Patella

Common limpets Patella vulgata, copyright S. Rae.

Belongs within: Patellogastropoda.

Patella is a genus of limpets found in the northeastern Atlantic (Nakano & Ozawa 2004). Representatives have a solid shell with a subcentral apex that may be marked by strong radial ribs (Knight et al. 1960).

Limpets of the Northeast Atlantic
Published 10 December 2012
The common limpet Patella vulgata, photographed by Rokus Groeneveld.

When Linnaeus published the tenth edition of his Systema Naturae in 1758, he defined the genus Patella as having a subconical shell with a single valve and without a respiratory opening. Starting from this fairly minimal set of criteria, it is not surprising that a very broad range of limpets from all over the world ended up passing through Patella at various times. However, as time goes by the definition of Patella became further refined, and currently both morphological (Ridgway et al. 1998) and molecular (Nakano & Ozawa 2004) studies have tied the name Patella to a clade of limpets found only in coastal waters of the north-east Atlantic Ocean and the Mediterranean.

The giant limpet Patella ferruginea, up to eight centimetres in diameter, photographed by E. Volto.

This restricted sense of Patella includes nine or ten recognised species, though discussions are ongoing about whether given populations should be regarded as conspecific or not, and a large number of subspecies have been described. Limpets are fairly conservative animals morphologically, offering a fairly narrow range of characters for taxonomic study. Matters are further confused by a certain degree of environmentally-related plasticity: individuals living higher in the tidal zone tend to be larger and higher-spired than individuals living subtidally (Weber & Hawkins 2002). Patella limpets are generally believed to be protandrous, starting their lives as males and eventually metamorphosing into females; however, a study monitoring sex changes in P. vulgata identified one individual that changed from female to male (Le Quesne & Hawkins 2006). Patella limpets have been used for food by humans in many parts of their range, and collection pressure is regarded as a significant threat to the endangered western Mediterranean species P. ferruginea.

Blue-rayed limpets Patella pellucida, from here.

Within the family Patellidae, the distribution of Patella is unusual: this genus is largely geographically isolated from other patellids in southern Africa and the Indo-Pacific. Only a single other patellid species, the western African Cymbula safiana, has a range overlapping with Patella species (Ridgway et al. 1998). The fossil record contains little evidence how this separation came about: patellids are rarely preserved, living as they do in high-energy environments, and their morphological simplicity makes them difficult to identify though genera can be distinguished by their shell microstructure. Patella proper has not been reliably identified earlier than the Pliocene (Ridgway et al. 1998). It has been suggested that the ancestors of Patella either migrated up the western coast of Africa, or became separated from other patellids by the closure of the Tethys Sea that once connected what is now the Mediterranean with the Indian Ocean. However, molecular analyses have placed Patella as the sister taxon to all other patellids; if correct, this could push its separation back past the Upper Cretaceous as a Japanese fossil from that time has been assigned to the patellid genus Scutellastra. This would be too early for the African dispersal or Tethyan explanations, and new proposals are required.

Systematics of Patella
<==Patella Linnaeus 1758BR05 (see below for synonymy)
    |--+--P. ferruginea Gmelin 1791NO04
    |  `--P. rustica Linnaeus 1758NO04
    `--+--+--P. aspera Röding 1798NO04
       |  `--P. (Ansates Sowerby 1839) [=Patina Gray 1847]KC60
       |       `--P. (*A.) pellucida Linnaeus 1758KC60, NO04 [=Helcion (*A.) pellucidusKC60, Patina pellucidaAH96]
       `--+--+--*P. (Patella) vulgata Linnaeus 1758KC60, NO04
          |  `--P. depressa Pennant 1777NO04
          `--+--P. lugubris Gmelin 1791NO04
             `--+--P. caerulea Linnaeus 1758NO04
                `--P. candei d’Orbigny 1839NO04
Patella incertae sedis:
  P. anthracophilaG31
  P. argenvilleiGH04
  P. caliculus Li 1930 [=P. calcilus (l. c.), P. calyculus (l. c.)]BC01
  P. calix Li 1930 [=P. calyx]BC01
  P. clypeasterC64
  P. costata [incl. P. alticostata]B97
  P. cruciata Linnaeus 1758L58
  P. discorsC64
  P. elegans [incl. P. candeana, Tectura fascicularis]G79
  P. exarata [incl. P. mazatlandica]C64
  P. fusca Linnaeus 1758L58
  P. grata Gould 1859C64
  P. livescensC64
  P. lutea Linnaeus 1758L58
  P. miyakoensis Kase 1984TTE93
  P. nubecula Linnaeus 1758L58
  P. pallida Gould 1859C64
  P. pectenC64
  P. pediculusC64
  P. peziza [incl. Dispotaea byronensis]C64
  P. pustula Linnaeus 1758L58
  P. reticulata Linnaeus 1758L58
  P. safianaBBB-S95
  P. sandwicensis Pease 1861K65
  P. solandri Colenso 1845C45
  P. talcosaC64
  P. tramoserica Martyn 1784C64
  P. testudinaria Linnaeus 1758L58
  P. toreumaC64
  P. tuberculata Linnaeus 1758L58
  P. vespertina [incl. P. stipulata]C64
  P. (Ancistromesus Dall 1871)KC60
    |--P. (*A.) mexicana Broderip & Sowerby 1829KC60
    `--P. (A.) picaC60
  P. (Olana Adams & Adams 1854)KC60
    `--P. (*O.) cochlear Born 1778KC60
  P. (Patellastra Monterosato 1884)KC60
    `--P. (*P.) lusitanica Gmelin 1791KC60
  P. (Patellidea Thiele in Troschel 1891)KC60
    `--P. (*P.) granularis Linnaeus 1758KC60
  P. (Patellona Thiele in Troschel 1891)KC60
    `--P. (*P.) granatina Linnaeus 1758KC60

Patella Linnaeus 1758BR05 [=Patellus Montfort 1810KC60; incl. Costatopatella Pallary 1912KC60, Granopatella Pallary 1920KC60, Laevipatella Pallary 1920KC60, Patellaria Gmelin 1793 non Hoffm. 1789 (ICBN)KC60, Patellopsis Thiele in Troschel 1891KC60]

*Type species of generic name indicated

References

[AH96] Angerer, G., & G. Haszprunar. 1996. Anatomy and affinities of lepetid limpets (Patellogastropoda=Docoglossa). In: Taylor, J. D. (ed.) Origin and Evolutionary Radiation of the Mollusca pp. 171–175. Oxford University Press: Oxford.

[BBB-S95] Boubezari, K., G. Bitar & D. Bellan-Santini. 1995. Structure et organisation de trois moulières (Mytilus galloprovincialis et Perna perna) de la région d’Alger. Mésogée 54: 63–72.

[BR05] Bouchet, P., & J.-P. Rocroi. 2005. Classification and nomenclator of gastropod families. Malacologia 47 (1–2): 1–397.

[BC01] Boyko, C. B., & J. R. Cordeiro. 2001. Catalog of Recent type specimens in the Division of Invertebrate Zoology, American Museum of Natural History. V. Mollusca, part 2 (class Gastropoda [exclusive of Opisthobranchia and Pulmonata], with supplements to Gastropoda [Opisthobranchia], and Bivalvia). Bulletin of the American Museum of Natural History 262: 1–170.

[B97] Brazier, J. 1897. Note on the shells found in kitchen middens at Bondi Bay. Proceedings of the Linnean Society of New South Wales 21 (4): 817–818.

[C64] Carpenter, P. P. 1864. Supplementary report on the present state of our knowledge with regard to the Mollusca of the west coast of North America. Report of the British Association for the Advancement of Science 33: 517–686.

[C45] Colenso, W. 1845. Memoranda of an excursion, made in the Northern Island of New Zealand, in the summer of 1841–2; intended as a contribution towards the natural productions of the New Zealand groupe: with particular reference to their botany. Tasmanian Journal of Natural Science 2: 210–234.

[C60] Cox, L. R. 1960. Gastropoda: general characteristics of Gastropoda. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt I. Mollusca 1: Mollusca—General Features, Scaphopoda, Amphineura, Monoplacophora, Gastropoda—General Features, Archaeogastropoda and some (mainly Paleozoic) Caenogastropoda and Opisthobranchia pp. I84–I169. Geological Society of America, and University of Kansas Press.

[G31] Grabau, A. W. 1931. The Permian of Mongolia: A report on the Permian fauna of the Jisu Honguer limestone of Mongolia and its relations to the Permian of other parts of the world. American Museum of Natural History: New York.

[GH04] Gray, D. R., & A. N. Hodgson. 2004. The importance of a crevice environment to the limpet Helcion pectunculus (Patellidae). Journal of Molluscan Studies 70: 67–72.

[G79] Guppy, R. J. L. 1879. First sketch of a marine invertebrate fauna of the Gulf of Paria and its neighbourhood. Part I.—Mollusca. Journal of Conchology 2: 151–172.

[K65] Kay, E. A. 1965. Marine molluscs in the Cuming collection, British Museum (Natural History) described by William Harper Pease. Bulletin of the British Museum (Natural History): Zoology Supplement 1: 1–96, 14 pls.

[KC60] Knight, J. B., L. R. Cox, A. M. Keen, R. L. Batten, E. L. Yochelson & R. Robertson. 1960. Gastropoda: systematic descriptions. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt I. Mollusca 1: Mollusca—General Features, Scaphopoda, Amphineura, Monoplacophora, Gastropoda—General Features, Archaeogastropoda and some (mainly Paleozoic) Caenogastropoda and Opisthobranchia pp. I169–I331. Geological Society of America, and University of Kansas Press.

Le Quesne, W. J. F., & S. J. Hawkins. 2006. Direct observations of protandrous sex change in the patellid limpet Patella vulgata. Journal of the Marine Biological Association of the United Kingdom 86: 161–162.

[L58] Linnaeus, C. 1758. Systema Naturae per Regna Tria Naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. Laurentii Salvii: Holmiae.

[NO04] Nakano, T., & T. Ozawa. 2004. Phylogeny and historical biogeography of limpets of the order Patellogastropoda based on mitochondrial DNA sequences. Journal of Molluscan Studies 70: 31–41.

Ridgway, S. A., D. G. Reid, J. D. Taylor, G. M. Branch & A. N. Hodgson. 1998. A cladistic phylogeny of the family Patellidae (Mollusca: Gastropoda). Philosophical Transactions of the Royal Society of London Series B 353: 1645–1671.

[TTE93] Tracey, S., J. A. Todd & D. H. Erwin. 1993. Mollusca: Gastropoda. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 131–167. Chapman & Hall: London.

Weber, L. I., & S. J. Hawkins. 2002. Evolution of the limpet Patella candei d’Orbigny (Mollusca, Patellidae) in Atlantic archipelagos: human intervention and natural processes. Biological Journal of the Linnean Society 77: 341–353.

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