''Pseudunela viatoris'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 ...

, an

acochlidian Acochlidiacea, common name acochlidians, are a taxonomic clade of very unusual sea snails and sea and freshwater slugs, aquatic gastropod mollusks within the large clade Heterobranchia. Acochlidia is a variant spelling. Description These ar ...

, a shell-less marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the family

Pseudunelidae ''Pseudunela'' is a genus of minute sea slugs, acochlidians, shell-less marine or temporary brackish or brackish gastropod mollusks in the clade Acochlidiacea. ''Pseudunela'' is the only genus in the family Pseudunelidae. ''Pseudunela'' is the ...

. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

''viatoris'' is after the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word “viator” (engl. pilgrim/voyager) according to its supposed ability to travel over long distances.

Distribution

''Pseudunela viatoris'' is known from

Viti Levu Viti Levu (pronounced ; ) is the largest island in Fiji. It is the site of the country's capital and largest city, Suva, and home to a large majority of Fiji's population. Geology Fiji lies in a plate tectonics, tectonically complex area betwe ...

, Fiji and Gili Lawa Laut, Indonesia. The type locality is Fiji, Viti Levu, Laucala Bay, Nukumbutho Island, GPS: 18°10.47′S, 178°28.34′E.

Description

The body size of living specimens of ''Pseudunela viatoris'' is 3–4 mm. The body is divided into an anterior head-foot complex and a posterior elongated visceral hump. The paired labial

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s are broad at the base and taper to the end. The

rhinophore A rhinophore is one of a pair of Chemoreceptor, chemosensory club-shaped, rod-shaped or ear-like structures which are the most prominent part of the external head anatomy in sea slugs, Marine (ocean), marine gastropod opisthobranch mollusks suc ...

s are tapered and shorter and thinner than the labial tentacles. The densely

ciliated The cilium (: cilia; ; in Medieval Latin and in anatomy, ''cilium'') is a short hair-like membrane protrusion from many types of eukaryotic cell. (Cilia are absent in bacteria and archaea.) The cilium has the shape of a slender threadlike pr ...

foot is as broad as the anterior head-foot complex and extends about one third of the elongated visceral hump. The heart bulb is visible externally in the anterior part of the visceral hump on the right body side. Subepidermal, needle-shaped calcareous

spicule Spicules are any of various small needle-like anatomical structures occurring in organisms Spicule may also refer to: *Spicule (sponge), small skeletal elements of sea sponges *Spicule (nematode), reproductive structures found in male nematodes ( ...

s are sparsely distributed in the cephalic tentacles, the foot and the visceral hump; in the anterior part of the latter they are larger than in the posterior part. The body colour is whitish translucent, the

digestive gland The hepatopancreas, digestive gland or midgut gland is an organ of the digestive tract of arthropods and molluscs. It provides the functions which in mammals are provided separately by the liver and pancreas, including the production of digestive ...

is brownish coloured (in specimens from Indonesia: orange-brownish shining through the epidermis). Epidermal glands are distributed particularly over the visceral hump. Whereas eyes are not visible externally in specimens from Fiji, eyes are weakly visible in some specimens from Indonesia. Eye diameter is 30-35 μm. Pseudunela viatoris 3

Nervous system In biology, the nervous system is the complex system, highly complex part of an animal that coordinates its behavior, actions and sense, sensory information by transmitting action potential, signals to and from different parts of its body. Th ...

digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller compone ...

circulatory system In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. It includes the cardiovascular system, or vascular system, that consists of the heart ...

excretory system The excretory system is a passive biological system that removes excess, unnecessary materials from the body fluids of an organism, so as to help maintain internal chemical homeostasis and prevent damage to the body. The dual function of excret ...

and

reproductive system The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are al ...

are described by Neusser et al. (2011) in detail.

Ecology

''Pseudunela viatoris'' is a minute species that lives in the spaces between sand grains in saltwater habitats, and it is thus considered to be a mesopsammic, marine interstitial animal that is part of the

meiofauna Meiobenthos, also called meiofauna, are small benthic invertebrates that live in marine or freshwater environments, or both. The term ''meiofauna'' loosely defines a group of organisms by their sizelarger than microfauna but smaller than macrof ...

of marine sands.

References

This article incorporates CC-BY-2.5 text from the reference

External links

* {{Taxonbar, from=Q12066532 Pseudunelidae Gastropods described in 2011