Molecular evidence linking the larval and adult stages of Mexiconema cichlasomae (Dracunculoidea: Daniconematidae) from Mexico, with notes on its phylogenetic position among Dracunculoidea

Abstract

We describe the larval developmental stages and life cycle of the dracunculid nematode Mexiconema cichlasomae in both the intermediate, Argulus yucatanus (Crustacea: Branchiura), and definitive hosts, Cichlasoma urophthalmus (Perciformes: Cichlidae), from the Celestun tropical coastal lagoon, Yucatan, Mexico. The morphological analyses showed significant differences between the total length of L1 found in M. cichlasomae gravid female and L2-L3 in A. yucatanus. This result indicates that the M. cichlasomae larval development occurs in the intermediate host. We obtained sequences from the small subunit (SSU) ribosomal marker from larval stages of M. cichlasomae in A. yucatanus and adult nematodes in C. urophthalmus. Our morphological and molecular results support conspecificity between M. cichlasomae larvae in A. yucatanus and the adult stages in C. urophthalmus. We briefly discuss the phylogenetic position of M. cichlasomae among the Daniconematidae, and provide evidence of the monophyly of the daniconematids associated with branchiurid intermediate hosts. Based on the phylogenetic results, we support the transfer of the Mexiconema genus to the family Skrjabillanidae and do not support the lowering of family Daniconematidae to subfamily.

Review of the parasitic nematodes of marine fishes from off the American continent

“…Such submissions limit checks on the accuracy of taxonomic identifications, and some likely misidentifications have been noted by some authors (see Černotíková et al ., 2011; Ailán-Choke et al ., 2019, 2020). However, despite the limited and sometimes inaccurate data, the genetic characterization of nematodes reported herein has been crucial for supporting species validity and the evaluation of their phylogenetic positions (Mejía-Madrid and Aguirre-Macedo, 2011 a , 2011 b ; Sardella et al ., 2017; Aguilar-Aguilar et al ., 2019; Sokolov and Gordeev, 2021), genetic variability (Li et al ., 2014), broad phylogenetic studies of higher taxa (Nadler and Hudspeth, 1998, 2000; Nadler et al ., 2007; Li et al ., 2018; Barton et al ., 2022), specific identification of larval forms (Palesse et al ., 2011; Haarder et al ., 2013; Roca-Geronès et al ., 2018) and even the elucidation of life cycles (May-Tec et al ., 2018). It should be mentioned that some of these works were not specifically carried out in marine waters off the American continent (Nadler and Hudspeth, 1998, 2000; Nadler et al ., 2007; Haarder et al ., 2013; Li et al ., 2014, 2018; Roca-Geronès et al ., 2018), but included nematode species that have been reported in this region.…”