Inventory of chiton species (Polyplacophora) from the rocky intertidal of the Northern Gulf of California, with an illustrated taxonomic key Author Reyes-Gómez, Adriana Doctorado en Biosistemática y Manejo de Recursos Naturales y Agrícolas. Author Vargas-Ponce, Ofelia Departamento de Botánica y Zoología. Author Galván-Villa, Cristian Departamento de Ecología Aplicada, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Camino Ing. Ramón Padilla Sánchez 2100, Zapopan, Jalisco, 45200, México. Author Salgado-Barragán, José Laboratorio de Invertebrados Bentónicos, Unidad Académica Mazatlán, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, México. Author Esqueda-González, Ma. Del Carmen Departamento de Ecología Aplicada, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Camino Ing. Ramón Padilla Sánchez 2100, Zapopan, Jalisco, 45200, México. Author Ríos-Jara, Eduardo Departamento de Ecología Aplicada, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Camino Ing. Ramón Padilla Sánchez 2100, Zapopan, Jalisco, 45200, México. text Zootaxa 2023 2023-05-26 5296 2 147 178 http://dx.doi.org/10.11646/zootaxa.5296.2.2 journal article 53422 10.11646/zootaxa.5296.2.2 ec74bbc1-8956-4286-95bb-a696b7f1227f 1175-5326 7973065 624273A6-3028-42C2-ABE2-A18BBF828156 Acanthochitona exquisita (Pilsbry, 1893) ( Figures 3F , 10G–L ) Acanthochites exquisitus Pilsbry, 1893: 44–47 . Chresonymy and synonymy in Watters (1990) . Type material. Lectotype , designated by Watters (1990) , ANSP 349332 . Type locality. Bahía Las Ánimas , Baja California (BC), México . FIGURE 11. Dorsal view of head valve (I) of Lepidozona serrata CUCBACM 00471 and Acanthochitona arragonites CUCBACM 00381. Intermediate valve (IV) of Chaetopleura lurida CUCBACM 00347 and A . arragonites CUCBACM 00381 in dorsal view. Dorsal and lateral view of tail (VIII) valve of Lepidozona subtilis CUCBACM 00474, showing the regionalization of the valves and radular teeth structures relevant for the taxonomic study of chitons. a. Notch. b. Apophysis. c. Jugal area. d. Mucro. e. Diagonal ridge. f. Antemucronal area. g. Postmucronal area. h. Lateral area. i. Posterior edge. j. Apex. k. Pleural area. l. Postmucronal slope. m. Insertion plate. n. Lateropleural area. Radula, plates or teeth that constitute the radula, the taxonomically important teeth are indicated with numbers. 1. Central tooth. 2. Minor lateral tooth. 3. Major lateral. 4. Major uncinal tooth. Material examined. Twenty– six specimens , BL 8.3–20.9 mm . Habitat. On large to medium–sized semi–submerged rocks, mainly on rough surfaces with coralline algae, either filamentous, crusty, green, brown or red. Remarks. Acanthochitona exquisita has a sculpture of pustules with one aesthete on the center of its base ( Figs 10J, K ). Intermediate valves with sub–triangular tegmentum and jugal area smooth ( Fig. 10H ). Major lateral radular tooth tricuspid, minor lateral teeth small and short, very reduced; the central tooth appears as a rectangular long plate ( Fig. 10L ). This species can reach body lengths between 25 and 34 mm and is considered a large species within the genus.