20 AMERICAN MUSEUM NOVITATES NO. 3963 
times not evident as the color changes gradually (Csorba et al., 2014). Overall, the general 
aspect of the dorsal fur in M. formosus and M. rufopictus is pale yellow-brown (Csorba et 
al., 2014). This pattern is very different from the distinctly banded tricolored orange fur of 
M. nimbaensis. Ventral fur of M. formosus and M. rufopictus is either bicolored light yellow 
with a narrow brown base, or unicolored light yellow (Csorba et al., 2014), again quite dif- 
ferent from tricolored buff to orange ventral fur of M. nimbaensis. The ear is faintly edged 
with black in the formosus-type species (Csorba et al., 2014) but not in M. nimbaensis. As in 
M. rufoniger, the dark pigment in the wing membranes of M. formosus is limited to more 
distal and posterior portions of the plagiopatagium and does not extend to the tibia and 
membranes next to the body as it does in M. nimbaensis. 
Measurements and craniodental features also distinguish Myotis nimbaensis from M. 
formosus and M. rufopictus. In terms of measurements, M. nimbaensis is only trivially dif- 
ferent or falls within the range of variation in measurements reported for M. formosus (FA 
= 45.5-53.0 mm; GLS = 17.91-19.45 mm; ZB = 11.76-12.94 mm; Csorba et al., 2014). How- 
ever, M, formosus as described by Csorba et al. (2014) can be distinguished based on having 
a sagittal crest that is missing or only very weakly developed (moderately well developed in 
M. nimbaensis), P3 that is not visible in lateral view of the skull (visible in M. nimbaensis), 
and a p3 with half the basal area of p2 (p3 is at least three quarters the basal area of p2 in 
M. nimbaensis). In addition, the skull of M. formosus lacks an expanded supraorbital region 
and appears to have a shorter rostrum than M. nimbaensis when seen in lateral view. Myotis 
rufopictus (FA = 51.0-52.5 mm; GLS = 18.2 mm; ZB = 11.17; Csorba et al., 2014) appears 
slightly smaller than M. nimbaensis, but both species are known from very few specimens, 
so the value of this observation is questionable. As described by Csorba et al. (2014), the 
skull profile of M. rufopictus ascends almost evenly with no frontal depression (i.e., no clearly 
defined break between rostrum and sloping forehead as seen in M. nimbaensis). Like Myotis 
formosus, M. rufopictus additionally lacks an expanded supraorbital region and it appears to 
have a shorter rostrum than M. nimbaensis when seen in lateral view. Morphology of P3 in 
M. rufopictus is unknown, but p3 is a very small tooth less than one quarter the basal area 
of p2 and displaced lingually halfway out of the line of toothrow (p3 at least three quarters 
the area p2 and not displaced in M. nimbaensis). 
ECHOLOCATION CALLS: Based on the echolocation calls recorded on the release of the 
holotype (n = 22), Myotis nimbaensis emits a broad bandwidth (84.1 + 13.1 kHz; FMAX: 104 
kHz, FMIN: 20 kHz) steep frequency-modulated pulse with a peak frequency of 42,5 kHz (+ 
4.2 kHz), an average call duration of 3.5 ms (+ 0.3 ms), and an interpulse interval of 113 ms 
(+ 5.3 ms; fig. 9). In comparison, echolocation calls of Myotis welwitschii have a lower peak 
frequency (34 kHz), shorter bandwidth (28.3 kHz) and shorter duration (2.4 ms; Schoeman 
and Jacobs, 2008: Monadjem et al., 2010: Collen, 2012). While there may be geographic varia- 
tion in call parameters between East African and Southern African Myotis tricolor populations, 
calls recorded from Southern Africa have a slightly higher peak frequency (47.84+3.1 kHz) but 
are shorter in bandwidth (46+23.9 kHz) and duration (3.3+0.6 ms; Schoeman and Jacobs, 2008: 
Monadjem et al., 2010). Echolocation calls of Myotis morrisi are unknown. Myotis bocagii, the 
