Pipistrellus crassulus Thomas, 1904: 206.
Pipistrellus ( Pipistrellus) crassulus: Hill and Harrison, 1987: 242, 272.
Hypsugo crassulus: Heller et al., 1994: 3, 4, 5.
Pipistrellus ( Vansonia) crassulus: Koopman, 1994: 116.
Hypsugo eisentrauti: Volleth and Heller, 1994: 13, 20, 26.
SMF 79.441 ( Rwanda), SMF 79.442 (DR Congo, Kivu region, Centre de Recherche en Sciences Naturelles, 850 m a.s.l.); FMNH 167775- 776, male ( Gabon), FMNH 108168, male ( Sudan), FMNH 83599, male ( Angola), FMNH 165170-171, male ( Uganda), FMNH 152767, male ( Kenya), BMNH 1904.2.8.1 ( holotype), SMF 79441 -442 ( DR Congo).
The species occurs from Cameroon and Angola eastwards to Kenya ( Fahr, 2013). Chromosome number of a specimen from DR Congo was: 2n = 30, aFN = 56 ( Volleth et al., 2001). This is the smallest species of the genus ( Tables 3 and 4).