taxonID	type	description	language	source
03A00548FFBBBD01ED9BA7B3A7BCFBB7.taxon	description	(Fig. 2) Material examined. Boca del Caimanero, Mazatlán. Jun 7,2018, 1 female (TL 16.5) in the buccal cavity and 1 male (TL 8.7) in the gill chamber of Mugil cephalus (Mugilidae), (ICML-EMU 13783). Distribution. From SW California to Mazatlán, including the Gulf of California (see Hadfield and Smit, 2020). Previous known hosts. Mugil cephalus and Mugil hospes (see Hadfield and Smit, 2020). Remarks. According to Brusca (1981), the genus Ceratothoa Dana, 1852 and Cymothoa Fabricius, 1793 are two of the most common genera of tonguebiters (cymothoids found inside the buccal-cavity of fish). According to Hadfield et al. (2014), species of Ceratothoa can be easily identified by the presence of a triangular cephalon, contiguous antennular bases, pleonite 1 narrower than the other pleonites, and an elongate body (2.1 – 2.9 times as long as wide). Ceratothoa gilberti is easily distinguished from the other Ceratothoa species because it is the only species without a considerable expansion at the base of the latter pereopods 5 – 7 (Bruce and Bowman, 1989). According to Brusca (1981) and Espinosa-Perez and Hendrickx (2001), only two species of Ceratothoa have been found on the eastern Pacific coast, Ce. gilberti and Ce. gaudichaudii (species inquirenda). In a comprehensive review of the fish hosts of Ce. gaudichaudii elaborated by Muñoz and Olmos (2007), the authors mentioned that the species has been found in the buccal cavity, branchial arches, and gill chamber of 14 fish species of elasmobranch and teleost fishes. However, none of those species belongs to the family Mugilidae and Ce. gilberti has only been found infesting Mugilids (Hadfield and Smit, 2020).	en	Salgado-Barragán, Mayra Ixchel Grano-Maldonado Gerardo Pérez-Ponce de León Hugo Aguirre-Villaseñor José (2025): New host records of parasitic isopods of Tropical Eastern Pacific marine fishes, with remarks on the taxonomy and distribution of the species. Nauplius (e 20250555) 33: 1-13, DOI: 10.1590/2358-2936e20250555, URL: https://doi.org/10.1590/2358-2936e20250555
03A00548FFBBBD00EE25A29CA7BDFD07.taxon	description	(Fig. 3) Material examined. Boca del Asadero, Nayarit, Nov 28, 2019, 21 females (TL 14.8 – 21.6) and 1 male (TL 12.9), caudal fin of Micropogonias altipinnis (Sciaenidae) (ICML-EMU 13784). Urías estuary: Oct 13, 2023, 3 females (TL 15 – 18.9) on Bagre panamensis (Ariidae) (ICML-EMU 13785 - A). Off Mazatlan bay: Ago 12, 2023, 2 females (TL 22.8 – 24) on caudal fin of M. altipinnis (ICML-EMU 13785 - B); Ago 27, 2023, 5 females (TL 12.0 – 16.8), fins of B. panamensis (ICML-EMU 13785 - C); Ago 27, 2023,1 female (TL 16.5), on Ophoioscion scierus (Sciaenidae) (ICML-EMU 13785 - D); Oct 9, 2023, 4 females (TL 14.2 – 18.5), on Hoplopagrus guentherii (Lutjanidae) (ICML-EMU 13785 - E); Oct 14, 2023, 2 males (TL 10.1 – 12.3) on fins of B. panamensis, (ICML-EMU 13785 - F); Dec 8, 2023, 25 females (TL 14.6 – 21.7) and 2 males (TL 12.0 – 12.3), on caudal fin of M. altipinnis, (ICML-EMU 13786); Dec 13, 2023, 5 females (TL 14 – 15.7), on B. panamensis (ICML-EMU 13785 - G); Dec 20, 2023, 2 females (TL 17.1), on B. panamensis (ICML-EMU 13785 - H); Jan 12, 2024, 2 females (TL 15.2 – 19.8) on B. panamensis; Jan 12, 2024, 2 females (TL 15.2 – 16.5) on Polydactylus opercularis (Polynemidae) (ICML-EMU 13785 - I). Additional record: Off Mazatlán Bay Mar 28, 2023, 1 female was observed on the dorsal fin of Aluterus monoceros (Monacanthidae). Distribution. California, from the Gulf of California to Ecuador and the Galapagos Islands. Previous known hosts. About 45 host fish species of 20 families (see Brusca, 1981; Del Moral-Flores et al., 2020). Remarks. Most of the reports of Nerocila in the Eastern Pacific had been referred to N. acuminata (e. g. Brusca, 1981), although those records are currently attributed to N. californica (Segal, 1987; Del Moral-Flores et al., 2020); this contention is supported by Boyko et al. (2024) who showed that the distribution of N. acuminata is restricted to the western Atlantic coast, with the vast majority of records across the Gulf of Mexico; instead, the distribution of N. californica extends from California, including the Gulf of California, to the Galapagos Islands. In this study, most of the specimens of N. californica were collected from the caudal fin of the fishes, especially on B. panamensis captured off Mazatlán and the Urías estuary; the highest parasite loads were recorded from the caudal fin of two specimens of M. altipinnis (21 and 27 parasites). In our study, we added M. altipinnis, B. panamensis, H. guentherii, A. monoceros, P. opercularis, and O. scierus as new hosts of N. californica (Tab. 1).	en	Salgado-Barragán, Mayra Ixchel Grano-Maldonado Gerardo Pérez-Ponce de León Hugo Aguirre-Villaseñor José (2025): New host records of parasitic isopods of Tropical Eastern Pacific marine fishes, with remarks on the taxonomy and distribution of the species. Nauplius (e 20250555) 33: 1-13, DOI: 10.1590/2358-2936e20250555, URL: https://doi.org/10.1590/2358-2936e20250555
03A00548FFBABD00E94EA50FA653F895.taxon	materials_examined	Material examined. Off Mazatlán Bay: Oct 13, 2018, 1 female (TL 32.5), in the buccal cavity of Lutjanus aratus (Lutjanidae) (ICML-EMU 13774); Oct 16, 2023, 1 female (TL 24.2), in buccal cavity and 1 male (TL 15.7) in gill chamber of Lutjanus peru (ICML-EMU 13779).	en	Salgado-Barragán, Mayra Ixchel Grano-Maldonado Gerardo Pérez-Ponce de León Hugo Aguirre-Villaseñor José (2025): New host records of parasitic isopods of Tropical Eastern Pacific marine fishes, with remarks on the taxonomy and distribution of the species. Nauplius (e 20250555) 33: 1-13, DOI: 10.1590/2358-2936e20250555, URL: https://doi.org/10.1590/2358-2936e20250555
03A00548FFB9BD02EDA2A33DA03FFB01.taxon	description	(Fig. 5) Material examined. Mazatlán Bay, Mar. 3, 2023, 1 female (TL 4.6), gills of Lutjanus argentiventris (Lutjanidae) (EMU 13780); 2 females (TL 7 – 10), gills of H. guentherii. Sep. 20, 2023, 2 females (TL 10.4 – 11.4), gills of H. guentherii. Nov. 4, 2023, 1 female (TL 15.3), gills Eucinostomus currani (Gerridae). Nov. 8, 2023, 1 female (T. L. 13.1), gills Balistes polylepis (Balistidae). Distribution. California, U. S. A., to Ecuador and Galapagos Islands (Brusca and France, 1992). Previous known hosts. In the Eastern Pacific, Anisotremus interruptus (Haemulidae), Mycteroperca jordani (Serranidae), Parapsettus panamensis (Ephippidae), Euthynnus lineatus (Scombridae), Scomberomorus sierra (Scombridae), Caranx sexfasciatus, Caranx caninus, Caranx caballus, Caranx vinctus, Chloroscombrus orqueta, S. peruviana, Hemicaranx leucurus (Carangidae), H. guentherii and L. guttatus (Lutjanidae) (Brusca and France, 1992; Miranda-Delgado et al., 2019; Santos-Bustos et al., 2020 a; Violante-González et al., 2016; 2020; Villalba et al., 2022; Osuna-Cabanillas et al., 2024). Remarks. According to Brusca and France (1992), Ro. signata can be distinguished from the other species of Rocinela by having a long medial process of the uropodal peduncle (more than 70 % of the uropod length), distal margin of pereonites smooth, and the propod of pereopods I – III not medially expanded with only 1 or 2 minute spiniform setae. Another character considered reliable for the identification of R. signata is the presence of a chromatophore pattern similar to an inverted “ W ” on the dorsum of the pleotelson (Moreira, 1972; Cardoso et al., 2017; Aguilar-Perera and Noh-Quiñonez, 2022). The specimens we sampled correspond with the description of Ro. signata given by Brusca and France (1992), however, only two of the six specimens of our study had a “ W ” - like pattern of chromatophores on the pleotelson (Fig. 5 b). Brusca and France (1992) had already pointed out that the chromatophore pattern was not constant among nearly 60 of the specimens from the Eastern Pacific they observed. Moreover, if the presence of Ro. signata in the Eastern Pacific is not the result of its introduction in relatively recent times, its amphi-American distribution is, at least, suspicious. In this context, Baddour et al. (2024) refer to a case of parasitism of Ro. signata on Fistularia commersonii (Fistulariidae) in Syria although they support their identification with a poor description and the presence of an inverted “ W ” in the pleotelson of the isopods. We cannot rule out that the presence of “ Ro. signata ” in Syria was a case of an introduction of the species in that region, but we consider that a key identification of this species based on the pigmentation of the pleotelson could be erroneous. The variations in the body parts and chromatophore patterns of the specimens reported as Ro. signata lead us to think that the wide distribution of this species could represent a species complex. A detailed study and the comparison of individuals from different populations, based on both, morphological and molecular analysis, is desirable to assess the taxonomic status of this species.	en	Salgado-Barragán, Mayra Ixchel Grano-Maldonado Gerardo Pérez-Ponce de León Hugo Aguirre-Villaseñor José (2025): New host records of parasitic isopods of Tropical Eastern Pacific marine fishes, with remarks on the taxonomy and distribution of the species. Nauplius (e 20250555) 33: 1-13, DOI: 10.1590/2358-2936e20250555, URL: https://doi.org/10.1590/2358-2936e20250555
03A00548FFB8BD02EC1DA30AA637F87E.taxon	description	(Fig. 6) Material examined. Mazatlán Bay: Sep. 13, 2023, 12 praniza larvae (TL 2.4 – 2.6), on gills of H. guentherii; Oct 8, 2023 29 praniza larvae (TL 1.8 – 2.1) on gills of E. currani; Jun 6, 2022 8 praniza larvae (TL 2.2 – 2.3) on gills of B. polylepis; Nov. 28, 2023, 153 praniza larvae (TL 2.3 – 2.6), on gills of Ephinephelus labriformis (Serranidae); Oct. 12 2023, 85 praniza larvae (TL 1.9 – 2.3), on gills of L. guttatus; Nov 5, 2023, 85 praniza larvae (TL 2.4 – 2.7), on gills of M. cephalus; Nov 12, 2023 383 pranizas larvae (TL 2.1 – 2.6), on gills of Diapterus peruvianus (Gerreidae); Feb 07, 2024 33 pranizas larvae (TL 2.0 – 2.4), on gills of Tylosurus pacificus (Belonidae). Distribution. Mazatlán Bay. Previous known hosts. In the Eastern Pacific, Caranx caninus, Caranx caballus, Caranx vinctus, Selene brevoortii (Carangidae); P. panamensis; Euthynnus lineatus, and Sarda orientalis (Scombridae) (Violante-González et al., 2016; 2020; Miranda-Delgado et al., 2019; Villalba-V á zquez et al., 2018; Santos-Bustos et al., 2020 b; and Osuna-Cabanillas et al., 2024). All these records were made as Gnathia sp. Remarks. At least seven studies on marine fish parasites along the Mexican Pacific coast have reported the presence of the praniza larva of Gnathia sp. (Violante-González et al., 2016; 2020; 2023; Villalba- Vázquez et al., 2018; Miranda-Delgado et al., 2019; Santos-Bustos et al. 2020 b; Osuna-Cabanillas et al., 2024). However, we acknowledge that the taxonomic identification of gnathiids is based on the free-living adult forms (Hadfield et al., 2009). We were unable to associate the praniza and zuphea larvae of the family Gnathiidae with adults of any known species. The identification of these isopods is based on the morphology of the adult males, and this is challenging as males can be difficult to obtain (Smit and Davies, 2004). Only free-living adults of the species Gnathia steveni Menzies, 1962 have been recorded along the Pacific coast of Mexico, particularly in Bahia San Quintin, west Baja California (Espinosa- Pérez and Hendrickx, 2002). The presence of such larvae in the five species of fish reported in this study in Mazatlán represents new host and locality records for this group of isopods (Tab. 1).	en	Salgado-Barragán, Mayra Ixchel Grano-Maldonado Gerardo Pérez-Ponce de León Hugo Aguirre-Villaseñor José (2025): New host records of parasitic isopods of Tropical Eastern Pacific marine fishes, with remarks on the taxonomy and distribution of the species. Nauplius (e 20250555) 33: 1-13, DOI: 10.1590/2358-2936e20250555, URL: https://doi.org/10.1590/2358-2936e20250555
