Promachoteuthis sulcus

{{Short description|Species of cephalopod}}

{{Use dmy dates|date=April 2022}}

{{Speciesbox

| genus = Promachoteuthis

| species = sulcus

| authority = Young, Vecchione & Roper, 2007

}}

Promachoteuthis sulcus is a species of promachoteuthid squid. It is distinguished from related taxa on the basis of several morphological features: Nuchal fusion between the head and mantle, much larger size of arm-suckers compared to club-suckers, greater width of tentacle-base than arm-base, a recessed club-base, and the presence of an aboral tentacle-groove.Young, R.E., M. Vecchione & C.F.E. Roper 2007. A new genus and three new species of decapodiform cephalopods (Mollusca: Cephalopoda). Reviews in Fish Biology and Fisheries 17(2–3): 353–365. {{doi|10.1007/s11160-007-9044-z}}

Promachoteuthis sulcus is known from a single specimen caught by the German research vessel R/V Walther Herwig in an open net off Tristan da Cunha, southern Atlantic Ocean ({{coord|36|49|S|12|17|W|scale:250000|name=Promachoteuthis sulcus (only specimen caught)}}), at a depth of {{convert|1750|–|2000|m|abbr=on}}.