Velutininae Gray 1840
- Dataset
- Neither slugs nor snails: a molecular reappraisal of the gastropod family Velutinidae
- Rank
- SUBFAMILY
Classification
- kingdom
- Animalia
- phylum
- Mollusca
- class
- Gastropoda
- order
- Littorinimorpha
- family
- Velutinidae
description
(FIGS 2, 3, 4 C – F, 6 C, D, 9 B, 10 B, C, 11 B, C, N, O)
description
Description: Body of small to medium size for the family, 0.5 – 11.0 cm total length. Shell moderately thin to thick, weakly to strongly calcified; ear, shield or cap shaped, low to high spire, with expanded aperture; smooth or weakly sculptured by axial growth lines; exposed or completely enclosed by the mantle. Periostracum moderately or well developed, occasionally hairy. Protoconch of 1.1 – 2.0 whorls; protoconch I of 0.50 – 0.64 whorls, nucleus diameter 125 – 186 μm, smooth or with microgranules; protoconch – teleoconch boundary not always visible. Mantle flat or dome shaped, outline rounded; thick or thin, with or without dorsal tubercles; with or without anterior and right lateral siphonal folds; texture smooth, wrinkled or jelly-like; colour highly variable, almost transparent to white, grey, beige, yellow, orange, brown, often patterned. Penis to the right of the right cephalic tentacle, with tip of the seminal duct protruding from the penis tip. Vas deferens without a free loop in haemocoel. Radula taenioglossate, formula 2: 1: 1: 1: 2, rachidian tooth squared, with broad base, rachidian cusp with or without one to six pronounced external denticles; lateral teeth squared or elongated, with a pointed triangular internal or external cusp, with or without one to six denticles on both sides; marginals narrow, with or without one small denticle on the internal side. Jaws short to elongated, composed of scale-like elements, with denticles on the masticatory margin.
discussion
Remarks: Velutinines can be diagnosed by their squared rachidian tooth with a broad base, and the jaws composed of scale-like elements, with denticles. Their shells can range from strongly calcified and completely exposed (e. g. Velutina) to almost without calcification and completely enveloped by the mantle (e. g. Onchidiopsis). Some genera (e. g. Velutina and Limneria) also have a hairy periostracum. In addition to the anterior inhalant siphon, an exhalant siphon is made by a right lateral mantle fold in some genera (e. g. Marsenina and Onchidiopsis). Before the present study, six genera (two of them with subgenera; see Gulbin & Golikov, 1997) were classified in this subfamily. However, the present molecular phylogeny suggests that Limneria and Velutina might be synonyms. In addition, pending molecular analysis of the type material, we propose to place Pseudosacculus in this subfamily, based on the description of the only included species, Pseudosacculus okai (Hirase, 1927). The radular formula (2: 1: 1: 1: 2) and morphology (Hirase, 1927: 125, fig. 8) and the presence of a small dorsal aperture in the mantle are congruent with this placement. It should be noted that Pelseneer (1935) suggested that Pseudosacculus okai might be classifiable in Marsenina, which would make Pseudosacculus a junior synonym.
distribution
Distribution: Arctic and temperate regions worldwide, 0 – 1200 m deep.
synonymic_list
Included genera: CartilagoƲelutina Golikov & Gulbin, 1990, CiliatoƲelutina Golikov & Gulbin, 1990, Cilifera Golikov & Gulbin, 1990, Limneria H. Adams & A. Adams, 1851, Marsenina Gray, 1850, Onchidiopsis Bergh, 1853, Piliscus Lovén, 1859, Pseudosacculus Hirase, 1928, Pseudotorellia Warén, 1989, TorelliƲelutina J. H. McLean, 2000, Velutina J. Fleming, 1820.
type_taxon
type genus Velutina J. Fleming, 1820.