Promachoteuthis sloani
Promachoteuthis sloani is a species of squid from the northern Atlantic Ocean. It was known from only three dead specimens until 2024 when a live specimen was observed and photographed in the Nazca Ridge. Very little is understood of its biology. P. sloani is characterised by several morphological features: nuchal fusion is absent between the head and mantle, the arms generally bear 3–4 series of suckers, and papillae are present on the tentacles.
The holotype is an immature female of 58 mm mantle length in near-perfect condition. It was caught by R/V G.O. SARS in 2004 at. The paratype, an immature female, is larger at 102 mm ML. It was caught by R/V Walther Herwig in 1973 at. Both were trawled in nets that fished to depths greater than 2,650 m.