A new species of Lecithostaphylus Odhner, 1911 (Trematoda: Zoogonidae) from the Pacific needlefish, Tylosurus pacificus, off the Pacific coast of Mexico, with a molecular assessment of the phylogenetic position of this genus within the family

New trematode species Lecithostaphylus halongi n. sp. (Zoogonidae, Microphalloidea) and Gymnotergestia strongyluri n. sp. (Fellodistomidae, Gymnophalloidea) from beloniform fishes in Vietnam

“…The genus Lecithostaphylus currently comprises 11 species of trematodes parasitizing the intestines of marine fish from several orders. The genus is cosmopolitan, and the range of its definitive hosts is fairly broad (Zhang et al, 1986;Cribb et al, 1992;Toman, 1992;Ramadan et al, 2003;Châari et al, 2013;Cabañas-Granillo et al, 2020). The East Asian territory is the type region for a single species of this genus, Lecithostaphylus fugus Zhang, Qiu & Li, 1986, detected from tetraodontids in China (Zhang et al, 1986).…”

“…Bray (2008 considered Lecithostaphylus as a valid genus of the subfamily Lepidophyllinae Stossich, 1904. Later, several complex studies indicated that Lecithostaphylus was phylogenetically distant from the genus Lepidophyllum Odhner, 1902 and could be separated into a distinct subfamily Lecithostaphylinae Odhner, 1911(Cabañas-Granillo et al, 2020Sokolov et al, 2021a;2021b). On the basis of molecular-based species clustering, Sokolov et al (2021b) resurrected the subfamily Lecithostaphylinae and provided a diagnosis of Lecithostaphylinae sensu lato, including the genera Lecithostaphylus (as the type genus), Deretrema Linton, 1910, Proctophantases Odhner, 1911and Steganoderma Stafford, 1904.…”

“…At present, the structure of the families Zoogonidae and Fellodistomatidae and the species differentiation within Lecithostaphylus and Gymnotergestia are mainly based on morphological data. Though there are several molecular studies of trematodes from each of these two families (Bray et al, 1999;Hall et al, 1999;Olson et al, 2003;Cribb et al, 2014Cribb et al, , 2015Cutmore et al, 2014;Antar & Gargouri, 2015;Sokolov et al, 2016;Wee et al, 2017;Cutmore et al, 2018;Pérez-Ponce de León et al, 2018;Cabañas-Granillo et al, 2020;Krupenko et al, 2020;Sokolov et al, 2021a, b), most of them do not provide morphological validation of the species under study. In many cases, this means that no sound taxonomical conclusions can be made.…”