Magnapinna sp. B is an undescribed species of bigfin squid known only from a single immature specimen collected in the northern Atlantic Ocean. It is characterised by its dark epidermal pigmentation, which is epithelial, as opposed to the chromatophoral pigmentation found in other Magnapinna species. The only known specimen of Magnapinna sp. B is a juvenile male of 95 mm mantle length ML held in the Bergen Museum. It was caught by the R/V G.O. SARS MAR-ECO cruise super station 46, local station 374 on July 11, 2004, at 42.8°N 29.3°W / 42.8; -29.3.
Magnapinna sp. C is an undescribed species of bigfin squid known only from a single specimen of 79 mm mantle length collected in the southern Atlantic Ocean and held in the Natural History Museum. It is characterised by several morphological features: the proximal tentacles are more slender than arm pair IV, pigmentation is contained in the chromatophores, and "white nodules" are absent from the fins and glandular regions of the proximal tentacles. Magnapinna sp. C was originally illustrated in The Open Sea in 1956 and identified as Octopodoteuthopsis.