Pelagic amphipods (Crustacea: Amphipoda: Hyperiidea) in western Mexico. 7 Superfamily Platysceloidea. Family Oxycephalidae Author Gasca, Rebeca 0000-0002-9716-1964 El Colegio de la Frontera Sur, Unidad Chetumal, Av. del Centenario km 5.5, Chetumal, Quintana Roo, 77014, Mexico. rebegasca @ gmail. com; https: // orcid. org / 0000 - 0002 - 9716 - 1964 & Currently retired. rebegasca@gmail.com Author Hendrickx, Michel E. Laboratorio de Invertebrados Bentónicos, Unidad Académica Mazatlán, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, PO Box 811, Mazatlán, 82000 Sinaloa, Mexico. text Zootaxa 2022 2022-03-03 5105 2 219 236 journal article 20349 10.11646/zootaxa.5105.2.3 d9ad8d5b-dd70-4efe-8a01-76ea5babc6b8 1175-5326 6332529 2B46C765-C80B-437B-B8C2-95335D589E9F Rhabdosoma brevicaudatum Stebbing, 1888 Rhabdosoma brevicaudatum Stebbing, 1888: 350 (key), 357; Brusca, 1981: 12 (list), 32 (key), fig. 21d; Siegel-Causey, 1982: 357 ; Vinogradov et al ., 1996: 536 (key), 540‒541, fig. 233; García Madrigal, 2007: 157 (list); Gasca, 2009: 89 (tab. 1); Lavaniegos & Hereu, 2009: 152 (appendix); Lavaniegos, 2014: 5 (tab. 1); Valencia et al ., 2013: 52 (tab. 1); Zeidler, 2016: 79 (passim), fig. 36D, 80 (key); Violante-Huerta et al ., 2021: 81 (tab. 1), 84‒85, fig. 2C. Material examined . 4F in one locality ( Fig. 3 ). TALUD V . St. 5 ( 22°00’57”N , 106°40’00”W ), December 13, 2000 , 4F , MN from surface to ca. 1400 m (TD> 1600 m ) (ICML-EMU-12964) . Distribution . Subtropical Pacific Ocean, Atlantic Ocean from equator to 40°N ; Mediterranean Sea. In the eastern Pacific from California to Costa Rica and Panama (García Madrigal 2007, Valencia et al . 2013 , Violante-Huerta et al . 2021 , this study). Remarks . The specimens identified as R. brevicaudatum have a very small article on top of callynophore, smaller than in Zeidler’s (2016) key, the telson length is about 1/3 of the length of the double urosomite and does not reach the tip of uropod 2. The specimens examined are very similar to those of R. minor examined herein. Males of this species are not kown. Reported as rare in the central and southern Gulf of California by Siegel-Causey (1982) , a pattern confirmed during our study ( Fig. 3 ). Also present in the Mexican portion of the California Current ( Lavaniegos & Hereu 2009 , Lavaniegos 2014 ).