Medusafissurella is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of minute deepwater keyhole limpet

Limpet

Limpet is a common name for a number of different kinds of saltwater and freshwater snails ; it is applied to those snails that have a simple shell which is more or less conical in shape, and either is not spirally coiled, or appears not to be coiled in the adult snails.The name limpet is most...

s, marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 gastropod mollusks or micromollusk

Micromollusk

A micromollusk is a descriptive term for a shelled mollusk which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine mollusks, although in addition, numerous species of land snails and freshwater mollusks also reach adult size at very small...

s in the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Fissurellidae, the keyhole limpets and slit limpets.

Etymology

In Greek mythology

Greek mythology

Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...

 Medusa

Medusa

In Greek mythology Medusa , " guardian, protectress") was a Gorgon, a chthonic monster, and a daughter of Phorcys and Ceto. The author Hyginus, interposes a generation and gives Medusa another chthonic pair as parents. Gazing directly upon her would turn onlookers to stone...

 was a Gorgon

Gorgon

In Greek mythology, the Gorgon was a terrifying female creature. The name derives from the Greek word gorgós, which means "dreadful." While descriptions of Gorgons vary across Greek literature, the term commonly refers to any of three sisters who had hair of living, venomous snakes, and a...

, a monster with snakes for hair. The radiating tentacles in Medusafissuralla recall the serpentine locks of this monster.

Description

Medusafissurella is closely associated with Amblychilepas and Dendrofissurella with which it shares radular

Radula

The radula is an anatomical structure that is used by molluscs for feeding, sometimes compared rather inaccurately to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus...

 and shell

Gastropod shell

The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...

 characters. But Medusafissurella has a smaller body than the species in Amblychilepas

Amblychilepas

Amblychilepas is a genus of sea snails, marine gastropod mollusks in the family Fissurellidae, the keyhole limpets.-Distribution:The species from this genus can be found in temperate waters of Australia, except Amblychilepas platyactis that is found along the Atlantic coast of the Cape Peninsula,...

, the genus to which it was previously assigned.

The body of species in Medusafissurella is larger than the shell. The anterior part of the shell is raised but is markedly narrowed. This character distinguishes Medusafissurella from most species in the genus Fissurella

Fissurella

Fissurella is a genus of small to medium-sized sea snails or limpets, marine gastropod mollusks in the family Fissurellidae, the keyhole limpets.- Ecology :...

. The edge of the anterior shell is thinner and sharper than in the rest of the shell. The posterior end of the shell is not raised at all or only slightly raised. The opening at the apex (foramen) has an oval shape. The sculpture

Sculpture (mollusc)

The sculpture of a mollusc shell is the three-dimensional ornamentation on the outer surface, as distinct from the basic shape of the shell itself or colouration. Sculpture may be concave as well as convex. Sometimes it has microscopic detail. Sculpture refers to the calcareous outer layer, not the...

 of the shell shows strong, scabrous ribs (= transverse folds) giving the impression of a rough surface with minute ribs. This character sets Medusafissurella apart from Amblychilepas and Dendrofissurella

The posterior portion of the foot is covered by the shell. The mantle fold

Mantle (mollusc)

The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...

s only slightly envelop the edge of the shell. The foot also shows elaborate propodial processes at the propodium (front part of the foot) with numerous subequal (= nearly equal) radiating tentacles, that are sometimes branched, while in Dendrofissurella the tentacles have a single, main branching structure. The function of these tentacles is not well understood. They may serve to trap or hold food, but then they would be better attached to the snout above them instead of being attached to the propodium. The large outer lateral tooth of the radula

Radula

The radula is an anatomical structure that is used by molluscs for feeding, sometimes compared rather inaccurately to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus...

 is quadricuspid ( = with four cusps). The eyes are situated at the base of the cephalic tentacles.

Species

• Medusafissurella chemnitzii, (Sowerby, 1835) : East Africa and Arabian Sea
  Arabian Sea
  The Arabian Sea is a region of the Indian Ocean bounded on the east by India, on the north by Pakistan and Iran, on the west by the Arabian Peninsula, on the south, approximately, by a line between Cape Guardafui in northeastern Somalia and Kanyakumari in India...
  
  
• Medusafissurella dubia L. A. Reeve, 1849 Southern and eastern Africa
• Medusafissurella salebrosa (Reeve, 1850) : Southwestern Africa