Pseudunela viatoris

Pseudunela viatoris is a species of sea slug, an acochlidian, a shell-less marine gastropod mollusk in the family Pseudunelidae.

Pseudunela viatoris
A live Pseudunela viatoris hf – head-foot complex.
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
(unranked):	clade Heterobranchia clade Euthyneura clade Panpulmonata clade Acochlidiacea clade Hedylopsacea[1]
Family:	Pseudunelidae
Genus:	Pseudunela
Species:	P. viatoris
Binomial name
Pseudunela viatoris Neusser, Jörger & Schrödl, 2011[2]

The specific name viatoris is after the Latin word “viator” (engl. pilgrim/voyager) according to its supposed ability to travel over long distances.^[2]

Distribution

Pseudunela viatoris is known from Viti Levu, Fiji and Gili Lawa Laut, Indonesia.^[2] The type locality is Fiji, Viti Levu, Laucala Bay, Nukumbutho Island, GPS: 18°10.47′S, 178°28.34′E.^[2]

Description

Photo of a dorsal view of a live Pseudunela viatoris. Body size is 3 mm.
lt – labial tentacle,
rh – rhinophore,
ey – eye,
hb – heart bulb,
dg – digestive gland,
vh – visceral hump.

The body size of living specimens of Pseudunela viatoris is 3–4 mm.^[2] The body is divided into an anterior head-foot complex and a posterior elongated visceral hump.^[2] The paired labial tentacles are broad at the base and taper to the end.^[2] The rhinophores are tapered and shorter and thinner than the labial tentacles.^[2] The densely ciliated foot is as broad as the anterior head-foot complex and extends about one third of the elongated visceral hump.^[2] The heart bulb is visible externally in the anterior part of the visceral hump on the right body side.^[2] Subepidermal, needle-shaped calcareous spicules 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.^[2] The body colour is whitish translucent, the digestive gland is brownish coloured (in specimens from Indonesia: orange-brownish shining through the epidermis).^[2] Epidermal glands are distributed particularly over the visceral hump.^[2] Whereas eyes are not visible externally in specimens from Fiji, eyes are weakly visible in some specimens from Indonesia.^[2] Eye diameter is 30-35 μm.^[2]

3D reconstruction of the general anatomy of the right side view of Pseudunela viatoris.
ot – oral tube,
cns – central nervous system,
ph – pharynx,
vd – vas deferens,
bf – basal finger,
p – penis,
pr – prostate,
pc – pericardium,
f – foot,
k – kidney,
alg – albumen gland,
ov – ovotestis,
vh – visceral hump,
dg – digestive gland.

Nervous system, digestive system, circulatory system, excretory system and reproductive system are described by Neusser et al. (2011) in detail.^[2]

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 of marine sands.^[2]