oddmarble's Journal

In this journal, I intend to provide information and propose ID tips for a few "controversial" species.

To begin with some context, Ascarosepion mestus and Sepia grahami were considered the same species centuries ago. This was back when cuttlefish taxonomy was mostly decided by the cuttlebone, and when neither of these species were known confidently from live animals.

Technically speaking, Sepia grahami should be sorted into Ascarosepion, both due to its morphology and due to close relations to a cuttlefish already placed in Ascarosepion - A. filibrachia.

The original description notes A. filibrachia was once considered a Chinese population of A. mestus, but this was a mistake influenced by the old custom of considering S. grahami synonymous with Ascarosepion mestus. The paper states that "Sepia filibrachia is similar to S. grahami Reid, 2001, particularly in the form of the cuttlebone, which is almost indistinguishable in the two species." When looking at photographs of both species live, they still appear similar, mostly different in the shape of their papillae and their color ranges.

With this information, we can assume more about the relationships of S. grahami - the recent paper that sorted cuttlefish taxonomy cites this paper regarding A. filibrachia's placement in Ascarosepion, noting "[S. filibrachia] was closely associated with S. plangon and S. papuensis, placing it in our Clade 2 (Ascarosepion)." All of these cuttlefish, including S. grahami, seem to have a few traits in common, most significant to me being the "striated" patterns they display, and large major papillae with paddle-like shapes. I will refer to this group as "striated cuttlefish".

In the aforementioned paper sorting cuttlefish taxonomy, the Ascarosepion clade shows a relationship between the striated cuttlefishes, and also shows a relationship between Ascarosepion mestus and Ascarosepion rozella. FAO's Cephalopods of the World, Vol. 1 from 2005 does not describe A. mestus but does describe A. rozella. The document says the cuttlefish is "purplish brown ... [the head is] papillose dorsally and laterally ... [with a dorsal] mantle covered with numerous small papillae." These traits are consistent with most observations of A. mestus as well, the most major difference visible in photos being the anterior mantle margin, which is narrow and triangular in A. rozella, while it is rounded and ovoid in A. mestus.

Regarding A. mestus lacking head papillae (according to the Australian Museum) I do not fully believe this. Papillae can be hard to distinguish in dead specimens, and the papillae seen above the eyes in presumed A. mestus are very small, so I doubt they would be easily preserved. There are other cuttlefish remarked to lack papillae in certain areas, only for the live animal to show signs of papillae, even if poorly defined.

Past this point, I will be remarking on some features I have noticed via combing through observations. I cannot say everything beyond this point is without exception, but I can say these features are consistent at least. An example of an inconsistent feature would be eye patterning. While S. grahami tends to have more white in the eye, the other two species occasionally have white as well - but all 3 species have yellow in the eye to some degree. There is no source that says A. rozella lacks yellow in the eye.

Compared to the striated cuttlefishes, A. mestus and A. rozella have purplish, desaturated coloration, and do not display striated patterns. They also have smaller papillae, with an erratic, "serrate" outline, especially when compared to cuttlefish like S. grahami, which have rounded papillae dorsally. Ascarosepion bandense is a good species to help visualize the difference in texture between these two Ascarosepion groups, as its skin has many ridges like A. mestus and A. rozella, albeit not serrate.

Now, here's the largest point of contention; the orange spot. Sepia grahami does have orange spots, but other Ascarosepion species have orange spots, or at the very least, some kind of spot in the same areas. For this reason, it is not a reliable diagnostic feature of Sepia grahami, however the vibrance of the spots in Sepia grahami distinguishes it from other species, so they are not wholly useless in ID either. When displayed, they are often very bright/saturated, while cuttlefish like A. mestus and A. rozella have less vibrant orange spots, almost goldish brown in comparison with that of Sepia grahami. This is a similar case in A. apama, and even A. plangon on rare occasions, but the spots are usually white rings in either species rather than an orange spot.

TLDR and my proposed ID key: I believe Sepia grahami is a distinct species from Ascarosepion mestus and Ascarosepion rozella, both visually and phylogenetically, and can be differentiated by its

• Vibrant coloration, often red, pink, or orange, with a strong orange spot if displayed
• Striated pattern, akin to that seen on A. plangon and A. papuense
• Smoother skin with large, rounded paddle-like papillae.

While the latter two species have

• Desaturated coloration, often purple, grey, or brownish, with a faded orange spot if displayed
• No striated pattern, but occasionally displays about 3-5 large white spots on the head like A. bandense
• Ridged skin with small, "serrate" papillae.

Not all of these features will be readily visible in a given observation, given the flexibility of a cuttlefish's appearance, but can cover most observations. A more consistent feature is the anterior mantle margin, which varies between species. It is rounded in A. mestus, acuminate and triangular in A. rozella, and intermediate in S. grahami - relating to the shape of their cuttlebones.

I hope this journal and the other resources provided are helpful - thank you for reading!