A new Benthopelagic species of Heterokrohnia (Chaetognatha) from the North Atlantic Ocean

A new species of Heterokrohnia, H. mirabiloides, is described from the “Discovery” collections made in the North-East Atlantic. It differs from the two other species of the “mirabilis” group mainly in the cephalic armature, particularly the posterior teeth which are much less numerous and bent at rigth-angle. Although H. mirabiloides is benthopelagic as are all the Heterokrohnia species, most specimens have been caught using benthic sampling gear (31 out of 33 specimens). On the other hand H. mirabilis has been found in both benthic and pelagic samples (14 and 19 specimens, respectively). It appears that H. mirabiloides is the shallowest living species of the genus because the great majority of specimens (24) have been found at depths between 1300 and 1400 m, whereas H. mirabilis appeared only in hauls below 2700 m.