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

A new species of Lecithostaphylus Odhner, 1911 (Zoogonidae) is described from the Pacific agujon needlefish, Tylosurus pacificus (Steindachner) (Belonidae), from two localities off the Pacific coast of Mexico. Morphologically, the new species agrees with the diagnosis of the genus Lecithostaphylus. Lecithostaphylus brayi sp. nov. differs from other congeneric species by a combination of morphological traits, including the overall body size, anterior and posterior extension of the vitelline follicles in the hindbody, and the presence/absence of papilla-like denticles on internal surface of ventral sucker. Lecithostaphylus brayi sp. nov. most closely resembles L. retroflexus (Molin, 1859), Odhner, 1911 and Lecithostaphylus tylosuri Châari, Derbel & Neifar, 2013 from Mediterranean needlefishes and Lecithostaphylus nitens (Linton, 1898) Linton, 1940 from needlefishes in multiple marine ecoregions; however, it can be distinguished by subtle morphological differences, host association, and geographical distribution. The new species will require further verification through a more detailed morphological study of L. nitens and, ideally, molecular data for L. nitens, L. retorflexus, and L. tylosuri. Newly generated 28S rDNA sequences allowed a phylogenetic assessment of the genus and show that Lecithostaphylus clades within the Zoogonidae, sister to the genera Deretrema Linton, 1910 + Proctophantastes Odhner, 1911, although the family Zoogonidae is not resolved as monophyletic. The inclusion of more representative genera in the molecular phylogenetic analysis will be needed to generate a more robust classification scheme for the Zoogonidae, and to discuss host specificity patterns for members of the family.