Alderia

Alderia is a genus of sacoglossan sea slugs in the family Limapontiidae. It comprises several described species found in temperate and subtropical coastal waters of the Northern Hemisphere.

Members are usually small to mid-sized with elongated, soft bodies and often translucent coloration that helps camouflage among algae and seagrass. They inhabit shallow marine habitats such as rocky shores, kelp beds, and seagrass meadows, where they graze on surfaces of green algae.

They feed primarily on green algae, including Ulva and related genera. Like other sacoglossans, their feeding relies on specialized mouthparts and digestive enzymes adapted for algal diets. Reproduction is typically sexual, and many sacoglossans are simultaneous hermaphrodites, with eggs laid in gelatinous masses that hatch into free-swimming larvae.

The genus Alderia is subject to taxonomic revision as molecular methods clarify species boundaries and evolutionary relationships within Limapontiidae and related sacoglossan families. Distribution records are patchy, and new species descriptions occur with increasing attention to small, cryptic marine invertebrates. The name Alderia is used in scientific nomenclature for this genus and occasionally appears in historical literature; it is not commonly used outside taxonomic contexts.