The validity of the genus Allonautilus Ward & Saunders, 1997 has been questioned (Harvey et al. 1999) but is supported by molecular data (Bonnaud et al. 2004, Bonacum et al. 2011). Some authors consider Allonautilus perforatus to be synonymous with A. scrobiculatus however, Ward and Saunders (1997) provide diagnostic characters to separate these species which are also separated geographically by wide expanses of deep water known to serve as barriers to dispersal in nautilids. We therefore treat both these species as valid and this is reflected in the geographic range given. Comparison between the mitochondrial genomes of A. scrobiculatus and Nautilus macromphalus found that the mitochondrial genomes were approximately 8% divergent overall, but that differentiation varied greatly among genes (Groth et al. 2015).

Allonautilus scrobiculatus is assessed as Data Deficient because, although life history data suggest this species may be very vulnerable to exploitation, there are no reliable data available on levels of exploitation or indeed on population trends.

This species is known from off Manus in the Bismark Archipelago and from Milne Bay, Papua New Guinea. It occurs in depths of 200–800 m (Saunders et al. 1987). The species has recently been confirmed within the Solomon Islands (Hamilton and Barord 2019) based on live collection and underwater video recordings. While its geographic range appears limited, high levels of neutral variation within the A. scrobiculatus mitochondrial genome suggests that large populations exist (Groth et al. 2015), however limited sightings indicate that there is insufficient ecological research to support this. The range map is based on the limited data currently available. Molecular phylogenetic work has shown that Nautilus pompilius sensu lato populations in the west Pacific, the Philippines and Osprey Reef (Australia) all represent distinct phylogenetic species whilst the populations off Northern Queensland and Papua New Guinea represent another (Bonacum et al. 2011). The separation of lineages appears to be related to the presence of deep water that can act as a barrier between populations. Since all nautilid species are apparently similar in their reproduction and life history cycle and hence all unlikely to be able to cross deep water, it is likely that each island group throughout the Indo-west Pacific that is isolated by deep water is home to a unique species.

The population size of this species is not known. It is rare in comparison to Nautilus pompilius sensu lato. Where the two species are sympatric, A. scrobiculatus occurs in a ratio of about 1:7 with N. pompilius in catches (Saunders et al. 1987).

Nautiluses live on the steep sides of coral reefs and adjacent substrates (Jereb and Roper 2005, Saunders and Ward 2010). They are probably best characterised as mobile bottom-dwelling fore-reef scavengers and opportunistic scavengers (Jereb and Roper 2005, Saunders and Ward 2010, Dunstan et al. 2011a); they will also take small crustaceans such as crabs. They themselves are preyed upon by sharks and other fishes and, in some regions, by octopuses that drill into the shell (Saunders et al. 1991). Triggerfish attacks have been observed on numerous occasions (Saunders et al. 2011). A maximum of ten eggs are laid and experiments in aquaria have indicated that eggs take up to a year to hatch (Barord and Basil 2014). Juveniles hatch at 25–30 mm diameter growing to 6 or 7 cm diameter within a year. Whilst most research has been conducted on Nautilus pompilius sensu lato, it is likely that all species have similar longevity (15–20 years) exhibiting slow growth and low fecundity. Uneven sex ratios have been reported, based on fisheries catch data which showed ratios of 20–30% female versus 70–80% male. Dunstan et al. (2011b) suggest, as have others previously, that these characteristics make nautiluses particularly vulnerable to over-exploitation.

Slow growth, low fecundity and the uneven sex-ratio of Allonautilus species make them susceptible to overfishing even where levels of exploitation are relatively low. Hence Allonautilus is potentially threatened by fishing activity, but the extent of the current fishing pressure on the population is not documented. According to the US Fish and Wildlife Service's second Federal Register Notice regarding the fifteenth regular meeting of the Conference of the Parties to CITES, more than 579,000 specimens of Allonautilus and Nautilus, approximately 99% of which were wild-harvested, were imported into the United States alone between 2005 and 2008. These specimens came mainly from the Philippines, Indonesia, and China with reports of Allonautilus increasingly found for sale in Indonesia.

Although no figures are available for trade, specimens of Allonautilus are imported into the USA and have increasingly been found for sale in Indonesia. The CITES trade database only reports trade statistics for the family Nautilidae, since the family was listed in its entirety on CITES Appendix II in 2017, and does not contain data on Allonautilus (CITES Trade 2018).

The family Nautilidae was listed under CITES Appendix II in 2017 and includes all Nautilus and Allonautilus species. Research is required as to the geographic extent of populations, population sizes, and the level of trade and harvest needs monitoring.