards the rostrum; posterior region of the braincase flattened and non-projected beyond the limit of the occipital condyles; well-developed mastoid processes; dorsal fur moderately long (LDF 5–6 mm), woolly and clearly bicolored, with tips ranging from Dresden Brown to Snuff Brown, and darker bases (Natal Brown); legs and dorsal surface of the uropatagium covered by fur that extend up to the knees or just beyond; plagiopatagium inserted into the foot by a broad band of membrane.

Myotis barquezi is a small to medium species of Myotis (Table 3), and fur texture and cranial morphology reassembles species allocated to the ruber-group (q.v., Moratelli et al. 2013, 2019a). Ears dark brown and comparatively medium-sized (EL 13–15 mm), reaching the portion of the rostrum between the eyes and nostrils when extended forward. Tragus long and slender, with a wide base and narrower spear-shaped terminal half, almost straight anterior edge, and rounded tip. Similar to M. armiensis and M. keaysi, membranes are Bone Brown, the dorsal surface of elbow, tibia, and uropatagium are densely furred, with hairs extending to the level of the knees or just beyond. The uropatagium lacks the fringe of hairs along the trailing edge. Plagiopatagium attached to the foot at the level of the toes by a broad band of membrane; toe nails are light brown.

Dorsal and ventral fur woolly and medium-sized (LDH 5–6 mm, LVH ~4.5 mm). Dorsal pelage clearly bicolored with medium-brown bases (near Natal Brown) and reddish tips, ranging from Dresden Brown to Snuff Brown. Darker bases comprise 2/3 of total hair length and changes abruptly from darker to lighter, with lighter tips comprising about 1/3 of hair length. Ventral pelage is also strongly bicolored, with Natal Brown bases (2/3 of hair length) and bright orangish tips (1/3 of hair length [near Clay Color]). The orangish venter contrasts with the reddish-brown dorsum.

Dental formula is I 2/3, C 1/1, PM 3/3, M 3/3 (2x) = 38, typical of most species of Myotis. Skull robust and medium-sized in length, resembling Myotis species of the ruber-group (GLS 13.1–13.5 mm). The second upper premolar (P3) aligned with toothrow, not displaced to the lingual side, and barely smaller than first upper premolar (P2). First lower molar (m1) myotodont, with postcristid connecting hypoconid and entoconid (Menu 1987). Braincase robust and globose; sagittal and lambdoidal crests presents, but sagittal crest does not reach the posterior edge of the skull or join the lambdoidal crests, although there is a triangular-shaped elevation between them; occipital region flattened and not projecting beyond the posterior limits of occipital condyles; well-developed mastoid processes. Frontal bone slightly sloping; rostrum comparatively short.

Myotis barquezi can be distinguished from all the species in the ruber-group (armiensis, elegans, keaysi, midastactus, moratellii, pampa, pilosatibialis, riparius, ruber, and simus), and species from the albescens-group that confirmedly or potentially occur in the South American southern cone (albescens, chiloensis, dinellii, izecksohni, lavali, levis, nigricans, and oxyotus), by the set of diagnostic traits reported above.

Among species from the ruber-group, M. barquezi most resembles M. keaysi from the Central Andes (see Novaes et al. 2021b), but it is much smaller, and differs in all external and cranial dimensions (e.g., FA > 38 mm and GLS > 13.5 mm in M. keaysi; whereas FA ~ 35 mm and GLS < 13.5 mm in M. barquezi), it also has shorter fur, and a lower sagittal crest. In addition, M. barquezi differs conspicuously from M. keaysi from Argentina by its reddish fur color, in contrast to brownish in M. keaysi populations from Argentina.

Myotis barquezi differs from M. ruber by its smaller size (both external and cranial; FA > 37.5 mm and GLS > 14.0 mm in M. ruber), shorter and clearly bicolored dorsal fur, dense fur along the leg and dorsal surface of the uropatagium, narrower interorbital constriction, and more developed mastoid processes. It differs from M. armiensis by its smaller size (FA > 36.0 mm in M. armiensis), clearly bicolored dorsal fur, lower sagittal crest, posterior region of the braincase flattened and non-projected beyond the limit of the occipital condyles. It differs from M. pilosatibialis by its smaller size (both external and cranial; FA > 36.0 mm in M. pilosatibialis), clearly bicolored dorsal fur, globose braincase (elongated in pilosatibialis), parietal bone strongly inclined forward, and shorter and broader rostrum. It differs from M. moratellii by its general smaller size (FA > 35.0 and GLS > 13.8 in moratellii), clearly bicolored dorsal fur, braincase lower in profile, posterior region of the braincase flattened and not projected beyond the limit of the occipital condyles, and sagittal crest lower.

Myotis barquezi can be distinguished from M. riparius by its clearly bicolored and reddish dorsal fur, presence of dense fur along the leg and dorsal surface of the uropatagium, parietal bone strongly inclined forward, posterior region of the braincase flattened and not projected beyond the limit of the occipital condyles, narrower interorbital constriction, and more developed mastoid processes. It differs from M. elegans by its larger size (both external and cranial; FA < 34.5 mm and GLS < 13.0 mm in M. elegans), more robust skull, higher sagittal crest, posterior region of the braincase flattened and not projected beyond the limit of the occipital condyles, narrower interorbital constriction, and more developed mastoid processes. It differs from M. pampa by its shorter fur (LDF < 6 in M. barquezi, LDF > 7 in M. pampa), ventral fur bicolored (being tricolored in M. pampa), skull more robust, sagittal crest present, posterior region of the braincase flattened and not projected beyond the limit of the occipital condyles, and more developed mastoid processes.

Myotis barquezi can be easily distinguished from M. simus and M. midastactus by its smaller size (FA > 36.0 mm and GLS > 13.5 mm in M. simus and M. midastactus), longer and clearly bicolored dorsal fur (being shorter [LDF < 4] and unicolored in M. simus and M. midastactus), legs and dorsal surface of the uropatagium covered by fur that extend up to the knees, plagiopatagium inserted into the foot by a broad band of membrane (attached at ankles in M. simus and M. midastactus); and narrower skull. In addition, tympanic bullae are comparatively larger in M. barquezi than in any other species from ruber-group, except M. elegans.

In comparison to the species from the albescens-group, M. barquezi can be easily distinguished from M. albescens by the absence of a fringe of hairs on the posterior margin of the uropatagium, reddish dorsal fur clearly bicolored (brownish with frosted appearance in albescens), yellowish ventral fur (whitish in albescens), frontal bone slightly sloping, sagittal crest present, and posterior region of the braincase flattened and not projected beyond the limit of the occipital condyles. It differs from M. dinellii and M. levis by its smaller size, absence of a fringe of hairs on the posterior margin of the uropatagium, comparatively shorter ears, narrower skull, posterior region of the braincase flattened and not projected beyond the limit of the occipital condyles. It differs from M. izecksohni and M. nigricans by the reddish and clearly bicolored dorsal fur, parietal bone strongly inclined forward, posterior region of the braincase flattened and not projected beyond the limit of the occipital condyles, and well-developed mastoid processes.

Myotis barquezi can be distinguished from M. chiloensis from its general smaller size (FA < 35.2 in M. barquezi; FA > 37 mm in M. chiloensis), ventral fur strongly bicolored with bright orange tips, shorter and broader skull, less inflated braincase, parietal bone strongly inclined forward, posterior region of the braincase flattened and not projected beyond the limit of the occipital condyles. It differs from M. lavali by its shorter and reddish fur, broader skull, parietal bone strongly inclined forward, posterior region of the braincase flattened and not projected beyond the limit of the occipital condyles, and well-developed mastoid processes. Differs from M. oxyotus by its smaller size (FA > 37 mm), shorter dorsal fur, ventral fur strongly bicolored with bright orange tips, shorter and broader skull, broader skull, parietal bone strongly inclined forward, posterior region of the braincase flattened and not projected beyond the limit of the occipital condyles. In addition, M. barquezi can be distinguished from all species of the albescens-group by its woolly fur (silky fur in albescens-group species, except M. chiloensis), dense fur on dorsal surface of the uropatagium (absent in all species of albescens-group), and tympanic bullae comparatively larger.

The specimens used here to describe M. barquezi (CML 7622 and 7623) were originally misidentified as Myotis lavali (Barquez et al. 2017: 291).

Medium-sized species (FA 33.5–37.5 mm, body mass 4–8 g; Table 4, Fig. 5), with silky, moderately long fur (LDF 5–8 mm, LVF 4–6 mm). Ears comparatively short (length 12–15 mm). Dorsal fur Mummy Brown from basis almost to the tip (ca. 4/5 of hairs length); tips (ca. 1/5) Antimony Yellow or paler usually strongly contrasting with the basal color, giving a yellowish or grayish frosting appearance. Yellowish tips can be less evident in a few specimens in which the dorsal fur seems nearly unicolored (especially in northeastern Argentina). Ventral fur strongly bicolored, with blackish bases (2/3 hair length) and whitish tips (1/3 hair length). Ventral fur often becomes progressively paler (whiter) from upper thorax to pelvic region. Membranes and ears Mummy Brown. Legs and dorsal surface of uropatagium naked. Fringe of hairs along the trailing edge of the uropatagium always present. Plagiopatagium attached to feet on the level of the base of the toes by a wide band of membrane. Skull moderate in size (GLS 13.8–15.2 mm, BCB 6.8–7.3 mm), rostrum comparatively short and broad, and frontal bone strongly sloping. P3 smaller than P2 and usually aligned to the toothrow, and visible in labial view. Sagittal crest absent; lambdoidal crests usually present and ranging from low to medium. Parietals slope anteriorly; occipital region rounded and projecting beyond the occipital condyle limits; braincase globular in dorsal view; postorbital and interorbital constrictions comparatively wide.

Figure 5. 

Adult female of Myotis albescens (CML 5108) from Salta, Argentina.

Occurs from southern Veracruz, Mexico, southward through Central America into Uruguay, northern Argentina and eastern Brazil, from humid tropical forests to savannas and semi-arid environments (Braun et al. 2009; Moratelli and Oliveira 2011; Moratelli et al. 2019a; Díaz et al. 2021). In Argentina, it occurs in Northwestern (Provinces of Jujuy, Salta, and Tucumán), Gran Chaco (Chaco, Formosa, and Santiago del Estero Provinces), Littoral regions (Provinces of Corrientes, Entre Ríos, and Misiones), and the Pampa area (Buenos Aires Province) (Barquez and Díaz 2020), from humid forests (Southern Andean Yungas) to scrublands (Dry Chaco) in an altitudinal range from 5 to 1,400 m.

Medium to large-sized species (FA 35.8–40.5 mm; body mass 4–8 g; Table 4, Fig. 6); with woolly, moderately long fur (LDF 6–8 mm, LVF 5–6 mm). Ears comparatively short (length 13–15 mm). Dorsal fur reddish and varying from Cinnamon Brown to Ochraceous Tawny, with slightly darker bases (1/3 hair length). The ventral fur strongly bicolored, with Prout’s Brown bases (2/3 hair length) and yellowish red tips (1/3 hair length). Membranes and ears are Mummy Brown. 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 robust and moderate in size (GLS 15.1–15.6 mm; BCB 6.7–7.2 mm); rostrum comparatively elongated; mastoid process well-developed. The P3 is smaller than P2 and can be aligned or displaced to lingual side in the toothrow. Sagittal crest present and usually low to medium; lambdoidal crests usually present and ranging from medium to high. Parietal straight or slightly inclined forward; occipital region flattened and not projected beyond the occipital condyle limits in most specimens; braincase elongated in dorsal view; postorbital and interorbital constrictions are comparatively narrow.

Figure 6. 

Adult male of Myotis ruber (MACN 18035) from Misiones, Argentina.

The distribution is associated with ombrophilous and seasonal tropical forests from Northeastern Brazil to northern Argentina and Paraguay, where it appears to be strongly associated to humid and dense forested environments (Weber et al. 2010; Moratelli et al. 2019a). In Argentina, we confirm the occurrence throughout ombrophilous tropical forests in Humid Chaco (Formosa Province) and moist Atlantic Forest (Misiones Province), in an altitudinal range from 70 to 550 m. However, literature indicates a wider distribution, with records in Buenos Aires, Corrientes, Entre Ríos, and Santa Fe provinces (Barquez and Díaz 2020).

Recent studies have indicated that M. nigricans is a complex of allopatric species (Moratelli et al. 2011a, 2016, 2017, 2019b). The name 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.

Figure 7. 

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

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.

Medium-sized species (FA 36.5–40.1 mm, body mass 6–8 g; Table 5, Fig. 8), with silky, moderately long fur (LDH 6–8 mm, LVH 4–7 mm). Ears comparatively long (length 16–19 mm). Dorsal fur bicolored, with blackish bases (2/3 hair length) and the tips (1/3 hair length) ranging from Mummy Brown to Bister. The ventral fur is strongly bicolored, with blackish bases (1/2 hair length) and tips (1/2 hair length) Ivory Yellow or Drab Gray. Membranes and ears Mummy Brown. Legs and dorsal surface of uropatagium naked. A fringe of hairs along the trailing edge of the uropatagium present. The plagiopatagium attached to feet on the level of the base of the toes by a wide band of membrane. Skull medium to large in size (GLS 14.4–15.5 mm, BCB 6.8–7.5 mm), and the rostrum is comparatively long and broad. The P3 is approximately the same size as P2, or slightly smaller, and usually aligned in the toothrow and visible in labial view. Sagittal crest absent or very low; lambdoidal crests usually present and ranging from low to medium. Parietals incline subtly forward to the frontal bone; occipital region rounded and projecting beyond the occipital condyle limits; braincase elongated in dorsal view; the postorbital and interorbital constrictions are comparatively narrow.

Figure 8. 

Adult male of Myotis levis (CML 4127) from Buenos Aires, Argentina.

This species occurs from Southeastern Brazil southward to Uruguay, Paraguay, and eastern Argentina, from ombrophilous Atlantic Forest to Pampa grasslands (LaVal 1973; Wilson 2008; Moratelli et al. 2019a). In Argentina it is present in the Provinces of Buenos Aires, Corrientes, Entre Ríos, Misiones, and Santa Fe, occurring in scrubland savannas in an altitudinal range from sea level to 200 m (Barquez and Díaz 2020).

Medium to large-sized species (FA 37.0–41.2 mm, body mass 5.5–9.5 g; Table 5; Fig. 9), with wolly, long fur (LDF 6.0–8.5 mm, LVF 5.0–7.5 mm). Ears comparatively short (length 14–16 mm). Dorsal fur subtly bicolored, with medium-brown bases (near Mummy Brown) and tips generally Brussels Brown or Cinnamon Brown. The ventral fur is strongly bicolored, with Mummy Brown bases (2/3 hair length) and Dresden Brown tips (1/3 hair length). Membranes and ears Mummy Brown. Legs and dorsal surface of uropatagium naked. The few hairs on the trailing edge of the uropatagium do not constitute the fringe of hairs characteristic of other species, such as M. albescens. The plagiopatagium attached to feet on the level of the base of the toes by a wide band of membrane. Skull medium to large in size (GLS 13.8–15.3 mm, BCB 6.3–7.4 mm), and the rostrum comparatively long and narrow. The P3 is approximately the same size than P2, aligned in the toothrow, and visible in labial view. Sagittal crest absent or, when present, very low; lambdoidal crests present and low. Parietals decay subtly forward to frontal bone; occipital region projects beyond the occipital condyle limits; braincase elongated in dorsal view; the postorbital and interorbital constrictions are comparatively narrow.

Figure 9. 

Adult female of Myotis chiloensis (MACN 16524) from Chubut, Argentina.

Myotis chiloensis occurs from Southern Chile, eastward into western Argentina and southward to Tierra del Fuego, in evergreen-deciduous forests, montane temperate forests, and Patagonian scrublands (Ossa and Rodríguez-San Pedro 2015; Moratelli et al. 2019a). In Argentina, it is present in the Provinces of Neuquén, Río Negro, Chubut, Santa Cruz, and Tierra del Fuego, in Valdivian Temperate Forests, Patagonian Steppes, and Magellanic Subpolar Forests in an altitudinal range from sea level to ca. 1,000 m.

Among all Myotis specimens from Argentina analyzed, only one voucher was identified as M. oxyotus (CML 10860). It is a medium-sized bat (FA 40.9 mm, body mass 4.0 g; Table 5; Fig. 10), with silky long fur (LDF 9.5 mm, LVF 7.5 mm). Ears comparatively short (length 19 mm). Dorsal fur strongly bicolored, with Blackish Brown bases (2/3 hair length) and Dresden Brown tips (1/3 hair length). The ventral fur strongly bicolored, with Blackish Brown bases and Light Grayish Olive tips. Membranes and ears are Mummy Brown. Legs and dorsal surface of uropatagium naked. A fringe of hairs along the trailing edge of the uropatagium absent. The plagiopatagium attached to feet on the level of the base of the toes by a wide band of membrane. The skull is large in size (GLS 14.83 mm, BCB 6.97 mm), and the rostrum comparatively short and narrow. The P3 is smaller than P2 and aligned in the toothrow and visible in labial view. Sagittal crest and lambdoidal crests very low. Parietals decay steeply to frontal bone; occipital region rounded and slightly projected beyond the occipital condyle limits; braincase globular in dorsal view; the postorbital and interorbital constrictions comparatively wide.

Figure 10. 

Adult female of Myotis oxyotus (CML 10860) from Jujuy, Argentina.

Myotis oxyotus is divided in two allopatric subspecies: Myotis o. oxyotus from South America and M. o. gardneri from Central America. Myotis o. oxyotus occurs along the Andes, from Venezuela southward to northern Argentina (Wilson 2008; Moratelli et al. 2019a). The only specimen recorded for Argentina is from El Mirador, 1 km NW Yavi (Yavi Department, Jujuy Province, 22°07′41″S, 65°27′58″W; 3,450 m a.s.l.), in Puna ecoregion (Urquizo et al. 2017)

Figure 11. 

Adult male of Myotis cf. simus (MACN 18033) from Corrientes, Argentina.

Medium to large-sized species (FA 34.7–39.4 mm, body mass 5–6 g; Table 6, Fig. 12), with silky, long fur (LDF 7–9 mm, LVF 6–8 mm). Ears comparatively long (length 14–17 mm). Dorsal fur strongly bicolored, with blackish bases (1/2 hair length) and tips ranging from Buff Brown to Aniline Yellow, forming two clearly color bands in the dorsal fur. The ventral fur is strongly bicolored, with blackish bases (2/3 hair length) and tips (1/3 hair length) ranging from Ivory Yellow to Pale Olive Buff. Membranes, rostrum, and ears are blackish, contrasting strongly with the body coloration. Legs and dorsal surface of uropatagium naked. A fringe of hairs along the trailing edge of the uropatagium present, but with scattered hairs, less evident than M. albescens and M. levis. The plagiopatagium attached to feet on the level of the base of the toes by a wide band of membrane. Skull medium to large in size (GLS 13.9–15.2 mm, BCB 6.5–7.1 mm), and the rostrum comparatively long and broad. The P3 is smaller than P2 and always aligned in the toothrow and visible in labial view. Sagittal crest absent in most specimens, but when present, is very low; lambdoidal crests usually very low. Parietals decay subtly forward to frontal bone; occipital region rounded and projects beyond the occipital condyle limits; braincase elongated in dorsal view; postorbital and interorbital constrictions comparatively narrow.

Figure 12. 

Adult male of Myotis dinellii (MACN 14747) from Córdoba, Argentina.

This species occurs from southern Bolivia southward through Argentina, occupying deciduous forests, savannas, and semiarid open environments (Wilson 2008; Sandoval and Barquez 2013; Gamboa-Alurralde et al. 2017; Moratelli et al. 2019a). In Argentina it is present from Southern Andean Yungas (Provinces of Tucumán and Salta), southward to High Monte, Southern Andean Steppe, Low Monte, and Patagonian Steppe (Provinces of Catamarca, Chubut, San Juan, and Mendoza), extending eastward to Dry Chaco, Espinal, and Humid Pampas (Provinces of Buenos Aires and Córdoba), occupying an altitudinal range from 50 to 2,500 m (Barquez and Díaz 2020).

Medium to large-sized species (FA 38.7–42.0 mm, body mass 6–8 g; Table 6, Fig. 13), with wooly long fur (LDF 7–8 mm, LVF 5–6 mm). Ears comparatively short (length 11–14 mm). Dorsal fur slightly bicolored, ranging from Mummy Brown and Cinnamon Brown to Ochraceous Tawny, with darker bases. Ventral fur strongly bicolored, with Clove Brown bases, and tips ranging from Ivory Yellow to Light Drab. Membranes and ears are Mummy Brown. Legs and dorsal surface of uropatagium covered by a dense pelage that extends to the knees (or just beyond). A fringe of hairs along the trailing edge of the uropatagium absent. Plagiopatagium attached to feet on the level of the base of the toes by a wide band of membrane. Skull moderate in size (GLS 13.5–13.8 mm, BCB 6.7–6.9 mm), and the rostrum comparatively elongated. The P3 is smaller than P2 and aligned in the toothrow and visible in labial view. Sagittal crest present and varying from low to medium; lambdoidal crests present and ranging from medium to high. Parietal subtly inclined forward in most individuals; posterior region of the braincase rounded and projected beyond the limit of the occipital condyles in most individuals; braincase is narrow in dorsal view; the postorbital and interorbital constrictions are comparatively wide. Specimens from Argentina are smaller and have darker fur than those of the Central Andes.

Figure 13. 

Adult female of Myotis keaysi (CML 9839) from Tucumán, Argentina.

Endemic to South America and strongly associated with highlands in the Andes, from Venezuela to northern Argentina, where it is present in habitats formed by Dense Ombrophylous Forest, Montana Nebular Forest and, in the areas of higher altitude, in Seasonal Forests dominated by shrubby vegetation and with sparse patches of arboreal vegetation (LaVal 1973; Moratelli et al. 2019a; Novaes et al. 2021b). In Argentina, it is recorded in Jujuy, Salta, Tucumán, and Catamarca, in Yungas Forest (450–1,700 m; Barquez and Díaz 2020)

Small to medium-sized species (FA 33.4–36.3 mm, body mass 4–5 g; Table 7; Fig. 14), with wooly, moderately long fur (LDF 6.5–7.5 mm, LVF 5.5–7.0 mm). Ears comparatively short (length 12–15 mm). Most individuals have dorsal fur subtly bicolored, with Bone Brown bases (2/3 hair length) and tips (1/3 hair length) ranging from Cinnamon-Brown to Snuff Brown, with a burnished aspect (e.g., CML 3155). However, some specimens have unicolored dorsal fur generally Cinnamon-Brown (e.g., CML 5412). Ventral fur strongly bicolored, with Clove Brown bases (2/3 hair length) and generally Deep Olive Buff tips (1/3 hair length). Membranes and ears are Mummy Brown. Legs and dorsal surface of uropatagium naked. Lack of a fringe of hairs along the trailing edge of the uropatagium. Plagiopatagium attached to feet on the level of the base of the toes by a wide band of membrane. Skull moderate in size (GLS 13.3–13.8 mm, BCB 6.3–6.4 mm), and the rostrum comparatively short and broad. The P3 is smaller than P2 and can be aligned in the toothrow or displaced to lingual side, but always visible in labial view. Sagittal crest present, ranging from low to medium; lambdoidal crests present and ranging from low to medium. Parietals decay anteriorly; occipital region is almost flattened, but projects beyond the occipital condyle limits; braincase elongated in dorsal view; postorbital and interorbital constrictions comparatively wide.

Figure 14. 

Adult female of Myotis riparius (MACN 20906) from Formosa, Argentina.

Myotis riparius occurs from Honduras, southward through South America into northern Argentina and eastern Brazil, occupying humid tropical forests to savanna environments (Novaes et al. 2017; Moratelli et al. 2019a). Myotis riparius has a marked geographic variation in relation to fur coloration and skull features, which has raised suspicions that this species is, in fact, a cryptic taxonomic complex (Novaes et al. 2017). Most specimens from Argentina have morphological features that are subtly distinct from those from Panama (including the type series) and northern South America, such as bicolored dorsal fur, skull with lower sagittal and lambdoid crests, and smaller skull and external size. On the other hand, a few specimens have fur color and cranial traits more similar to the forms from Central America and northern South America. We do not reject the hypothesis that Argentinean populations currently under the name riparius might be a distinct species; it is also not impossible that populations of M. riparius from Argentina may be hiding two sympatric cryptic species. However, more investigations are needed to understand the taxonomic status of the Argentinean populations currently named as M. riparius, and molecular data are needed to understand whether these patterns of variation represent independent evolutionary lineages.

In Argentina, M. riparius occurs in the northern portion, from Southern Andean Yungas (Jujuy, Salta, and Tucumán Provinces) throughout ombrophilous tropical forests in Humid Chaco (Province of Chaco and Formosa), Dry Chaco (Santiago del Estero), and moist Atlantic Forest (Misiones Province), in an altitudinal range from 70 to 2,000 m (Barquez and Díaz 2020). It is possible that records of M. riparius from the Pampa and Espinal ecoregions, in the provinces of Buenos Aires, Corrientes, and Entre Ríos, may represent the newly described Myotis pampa Novaes, Wilson & Moratelli, 2021. Therefore, specimens that resemble M. riparius from these regions need to be revised.

Among all Myotis specimens from Argentina analyzed, only one voucher (CML 10200) was identified as M. izecksohni. It is a medium-sized species (FA 37.8 mm, body mass 4 g; Table 7, Fig. 15). Ears comparatively short (length 12.1 mm). Silky, moderately long fur (LDH 6–8 mm, LVH 5–6 mm). Dorsal fur slightly bicolor, with blackish bases (2/3 hair length) and Bone Brown tips (1/3 hair length). Ventral fur strongly bicolored, with blackish bases (2/3 hair length) and Buffy Brown tips (1/3 hair length). Membranes and ears are Mummy Brown. Legs and dorsal surface of uropatagium naked. A fringe of hairs along the trailing edge of the uropatagium is absent. The plagiopatagium 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 14.6 mm, BCB 6.8 mm); the rostrum comparatively elongated; mastoid process weakly developed. The P3 is smaller than P2 and usually aligned to the toothrow. Sagittal crest and lambdoidal crests very low. Parietal straight or slightly inclined forward; occipital region is rounded and projected beyond the posterior limit of the occipital condyles; braincase elongated in dorsal view; the postorbital and interorbital constrictions comparatively broad.

Figure 15. 

Adult female of Myotis izecksohni (CML 10200) from Misiones, Argentina.

This species occurs from southeastern Brazil to northern Argentina, in dense ombrophilous forests (Moratelli et al. 2019a). The only record in Argentina is from humid and dense forests from Misiones (210 m) in the Alto Paraná Atlantic Forest (Barquez et al. 2017).

Small to medium-sized species (FA 33.8–39.6 mm, body mass 5–6 g; Table 7, Fig. 15), with silky and long fur (LDH 5–8 mm, LVH 4–6 mm). Ears are moderate in length (13–14 mm). Dorsal fur strongly bicolored, with Clove Brown bases (1/2 hair length) and Buffy Brown tips (1/2 hair length). The ventral fur strongly bicolored, with Bone Brown bases (1/2 hair length) and generally Pale Olive-Buff tips (1/2 hair length). Membranes and ears are Mummy Brown or lighter. Legs and dorsal surface of uropatagium naked. A fringe of hairs along the trailing edge of the uropatagium is absent. The plagiopatagium attached to feet on the level of the base of the toes by a wide band of membrane. Skull small to moderate in size (GLS 13.6–13.8 mm, BCB 6.5–6.7 mm), and the rostrum comparatively short and narrow. The P3 is smaller than P2 and usually aligned in the toothrow and visible in labial view. Sagittal crest usually present and very low, or even absent in some individuals; lambdoidal crests usually present and very low. Parietals decay anteriorly; occipital region rounded and projected beyond the occipital condyle limits; braincase is elongated in dorsal view; the postorbital and interorbital constrictions are comparatively narrow.

Myotis lavali occurs from Northeastern Brazil, throughout South American diagonal of open formations, to Paraguay and northern Argentina, in savannas, semi-arid fields, and seasonal forests (Moratelli et al. 2019a; Weber et al. 2019). In Argentina, it is present in Dry Chaco scrublands and Yungas Forest from Salta and Santiago del Estero Provinces, in an altitudinal range from 120 to 800 m.

The M. simus complex was taxonomically revised resulting in the recognition of the recently described species Myotis midastactus Moratelli & Wilson, 2014, based on individuals originally identified as M. simus from Bolivia (Moratelli et al. 2011b; Moratelli and Wilson 2014). Subsequently, populations of M. simus from Paraguay were reidentified as M. midastactus based on morphological traits (Moratelli et al. 2015). Moratelli et al. (2019a) considered that M. simus has two disjunct populations, one in dense humid forests along the Amazon Basin and the other in Brazilian Pantanal and Humid Chaco from Argentina and Paraguay. However, specimens from Argentina can be distinguished from M. simus from the Amazon Basin by paler pelage, and larger skull with lower sagittal crest. Considering the geographic discontinuity (Moratelli et al. 2011c) and morphological differences, it is likely that samples from Argentina represent a distinct taxon from M. simus from the Amazon Basin. On the other hand, one specimen from Argentina is more similar to M. midastactus in fur color (MACN 18033) but differs slightly in cranial traits. Other specimens from Argentina differ conspicuously from M. simus and M. midastactus in fur color. Thus, samples from Argentina may (i) represent a population of M. midastactus (with subtle geographic variation in relation to fur color); (ii) represent Myotis guaycuru Proença, 1943, a species described for the Brazilian Cerrado-Pantanal transition and currently considered a junior synonym of M. simus; (iii) represent a third and unnamed species, with occurrence restricted to the Argentinean Humid Chaco. If the third hypothesis is confirmed, M. guaycuru could be the valid name for the populations currently considered as M. midastactus from Bolivia and Paraguay. However, due to morphological similarity and the absence of phenotypic discontinuity, the resolution of this issue depends on the analysis of new specimens from all ecoregions based on morphological and molecular approaches.

In Argentina, this taxon is medium to large-sized (FA 38.0–41.3 mm, body mass 8.0–9.5 g; Table 6; Fig. 11), with wooly and very short fur (LDF 2.7–3.4 mm, LVF 2.5–2.9 mm). Ears are comparatively short (length 10–14 mm). Dorsal fur ranges from Clay Color to Wood Brown, without contrast between bases and tips. The ventral fur weakly bicolored, with Drab bases (1/2 hair length) and tips (1/2 hair length) ranging from Colonial Buff to Pale Olive-Buff. Membranes and ears are Clove Brown or lighter. Legs and dorsal surface of uropatagium are naked. A fringe of hairs along the trailing edge of the uropatagium is absent. The plagiopatagium attached to feet at the ankles level or on the base of the toes by a narrow band of membrane. Skull medium to large in size (GLS 14.0–15.0 mm, BCB 6.8–7.5 mm), and the rostrum comparatively short and broad. The P3 smaller than P2 and usually displaced to lingual side in the toothrow. Sagittal crest and lambdoidal crests present and ranging from low to medium. Parietals slope anteriorly; occipital region flattened and subtly projects beyond the occipital condyle limits; postorbital and interorbital constrictions comparatively wide.

Figure 16. 

Adult female of Myotis lavali (CML 5404) from Santiago del Estero, Argentina.

Argentinean populations of M. cf. simus are present in Humid Chaco and Mesopotamian Savanna from Formosa and Corrientes Provinces, and in the Delta e Islas del Paraná in Santa Fe Province, occupying an altitudinal range from 46 to 200 m (Pavé and Gavazza 2022).