altum, Sicydium Meek [S. E.] 1907:149 [Field Columbian Museum, Zoölogical Series v. 7 (no. 5); ref. 15159] Turrialba, Costa Rica. Holotype: FMNH 6034. Paratypes: FMNH 6101 (2). Type catalog: Ibarra & Stewart 1987:79 [ref. 12367]. •Valid as Sicydium altum Meek 1907 -- (Bussing 1987:236 [ref. 22927], Bussing 1996:823 [ref. 22890], Bussing 1998:402 [ref. 24179], Murdy & Hoese 2003:1795 [ref. 27111], Kullander in Reis et al. 2003:662 [ref. 27061], Van Tassell 2011:145 [ref. 31732], de Lucena et al.2013:143 [ref. 32517], Angulo et al. 2013:1009 [ref. 33194], Parenti 2021:414 [ref. 38603], Angulo et al. 2023:38 [ref. 40676]). Current status: Valid as Sicydium altum Meek 1907. Oxudercidae: Sicydiinae. Distribution: Central America: Nicaragua and Costa Rica. Habitat: freshwater, brackish, marine.