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Diversity at the bottom of the trench: first records of hadal Solenogastres in the Northwest Pacific

World Congress of Malacology, California.

Authors/Editors: Bergmeier F S
Haszprunar G
Joerger K M
Publication Date: 2019
Type of Publication: Congress Contributions and Posters

Characterized by the total absence of light, enormous hydrostatic pressure and extremely limited food availability, the hadal zone of the deep sea (i.e. marine trenches) has long been considered void of life until first discoveries of Metazoa in the mid-20th century. Exploration of these deepest parts of the world’s oceans is still ongoing and here we present the first records of hadal Solenogastres discovered in the Kuril-Kamchatka Trench in the Northwest Pacific during the German-Russian KuramBio II cruise in 2016. In total, we discovered 6 distinct morphospecies (16 specimens) at the bottom of the trench and 9 morphospecies on the slopes of the trench (11 specimens). Species are analyzed based on an integrative taxonomic approach combining data from external characteristics (i.e. scleritome features) with molecular species delineation, within a phylogenetic framework of 60 species of deep-sea Solenogastres in the Northwest Pacific summarizing data from nine cruises to adjacent bathyal and abyssal areas.
The majority of the discovered species is considered new to science, but allows classification among nine established families based on scleritome features. Some species, however, require comparative molecular data from their Atlantic or South Pacific congeners to exclude the presence of wide-range species.
Most species have been collected as singletons and the faunal composition of the trench differs remarkably from the solenogaster fauna inhabiting nearby abyssal plains and basins. The discovery of specialized food sources in hadal Solenogastres provides some further indication that the trench fauna might not just resemble a subset of bathyal source populations but rather includes at least some endemics.