Capulidae


The Capulidae, the cap snails or cap shells, are a taxonomic family of limpet-like sea snails, marine gastropod molluscs.
Capulidae is the only family in the superfamily Capuloidea. Capulidae is assigned to the paraphyletic order Littorinimorpha, but is more closely related to neogastropods than some other littorinimorphs as it is a member of the clade Latrogastropoda.
The name Trichotropidae was previously used for this family, but this name is invalid, as it is a junior synonym.

Characteristics

The foot is complicated on its anterior margin. The shell adheres to the animal by a circular muscle, leaving an opening in front for the issue of the head and the entrance to the branchial cavity. The gills form a single ridge across the roof. The aperture is in the form of an extended proboscis, with a deep groove above. The tentacula, which are two in number, have the eyes at their external base. The anus is on the right side of the branchial cavity.
Cup-shaped or bonnet-like, the shells of this family start with flat, tightly coiled initial whorls. From this beginning, they expand rapidly in a planospiral way, flaring out dramatically like a funnel.
The interior of the shell is porcelaneous. Some forms develop internal partitions or septa, a feature that makes them superficially resemble the Calyptraeidae. Externally, the shell is covered by a thick periostracum that feels either felt-like or hairy. There is no operculum.
Species in this family are parasites, praying mostly on other molluscs. They steal the food from these animals with a long proboscis.

Genera

Genera within the family Capulidae include:
;Subfamily Capulinae J. Fleming, 1822 Ariadnaria Habe, 1961
;Subfamily † Lysinae Saul & Squires, 2008
; Genera brought into synonymy :Actita Fischer von Waldheim, 1823: synonym of Capulus Montfort, 1810Antitrichotropis Powell, 1951: synonym of Torellia Jeffreys, 1867Ariadna P. Fischer, 1864: synonym of Ariadnaria T. Habe, 1961 Brocchia Bronn, 1828: synonym of Capulus Montfort, 1810Capulonix Iredale, 1929: synonym of Capulus Montfort, 1810Dolichosirius Iredale, 1931: synonym of Sirius Hedley, 1900
  • Eosirius P. A. Maxwell, 1966: synonym of † Trichosirius P. A. Maxwell, 1966 represented as Trichosirius H. J. Finlay, 1926Iphinoe H. Adams & A. Adams, 1856 : synonym of Neoiphinoe Habe, 1978
  • Mesostoma Deshayes, 1861: synonym of † Cerithioderma Conrad, 1860 Neoconcha E.A. Smith, 1907: synonym of Torellia E.A. Smith, 1907Opposirius Iredale, 1931: synonym of Sirius Hedley, 1900Ovotropis Egorov & Alexeyev, 1998: synonym of Neoiphinoe Habe, 1978Pileopsis Lamarck, 1822: synonym of Capulus Montfort, 1810Opposirius Iredale, 1931: synonym of Sirius Hedley, 1900Trichoconcha E.A. Smith, 1907: synonym of Torellia Jeffreys, 1867
  • Tropidothais L. R. Cox, 1925: synonym of † Lysis Gabb, 1864