The World Register of Marine Species (WoRMS) / MolluscaBase concurrently awknowledge Muusoctopus hydrothermalis and Vulcanoctopus hydrothermalis as valid taxa. This is problematic because they are synonyms of one another, and even the primary literature acknowledges this (Voight et al., 2012; Ibáñez et al., 2014). This paradox is a consequence of opinion among those involved with octopus taxonomy. Genetically, this species nestled among Benthoctopus. The phylogenetic validity of this genus is considered untenable by those who have conducted research on these octopuses, and - as a consequence - they regard Benthoctopus as a junior synonym of Muusoctopus. WoRMS agrees with this conclusion and has placed all of the children taxa of Benthoctopus into Muusoctopus. However, some continue to treat Vulcanoctopus as a valid, independent genus because # hydrothermalis exhibits unique morphology not present among its supposed congeners under Muusoctopus. However, it also shares characteristics diagnostic of Muusoctopus sp. Most authors have dismissed the species' unique characteristics as justification for keeping in a monospecific genus when it genetically falls within the Muusoctopus clade. This is the position recommend for iNaturalist, because recognizing Vulcanoctopus delegitimatizes the merging of Benthoctopus with Muusoctopus. Its legitimacy is dependent on keep these two valid.

References:
• Voight, J.R. (2012). "Meristic variation in males of the hydrothermal vent octopus, Muusoctopus hydrothermalis (Cephalopoda: Octopodidae)". Journal of the Marine Biological Association of the United Kingdom. 92(2): 361-366.
• Ibáñez, Christian M. Pardo-Gandarillas, María C. Peña, Fabiola Gleadall, Ian G. Poulin, Elie and Sellanes, Javier 2016. "Phylogeny and biogeography of Muusoctopus (Cephalopoda: Enteroctopodidae)". Zoologica Scripta, Vol. 45, Issue. 5, p. 494.