| Tambja | |
|---|---|
 | |
| Tambja sagamiana in Sukumo Bay, Kōchi Prefecture, Japan, head end towards the right | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Order: | Nudibranchia |
| Family: | Polyceridae |
| Subfamily: | Nembrothinae |
| Genus: | Tambja Burn, 1962 |
Tambja is a genus of colorful sea slugs, dorid nudibranchs, shell-less marine gastropod mollusks in the family Polyceridae.
These nudibranchs feed on bryozoans. They have a radula which bears a rachidian tooth whose upper margin is either smooth or notched; the lateral tooth has two crowns, and the other teeth are so flat as to resemble plates.
The most significant external feature of the genus Tambja is the ovular structure of "lateral slots" located between the rhinophores and the oral tentacles. In many species, they look a bit like the "cheekbones" of the animal, and many are coloured as if they have applied blush. In species like Tambja morosa and Tambja verconis they are very pronounced. Yet in other species, like Tambja dracomus and Tambja kava, they are far smaller and more subtle, or can even be obscured by the brim of the anterior mantle margin.
.jpg)
These ovular structures are lamellate upon close inspection, and sit over a horizontal slit in the slug's body that can dilate at will. Dissection led to the discovery that it is connected to the rhinophores internally, confirming that the purpose of these structures are sensory in nature.
All species of Tambja are considered to have these pre-rhinophoral sensory organs. The only species who are unconfirmed to possess them are species that are only known from a single observation or single preserved specimen. This makes pre-rhinophoral sensory organs the most defining external diagnostic feature of Tambja sea slugs, as neither Nembrotha, Martadoris, nor Tyrannodoris possess these lateral slots. The type species of Roboastra, Roboastra gracilis also does not possess them.
The only exceptions are Roboastra tentaculata and the several related, unnamed Roboastra species do. These animals however can be easily separated from Tambja sea slugs, as they possess the dorso-laterally grooved oral tentacles distinct to Roboastra. The presence of the lateral slots in addition to other very Tambja-like internal anatomy have lead some to insist they should be removed from genus Roboastra, yet they continue to remain therein on basis of former a sister-clade with R. gracilis.
Species in the genus Tambja include:
Species brought into synonymy:
