Las Cruces Acolid, Phidiana lascrucensis

Las Cruces Acolid, Phidiana lascrucensis. Underwater photograph taken in Zihuantanejo Bay, Guerrero, January 2019. Photograph courtesy of Ron Woheau, Zihuantanejo. Identification courtesy of Bob Hillis, Ivins, Utah.

Phylogeny:  The Las Cruces Aeolid,  Phidiana lascrucensis (Bertsch and A.J. Ferreira, 1974), is a member of the Facelinidae family of Sea Slugs. The genus Phidiana is one of thirty-one genera in that family, and there are fifteen species in this genus. They are known in Mexico as eolido de las cruces.

Morphology:   Las Cruces Aeolids are soft-bodied gastropods that lose their shells during their larval phase. They have elongate, deep bodies, with a tapering tail. The anterior end of their foot is angular. Their mantle forms a series of finger-like projections (cerata) along the entire back of the animal. These cerata function as gills, they assist with digestion, and they can incorporate stinging cells, from their prey, as a defense mechanism. Las Cruces Aeolids have long rhinophores (horn-like projections) on their heads. Rhinophores are chemosensory organs help them to locate food and potential mates. These nudibranchs lack complex eyes, but have photoreceptors that sense light and dark. Las Cruces Aeolids have translucent orange to yellow-orange bodies with white markings including the tips of their rhinophores and oral tentacles. They are covered with white specks on the dorsal surface. They reach a maximum of 2.5 cm (1.0 inches) in length.

Habitat and Distribution:  Las Cruces Aeolids are found in rocky areas within the intertidal zone, and to depths up to 20 m (66 feet). They are a tropical Eastern Pacific species. In Mexican waters they range from the Central Gulf of California south to Guatemala. They are absent from the northern portion of the Gulf and from along the west coast of the Baja Peninsula.

Diet:  The Las Cruces Aeolid has been  poorly studied and understood species. There is very little documentation regarding their diet. In general, aeolids are relatively fast moving, aggressive, predators feeding on coral polyps and other cnidarians, sea slug eggs, and algae. Some species store the stinging cells (nematocysts) from their food in cnidosacs at the end of their cerata, to serve as a defense.

Predators: Las Cruces Aeolids are primarily eaten by other nudibranchs. There are also accounts of them being eaten by fish and Navanax, Navanax inermis.

Reproduction:   Las Cruces Aeolids are simultaneous hermaphrodites (having male and female reproductive organs). They reproduce sexually by hypodermic insemination. This occurs when both mating partners dart their penis toward each other to induce one to act as a male and the other as the female. The victorious one to penetrate the body wall is the dominant male. The eggs are laid as a mass on the bottom stratum. The eggs hatch into veliger larva and later metamorphose into adults.

Synonyms:  None. Historically Phidiana mariadelmarae was considered a synonym, however the World Registry of Marine Species (WoRMS) now lists that Phidiana mariadelmarae to be a valid subspecies.