Two old, one new and two current genus names are discussed. The old names are
Schizoctopus Hoyle, 1886, for which a type species is here designated, and
Tritaxeopus Owen, 1881, which is here associated with the ‘
Octopus horridus group’ of species. The two current genus names concern two species of octopus with males hectocotylized on the third left arm:
Scaeurgus unicirrhus (delle Chiaje in d’Orbigny, 1841) and
Pteroctopus tetracirrhus (delle Chiaje, 1830). The type species of the genus names
Scaeurgus and
Pteroctopus have been identified as synonyms (rendering these genus names synonyms, also) but approval of an unchallenged redesignation of the type species of
Scaeurgus provides an appropriate solution to this problem that would best maintain taxonomic stability.
A new genus name is proposed for the species
Octopus januarii Hoyle, 1885, which was previously placed in
Benthoctopus Grimpe, 1921. This follows the recent identification of the type species of three genera (
Bathypolypus,
Benthoctopus and
Atlantoctopus, all described by Grimpe, 1921) as belonging to a single genus (excluding
Octopus januarii), of which
Bathypolypus is the senior synonym. It is here observed that the species closest in morphology to Hoyle’s
‘Octopus’ januarii appears to be
‘Octopus’ longispadiceus (Sasaki, 1917), although the former has no ink sac while the latter has. The common features of these two species include close similarities in the internal structure of the male pseudophallus. Comparisons are made with structural features of the pseudophallus in
Enteroctopus dofleini (Wülker, 1910),
‘Octopus’ hongkongensis Hoyle, 1885, and
‘O.’ conispadiceus (Sasaki, 1917), and it is suggested that all five species may be related at the subfamily level.
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