Argentinean Myotis (Chiroptera, Vespertilionidae), including the description of a new species from the Yungas

Myotis is the most speciose genus of mammals in the world and recent taxonomic revisions have revealed an impressive diversity of species in South America. Even so, the phenotypic conservatism of some taxa makes taxonomic delimitation difficult. We perform a taxonomic review of Myotis from Argentina based on qualitative and quantitative morphological characters. Our results confirm the occurrence of 12 species ( M. albescens , M. chiloensis , M. dinellii , M. izecksohni , M. keaysi , M. lavali , M. levis , M. nigricans , M. oxyotus , M. riparius , M. ruber , and M. cf. simus ) and revealed an additional new species for the Yungas Forest. The new species is small to medium (forearm length ~ 35 mm) and can be distinguished from its congeners by a set of characters that includes forearm length, cranial measurements, discrete craniodental characters, and fur color. This review does not exhaust the need for new systematic studies with Argentinean Myotis , considering the possibility of occurrence of new species and the great morphological variation found for some complex taxa.


Introduction
Myotis Kaup, 1829 currently comprises more than 140 species distributed worldwide, and 24 are recognized from South America (Moratelli et al. 2019a(Moratelli et al. , 2019b;;Carrión-Bonilla and Cook 2020;Novaes et al. 2021aNovaes et al. , 2021bNovaes et al. , 2021c;;MDD 2022).Recent taxonomic reviews revealed a high diversity within Myotis (e.g., Moratelli et al. 2011aMoratelli et al. , 2013Moratelli et al. , 2016Moratelli et al. , 2017Moratelli et al. , 2019b;;Novaes et al. 2021aNovaes et al. , 2021bNovaes et al. , 2021c)), refuting the hypothesis of LaVal that indicated a relatively low number of species in South America due to late colonization, and competition with other well-established insectivorous bat lineages (LaVal 1973).Although the arrival of Myotis in South America is estimated for the Plio-Pleistocene interval, the genus has undergone a fast and wide-ranging process of diversification (Stadelmann et al. 2007).Therefore, the hypothesis of LaVal was skewed by incomplete taxonomic knowledge in the past, and has no biological correspondence, as shown by most recent phylogenetic and taxonomic studies (Stadelmann et al. 2007;Larsen et al. 2012;Moratelli et al. 2011aMoratelli et al. , 2017;;Carrión-Bonilla and Cook 2020;Novaes et al. 2021aNovaes et al. , 2021b)).
Specifically, no reviews focusing on the species of Myotis from Argentina have been carried out so far.Nevertheless, several studies have made important contributions to our knowledge on the genus in this region (e.g., Barquez et al. 1999Barquez et al. , 2017;;Lutz et al. 2016;Urquizo et al. 2017;Novaes et al. 2018).Currently, 12 species of Myotis are known for Argentina (Barquez andDíaz 2009, 2020;Barquez et al. 2017;Urquizo et al. 2017), even though taxonomic limits are still poorly defined for some species (Novaes et al. 2018).
Based primarily on the large samples of Myotis available in scientific collections, we provide an overview of the taxonomic diversity of Myotis in Argentina, and describe a new species from Yungas Forest.

Methods
This research is part of a critical review of Neotropical Myotis, and more than 7,500 specimens from different localities in South America and Central America have been examined, covering all species currently recognized and their type specimens.Our analyses here were based on 187 specimens from Argentina, deposited in 11 scientific collections: American Museum of Natural History skull (GLS), condylocanine length (CCL), condylobasal length (CBL), condyloincisive length (CIL), basal length (BAL), zygomatic breadth (ZB), mastoid breadth (MAB), braincase breadth (BCB), interorbital breadth (IOB), postorbital breadth (POB), breadth across canines (BAC), breadth across molars (BAM), maxillary toothrow length (MTL), length of the upper molars (M1-3), mandibular length (MAL), and mandibular toothrow length (MAN).See Table 1 for a detailed description of each measurement.
To characterize and discriminate samples, Principal Component (PCA) and Discriminant Function (DFA) analyses were performed in R platform, with 'MASS' (Vanables and Ripley 2002) and 'Lattice' (Sarkar 2008) packages.For these morphometrical analyses, we selected a subset of the skull dimensions (GLS, CIL, MAB, BCB, POB, IOB, BAM, MTL, M1-3, MAN, MAL) representing different axes of length and width of skull, rostrum, and mandible.As multivariate procedures require complete data sets, missing values (less than 5% of the total dataset) were estimated from the existing raw data using Amelia II package (Honaker et al. 2011) implemented in R platform.Measurements were transformed to natural logs, and covariance matrices were computed considering all variables.Due to the disparity among samples, we randomly selected a maximum of 10 individuals per species, covering almost all Myotis species from Argentina, except for M. izecksohni and M. oxyotus, with only one specimen available each.Qualitative traits employed here to characterize and distinguish species follow Moratelli et al. (2013) and Novaes et al. (2021b), being: (i) presence and height of the sagittal crest; (ii) presence and height of lambdoidal crests; (iii) shape of the braincase roof, being the upper portion formed by the sagittal and parietal suture; (iv) shape of the posterior region of the braincase, being formed by the interparietal and supraoccipital bones; (v) development of the mastoid process; (vi) fur on the leg and dorsal surface of the uropatagium; and (vii) fur texture and coloration.The dental nomenclature follows Miller (1897) and capitalized color nomenclature follows Ridgway (1912).
Principal Component Analysis (Fig. 1) showed that 86% of the variation is related to skull size (PC1), especially in measurements associated with skull and mandible length (GLS, CIL, MAL), mastoid and braincase breadth (Table 2).Vector correlation loadings on PC2 indicate that this component is related to the shape, and represented 30% of the variation.This analysis indicates a wide overlap along the first and second axes.The first two discriminant functions (DF1 and DF2) of the Discriminant Function analysis represented 41% and 29% of the skull variation, respectively.There is partial discrimination among the species samples, except for M. dinellii and M. levis, which are totally overlapping, and M. nigricans and M. lavali which are partially overlapping.Along these axes, Myotis sp.nov. is fully distinct from all other analyzed species.
Skull and external linear morphometric measurements indicated that Myotis sp.nov. is consistently smaller than most species found in Argentina; but there is partial overlap for forearm length and some cranial measurements with M. lavali, M. nigricans, and M. riparius (Tables 3-7).Additionally, qualitative morphological characters unequivocally distinguish these species.We present here the description of a new species from Salta Province, including a morphological diagnosis and comparisons with other Neotropical Myotis species.Paratype.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.

Distribution and habitat.
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).
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).
Etymology.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).
Diagnosis.Small to medium sized species 2 mm; GLS 13.1-13.5mm); 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.

Morphological description and comparisons.
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. 2013Moratelli et al. , 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 13.1-13.5mm).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.
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. el-egans), 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.
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 13.8-15.2mm, 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.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.

Myotis albescens Myotis ruber
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).

Myotis nigricans (Schinz, 1821)
Comments.Recent studies have indicated that M. nigricans is a complex of allopatric species (Moratelli et al. 2011a(Moratelli et al. , 2016(Moratelli et al. , 2017(Moratelli et al. , 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  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 12.4-14.2mm, 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.

Myotis levis (I. Geoffroy, 1824)
Comments.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.
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).

Myotis oxyotus (Peters, 1866)
Comments.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

Myotis dinellii Thomas, 1902
Comments.Medium to large-sized species (FA 34.7-39.4mm, body mass 5-6 g; Table 6, Fig. 12), with silky, long fur (LDF 7-9 mm, LVF 6-8 mm).Ears compara- tively 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 13.9-15.2mm, 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.

Myotis riparius Handley, 1960
Comments.Small to medium-sized species 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 indi- Skull moderate in size , 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.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 investiga- tions 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)

Myotis izecksohni Moratelli, Peracchi, Dias & Oliveira, 2011
Comments.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.
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).

Myotis lavali Moratelli, Peracchi, Dias & Oliveira, 2011
Comments.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 13.6-13.8mm, 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.
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).

Discussion
Myotis barquezi occurs in humid seasonal forests from Southern Andean Yungas, an ecoregion with a high richness of mammals, including endemic species (Ojeda and Mares 1989;Barquez and Díaz 2001;Ojeda et al. 2008;Sandoval et al. 2010;d'Hiriart et al. 2015).Our revision of museum specimens indicates the occurrence of another five Myotis species for the Yungas Forest (M.albescens, M. dinellii, M. keaysi, M. lavali, and M. riparius).Historical records of M. nigricans for this ecoregion (i.e., Ojeda and Mares 1989;Barquez and Díaz 2001) need to be revised, considering that recent taxonomic revisions have indicated that this species corresponds to a cryptic complex (Moratelli et al. 2011a;Novaes et al. 2022).Although the Argentine Yungas have received an extensive sampling effort for the bat assemblage during the past 50 years (Barquez and Díaz 2001;Gamboa-Alurralde et al. 2017), the discovery of M. barquezi reveals the need for continued field sampling, associated with careful taxonomic investigations.In addition, there is the possibility of occurrence of other Myotis in Argentina not included in this study, for example M. pampa, a species recently described from pampa grassland in Uruguay close to the Argentina boundary (Novaes et al. 2021c).
Despite recent taxonomic revisions of Neotropical Myotis, we consider that a large part of Myotis species from Argentina have insufficient taxonomic knowledge.Of the 13 species listed for Argentina, three (M.keaysi, M. riparius, and M. simus) show strong morphological variation in relation to the type specimens and topotype series (Moratelli et al. 2011b;Novaes et al. 2017Novaes et al. , 2021b)), with poorly delimited taxonomic limits, which may hide cryptic diversity; and three are known from few specimens (M.barquezi, M. izecksohni, and M. oxyotus).

Figure 1 .
Figure 1.Plots showing dispersion points and vector correlation of skull measurements of Principal Component Analysis (upper) and Discriminant Function Analysis (lower) for Myotis species from Argentina.

Figure 2 .
Figure 2. Dorsal (A) and ventral (B) views of the skin of the holotype of Myotis barquezi (CML 7623).

Figure 3 .
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.

Figure 4 .
Figure 4. Map of part of South America with type locality of Myotis barquezi (red star).
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.The distribution is associated with ombrophilous and seasonal tropical forests from Northeastern Brazil to
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 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.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
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.
and Yungas Forest from Salta and Santiago del Estero Provinces, in an altitudinal range from 120 to 800 m.Myotis cf.simus Comments.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. si-mus 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

Table 2 .
Vector correlation loadings with original variables of principal components (PC1 and PC2) and discriminant functions (DF1 and DF2) for selected samples of the Argentinean Myotis.

Table 4 .
External and craniodental measurements of Argentinean populations of Myotis albescens, M. ruber, and M. nigricans, including morphometric variation and number of samples (N).The measurements are in millimeters.Acronyms and descriptions are available in Table1.

Table 5 .
External and craniodental measurements of Argentinean populations of Myotis levis, M. chiloensis, and M. oxyotus, including morphometric variation and number of samples (N).The measurements are in millimeters.Acronyms and descriptions are available in Table1.

Table 6 .
External and craniodental measurements of Argentinean populations of Myotis cf.simus, M. dinellii, and M. keaysi, including morphometric variation and number of samples (N).The measurements are in millimeters.Acronyms and descriptions are available in Table1.

Table 7 .
External and craniodental measurements of Argentinean populations of Myotis riparius, M. izecksohni, and M. lavali, including morphometric variation and number of samples (N).The measurements are in millimeters.Acronyms and descriptions are available in Table1.