ti 
AMERICAN MUSEUM NOVITATES NO. 3963 
INTRODUCTION 
The genus Myotis is the most speciose genus of bats with over 120 extant species and a 
range that covers most of the world (Simmons, 2005; Simmons and Cirranello, 2020). Myotis 
bats are primarily insectivorous and range from tiny species that weigh only a few grams (e.g., 
Myotis elegans, 3-5 g; Reid, 2009) to quite large species (e.g., Myotis chinensis, 30-40 g; Francis, 
2001), and have color patterns that range from brown or black to brightly colored yellow or 
orange, including some dichromatic taxa with particolored orange and black wings (e.g., Myotis 
welwitschii; Monadjem et al., 2010). Members of the genus are recognized by a combination of 
traits including ears that are longer than they are wide, a lanceolate tragus, a simple narial 
region with nostrils that open anterolaterally and not dorsally, a dental formula of [2/3, C1/1, 
P3/3, M3/3 = 38 (although some species lack p3 and P3), a single-rooted p3 that is somewhat 
smaller than p2, myotodont lower molars (although a few species are seminyctalodont), lower 
molars that have a relatively deep talonid basin, well-developed entocristid, and lack a lingual 
cingulid, a relatively high-crowned lower canine with well-developed mesial and distolingual 
shelves, a tall, daggerlike upper canine with a distinct lingual ridge, anterior upper premolars 
that are reduced in size compared to the P4, which is simple with rounded labial shelf, and an 
M1 and M2 with a distally open protofossa and lacking a paraconule and metaloph, and having 
a hypocone that is either small or absent (Findley, 1972; Koopman, 1994; Ruedi et al., 2015; 
Gunnell et al., 2017). Many species are cryptic and difficult to distinguish from similar conge- 
ners, and more than 20 new species have been described or elevated from synonymy in the last 
decade (Simmons, 2005; Simmons and Cirranello, 2020). 
Only 11 species of Myotis are currently known from continental Africa, and only eight of 
these occur in tropical sub-Saharan regions, suggesting that new and/or cryptic species of 
Myotis likely remain to be discovered given the vast size and diverse habitats of the African 
continent (Patterson et al., 2019; Simmons and Cirranello, 2020). A recent study of genetic 
variation among and within populations of African Myotis by Patterson et al. (2019) found 
evidence of strong geographic structure within two species (M. tricolor and M. welwitschii) 
suggesting possible cryptic species in these complexes. As with many African bat taxa, sam- 
pling effort has been very uneven, especially in tropical areas, and large sampling gaps remain 
for all Myotis species (Patterson et al., 2019). 
The Nimba Mountains are an isolated mountain range in West Africa that straddles the 
borders of Guinea, Liberia, and Céte d'Ivoire (fig. 1). With peaks rising between 1600-1750 m 
above sea level, the mountain range is surrounded by lowland habitats and occupies a transition 
zone between the tropical forest zone and moist woodlands. The Nimba Mountains support 
exceptional biodiversity including a diverse bat fauna that includes several threatened and 
endangered species (Brosett, 2003; Denys et al., 2013; Monadjem et al., 2016). In January and 
February 2018, and in March 2019, we conducted field surveys to assess the species diversity 
and distribution patterns of subterranean roosting bats in the northern (Guinean) portion of 
the Nimba Mountains. Surveys were carried out in the Mining Concession and Perimeter, 
managed by Société des Mines de Fer de Guinée S.A (SMFG), as well as in the adjacent World 
Heritage Site and surrounding lowlands, as part of SMFG's environmental and social impact 
