Fissurellidae

Fissurellidae, commonly called keyhole limpets or slit limpets, is a taxonomic family of small to medium-sized limpet-like sea snails, marine gastropod molluscs in the clade Vetigastropoda.Rosenberg, G. (2012). Fissurellidae. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=111 on 2013-01-02

Their common name derives from the small hole in the apex of their cone-like shells. Although superficially resembling "true" limpets, they are in fact not closely related to them.

Distribution The distribution of fissurellids is worldwide, from cold waters to tropical waters.Powell A. W. B., New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand 1979

Habitat Fissurellids live in habitats on and under rocks in the lower intertidal zones to deeper waters.

Shell description

Keyhole limpets somewhat resemble true limpets because of the simple conical shape of their shells, but in reality they are not closely related to true limpets, which are in the clade Patellogastropoda.

This conical shape and the low profile of the shell allow keyhole limpets to withstand wave attack on exposed rocks to which they attach firmly with their strong, muscular foot.

The shell may vary in color and pattern. The shell has a reticulate (= net-like) structure with strong radial ribs and lacks an operculum.

The shell ranges from 3 mm to 13.2 cm. The great keyhole limpet (Megathura crenulata) measures up to 13.2 cm.

For respiration, the shells of fissurellids have a single apical or subapical perforation ("keyhole"). This opening at the top allows a direct exit of exhalant water currents together with waste products from the mantle cavity. The water enters under the edge of the shell near the head and passes over large paired gills. Most young species in this family have a marginal slit in the middle of the anterior end of the spiral shell. Some species possess just a short internal groove at the anterior end. The paired organs in the mantle cavity represent a primitive condition in gastropods.

The soft body consists of a well-developed head, a short muzzle. It has a broad and flat foot and a well-developed mantle. This foot exerts a strong suction, adhering the keyhole limpet to its hard substratum. The mantle extends in some species partly or completely (as in Megathura crenulata) over the shell. The tentacles at the epipodium (the lateral grooves between foot and mantle) are well developed. The species in Medusafissurella have numerous subequal tentacles at the propodium, while the species in Dendrofissurella have an outgrowth with main trunk and side branches at the propodium. The eyes are situated on rudimentary pedicels at their outer bases. The sides are ornamented with short cirri. There are two, symmetrical branchial plumes . The anal siphon occupies the anterior notch or perforated summit of the shell.Tryon G. W. 1873. American marine conchology: or, Descriptions of the shells of the Atlantic coast of the United States from Maine to Florida

In addition to the possession of this hole, slit or groove, keyhole limpets differ in several other ways both internally and externally from true limpets.

Feeding habits Keyhole limpets are in essence herbivorous, feeding primarily on algae, but are also detritus feeders. They play an important role in marine ecosystems by controlling the growth of algae on rocky substrates.

A few species in the genera Diodora and Emarginella are carnivorous, feeding on sponges. Puncturella has been reported to digest diatoms and detritus. Puncturella aethiopica feeds mainly on Foraminifera. They are also prey for various marine animals, including starfish and some mollusk-eating birds.

Taxonomy Family Fissurellidae Fleming, 1822 Subfamily Diodorinae Odhner, 1932 Subfamily Emarginulinae Children, 1834 Subfamily Fissurellinae Fleming, 1822 Subfamily Hemitominae Kuroda, Habe & Oyama, 1971: synonym of Zeidorinae Naef, 1913 Subfamily Zeidorinae Naef, 1913

This classification was based by Bouchet & Rocroi on the studies by Keen (in Moore) (1960), Christiaens (1973) and McMean (1984).

Aktipis S.W., Boehm E. & Giribet G. (2011) then raised the tribe Diodorini to the status of subfamily Diodorinae.Aktipis S.W., Boehm E. & Giribet G. (2011) Another step towards understanding the slit-limpets (Fissurellidae, Fissurelloidea, Vetigastropoda, Gastropoda): a combined five-gene molecular phylogeny. Zoologica Scripta 40: 238-259

Genera Genera within the family Fissurellidae include:

Agariste Monterosato, 1892 Altrix Palmer, 1942 Amblychilepas Pilsbry, 1890 † Arginula K. van W. Palmer, 1937 † Atractotrema Cossmann, 1888 Buchanania Lesson, 1830 Clathrosepta McLean & Geiger, 1998 Clypidina Gray, 1847 Cornisepta McLean & Geiger, 1998 Cosmetalepas Iredale, 1924 Cranopsis Adams, 1860 Dendrofissurella Mclean and Kilburn, 1986 Diodora Gray, 1821 Emarginula Lamarck, 1801 † Entomella Cossmann, 1888 Fissurella Bruguière, 1789 Fissurellidea d'Orbigny, 1841 Fissurisepta Seguenza, 1863 Hemimarginula McLean, 2011 Hemitoma Swainson, 1840 Laeviemarginula Habe In Kuroda, 1953 Laevinesta Pilsbry and McGinty, 1952 Leurolepas J. H. McLean, 1970 Lucapina Sowerby II, 1835 Lucapinella Pilsbry, 1890 Macroschisma Sowerby, 1839 Manganesepta McLean & Geiger, 1998 Medusafissurella Mclean and Kilburn, 1986 Megathura Pilsbry, 1890 Monodilepas Finlay, 1927 Montfortia Récluz, 1843 Montfortista Iredale, 1929 Montfortula Iredale, 1915 Montfortulana Habe, 1961 Nesta Adams, 1870 Octomarginula McLean, 2011 † Palaeoloxotoma Hansen, 2019 Parmaphorella Strebel, 1907 Profundisepta McLean & Geiger, 1998 Puncturella R. T. Lowe, 1827 Pupillaea Gray In Sowerby, 1835 Rimula DeFrance, 1827 Rimulanax Iredale, 1924 (taxon inquerendum) Scelidotoma Choe, Yoon and Habe, 1992 Scutus Montfort, 1810 Stromboli Berry, 1954 Tugali Gray in Dieffenbach, 1843 Tugalina Habe, 1953 Vacerrena Iredale, 1958 Variemarginula McLean, 2011 Zeidora A. Adams, 1860

Genera brought into synonymy Austroglyphis Cotton & Godfrey, 1934: synonym of Diodora Gray, 1821 Aviscutum Iredale, 1940: synonym of Scutus Montfort, 1810 Capiluna Gray, 1857: synonym of Diodora Gray, 1821 Cemoria Risso, 1826 [ex Leach MS]: synonym of Puncturella Lowe, 1827 Cremoria [Gray, 1842]: synonym of Puncturella Lowe, 1827 Elegidion Iredale, 1924: synonym of Diodora J. E. Gray, 1821 Emarginella Pilsbry, 1890: synonym of Emarginula Lamarck, 1801 Entomella Cotton, 1945: synonym of Emarginula Lamarck, 1801 Fissuridea Swainson, 1840: synonym of Diodora J. E. Gray, 1821 Glyphis Carpenter, 1857: synonym of Diodora J. E. Gray, 1821 Legrandia Beddome, 1883: synonym of Zeidora A. Adams, 1860 Megatebennus Pilsbry, 1890: synonym of Fissurellidea d'Orbigny, 1839 Nannoscutum Iredale, 1937: synonym of Scutus Montfort, 1810 Nesta H. Adams, 1870: synonym of Zeidora A. Adams, 1860 Notomella Cotton, 1957: synonym of Emarginula Lamarck, 1801 Parmophoridea Wenz, 1938: synonym of Parmaphorella Strebel, 1907 Parmophorus Blainville, 1817: synonym of Scutus Montfort, 1810 Plagiorhytis P. Fischer, 1885: synonym of Montfortula Iredale, 1915 Scutum P. Fischer, 1885: synonym of Scutus Montfort, 1810 Semperia Crosse, 1867: synonym of Emarginula Lamarck, 1801 Sipho T. Brown, 1827: synonym of Puncturella Lowe, 1827 Siphonella Issel, 1869: synonym of Montfortista Iredale, 1929 Subemarginula Gray, 1847: synonym of Hemitoma Swainson, 1840 Subzeidora Iredale, 1924: synonym of Emarginula (Subzeidora) Iredale, 1924 Tugalia Gray, 1857: synonym of Tugali Gray, 1843 Vacerra Iredale, 1924: synonym of Puncturella Lowe, 1827 Zidora P. Fischer, 1885: synonym of Zeidora A. Adams, 1860

Fissurellidae

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