Description of a new species of Liropus (Crustacea, Amphipoda) from Puerto Vallarta, Pacific coast of Mexico Author Alarcón-Ortega, Lucy C. Instituto de Ciencias del Mar y Limnología (ICMyL), Universidad Nacional Autónoma de México (Unidad Académica Mazatlán), Avenida Joel Montes Camarena s / n, Cerro del Vigía PO Box 811, Mazatlán C. P. 82040, Mexico. & Instituto de Investigaciones Oceanológicas-UABC, Carretera Tijuana-Ensenada 3917, Colonia Playitas, Ensenada, B. C., C. P. 22860, Mexico Author Carballo, José L. 0000-0002-5146-7597 Instituto de Ciencias del Mar y Limnología (ICMyL), Universidad Nacional Autónoma de México (Unidad Académica Mazatlán), Avenida Joel Montes Camarena s / n, Cerro del Vigía PO Box 811, Mazatlán C. P. 82040, Mexico. & Laboratorio de Biología Marina, Departamento de Zoología, Universidad de Sevilla, Avda. Reina Mercedes, 6, 41012, Sevilla, Spain & jlcarballo @ ola. icmyl. unam. mx; https: // orcid. org / 0000 - 0002 - 5146 - 7597 jlcarballo@ola.icmyl.unam.mx text Zootaxa 2022 2022-06-17 5154 5 528 536 journal article 77230 10.11646/zootaxa.5154.5.2 b6528a71-4b81-4919-81d0-6f290763bcdd 1175-5326 6655447 6EBF7031-EFFE-4E36-A611-21D85AB6F61C Key of the World species of Liropus Mayer, 1890 Modified from Guerra-García (2004) , Guerra-García et al. (2008) , and Guerra-García and Hendrycks (2013) . 1a. Pereopods 3 and 4 one-articulate......................................................................... 2 1b. Pereopods 3 and 4 two-articulate............................................... L. azorensis Guerra-García, 2004 2a. Pereopod 5 with three-articulate.......................................................................... 3 2b. Pereopod 5 with two-articulate........................................................................... 5 3a. Body dorsally smooth......................................................... L. nelsonae Guerra-García, 2003 3b. Body with an anterolateral projection in pereonites 2, 3 and 4 in males........................................... 4 4a. Head with two anterolateral acute projections.................................... L. willyi Guerra-García et al. , 2018 4b. Head with two tiny dorsal tubercles, near the eyes............................... L. vitucoi Guerra-García et al. , 2018 5a. Flagellum of antenna 1 two-articulate..................................................................... 6 5b. Flagellum of antenna 1 more than two-articulate............................................................. 7 6a. Gnathopod 2 propodus bearing a medial deep triangular cleft with roughly serrate margins distally... L. japonicus Mori, 1995 6b. Gnathopod 2 propodus palm providing one large grasping spine................................................ 8 7a. Head smooth......................................................................................... 9 7b. Head with one or two projections........................................................................ 10 8a. Pereonite 4 with a distally dorsal acute projection................................. L. gurui Guerra-García et al ., 2015 8b. Pereonites 2, 3, 4 and 5 each with one dorsaldistal projection...................................... L. alarconi n. sp. 9a. Gnathopod 2 basis with a basal constriction.............................................. L. minimus Mayer, 1890 9b. Gnathopod 2 basis with parallel margins, lacking constriction............................... L. elongatus Mayer, 1890 10a. Head with a single anterior projection (= rostrum)....................................... L. gracilis Chevreux, 1927 10b. Rostrum absent, but a pair of anterolateral projections present............................... L. africanus Mayer, 1920 11a. Dorsal projection on pereonites 3, 4 and 5 in males, and 3 and 5 in females................................................................................................ L. cachuchoensis Guerra-García, Sorbe & Frutos, 2008 11b. Anterolateral projection on pereonites 2, 3 and 4....................... L. minusculus Guerra-García & Hendrycks, 2013 12a. Pereonites 2 and 3 with a pair of anterolateral acute and directed downwards projections............................................................................................... L. isabelensis Sánchez Moyano et al. , 2015 12b. Pereonites 2 and 3 without dorsal or anterolateral projections.................... L. guerragarciai Mauro & Serejo, 2015