Seminole rams-horn - Helisoma duryi (Wetherby, 1879) - (alien invader) - Cyprus

 See also

List of non-marine molluscs of Cyprus - Freshwater snails and Land snails of Cyprus

(alien invader)
Planorbella duryi, common name the Seminole rams-horn, is a species of air-breathing freshwater snail, a pulmonate gastropod mollusk in the family Planorbidae, the ram's horn snails. The species is endemic to Florida and is found frequently in home aquariums. In the wild they are brown. In captivity they have been bred to come in many colours. This species of snail is endemic to the freshwater ecosystems of the US state of Florida. Fossils of the species have been found dating back to the Piacenzian, in the Tamiami formation.

It has been introduced to Hawaii and lives in the wild there. It is an introduced species in various European islands and countries including. They are found in most freshwater habitats including streams and ponds. This species is listed by natureserve as G5,

They are hermaphrodites. They lay eggs and are very fast breeders

They are a very common aquarium snail. Eggs can get into aquariums on plants. Some people consider them pests due to their ability to breed very fast and overpopulate. Other people value them as part of their clean up crew. From Wikipedia, the free encyclopedia

Photos by George Konstantinou

Spike-topped apple snail or mystery snail - Pomasea bridgesii (Reeve 1856) - (alien invader) - Cyprus

See also

List of non-marine molluscs of Cyprus - Freshwater snails and Land snails of Cyprus

 Pomacea bridgesii, common name the spike-topped apple snail or mystery snail, is a South American species of freshwater snail with gills and an operculum, an aquatic gastropod mollusk in the family Ampullariidae. These snails were most likely introduced to the United States through the aquarium trade.

Mystery snails possess structurally complex eyes at the tip of a cephalic eyestalk. They are able to regenerate the eye completely after amputation through the mid-eyestalk. They are born with both gills and lungs. Mystery snails also possess a siphon which is a small tube used to breathe air. They frequently surface to breathe

The native distribution of this snail is Bolivia, Brazil, Paraguay and Peru

This species is non-indigenous in Hawaii since 1960 (Pomacea bridgesii diffusa), southeast Asia since the 1980s, and Florida since the early 1980s (Pomacea bridgesii diffusa)

Most mystery snails lay their eggs above the water line. They are gonochoristic which means a male and female must be present for reproduction. The eggs take 2–4 weeks to hatch. The snails can produce as many as two hundred offspring from one egg-laying event. Sometimes not all the eggs are fertilized so they do not all hatch. When they do hatch, the hatchlings run the risk of being eaten if they share an aquarium with fish.[5] Hatchling mystery snails will grow quickly if given an appropriate amount of food and calcium. A hatchling mystery snail will start as a speck and can grow to the size of a pea in just over a week. A mystery snail is considered to be breeding size once it is almost the size of a golf ball, which can take as little as two months with the proper diet.

Mystery Snails are often found in lakes or rivers, where the oxygen levels is low,and are equipped with both an air tube and lung, as well as a gill, allowing them to easily breathe and take in the proper oxygen needed for survival. Pomacea bridgesii are mainly found in tropical environments and unable to sustain conditions under 50 degrees. From Wikipedia, the free encyclopedia - https://en.wikipedia.org/wiki/Pomacea_bridgesii

(alien invader)  

Photos by George Konstantinou

Great ramshorn - Planorbarius corneus (Linnaeus 1758) - Cyprus

See also

List of non-marine molluscs of Cyprus - Freshwater snails and Land snails of Cyprus

 (alien invader) 

Planorbarius corneus, common name the great ramshorn, is a relatively large species of air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Planorbidae, the ram's horn snails, or planorbids, which all have sinistral or left-coiling shells.

he shell of this species appears to be dextral in coiling, even though it is in fact sinistral or left-handed.

Distribution

Planorbarius corneus is distributed from western Europe, through central Europe and into the Caucasus, north into Siberia and south into the Middle East. In western Europe, it has been recorded in Belgium, France and the British Isles (including Britain, Ireland, the Isle of Man, Guernsey and Jersey). It is not found in Spain, but it has been recorded on some Spanish and Portuguese Atlantic islands, including Madeira, the Azores, the Canary Islands. In the Nordic countries, it has been recorded in Denmark, Finland, Sweden and Norway. Its range extends through central Europe (including Austria, Germany, the Netherlands, Luxembourg, Lichtenstein, Switzerland and the Czech Republic) into southern Europe (where it has been recorded in Greece and Italy) and eastern Europe and the Caucasus (including Albania, Armenia, Azerbaijan, Bosnia and Herzegovina, Bulgaria, Croatia, Estonia, Hungary, Latvia, Lithuania, Macedonia, Montenegro, Poland, Romania, Serbia, Slovakia, Slovenia and Ukraine). The species is also found in western Asia, having been recorded in Kazakhstan, Iran, western regions of Russia, Turkey, Turkmenistan and Uzbekistan.

Additionally, as the species is sometimes sold in the aquarium trade, it is also found outside of its main range in small ponds where they have been released or placed.

Description

All species within family Planorbidae have sinistral shells.

Planorbarius corneus is the largest European species of ramshorn snail (family Planorbidae), with a shell typically measuring 35 millimetres (1.4 in) across when fully-grown.

The 10–17 by 22–40 millimetres (0.39–0.67 by 0.87–1.57 in) coiled shell has between 3 and 4.5 rounded whorls with deep sutures, the last whorl predominating. The upper side is weakly depressed and the lower side is deeply depressed (flattened on the underside but spire recessed on the upper side). There is no keel. The shell is light yellowish with a brown, reddish or greenish periostracum, radially and spirally weakly striated. The aperture is wide and almost circular. The animal is brown or reddish

Habitat

This large planorbid is found in water which is still, or only moving slowly, where there is a good growth of many different kinds of pond weeds, and where there are high levels of calcium dissolved in the water.

P. corneus under high temperatures has been studied by Kartavykh & Podkovkin (2002).

Reproduction

Reproduction in spring and autumn at water temperatures above 15 °C, eggs (diameter 1.2-1.7 mm) are laid in mostly elongate capsules of 8–15 mm width, each strain containing 12-40 eggs, fixed to aquatic plants, embryos are reddish with transparent shells, juveniles hatch after 14–16 days, life span up to 3 years. Self-fertilization is possible, one single released animal can establish a stable population, but only 5% of the juveniles in self-fertilized eggs will hatch

As aquarium pets

P. corneus are available from commercial breeders, and they are easy to keep, as they do not need a minimum aquarium size, do not need heating, and likewise, the tank usually does not need to be oxygenated – though it helps to supply the microorganisms that process snail manure and food leftovers. They are said to only feed on living plants when other food sources (like algae and plant detritus) have become rare. They need calcium-rich water, so depending on the water source, they need additional calcium from cuttlebones or ground egg shells. The snails can be fed with any fish food, and vegetables like spinach leaves, green lettuce leaves and zucchini slices. In case of leafy or vegetable food, leftovers should be quickly removed in order to keep ammonium and nitrate levels low. Depending on the locale, a water conditioner is needed to remove copper, chlorine and other harmful ions from the water.

Both the European-Asian P. corneus and the smaller, North-American Planorbella duryi are known as "Ramshorn snails" in the aquarium trade and can be kept the same way, yet the adult Planorbella ones are significantly smaller, and their shells are smooth, shining and not striated. From Wikipedia, the free encyclopedia - https://en.wikipedia.org/wiki/Planorbarius_corneus

Photos by George Konstantinou

.

 

Red-rimmed melania - Melanoides tuberculata (O. F. Muller 1774) - Cyprus

See also 

Mienis, H.K., Rittner, O. & Konstantinou, G. Additions To The List Of The Inland Molluscs Of Cyprus. Triton, No. 26, Nov. 2012. p.36-40.

List of non-marine molluscs of Cyprus - Freshwater snails and Land snails of Cyprus

Family Thiaridae

The red-rimmed melania (Melanoides tuberculata), also known as Malayan livebearing snails or Malayan/Malaysian trumpet snails (often abbreviated to MTS) by aquarists, is a species of freshwater snail with an operculum, a parthenogenetic, aquatic gastropod mollusk in the family Thiaridae.

The common name comes from the presence of reddish spots on the otherwise greenish-brown shell.

The species name is sometimes spelled Melanoides tuberculatus, but this is incorrect because Melanoides Olivier, 1804 was clearly intended to be feminine because it was combined with the feminine specific epithet fasciolata in the original description.

This species is native to northern Africa and southern Asia, but it has been accidentally introduced in many other tropical and subtropical areas worldwide. It has also been accidentally introduced to heated aquaria in colder parts of the world.

This species has an elongate, conical shell, which is usually light brown, marked with rust-colored spots. An operculum is present. In some places, such as in Israel, the shells are colored in black or dark brown, probably to help conceal the snail on the background of the basalt rocks of the Sea of Galilee (Kinnereth).

The average shell length is about 20–27 millimetres (3⁄4–1+1⁄8 in)[8] or 30–36 millimetres (1+1⁄8–1+3⁄8 in), but exceptional specimens may be up to 80 millimetres (3+1⁄8 in) long. Shells of this species have 10–15 whorls

Although normally a freshwater snail, this species is very tolerant of brackish water, and has been recorded in waters with a salinity of 32.5 ppt (1,024 specific gravity salinity).

It is however a warm-climate species. It appears to prefer a temperature range of 18 to 25 °C (64 to 77 °F) or of 18 to 32 °C (64 to 90 °F). Research has been conducted to determine the snail's lethal high water temperature, which is about 50 °C (122 °F). This information is helpful in the disinfection of fishing gear and research equipment, which otherwise may inadvertently spread the snails to uninfested waters.

This species is resistant to low oxygen levels. The pollution tolerance value is 3 (on scale 0–10; 0 is the best water quality, 10 is the worst water quality).

This snail feeds primarily on algae

Red-rimmed melania females are both parthenogenic and ovoviviparous. Females can be recognized by their greenish coloured gonads while males have reddish gonads. Under good conditions, females will produce fertilised eggs that are transferred to a brood pouch where they remain until they hatch (parthenogenesis and viviparity). Melanoides tuberculata has 1–64 embryos in its brood pouch. Snails will begin reproducing at a size as small as 5 millimetres (1⁄4 in) or 10 millimetres (3⁄8 in) in length and broods may contain over seventy offspring (iteroparity). The size of the shell of the parent at peak release of juveniles is 20.0 millimetres (3⁄4 in). The size of juveniles at birth is 1.2–2.2 millimetres (3⁄64–11⁄128 in).

Melanoides tuberculata grows to a similar size as Tarebia granifera, are similar in size at first birth and juvenile output.

It is a r-strategist species

Red-rimmed melanias can sometimes be an agricultural pest species, as has been reported on Chinese cabbage plantations in Hong Kong

Red-rimmed melanias are quite commonly found in freshwater aquaria, but opinion in the hobby is divided between those who see them as a pest species, and those who value their usefulness as algae-eaters and substrate-cleaners. From Wikipedia, the free encyclopedia - https://en.wikipedia.org/wiki/Red-rimmed_melania

               Red-rimmed melania -  Melanoides tuberculata fossils from Cyprus Found by George Konstantinou

     Photos Larnaca 23/8/2023 by George Konstantinou

  

Galba truncatula (Müller, 1774) - Cyprus

See also

List of non-marine molluscs of Cyprus - Freshwater snails and Land snails of Cyprus

Galba truncatula is a species of air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Lymnaeidae, the pond snails.

Until recently, this species was known as Lymnaea truncatula.

Galba truncatula is the vector mainly involved in fascioliasis transmission to humans

Galba truncatula is believed to be native to Europe, but it has been introduced in other parts of world. Currently, Galba truncatula is commonly distributed in all European countries, including most Mediterranean islands such as Corsica, Malta, the Azores, Madeira, the Faroe Islands, the Balearic Islands, and the Canary Islands. Despite the fact that Galba truncatula has spread worldwide, exact distribution maps of the species are not available. In addition, most reports are based on morphological determination of the snail. Molecular evidences on the presence of Galba truncatula from non-European areas are limited. Galba truncatula has also been found in North and South America, several parts of Africa, and Asia.

In South America, the presence of Galba truncatula has already been molecularly verified in Bolivia, Peru, Argentina, Chile and Venezuela. In Africa, Galba truncatula is present mainly in Northern parts (i.e. Morocco, Algeria, Tunis, Egypt but also in South Africa, Ethiopia, Kenya, and Tanzania.

In Asia, the snail occurs in Russia but other Asian countries were reported very rarely. Galba truncatula was found in Iran, Pakistan[ and India

The height of the shell is 5–10 mm and the width of the shell is 2.5–6 mm.

The maximum length of the shell is 12.00 mm. Whorls are stepped The columella is folded.

Tentacles are wider and with a wide base Eyes are small. Mantle roof shows larger unpigmented whitish spots giving a pale appearance to the shell of living specimens by transparency.

The first bilateral teeth is tricuspid in radula. The praeputium/penis sheath length ratio is 2.50–5.90 mm (mean 3.44 mm).

Two species that have a similar morphology: Galba neotropica and Galba schirazensis.[Although several phenotypic characteristics may a priori be helpful for a preliminary specimen classification, a definitive classification of a specimen can only be obtained by the sequencing of at least one of the molecular markers used: ITS-2, ITS-1, 16S and cox1. Moreover, mixed populations of Galba truncatula and Galba schirazensis have already been described in the field

Galba truncatula can occupy both temporary and permanent freshwater ecosystems.The species occurs commonly in shallow well aerated water, in marshes, ponds, lakes, streams, rivers, water ditches. In France, the populations of Galba truncatula are declining because its habitat is threatened by modern agricultural practices. In case of larger water bodies, the snail occurs mostly on the edge between water and land, sometimes outside water layer on mud. Galba truncatula can be very abundant, with high population densities and it has an evident anthropophily including usual presence in human neighbourhood.

Galba truncatula is amphibious organism and can survive long dry periods. This is caused by its high ability to aestivate during drought conditions. It is known that Galba truncatula can survive 6 weeks to 4.5 months of dry periods in aestivated stage in mud. In the laboratory cultures, Kendall (1949) observed survival over 1 year in Petri dishes without water.

The species requires alkaline pH (pH range 7.0 up to 9.6) and calcium content over 0.3 

Galba truncatula can live at a very high altitude such as in the Northern Bolivian Altiplano (an area located between 3800 and 4100 m high altitude).

Feeding habits

Galba truncatula feed on algae and fresh or decomposed parts of plants.

Life cycle

In Europe, it has usually 2 generations per year and snails can live up to 2 years. During very wet years, the species can produce occasionally 3 generations per year.

They are hatching from eggs. The shape of egg cluster is rounded to oval shape even when containing more eggs.There are usually 2–15 eggs in cluster., From Wikipedia, the free encyclopedia - https://en.wikipedia.org/wiki/Galba_truncatula

Photos by George Konstantinou

Pisidium personatum (Malm, 1855) - Cyprus

See also

List of non-marine molluscs of Cyprus - Freshwater snails and Land snails of Cyprus

Pisidium personatum is a species of freshwater bivalve from the family Sphaeriidae.

Description

The 2.5-3.5 mm shell is a characteristic round-regular oval shape. It has centrally placed low, rounded umbos. The surface (periostracum) is dull or silky with very fine irregular concentric striations. The colour is yellowish to greyish but it is invariably coated in a red-brown to dark brown deposit.

Distribution

Its native distribution is European-Siberian.

Czech Republic – in Bohemia, in Moravia, least concern (LC)

Germany – distributed in all of Germany but in 5 states in red list (Rote Liste BRD).

Nordic countries: Denmark, Faroes, Finland (near threatened), Iceland, Norway and Sweden

Great Britain, Cyprus  and Ireland. From Wikipedia, the free encyclopedia

Photos by George Konstantinou

River limpet - Ancylus fluviatilis (Müller, 1774) - Cyprus

See also

List of non-marine molluscs of Cyprus - Freshwater snails and Land snails of Cyprus

The river limpet (Ancylus fluviatilis) is a species of very small, freshwater, air-breathing limpet, an aquatic pulmonate gastropod mollusk in the tribe Ancylini within the family Planorbidae, the ram's horn snails and their allies.

The 5–8 mm.limpet-like shell has a backwardly directed, conical apex. The shell shape is higher than Acroloxus and Ferrissia.The apex is blunt when seen from above, but appears more pointed from the side. The shell is bent backwards and very weakly to the right side. It is thin and translucent, with reticulate sculpture and fine growth lines. In colour it is light yellowish to reddish brown or dull pale brown. The animal is grey with black dots near the head and almost entirely covered by the shell. The tentacles are triangular with eyes at their base. The genital pore and pneumostome are very small and located at the right side.

The distribution type is (probably since de-limitation of various southern and eastern forms which may be given independent species status is not understood) Eurosiberian Southern-temperate.

This freshwater limpet is rheophile, which lives in oxygen-rich fast-running waters and also in karst springs. It does not occur in waters which freeze in winter. They need a hard substrate with suitable (not too low and not too rich) algae growth, which is why they are frequent in Central Europe especially in rivers and streams. In North America and Western Europe they occur in lakes. In contrast to many other freshwater snails, the animals tolerate a base-poor acidic environment. Southern European, North African and Middle East representative of the species group can survive exposure due to low water levels up to a certain extent by forming a protective layer on the underside of the shell. In Central European forms, this is possible only to a limited extent, but they may survive low water levels by adhering firmly on the stone surface..From Wikipedia, the free encyclopedia - https://en.wikipedia.org/wiki/Ancylus_fluviatilis

Photos by George Konstantinou

European physa, tadpole snail, bladder snail, and acute bladder snail - Physella acuta (Draparnaud, 1805) - Cyprus

See also

List of non-marine molluscs of Cyprus - Freshwater snails and Land snails of Cyprus

Physella acuta is a species of small, left-handed or sinistral, air-breathing freshwater snail, an aquatic gastropod mollusk in the family Physidae. Common names include European physa, tadpole snail, bladder snail, and acute bladder snail. In addition, Physa acuta, Physa heterostropha (Say, 1817) and Physa integra (Haldeman, 1841) are synonyms of Physella acuta (Draparnaud, 1805).

Etymology

The etymology of the name Physella is obscure but could be ultimately from a Greek root. "Physella" (as a place name) is recorded in Giovanni Gemisto's printed edition of Pliny's encyclopedia, perhaps lifted from Ermolao Barbaro's Castigationes Plinianae where it is recorded as Physcella. The French naturalist Jacques Draparnaud was the first to describe a species of the genus Physella and coined the name.

Snails in the family Physidae have shells that are sinistral, which means that if the shell is held with the aperture facing the observer and the spire pointing up, then the aperture is on the left-hand side.

The shells of Physella species have a long and large aperture, a pointed spire, and no operculum. The shells are thin and corneous and rather transparent.

Distribution

It was once thought that the indigenous distribution of Physella acuta is Mediterranean. However, when Physella heterostropha is considered to be a synonym, then the indigenous distribution of the species includes North America.

Physella acuta is a common species which is common in all of North America and Europe including the United Kingdom. The species seems to have first spread through the Mediterranean regions and then more slowly into Northern Europe. This species has been introduced into New Zealand and is widespread throughout both islands in ponds, lakes, and running water

Habitat

This species lives in freshwater rivers, streams, lakes, ponds, and swamps.

Physella acuta is frequently found in anthropogenic reservoirs, occurring in warm water discharges from power stations and in some rivers, but very rarely and not numerously in clay pit ponds. It can survive well under temporary harsh conditions (extreme temperature and water pollution), as long as they are short-lived.

Feeding habits

These snails eat dead plant and animal matter and various other detritus.

Because Physella acuta forages mainly on epiphytic vegetation and on the macrophytes, whereas other gastropods (Planorbis planorbis, Radix ovata) exploit the algal cover or phytobentos on the bottom, competition between Physella acuta and other gastropods appears to be minimal. From Wikipedia, the free encyclopedia - https://en.wikipedia.org/wiki/Physella_acuta

Photos by George Konstantinou

Carychium minimum (Müller, 1774) - Cyprus

See also

List of non-marine molluscs of Cyprus - Freshwater snails and Land snails of Cyprus

Carychium minimum is a species of very small air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Ellobiidae.

Description

The width of the shell is 0.9-1.1 mm. The height of the shell is 1.6-2.2 mm. It is wider than the shell of Carychium tridentatum which it closely resembles. As in C. tridentatum shell is dull white and cylindrical and the mouth is oval with two denticles and a thickened lip. However if the last whorl above the aperture is opened this shows the plica parietalis (a spiral ridge on the parietal region projecting into the interior of the shell) descending in a simple way downwards

Distribution

The distribution of Carychium minimum is Euro-Asiatic.

Northern Europe: Denmark, Finland, Norway, Sweden.

Western Europe: Belgium, France and Corsica, Great Britain and Channel Islands, Ireland, Luxembourg, Netherlands, Switzerland.

Central Europe: Austria, Czech Republic, Germany, Hungary, Liechtenstein, Poland, Slovakia, Slovenia.

Southern Europe: Greece including North Aegean Islands, Italy.

Southeastern Europe: Albania, Bosnia-Herzegovina, Bulgaria, Croatia, Montenegro, Romania, Serbia.

Southwestern Europe: Andorra, Portugal including Azores and Madeira, Spain.

Eastern Europe: Belarus, Crimea, Estonia, Kaliningrad, Latvia, Lithuania, Moldova, Ukraine, European Russia.

Southwestern Asia: Turkey,citation needed Armenia, Azerbaijan, Georgia

Western Siberia

Central Asia: northern, central, and eastern Kazakhstan

North America - introduced: Canada (British Columbia, Ontario, New Brunswick); USA (California, Massachusetts, New York, Pennsylvania). From Wikipedia, the free encyclopedia - https://en.wikipedia.org/wiki/Carychium_minimum

Photos by George Konstantinou

Gyraulus piscinarum (Bourguignat, 1852) - Cyprus

See also

List of non-marine molluscs of Cyprus - Freshwater snails and Land snails of Cyprus

Gyraulus piscinarum is a species of gastropods belonging to the family Planorbidae.

The species is found in Southeastern Europe (Bulgaria, Turkey) and Western Asia (Turkey, Syria, Lebanon, Israel, Iran). However, the specific range is uncertain because of uncertainty in assigning specific populations to this species

Gyraulus is a genus of small, mostly air-breathing, freshwater snails, aquatic pulmonate gastropod mollusks in the family Planorbidae, the ram's horn snails.

The genus Gyraulus is known from the Early Cretaceous to the present. Fossils attributed to Gyraulus sp. have been found in the lakebottom sediments of the Yixian Formation in China, dating to 125 million years ago.

The minute species Gyraulus crista, although technically a pulmonate gastropod, does not use air for respiration, but instead has a mantle cavity which has much water. These snail snails live on water plants in freshwater. Shell of the species within this genus are small, and are mostly almost planispiral in their coiling. From Wikipedia, the free encyclopedia

Photos by George Konstantinou

Theodoxus anatolicus (Recluz 1844) - Cyprus

See also

List of non-marine molluscs of Cyprus - Freshwater snails and Land snails of Cyprus

Theodoxus anatolicus is a species of a freshwater snail with an operculum, an aquatic gastropod mollusk in the family Neritidae, the nerites. 

Distribution

This species occurs in:

Turkey

Cyprus

Theodoxus is a genus of nerites, small water snails with an operculum, some of which live in freshwater, and some in both freshwater and brackish water, aquatic gastropod mollusks in the family Neritidae, the nerites.

The shell in this genus is semiovular with a flat apertural plain. There is no umbilicus. The columella and inner whorls are dissolved.

Species in the genus Theodoxus are highly variable in size, in color pattern of the periostracum, in details of the operculum and in theradula, and all these factors can make identification to species level very challenging

These animals are live on stones, and often also under stones, in up to 5-6 m depth or deeper, feeding on algal covers. Theodoxus needs rough surfaces in order to be able to digest its food, so a stony substrate is necessary. Green algae are not consumed;Theodoxus has no cellulases. These snails lay egg capsules containing 30-70 eggs each, usually on the shells of other Theodoxusanimals; only one juvenile grows, the other eggs serve as food

There were no systematic review of the genus Theodoxus as of 2007. Bunje (2004) noted at least 34 extant taxa at species level in the genus Theodoxus. IUCN Red List (2015) provided conservation status for 23 species of Theodoxus.  From Wikipedia, the free encyclopedia

Photos Lutra Afroditis by George Konstantinou

Melanopsis praemorsa (Linnaeus,1758) - Cyprus

See also

List of non-marine molluscs of Cyprus - Freshwater snails and Land snails of Cyprus

Melanopsis praemorsa is a species of freshwater snail in the family Melanopsidae

Melanopsis is a genus of freshwater snails with a gill and an operculum, aquatic gastropod mollusks in the family Melanopsidae. 

The genus first appeared in the Cretaceous.Melanopsis is the type genus of the family Melanopsidae. From Wikipedia, the free encyclopedia

Photos Lutra Afroditis by George Konstantinou