In a remarkable fusion of historical preservation and cutting-edge parasitology, researchers have unveiled a new species of trematode, Genitocotyle necromnemos, from the cardinal fish Apogon imberbis

Purpose Opecoelids, a diverse group of digenean trematodes, pose a taxonomic challenge due to morphological similarities. The genus Genitocotyle is little studied with only five recognized species. Recent phylogenetic advancements have refined Opecoelidae classification, recognizing 15 subfamilies, including opecoelins, distinguished by the absence of a cirrus sac and a canalicular seminal receptacle. Within this subfamily, the genus Genitocotyle remains understudied, with only five recognized species. The aim of this study is to describe a new species and to clarify a long-standing taxonomic ambiguity. Methods Two historical specimens of Genitocotyle from Apogon imberbis off Madeira, preserved in the Natural History Museum, London, were examined alongside newly collected specimens from Algerian waters. Comparative morphological analyses, including illustrations and morphometric measurements, were conducted. Results Genitocotyle necromnemos n. sp. is described, differing from its congeners by its larger body size, the more numerous eggs, the extended post-testicular region, the seminal vesicle restricted to the forebody, the extension of the vitellarium and the shape of the ovary. This new species designation clarifies the identity of some museum specimens, undescribed since their collection in 1951. Conclusion This study highlights the importance of museum collections for the clarification of taxonomic uncertainties and the expansion of knowledge about the biodiversity of trematodes. The result contribute the systematics of opecoelines and emphasise the ecological and biogeographical importance of Genitocotyle spp. in marine fish hosts.

In a remarkable fusion of historical preservation and cutting-edge parasitology, researchers have unveiled a new species of trematode, Genitocotyle necromnemos, from the cardinal fish Apogon imberbis in the Western Mediterranean. This significant discovery, detailed in the recent publication in Acta Parasitologica, not only enriches our understanding of the biodiversity harbored within marine ecosystems but also highlights the untapped potential of museum collections as reservoirs of scientific breakthroughs.

Apogon niger Doderlein, 1883 of the western Pacific and Apogon nigripinnis Cuvier, 1828 (Apogon thurstoni Day, Amia nigripes Ogilby, and Amia atripes Ogilby are synonyms) of the eastern Indian Ocean and Australia are regarded as valid speci...

In a study of the type specimens of A. taeniatus EHRENBERG 1828 and A. bifasciatus RUPPELL 1838, both species were found to be identical. RUPPELL based his bifasciatus on higher dorsal fin counts, VII + I,9 as opposed to VI + I,8 in his spe...

Apogon niger Doderlein, 1883 of the western Pacific and Apogon nigripinnis Cuvier, 1828 (Apogon thurstoni Day, Amia nigripes Ogilby, and Amia atripes Ogilby are synonyms) of the eastern Indian Ocean and Australia are regarded as valid speci...