Three new species of Amphipoda (Crustacea: Peracarida) from the remote oceanic island of Trindade, off the coast of south-eastern Brazil Author Guedes-Silva, Elkênita Departamento de Invertebrados, Museu de Zoologia, Universidade de São Paulo, São Paulo, Brazil; Author Souza-Filho, Jesser F. Departamento de Oceanografia, Laboratório de Carcinologia, Universidade Federal de Pernambuco, Recife, Brazil Author Tavares, Marcos Departamento de Invertebrados, Museu de Zoologia, Universidade de São Paulo, São Paulo, Brazil; text Journal of Natural History 2024 2024-10-22 58 45 - 48 2075 2098 http://dx.doi.org/10.1080/00222933.2024.2410452 journal article 305691 10.1080/00222933.2024.2410452 231ba7c2-f7b4-4a76-9fbb-7ea609eb46e8 1464-5262 14243227 Key to species of Colomastix from Brazil (adult males) 1a. Gnathopod 1 vestigial .................................................................................................... 2 1b. Gnathopod 1 fully developed ..................................................................................... 4 2a. Head interantennal plate with anteroventral margin serrated ............................ ...................................................................................... C . trispinosa Silvany et al ., 2019 2b. Head interantennal plate with anteroventral margin not serrated ............. 3 3a. Head subequal in length to pereonites 1 and 2 combined; pleopods 1–3 outer rami 4-articulate; uropod 1 inner ramus longer than outer rami; telson lateral margins smooth ................................ C. iemanja Silvany and Senna, 2019 3b. Head subequal in length to pereonite 1 and half-length of pereonite 2; pleopods 1–3 outer rami 4-articulate, inner ramus 3-articulate; uropod 1 inner ramus distal 1/4 of lateral margins closing upon itself, forming a tube with a terminal concavity; telson fringed with numerous short robust setae .... ...................................................................................... C. tubulosa Silvany and Senna, 2019 4a. Head interantennal plate with anteroventral angle projecting beyond anterodorsal angle; uropod 1 asymmetric, right uropod inner apex somewhat expanded and rudder-shaped, left uropod with the rudder-shaped structure atrophied; telson serrate posterolaterally, devoid of hook processes ..... .............................................................................. C. marielle Silvany and Senna, 2019 4b. Head interantennal plate with anteroventral angle not projecting beyond anterodorsal angle; uropod 1 male symmetric; inner ramus tip resembling a ‘venom gland and stinger of a scorpion’ in lateral view; telson ventrodistally with a pair of strong, curved hooks .................................. C. scorpio sp. n.