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.^[2] Very little is understood of its biology.^[1] 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.^[3]

Promachoteuthis sloani
The third known specimen of P. sloani, collected during the summer 2009 cruise of the NOAA ship Henry B. Bigelow[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Order:	Oegopsida
Family:	Promachoteuthidae
Genus:	Promachoteuthis
Species:	P. sloani
Binomial name
Promachoteuthis sloani Young, Vecchione & Piatkowski, 2006

The holotype is an immature female of 58 mm mantle length (ML) in near-perfect condition. It was caught by R/V G.O. SARS in 2004 at 53°05′N 36°46′W. The paratype, an immature female, is larger at 102 mm ML. It was caught by R/V Walther Herwig in 1973 at 46°00′N 15°49′W. Both were trawled in nets that fished to depths greater than 2,650 m.^[3]