The 36 species (associated in eight genera) reported for Vespertilionidae family are widely distributed across South America. In Ecuador, occur 20 species of these vesper bats and the genus Myotis is the most diverse with eight species (Gardner 2008, Burgin et al. 2018). The Myotis species list include: M. nigricans Schinz 1821 (Black Myotis); M. oxyotus Peters 1867 (Montane Myotis); M. albescens Geoffroy 1806 (Silver-tipped Myotis); M. caucensis Allen 1914 (Cauca Myotis); M. diminutus Moratelli and Wilson 2011 (Diminutive Myotis); M. keaysi Allen 1914 (Hairy-legged Myotis); M. simus Thomas 1901 (Velvety Myotis) and; Myotis riparius Handley 1960 (Riparian Myotis).
Myotis riparius occurs from sea level to about 2000 m (LaVal 1973, Novaes et al 2015). In Ecuador M. riparius is reported frequently at altitudes ranged between 10 to 1240 m, on both Andeans slopes, inhabits dry forest, rain forest, subtropical zones and even humanmodified habitats (Tirira 2017). This species is small, the forearm is 32.3 - 39.8 mm, with moderately long woolly fur, the dorsal hairs are brown and ventral hairs bicolored with yellowish tips and blackish bases; however, these patterns have geographic variation (LaVal 1973, Novaes et al. 2017). Besides, the uropatagium lacks a fringe of hairs on the edge; the plagiopatagium is broadly attached to the foot base. The skull is medium size 13.2 - 15.2 mm of length, the third upper premolar (P3) is often displaced to the lingual position, or less frequently positioned almost in the toothrow, the sagittal and lambdoidal crests are present and can vary from high to low (López-González et al. 2001, Moratelli et al. 2013, Novaes et al. 2017).
Despite M. riparius distribution and the habitats that it occupies are both relative well understood, records from southern Ecuador are found in few localities (Romero 2018). Consequently, in this note we are recording two new localities for M. riparius in the southern Andes of Ecuador. The specimens were captured in a moist cold temperate forest in the south-eastern Andes which corresponds to the temperate zoogeographic region (Holdridge 1967, Albuja et al. 2012). The individuals were collected using mist nets (6 m × 2.40 m). The nets were located at the ground level among paths which intersect the forest. All specimens were deposited in the mammalian collection of Zoology Museum of Universidad del Azuay.
The first specimen (MZUA-MA406) was collected at May 18, 2018 in the Estación Científica San Francisco (ECSF) located in the province of Zamora Chinchipe (3.97°S, 79.07°W, 2200 m), 17 km from Zamora city (Fig. 1). The individual was a subadult male with abdominal testes. This specimen has a medium sized body (Table 1), reddish-brown dorsal hairs and ventral hairs with brown bases and yellowish tips (Fig. 2 A, B). The skull presents medium-sized sagittal and lambdoidal crests; the P3 is displaced on the lingual side (Fig. 3 A, B, C, D) and the ratio between the breadth across canines and postorbital breadth is >1.
The second specimen (MZUA-MA486) was collected at December 7, 2019, near Arenales camp in Mazar Hydroelectric Central (2.57°S, 78.56°W, 2317 m), 31 km from Paute city, province of Azuay (Fig. 1). The individual was an adult male with scrotal testes. This specimen is a medium sized bat (Table 1) with dark-brown dorsal hairs and bicolored ventral hairs with light-brown tips and darker bases (Fig. 2 C, D). The skull has high lambdoidal and sagittal crests; the P3 in lingual position (Fig. 3 E, F, G, H), and the ratio between the breadth across canines and postorbital breadth is > 1.
The all characters of the specimens reported correspond to the species description of Myotis riparius (Barquez et al. 1999, López-González et al. 2001, Moratelli et al. 2013, Lutz et al. 2016, Novaes et al. 2017). Therefore, the skull traits used to recognize the species identity: i) presence of sagittal and lambdoidal crests; ii) the relation between breadth across canines and postorbital breadth > 1 (BAC/POB) and; iii) the position of P3 in relation to toothrow. In addition, the presence of sagittal and lambdoidal crests differentiated these specimens from Myotis nigricans (Barquez et al. 1999, López-González et al. 2001, Moratelli et al. 2013, Lutz et al. 2016, Novaes et al. 2017).
Myotis riparius records in South America are below 2000 m in ecosystems such as tropical rain forest, savanna, deciduous forest and anthropic environments (Barquez et al. 1999, Novaes et al. 2015). The only record of this species in montane forest is reported in Central America (Costa Rica) at 2000 m (LaVal 1973). Consequently, these records would be the first in South America for M. riparius in montane forests upper the 2000 m above the known limits for the species. Thus, Arenales camp becomes in the known highest record for this species (Fig. 1A).
The record of M. riparius in the high Andes can be explained by its plasticity in habitat choice, because the specie has been recorded in diverse habitats in its geographic distribution range. (LaVal 1973, Novaes et al. 2015). In Ecuador, the ecosystems of the south-eastern slope of the Andes cover large forests which are interconnected (Kvist et al. 2006). This phenomenon may allow to M. riparius and other bats to move across forests with potential elevation movements along the Andean slope. Within this framework, this study improves the knowledge of distribution patterns for southern Ecuador due to we demonstrated that M. riparius occurs in high-altitude Andean forest at least seasonally. Finally, more studies are necessary to determine which particular factors influence the distribution and movement of this species.