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 armatum (H. Milne Edwards, 1840) Oxycephalus armatus H. Milne Edwards, 1840: 101 . Rhabdosoma armatum .— Brusca, 1981: 12 (list), 32 (key), fig. 21b; Siegel-Causey, 1982: 350 (key), 351; Vinogradov et al ., 1996: 536 (key), 536‒540, fig. 231; García Madrigal, 2007: 157 (list); Gasca, 2009: 89 (tab. 1); Lavaniegos & Hereu, 2009: 152 (appendix); Zeidler, 2016: 76‒79 (passim), figs. 35, 36A, 36Md, 36Mxp, 79 (key). Material examined . 2F in two localities ( Fig. 3 ). TALUD I. St. 5 (ca. 23°16’ N , 107°31’W ), December 11, 1989 , 1F, BO from surface to ca. 200 m (TD> 1500 m ) (ICML-EMU-12962); St. 6 ( 23°15’54”N , 107°31’12”W ), December 12, 1989 , 1F, BO, from surface to 1550 m (TD> 2000 m ) (ICML-EMU-12963) . Distribution . Tropical and subtropical waters in the Pacific, Atlantic, and Indian Oceans. In the eastern Pacific from California to Peru ( Vinogradov et al . 1996 , García Madrigal 2007, this study). Remarks . Species of Rhabdosoma have an easily recognized slender and elongated body. Rhabdosoma armatum can be distinguished mainly by the shape and proportions of the telson, with double urosomite, and uropods. Most commonly found in 25‒50 m depth ( Vinogradov et al . 1996 ). Rare in the southern Gulf of California and always present in surface waters ( Siegel-Causey 1982 ). Also recorded in the Mexican portion of the California Current ( Lavaniegos & Hereu 2009 ). Another rare species ( two specimens in two localities) in our survey ( Fig. 3 ).