Auxis

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Megaclassis: Osteichthyes
Superclassis/Classis: Actinopterygii
Classis/Subclassis: Actinopteri
Subclassis/Infraclassis: Neopterygii
Infraclassis: Teleostei
Megacohors: Osteoglossocephalai
Supercohors: Clupeocephala
Cohors: Euteleosteomorpha
Subcohors: Neoteleostei
Infracohors: Eurypterygia
Sectio: Ctenosquamata
Subsectio: Acanthomorphata
Divisio/Superordo: Acanthopterygii
Subdivisio: Percomorphaceae
Series: Pelagiaria
Ordo: Scombriformes

Familia: Scombridae
Subfamilia: Scombrinae
Genus: Auxis
Species (2): A. brachydorax – A. eudorax
Name

Auxis Cuvier, 1829: 199

Type species: Scomber rochei Risso, 1810, by monotypy.

References
Links

Auxis in the World Register of Marine Species

Vernacular names
日本語: ソウダガツオ属

Auxis is a genus of ocean-dwelling ray-finned bony fish in the family Scombridae, and tribe Thunnini, also known as the tunas. Auxis, commonly and collectively called the frigate tunas, is one of five genera of tunas which comprise the Thunnini tribe.
Species

There are four extant species in the genus Auxis, which were formerly regarded as two polytypic species, each with two subspecies.[1] In 2021, the extinct species Auxis koreanus was described from the Neogene of South Korea.[2]
Extant species

Auxis brachydorax Collette & Aadland, 1996
Auxis eudorax Collette & Aadland, 1996
Auxis rochei Risso, 1810 (bullet tuna)
Auxis thazard Lacépède, 1800 (frigate tuna)

Extinct species

†Auxis koreanus Nam et al., 2021[2]

Description

Auxis can reach a length of 50–65 centimetres (20–26 in). They have a strong, fusiform body with a sharpened head. The teeth are small and conical. The two dorsal fins are separated by a wide gap. The pectoral fins are short. They have a dark, blue-black back, the top of the head may be deep purple or almost black. The belly is whitish and without streaks or spots.
Distribution

These fishes are widespread in all tropical and subtropical seas and oceans, and both mentioned species are present in the Mediterranean Sea with their subspecies (A. thazard thazard and A. rochei rochei).
Ecology

Auxis species are the predominant prey of pelagic gamefish off of the east coast of the United States.[3]
As food

In Japan the two species in the genus are collectively called sōdagatsuo (Japanese: ソウダガツオ,宗太鰹), and this is also the common genus name. In Japanese cuisine, these fish are processed into sōdabushi, a product much like katsuobushi, though not really used in fine-dining restaurants or as condiment, but as a fish stock ingredient at more budget type popular-dining places, e.g., soba noodle shops.

Although fresh fish might be eaten as sashimi or grilled, it has a lot of dark-red meat (chiai), so it is valued much less than the similar katsuo (skipjack tuna). And it degrades quickly so shipment out to market is limited. The frigate tuna (hirasoda) is considered superior between the two.
Fossil record
Fossil of Auxis propterigius from Monte Bolca

Fossils of Auxis have been found in the Pliocene of Italy and United States (age range: from 5.3 to 3.6 million years ago.).[4]
References

Froese, Rainer and Pauly, Daniel, eds. (2018). Species of Auxis in FishBase. April 2018 version.
Nam, G.; Nazarkin, M. V.; Bannikov, A. F. (2021). "First discovery of the genus Auxis (Actinopterygii: Scombridae) in the Neogene of South Korea". Bollettino della Società Paleontologica Italiana. 60 (1): 61–67. doi:10.4435/BSPI.2021.05.
Robins, Rick. "Time to Protect Our Bullet Tunas". sportfishingmag.com. Sport Fishing Mag. Retrieved 21 June 2019.
Paleobiology Database