Turbellarian taxonomic database

Abstract / Notes

"Marine microturbellarians are an assemblage of meiofaunal flatworms abundant in sediments and on seaweeds
around the world. The diversity and distribution of these animals in Japan are poorly understood. Here, we
provide an overview of all recorded species in Japan and characterize two new species of the rhabdocoel genus
Reinhardorhynchus based on morphological features and a molecular phylogeny inferred from 18S and 28S rDNA
sequences. Reinhardorhynchus ryukyuensis sp. nov. can be distinguished from other species in the genus by the
lack of an armed cirrus and by the presence of two larger opposing hooks and five smaller interconnected hooks
in its male copulatory organ. Reinhardorhynchus sagamianus sp. nov. differs from its congeners because its
male copulatory organ combines a bipartite cirrus armed with a belt of overlapping scale-like spines, an
unarmed accessory cirrus, and two large distal accessory hooks. Our molecular phylogenetic analyses show that
R. ryukyuensis sp. nov. and R. sagamianus sp. nov. form a clade with all the other species of
Reinhardorhynchus for which DNA sequence data are available. Within this clade, R. sagamianus sp. nov. is in a
clade that also includes R. riegeri and R. anamariae. The discovery of these new species highlights the
importance of uncovering and documenting the hidden biodiversity along Japan’s coastal margin."

Return to taxon listing