Identifying Nautilus Shells

[Archi]

I was wondering if anyone could help me with identifying these shells, I'm tossing up between Nautilus Macromaphalus and Nautilus Pompilius.

(If it helps, they're from Indonesia)

 

[gjbarord]

Just off of first appearance I would say that they are macromphalus. The key characteristic to look at in regards to nautilus identification is the umbilicus, which is the inner 'coil' of the nautilus at the center of the shell. This is covered in some nautilus and not covered in others.

The striped pattern also appears to be different between those two species. I will double check the ID later today as soon as I can find my reference.

Greg

 

[Argonautautidae]

None of these are N. macromphalus since that species has an open umbilicus and different pattern on the shell. They are probably N. pompilius.

 

[robyn]

I'll second that - macromphalus (big bellybutton) has an open spiral - these look to be either pompilius or belauensis, and my understanding is that the major differentiating factor between the two is size - belauensis is typically much larger.

Having said that:

The stripe pattern and size is often totally different within the same species - here's a pic of two pompilius from the philippines and vanuatu: so basically I don't know. I would go with pompilius beacuse its more common than belauensis (IIRC)

 

[Archi]

So, have we concluded a pompilius? I was also wondering if it was different species between the two shells, or if the right one was just a juvenile or different gender.

 

[gjbarord]

What is the diameter of the two shells? Is the picture on the right just a little blurry?? (it looked as if there is a slight spiralling to the umbilicus and looks open)

Is the shell smooth or does it feel like a multitude of "cross-grids" along it?

Greg

 

[Archi]

Just to correct my last post, I meant the one on the left, the smaller one. Also, here are the measurements. Hope they help!

 

[gjbarord]

The largest reported size for pompilius, I believe, is 17 cm. So I would think that at least the larger one is not pompilius.

What about the cross-grid texture on the shells??

Greg

 

[Argonautautidae]

The largest N. pompilius shell I am aware of measures 268 mm in diameter. 20 cm is pretty big but nothing extraordinary.

 

[Archi]

Just remember that I measured from the longest point to the longest point, other specimens may not have been measured that way. As for the texture, there doesn't seem to be any 'cross-grid', rather they have 'bumps' running horizontally (horizontal in the bottom left picture in my first post). It also seems that the smaller one's (the one on the left) 'bumps' are raised quite a bit more than the larger shell (the one on the right).

 

[xsimona]

Stenomphalus-Perforatus-Belauensis.....

Hi all,
first of all, thanks to the web to create a common space to share !
I just want to put on the table two or three doubts i have about the classification of Nautilus Species.

1. Are the Nautilus Belauensis from Palau and Nautilus Repertus from Australia still considered different from the Nautilus Pompilius, as the Suluensis ?? How must they be nammed ???

2. It's still considerated as a different species the Allonautilus Perforatus founded around Bali ?? (only two or three shells without any soft tissue semains ?). Could these shells be simply from Scrobiculatus (with strongly marked ribs) from Timor or surroundings, transportated by currents to Bali ?

3. The last one: Stenomphalus. The technically described (and pictured on books and FAO documents) have white shell patterns, and lives at the Great Coral Reef. On the internet, you can find lots of pictures of shells called "stenomphalus" with the same shell patterns that many Pompilius have. Many babe Pompilius shells, have open umbilicus, and maybe some isolated specimens or populations retain this characteristic even wen they are adults. These shells come from the Phillipines, Malaysia, etc. What do you think about ?? Are they Stenomphalus, or just Pompilius with open umbilicus ???

Thanks !!
Xavier
[email protected]

 

[monty]

to TONMO! I'll not too up on the systematics of nautilus, but at least number 3 I can address: from what I know about nautilus shell growth, I can't think of any mechanism that would close an open umbilicus later in life, since there's not really any tissue that secretes new shell anywhere except the mantle cavity, so I would be very surprised to find that that changed between juveniles and adults. I haven't been paying attention to any taxonomy since people have started doing molecular and developmental studies of nautilus, so I don't know if that's caused any new excitement in the classifications.

ToLweb has a page describing a lot of the current state of affairs, with an impressive bibliography of the papers describing the current beliefs: Nautilidae Taxa

It looks like Saunders has been doing an impressive taxonomic review lately, so checking out his recent review (1998) is probably going to be the best place to get detailed answers to these sorts of questions.

 

[vw1]

I just want to put on the table two or three doubts i have about the classification of Nautilus Species.

There are only 3 definite species of Nautilus. These are: N. pompilius (with numerous synonyms), N. macromphalus (differing only in shell form, but consistent and different enough to be distinct) and N. scrobiculatus (Allonautilus is dead). N. perforatus is probably just a local morph of N. scrobiculatus; N. stenomphalus differs in a few characters from N. pompilius and is possibly a good species on anatomical and molecular (not shell) grounds.

The umbilicus in involute species can be infilled with callus material, as is normally (but not always) the case with N. pompilius. The callus is possibly secreted by the hood. The umbilicus of N. macrompalus and N. scrobiculatus is too wide for infilling.

At present reserch is beginning on a probable Triassic species of Nautilus, which would extend the timerange back from the Eocene. These shells do not seem to differ at greater than species level from N. scrobiculatus.

Speaking of N. perforatus, I would like some specimens for research purposes… if anyone knows where I can get them at a reasonable price, please contact me by p-mail:
[email protected]

 

[robyn]

Hi Andrew,

I am interested in your statement 'Allonautilus is dead'. Can you elaborate on that perhaps? I am curious to know whether perhaps there is newer molecular evidence to refute Ward 1987 and/or Harvey et al., 1999?

Thanks!

Robyn

 

[CuttlePhilly]

Just to throw a wrench into this thread (and I'm NOT speaking as an expert here) - just got the April 5-11 issue of New Scientist magazine which has a GREAT 4 page article on nautiluses which says there are currently 7 recognized species of nautilus, but that they are discovering that 10's of different unclassified species have all been classified as N. pompilus in the past. Some taxonomists are calling for the scrapping of the species Nautilus pompilius altogether!!!

Quick list of official Nautilus species:
1. Allonautilus perforatus
2. King Nautilus (Allonautilus scrobiculatus)
3. Emperor Nautilus (Nautilus pompilius)
4. Palau Nautilus (Nautilus belauensis)
5. Nautilus repertus
6. White-Patch Nautilus (Nautilus stenomphalus)
7. Bellybutton Nautilus (Nautilus macromphalus)

Seems like they're about to re-write the book on how many species there are and what they are called... There's even a new genus for two of the above nautiluses (Allonautilus)!!!

Here's a link to my synopsis of the article (with a link to the actual article): Great article on the Chambered Nautilus

= Bender =