Deep sea photos from James Cameron and Disney


Jul 28, 2005
Just picked up Steve's posting by chance (I was on the list but not this online forum) & since my name is mentioned it deserves a reply (even if a little late) to put the record straight. I have two points to make:-

1. snip I have yet to see a redescription of 'Benthoctopus piscatorum' (the type species of Benthoctopus) snip

The species piscatorum Verrill was redescribed by Muus in 2002 (reference below), who concluded (after inspecting the type material carefully) that "beyond reasonable doubt" it is the same species as Bathypolypus bairdii, and went on (two more pages) to explain the identities of other specimens previously described as species piscatorum. Species piscatorum is the type species of Benthoctopus, so (as Steve rightly noted) the conclusion is:-

Benthoctopus piscatorum = Bathypolypus bairdii
Therefore genus Benthoctopus = genus Bathypolypus

2. snip There's another genus out there, Atlantoctopus, that really hasn't received the systematic treatment warranted before any new genera were proposed. snip

My paper (that Steve talks about in his posting) mentioned briefly what is known about Atlantoctopus, which is not very much. Here it is in a little bit more detail:-

The genus Atlantoctopus was coined to describe Octopus lothei Chun, 1914. Unfortunately, there was only one type specimen and it was a female that, as far as anyone knows, no longer exists and was never described in enough detail to allow us to make good comparisons with other species. Robson (1932) suggested that Atlantoctopus lothei is the same as species ergasticus. This is not unreasonable: Bathypolypus ergasticus (also redescribed by Muus) occurs in an area of the Eastern Atlantic that includes the type locality of Atlantoctopus lothei (near the Canary Islands at depth 746 fathoms, =1365m). We cannot be 100% certain that Robson was right but unless someone can prove he was wrong, a reasonable conclusion is:-

Atlantoctopus lothei = Bathypolypus ergasticus
Therefore genus Atlantoctopus = genus Bathypolypus

Comparing specimens to identify species always involves some degree of doubt, but these points ought to satisfy Steve that my acceptance of Benthoctopus and Atlantoctopus as synonyms of Bathypolypus is not uncritical. As science progresses, I might be proven wrong. Until that happens, I'm happy to stand by what I wrote in my paper.

For me, anyway, Muus published a landmark paper making it clear that all three genus names belong with Bathypolypus, which is well characterized now: briefly Bathypolypus species are deep-water octopuses with no ink sac, a stout body and short arms; males have a modified third arm ending in a distinctive expanded ligula that has prominent continuous ridges across its inner surface; and the skin usually has papillae, including large cirri above the eyes.

Most of the remaining so-called 'Benthoctopus' species are very different (although, like Bathypolypus, they typically have no ink sac) and the genus names have yet to be sorted out (I and several other people are working on different species in this group at the moment). In my paper that Steve mentioned, I proposed the new genus name Muusoctopus (out of respect for Bent Muus) for the best known of these (species januarii) and pointed out some similarities with species (WITH an ink sac) that I see often here where I live in Japan.


Muus, B. (2002). The Bathypolypus-Benthoctopus problem of the North Atlantic (Octopodidae, Cephalopoda). Malacologia 44(2): 175-222.

Robson, G.C. (1932). A monograph of the recent Cephalopoda based on the collections in the British Museum (Natural History). Part II. The Octopoda (excluding the Octopodinae). London, British Museum (Natural History).


Steve O'Shea said:
It's probably Vulcanoctopus (a vent-dwelling taxon) - although the genus is rather poorly known (similar in many respects to 'Benthoctopus').

Actually, the genus Benthoctopus is probably little more than a synonym of Bathypolypus (as the type species of Benthoctopus was actually a Bathypolypus); differentiating the two in accordance with more recent diagnoses, presence or absence of a crop diverticulum, and presence or absence of lateral cusps on the rachidian tooth of the radula, doesn't work for all species. I have yet to see a redescription of 'Benthoctopus piscatorum' (the type species of Benthoctopus), so I am wary of uncritically accepting this synonymy until I do. Nevertheless, and in no way am I criticising Ian Gleadall's work at all, Ian has described a new genus to accomodate at least one of the species typically referred to Benthoctopus - Muusoctopus, and we may well find that a number of other species will eventually be attributed to this genus (Gleadall 2004). There's another genus out there, Atlantoctopus, that really hasn't received the systematic treatment warranted before any new genera were proposed.

Gleadall, I.G. 2004. Some old and new genera of octopus. Interdisciplinary Information Series 10(2): 99-112.
Apr 3, 2003
Hello, Ian and welcome!

Thank you for the citations and information here. Everyone on TONMO would be very interested in knowing more about your research. It sounds fascinating. It's clear that you feel strongly about your work. I have no doubt that changes in taxonomy can take time to be accepted by the scientific community and that this must be frustrating for someone in the avant garde. I hope you'll post more, particularly with photos, so that a layperson like myself can see and understand the differences or lack of differences to which you refer.



Steve O'Shea

TONMO Supporter
Nov 19, 2002
Hi Ian. Hey, I wasn't being critical of your work, and said that in the post. I only brought Muusoctopus up because an identification was proposed for a white octopus from a vent (the sort of place that Vulcanoctopus occurs in), and at that time your paper was brand-spanking new and not everyone would be aware of it.

I'm hearing many stories about current, detailed revisions of 'bathypolypodine' genera; and how the entire 'bathypolypodine' group is in chronic need of revision. Voss (1988), to the best of my knowledge, first noted the similarity between Benthoctopus piscatorum and 'typical' species of Bathypolypus, but Robson (1932) made many rather interesting comments also, to the effect that many of these 'Benthoctopus' and 'Bathypolypus' species appeared to be derived from littoral descendants attributed to Octopus and Enteroctopus. I also examined, figured and described the type of Benthoctopus piscatorum (1999: Fig 115a, b; pp. 191-199), discussed inadequacies in the then-accepted diagnoses, but did not effect any generic synonymy because of the instability that this would cause (synonymy is easy to advocate, whereas a solution is far more difficult, and I did not want to see another catch-all genus like 'Octopus' created); I retained the genus Bathypolypus as distinct from Benthoctopus because major differences were apparent between species historically attributed to the two (even though problems existed with type specimens of type species of respective genera).

All that someone has to do now, to really throw a spanner in the works, is to identify a closer relationship between 'Benthoctopus' piscatorum and a species of littoral, local Octopus than between 'Benthoctopus' piscatorum and Bathypolypus articus (for instance, a specimen of 'Benthoctopus' robustus in Santa Barbara has an ink sac, as does a species of Graneledone off South Africa (don't know if that's been published or not)); the ink sac probably has been lost on many ocassions, so that not all species without this character are similarly related. All that the synonymy of Benthoctopus with Bathypolypus has achieved is to create a systematic mess. Nobody is going to tell me that any of the New Zealand, and most South Pacific species attributed to Benthoctopus are more closely related to Bathypolypus articus than they are to, for instance, Enteroctopus zealandicus, but now, as the classification stands, that's exactly what I am being told - AND THAT'S CRAP!!

Unfortunately, if Muus's synonymy is correct, and the CODE is followed, chronological priority rules synonymy as one possible course of action (but not necessarily the only course of action). However, advocating this synonymy would cause great nomenclatural instability - something people realised > 70 years ago. Admittedly something had to be done, but due process was not followed; the mess should have been resolved by: 1) recognising a problem existed [everyone knew this]; 2) revising the group in entirety at a) a regional level, and b) an international level [not been done]; 3 resolving the problem [not been done]; and 4) publishing a solution [done].

A lot of work remains to be done. That's why you see very few monographic treatments out there.

I wasn't being critical of your work at all, Ian. I was just saying that I would prefer to have seen a monographic review of the group before any synonymy was effected. As the entire argument seems to be based on priority, Atlantoctopus would appear to be the next available name for the majority of species previously attributed to Benthoctopus. Whoever revises it first (as 1st revisor) gets the say in the matter (in accordance with this darn priority), but we also know that the 'most recent' revision is never the 'last word', unless a meteor hits Earth tomorrow. I wish someone would hurry!

[ps., my very first post on TONMO was much like yours; that dark and dastardly Colin was, I thought, criticising some press release of mine ... and I responded to it. I hung around after that, because the site is cool and we all have a contribution to make. Please do post away, and if you want to call me a pudding head, feel free to do that also. Cheers. Me]