Allonautilus perforatus
{{Short description|Species of mollusc}}
{{Speciesbox
| image = Allonautilus perforatus.jpg
| status = CITES_A2
| status_system = CITES
| status_ref = {{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org}}
| genus = Allonautilus
| species = perforatus
| authority = (Conrad, 1847)
| synonyms =
- Nautilus perforatus
Conrad, 1847
}}
Allonautilus perforatus, also known as the Bali chambered nautilus or the Indonesian nautilus, is a proposed species of nautilus native to the waters around Bali, Indonesia. It is known only from drifted shells and, as such, is the least studied of the seven recognized nautilus species. Thus, not much is known about it outside of the shell.
Habitat and distribution
The nautilus is reported to live on the coastal reefs of Baliand Papua New Guinea. They have been reported to live in nearby deep-water habitats as well.{{Cite journal|last1=Groth|first1=Jeff G.|last2=Arbisser|first2=Ilana|last3=Landman|first3=Neil H.|last4=Barrowclough|first4=George F.|date=April 2015|title=The Mitochondrial Genome of Allonautilus (Mollusca: Cephalopoda): Base Composition, Noncoding-Region Variation, and Phylogenetic Divergence|url=https://bioone.org/journals/American-Museum-Novitates/volume-2015/issue-3834/3834.1/The-Mitochondrial-Genome-of-Allonautilus-Mollusca--Cephalopoda--Base/10.1206/3834.1.full|journal=American Museum Novitates|issue=3834|pages=1–13|doi=10.1206/3834.1|s2cid=55734274|issn=0003-0082}} A. perforatus has been estimated to live at depths of 100~600 meters much like other extant Nautiloids.
Ultimately little is known about the exact distribution of A. perforatus compared with the more abundant relatives such as A. scrobiculatus. Shells of the nautilus are sold in Balinese market placesWard, P.D. & W.B. Saunders 1997. [https://www.jstor.org/stable/1306604 Allonautilus: a new genus of living nautiloid cephalopod and its bearing on phylogeny of the Nautilida]. Journal of Paleontology 71(6): 1054–1064. and tend to be less common. Newer specimens found via the shell trade may have been live-taken by fishers, which is raising hopes among scientists for obtaining live specimens for study.{{Cite web |title=The Chong Chen Archives {{!}} ConchologyNAUTILIDAE ALLONAUTILUS PERFORATUS |url=https://conchology.be/?t=94&ID=17&family=NAUTILIDAE&species=ALLONAUTILUS%20PERFORATUS&srsltid=AfmBOoqMsBbtusiFrblEeSBwKBXLux4aJrBNuFkkKqI2mIVY2bOWB7rx |access-date=2025-03-30 |website=conchology.be |language=en}}
Reports from these markers detail that the shells have notable Octopus borings in their chambers. Markings indicate that the nautilus obtained are shells that have drifted onto the shoreline. Likely due to predation by Octopus, the shells are empty upon arrival.
Due to the A. scrobiculatus specimen being isolated in the region of Papua New Guinea, in addition to being close relatives, it is thought that both species of the nautilus are organisms that are isolated geographically.
Commercial use of shells
Known to be valued in the commercial market as collectibles, nautilus shells and are traded around the world.{{Cite journal|last=De Angelis|first=Patricia|date=2012-01-01|title=Assessing the impact of international trade on chambered nautilus|url=http://www.sciencedirect.com/science/article/pii/S0016699511000982|journal=Geobios|language=en|volume=45|issue=1|pages=5–11|doi=10.1016/j.geobios.2011.11.005|issn=0016-6995|url-access=subscription}} A. perforatus are traded locally in Bali, Indonesia. These markets tend to last for a brief period of time before eventually becoming nonfunctional.
In addition to their trading and commercial value as souvenirs, shells are also owned by museums for collection.
Taxonomy
Little is known about wild specimens of A. perforatus and this nautilus has mostly been distinguished by shells that have drifted onto land, and more recently, specimens that have been obtained via the Balinese shell trade.{{Cite journal|last1=Bonacum|first1=James|last2=Landman|first2=Neil H.|last3=Mapes|first3=Royal H.|last4=White|first4=Matthew M.|last5=White|first5=Alicia-Jeannette|last6=Irlam|first6=Justin|date=March 2011|title=Evolutionary Radiation of Present-Day Nautilus and Allonautilus|url=https://bioone.org/journals/American-Malacological-Bulletin/volume-29/issue-1_2f_2/006.029.0221/Evolutionary-Radiation-of-Present-Day-Nautilus-and-Allonautilus/10.4003/006.029.0221.full|journal=American Malacological Bulletin|volume=29|issue=1/2|pages=77–93|doi=10.4003/006.029.0221|s2cid=86014620|issn=0740-2783|url-access=subscription}} Thus, not much is known about this particular creature. The genus Allonautilus contains only two species, A. perforatus and A. scrobiculatus, with a more restricted distribution overall than the genus Nautilus.
=Taxonomic Status=
The current taxonomic status of A. perforatus is currently disputed among scholars. The World Register of Marine Species (WoRMS) describes the status as nomen dubium, indicating that the name is of uncertain application and the species is not officially recognized.{{cite web
|url=https://www.marinespecies.org/aphia.php?p=taxdetails&id=342268
|title=WoRMS - World Register of Marine Species - Allonautilus perforatus (Conrad, 1849)
|website=World Register of Marine Species
|access-date=2025-06-20
}}
Morphology
Like other nautilus species, A. perforatus has a coiled shell covering its internal body. The shell has multiple chambers, the outermost chamber being where the nautilus lives. In addition the organism possesses tentacles that form two rings around its mouth.
A. perforatus shows a shell shape and coloration very similar to that of A. scrobiculatus and shares with this species the characteristic open umbilicus. However, it bears highly distinctive shell-ribbing, which is unique among extant ectocochleate cephalopods, and lacks scrobiculate shell sculpture.
Until recently, it was not known whether or not A. perforatus possessed the thick encrusting layer (periostracum) characteristic of A. scrobiculatus. Newer specimens have shown to have a (periostracum). Maximum known shell diameter is around 180 mm.Jereb, P. 2005. Family Nautilidae. In: P. Jereb & C.F.E. Roper, eds. Cephalopods of the world. An annotated and Illustrated catalogue of species known to date. Volume 1. Chambered nautiluses and sepioids (Nautilidae, Sepiidae, Sepiolidae, Sepiadariidae, Idiosepiidae and Spirulidae). FAO Species Catalogue for Fishery Purposes. No. 4, Vol. 1. Rome, FAO. pp. 51–55. Sexual dimorphism are apparent as females tend to be smaller in size. The shell also possesses a series of plicae (ribs) on the sides of the body chamber neat the organism's aperture. Plicae tend to be 30mm long and its crests 10mm apart, and are explicitly expressed on both the inside and outside of the shell.
References
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