Rich but morphologically problematic: an integrative approach to taxonomic resolution of the genus Neospirorchis (Trematoda: Schistosomatoidea)

Neospirorchis Price, 1934 is a genus of blood flukes that infect the cardiovascular system, including vessels surrounding the nervous systems of marine turtles. Although the genus comprises just two named species, the available molecular data suggest substantial richness which has not yet been formally described. The lack of description of species of Neospirorchis is probably explained by their small, slender, elongate bodies, which allow them to infect numerous organs and vessels in their hosts, such as the heart and peripheral vessels of nervous system, endocrine organs, thymus, mesenteric vessels, and gastrointestinal submucosa. This morphology and site of infection means that collecting good quality, intact specimens is generally difficult, ultimately hampering the formal description of species. Here we supplement limited morphological samples with multi-locus genetic data to formally describe four new species of Neospirorchis infecting marine turtles from Queensland, Australia and Florida, USA; Neospirorchis good-manorum n. sp. and Neospirorchis deburonae n. sp. are described from Chelonia mydas, Neospirorchis stacyi n. sp. is described from Caretta caretta, and Neospirorchis chapmanae n. sp. from Ch. mydas and Ca. caretta. The four new species are delineated from each other and the two known species based on the arrangement of the male and female reproductive organs, on the basis of cytochrome c oxidase subunit 1 (cox1), internal transcribed spacer 2 (ITS2), and 28S ribosomal DNA (rDNA) molecular data, site of infection, and host species. Molecular evidence for three further putative, presently undescribable, species is also reported. We propose that this integrated characterisation of species of Neospirorchis, based on careful consideration of host, molecular and key morphological data, offers a valuable solution to the slow rate of descriptions for this important genus. We provide the first known life cycle data for Neospirorchis in Australian waters, from Moreton Bay, Queensland; consistent with reports from the Atlantic, sporocysts were collected from a terebellid polychaete and genetically matched to an unnamed species of Neospirorchis infecting Ch. mydas from Queensland and Florida. (C) 2023 The Authors. Published by Elsevier Ltd on behalf of Australian Society for Parasitology. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).