Chronologic evolution of the attachment of Neogrubea spp. (Monogenea: Mazocraeidae) to gills: Ontogenetic and taxonomic implications

HERNÁNDEZ, J.S., MONTERO, F.E, DEL DEDO-GARCIMARTÍN, M., BERÓN-VERA, B., CRESPO, E.A., RAGA, J.A.

Mérida, Yucatán, México

Congreso; ANNUAL MEETING OF THE AMERICAN SOCIETY OF PARASITOLOGISTS. ?FROM ALASKA TO CHIAPAS: THE FIRST NORTH AMERICAN PARASITOLOGY CONGRESS?.; 2007

Chronologic evolution of the attachment of Neogrubea spp. (Monogenea: Mazocraeidae) to gills: Ontogenetic and taxonomic implications. Hernández, J.S.1, Montero, F.E.2, Del Dedo-Garcimartín, M.1, Berón-Vera, B.3, Crespo, E.A.3, Raga, J.A.1 1 Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain. 2 Department  of Animal Biology, Plant Biology and Ecology, Autonomous University of Barcelona, Barcelona, Bellaterra, Spain. 3Centro Nacional Patagónico (CENPAT) Blvd. Brown 3600. CP 9120. Puerto Madryn, Chubut, Argentina The attachment mechanism of the oncomiracidia of the oligonchoideans is based on larval hooks. The use of this traumatic mechanism continues along earlier juvenile stages. The attachment system is replaced by new and much harmless structures developed in mature adults; clamps or suckers. While these clamps/suckers become numerous enough or large to hold the whole worm?s body to the gill, the larval hooks remain in a movable terminal lappet and are also functional. Along this time both perforation and clamping are combined to hold the worms. Finally, terminal lappet and hooks degrade and in many polyopistocotyleans fall down. In Grubeinae genera (Grubea spp. and Neogrubea spp.) the terminal lappet with the hooks remains in the mature body, often integrated in the posterior end tissue or in a vestigial terminal lappet. Here we show morphological changes of hooks and clamps of Neogrubea spp. during development. The morphological evolution seems related with the use of both structures in time. Hooks reach their definitive size and shape when attaching to the host, not suffering posterior growth or degeneration associated to absence of use or senescence. Meanwhile the clamps, which are almost in use for attachment since their development up to death, change gradually and constantly in morphology, size and orientation. The fact that none of the larval hooks change their shape, degrade or disappear along the development of any of the species of Neogrubea sp. is relevant for the species taxonomy. The number of hooks (2/3 pairs) has been used to differentiate species. However, our examinations reveal that all the species always have 3 pairs of hooks during their whole development. Therefore, this trait should not be considered in taxonomy. Based on new diagnostic traits (number and shape of genital atrium spines and presence/absence of musculature rings around the mouth) and some used earlier (extension of vitellaria) we distinguish 4 species of Neogrubea including a new one on Stromateus stellatus from the South Pacific. Supported by BBVA Foundation (project nº BIOCON 04)