''Aiteng marefugitus'' is a species of fully

terrestrial Terrestrial refers to things related to land or the planet Earth, as opposed to extraterrestrial. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on o ...

sea slug Sea slug is a common name for some Marine biology, marine invertebrates with varying levels of resemblance to terrestrial Slug, slugs. Most creatures known as sea slugs are gastropods, i.e. they are Sea snail, sea snails (marine gastropod moll ...

found only on the Ulong Island of

Palau Palau, officially the Republic of Palau, is an island country in the Micronesia subregion of Oceania in the western Pacific Ocean. The Republic of Palau consists of approximately 340 islands and is the western part of the Caroline Islands ...

. The species name is derived from Latin, meaning "fled from the sea".

Description

''A. marefugitus'' is a very small slug, reaching only . It possesses a dark grey mantle on a light grey body, with two tiny black eyes. Its external anatomy is similar to other species in the genus, having neither a shell nor gills. Its excretory system is characterized by a long nephridial duct, which is assumed to reabsorb salt from the slug's urine. It lays large oocytes, which could supply its young with enough yolk to allow fully terrestrial development of the eggs.

Evolution & Taxonomy

''A. marefugitus'' is a member of the order Acochlidia, of the clade

Panpulmonata Panpulmonata is a taxonomic clade of snails and slugs in the clade Heterobranchia within the clade Euthyneura. Panpulmonata was established as a new taxon by Jörger et al. in October 2010. The older name "Pulmonata" referred to a group of euth ...

. Molecular analysis revealed the species as distinct from others in its genus, and showed the species split from a common ancestor of the other two species. This speciation is predicted to have occurred in the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

, roughly the same time the Palauan islands were formed. After the islands' formation, the humid climate and lack of competition may have allowed the sea slug to colonize a habitat which would lack native slugs.

Ecology

Ulong Island is a humid, tropical rainforest with rocky outcroppings. ''A. marefugitus'' is found at altitudes between 20 and 30 meters above sea level, where it lives within

leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituen ...

. Though this species has not been observed feeding, other species in the genera feed on insect larvae, pupae, and gastropod eggs.

References

{{taxonbar, from=Q106223533 Aitengidae Gastropods described in 2015 Fauna of Palau