mortenthaleri, Nannostomus marginatus Paepke [H.-J.] & Arendt [K.] 2001:144, Figs. 1-6, 10-13, 15 [Verhandlungen der Gesellschaft für Ichthyologie 2001; ref. 26010] Small tributary of Rio Nanay at the village of Alvarenga, Loreto, Province of Maynas (=Iquitos), 3°31'10"S, 74°25'40"W, Peru. Holotype: MUSM 17719. Paratypes: MUSM 17720 (3); MTD F 24773 (3); ZMB 33228 (4), 33229 (6, stained and partially damaged). Type catalog: Zarske 2003:19 [ref. 27474]. •Synonym of Nannostomus marginatus Eigenmann 1909, but a valid subspecies as described -- (Paepke & Arendt 2001:143 [ref. 26010]). •Valid as Nannostomus mortenthaleri Paepke & Arendt 2001 -- (Weitzman & Weitzman in Reis et al. 2003:245 [ref. 27061], Zarske 2009:11 [ref. 30197], Meza-Vargas et al. 2021:15 [ref. 39298], Marinho 2024:388 [ref. 40817]). Current status: Valid as Nannostomus mortenthaleri Paepke & Arendt 2001. Lebiasinidae: Pyrrhulininae. Distribution: South America: Nanay River drainage, Loreto, Peru. Habitat: freshwater.