Morphology, DNA barcoding and seasonal occurrence of Ergasilus lizae Krøyer, 1863 (Copepoda: Ergasilidae) parasitizing mullets from northwestern Mexico

Syst Parasitol (2024) 101:54 https://doi.org/10.1007/s11230-024-10179-8 Morphology, DNA barcoding and seasonal occurrence of Ergasilus lizae Krøyer, 1863 (Copepoda: Ergasilidae) parasitizing mullets from northwestern Mexico Francisco Neptalí Morales‑Serna · Selena Camacho‑Zepeda Received: 21 February 2024 / Accepted: 26 July 2024 © The Author(s) 2024 Abstract Ergasilus lizae Krøyer, 1863 is a parasitic copepod known to infect mullets (Mugilidae) in different parts of the world. It was originally reported from the east coast of North America, but the original description lacks enough detail, making identification with this information difficult. In this study, we provide a redescription of E. lizae found on Mugil curema Valenciennes and M. cephalus Linnaeus, caught in two coastal lagoons of northwestern Mexico during two climatic seasons: warm/rainy and cold/dry. The prevalence of this parasite was higher in the warm season than in the cold season. To facilitate the species identification, new sequences of the barcoding gene (COI mtDNA) of E. lizae were generated and compared against unpublished sequences of E. lizae available in the Barcode of Life Database (BOLD). Our results suggest that the sequences of BOLD possibly belong to a species misidentified as E. lizae. F. N. Morales‑Serna (*) Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Mazatlán, Mexico e-mail: S. Camacho‑Zepeda Posgrado en Ciencias en Recursos Acuáticos, Facultad de Ciencias del Mar, Universidad Autónoma de Sinaloa, Mazatlán, Mexico Introduction The Ergasilidae Burmeister, 1835 (Crustacea: Copepoda: Cyclopoida) is a family of copepods whose adult females are commonly found parasitizing teleosts, while adult males and larval stages are planktonic in all salinity regimes (Amado et al., 1995). Within this family, Ergasilus von Nordmann, 1832 is the most speciose genus with 163 species (Walter & Boxshall, 2024). Ergasilus lizae Krøyer, 1863, considered a cosmopolitan parasite of mullets, was originally reported from Mugil curema Valenciennes from New Orleans (east coast of USA), and then from other parts of the world, including Italy, Egypt, France, Israel, Turkey, Chile, Brazil, Australia and Mexico (Causey, 1960; Roberts, 1970; Kabata, 1992; Knoff et al., 1994; El-Rashidy, 1999; Özer & Kirca, 2013). As the original morphological description is inadequate, Kabata (1992) redescribed E. lizae based on specimens collected from Mugil cephalus Linnaeus and Trachystoma petardi (Castelnau) caught in Brisbane River, Australia. However, based on lectotype material deposited in Copenhagen Zoological Museum, El-Rashidy (1999) argued that the Australian material revised by Kabata (1992) is not conspecific with E. lizae. In his doctoral thesis, El-Rashidy (1999) redescribed E. lizae with detailed illustrations. Unfortunately, El-Rashidy’s (1999) work was never published. In northwestern Mexico, E. lizae was reported by Causey (1960) from M. cephalus collected in Vol.: (0123456789) 54 Page 2 of 12 Mazatlán, Sinaloa state and San Blas, Nayarit state, but comments related to the species identification were not provided. As far as we know, the presence of E. lizae in Mexican fishes has not been confirmed in previous studies other than Causey (1960). In fact, ergasilids remain largely unstudied in Central America and Mexico and many reports are referred to as Ergasilus sp. (Suárez-Morales & Santana-Piñeros, 2008; Jiménez-García & Suárez-Morales, 2017). The identification of ergasilids could be more precise with the integration of morphological and molecular data, particularly the barcoding gene, cytochrome c oxidase subunit I (COI mtDNA). However, the number of COI sequences is currently limited to very few species of Ergasilus, in part due to difficulties in the amplification process (Míč et al., 2023). Recently, a comparative analysis of COI sequences of ergasilids could only include sequences for three known species of Ergasilus due to the unavailability of verifiable published sequences (Fikiye et al., 2023). One of those three species was E. lizae whose unpublished sequences are available in the Barcode of Life Database (BOLD). These sequences were generated from specimens found in Fundulus diaphanus (Lesueur) collected in Richelieu River, Quebec, Canada. In the present study, we provide morphological data of specimens of E. lizae collected from M. curema and M. cephalus from two coastal lagoons in Sinaloa state, northwestern Mexico. Newly generated COI sequences of E. lizae were compared with sequences retrieved from BOLD. Additionally, the prevalence and intensity of the infection in warm and cold seasons were assessed. Materials and methods Fish and parasite collection Ninety-three specimens of M. curema were purchased from local fishermen in two seasons. These fish were caught during August 2022 (warm/rainy season, with an average temperature of 32 °C) and January 2023 (cold/dry season with an average temperature of 19 °C) in Urías estuary and Huizache-Caimanero coastal lagoon, southern Sinaloa state, northwestern Mexico (Figure 1, Table 1). Additionally, 21 specimens of M. cephalus were purchased from fisherman, caught during August 2023 in Huizache-Caimanero. Vol:. (1234567890) Syst Parasitol (2024) 101:54 Both lagoons have multiple anthropogenic stressors (Martínez-Salcido et al., 2018). Urías estuary has been strongly impacted by sewage and industrial effluents from the Mazatlán harbor, whereas Huizache-Caimanero lagoon has mostly been impacted by agriculture. The geographical distance between these lagoons is approximately 45 km. In the laboratory, fish were identified to species level following Froese and Pauly (2023). The total length (cm) of each fish was recorded. Gills were removed and examined for the presence of parasitic copepods with the aid of a dissecting microscope (Motic, Richmond, BC, Canada). Copepods were counted, removed using fine needles and preserved in 96% ethanol. Morphological analysis Copepods were cleared in 85% lactic acid for a few minutes and then examined under a Leica DMLB microscope. The total body length, from the anterior margin of the prosome to the posterior margin of caudal rami (excluding caudal setae), was measured using an ocular micrometer. Drawings of the entire body and dissected appendages, temporarily mounted in slides with lactic acid, were made with the aid of a drawing tube. Final illustrations were digitally inked using INKSCAPE 1.0. The voucher specimens were deposited in the Copepoda collection of the Instituto de Ciencias del Mar y Limnología, Unidad Académica Mazatlán (ICML-EMUCOP), Sinaloa, Mexico. Molecular analysis Total DNA was extracted using the Jena Bioscience kit, following the manufacturer’s instructions (Jena Bioscience, Jena, Germany). Amplification and sequencing of the COI gene were carried out using invertebrate universal “Folmer” primers LCO1490 (5′-GGT CAA CAA ATC ATA AAG ATA TTG G-3′) and H (...truncated)