Myosotella myosotis

Myosotella myosotis (Draparnaud, 1801)
Mouse-ear Snail

  • Auricula myosotis Draparnaud [1801]: 53.
  • Melampus borealis Conrad 1832: 345.
  • ? Auricula sayi C. H. Küster 1844: 42, nomen dubium.
  • Alexa bermudensis H. Adams & A. Adams 1855: 33.
  • Melampus turritus “Say MS” Binney 1859: 174.
  • Alexia setifer Cooper 1872: 153, pl. 3, figs A1–A3.
  • Alexia setifer var. tenuis Cooper 1872: 154, pl. 3, fig. A4.
  • Tralia (Alexia) myosotis form junior Dall 1885: 278.
  • Alexa myosotis marylandica Pilsbry 1900: 40.
  • Alexa bidentata form americana Kobelt 1901 in 1897–1901: 312, pl. 33, figs 1, 2.
  • Many additional synonyms in Europe, Australia, mid-Atlantic Islands, and elsewhere (Martins 1996).
Myosotella myosotis; Horton Bay, Mayne Island, Strait of Georgia, BC.

Identification. Shell elongate-ovate. Spire tall, with sides straight or scarcely convex. Apex acutely pointed. Suture rather shallow. Whorls ca 7 , not very convex in profile. Periphery rounded, medial. Protoconch smooth, but most often eroded. Teleoconch with first three whorls deeply pitted in spiral rows, then smoothish or with irregular, often quite strong growth wrinkles; particularly when shell eroded, low colabral riblets often evident; occasional varix present at site of growth rest. Juveniles and occasionally well-preserved adults with 1 spiral row of well-spaced periostracal hairs (which correspond to the pits). Aperture subovate-elongate, acutely angled above, ca 70% of shell height, with 1 strong, medial parietal plica, 1 strong columellar plica, and 1 low, callus-like protuberance (usually absent) above; plicae white. No palatal lirae in BC specimens, although 1 or more are reported elsewhere (Frias Martins 1996). Lip expanded when mature but generally thin. Parietal callus glazed, transparent, inconspicuous. No umbilicus. Shell weakly glossy, yellowish or more frequently reddish brown; lip pale. Height to 8.4 mm (higher than wide).

Animal greyish-white, darker, blackish anteriorly and dorsally and on tentacles; sole of foot yellowish grey. Blackish eye spots at base of tentacles. Foot yellowish.

Easily differentiated from Melampus bidentatus, the only other semimarine ellobiid in Canada, by its smaller, more elongate shell, tall spire, broader aperture, among other characters.

Habitat. Semimarine supralittoral zone along the coast, in salt marshes of sheltered bays. Living under driftwood and plants such as pickleweed (Salicornia), and occasionally under cobbles and along the strand line, under detritus and dislodged eelgrass (Zostera).

This is a semimarine salt-marsh snail, included here to complete the family Ellobiidae.

Global range. Mediterranean and Eastern Atlantic coasts, including Bermuda; Azores and Madeira; South Africa; Nova Scotia to Cuba; California; South Africa; Australia (Frias Martins 1996). All North American occurrences of M. myosotis are introductions (Frias Martins 1996). The wide distribution to many places worldwide is probably due to being transported in ships’ ballast or cargo (Climo 1982).

Canadian range. Introduced British Columbia (Strait of Georgia, north to at least Union Bay, Vancouver Island) and Nova Scotia (Halifax; Bousfield 1960, unpublished data). Expected for New Brunswick and PEI. Probably first noticed in BC by Grass (1967), who found it in Boundary Bay.

Etymology. Greek, myos, “mouse” + otis, “ear”, a reference to the shape of the shell.

Remarks. In the literature, M. myostis has variously been placed in Alexia, Phytia, or Ovatella (among others), but Frias Martins (1996, 1999) resurrected Myosotella for this species.

References

  • Adams H, Adams A (1855) Contributions towards the natural history of the Auriculidæ, a family of pulmoniferous Mollusca; with descriptions of many new species from the Cumingian Collection. Proceedings of the Zoological Society of London for 1854 22: 30–32; (262): 222–237.
  • Binney WG (1859) A supplement to the terrestrial air-breathing mollusks of the United States and the adjacent territories of North America. Vol. IV. Boston Journal of Natural History 7: i–viii, 1–207, pls 75–80.
  • Bousfield E (1960) Canadian Atlantic sea shells. National Museum of Canada, Ottawa, vi + 72 pp.
  • Climo FM (1982) The systematic status of Auricula (Alexia) meridionalis Brazier, 1877 and Rangitotoainsularis Powell, 1933 (Mollusca: Ellobiidae) in Australasia. National Museum of New Zealand Records
  • Conrad TA (1832) On some fossil and Recent shells of the United States. American Journal of Science 23: 339–346.
  • Cooper JG (1872) On new Californian Pulmonata, etc. Proceedings of the Academy of Natural Sciences of Philadelphia 1872: 143–154, pl. 3.
  • Dall WH (1885) Notes on some Floridian land and fresh-water shells with a revision of the Auriculacea of the eastern United States. Proceedings of the United States National Museum 8: 255–289, pls 17, 18.
  • Draparnaud J [1801] (“An IX”) Tableau des mollusques terrestres et fluviatiles de la France. Renaud / Bossange, Masson & Besson, Montpellier / Paris, 116 pp.
  • Grass AL (1967) Alexia myosotis (Ellobiidae) in British Columbia. The Canadian Field-Naturalist 81: 278–279.
  • Kobelt W (1897–1901) Die Familie Auriculacea. In: Martini FHW, Chemnitz JH (Eds) Systematisches Conchylien-Cabinet, 1 (16). Bauer & Raspe (Emil Küster), Nürnberg, 1–76, pl. 10, 11, 13 [1897]; 77–228, pl. 12, 14–30 [1898]; 229–268, pl. 31, 32 [1900]; 269–316, pl. 33 [1901].
  • Küster CH (1841–1845) Die Ohrschnecken (Auriculacea.) In Abbildungen nach der Natur mit Beschreibungen. Mollusca Gasteropoda. Auriculacea. Ohrschnecken. Systematiches Conchylien-Cabinet.
  • Martins AM de F (1996) Anatomy and systematics of the Western Atlantic Ellobiidae (Gastropoda: Pulmonata). Malacologia 37: 163–332.
  • Martins AM de F (1999) On the generic separation of Ovatella Bivona, 1832 and Myostella Monterosato, 1906 (Pulmonata: Ellobiidae). Iberus 17: 59–75.
  • Pilsbry HA (1900) Notices of new American snails. The Nautilus 14: 40–41.