Family Ellobiidae L. Pfeiffer, 1854 (1822)
The ellobiids, a worldwide family of snails, are adapted to life at the edge of the sea and on land, and include a Palaearctic genus of exclusively cave-dwellers. Most members are tropical and marine or semimarine, living in a variety of habitats, including along the strand line, in mangroves and salt marshes in brackish water, and on rocky intertidal shores. In Canada, there are eight species, but only the genus Carychium (subfamily Carychiinae, sometimes treated separately as a family) is fully terrestrial. For completeness, two additional, semimarine species of this intriguing family of snails are included here.
Subfamily Carychiinae Jeffreys, 1839
Genus Carychium O. F. Müller, 1774
- Carychium O. F. Müller 1774: 125; type species by monotypy: Carychium minimum O. F. Müller, 1774.
- Saraphia Risso 1826: 83; type species by monotypy: Saraphia tridentata Risso, 1826.
There are over 20 species of Carychium in North and Central America, Eurasia, and Southeast Asia. In Canada, there are six species, among which are two introduced European species.
Subgenera are used by some authors (e.g., Strauch 1977; Stworzewicz 1999; Falkner et al. 2002). However, Bank & Gittenberger (1985) recommended against recognizing subgenera based on the form of the internal lamella. Saraphia and Carychium (sensu stricto)are distinguished by the form of the columellar lamella inside the shell: in the former, the lamella forms a regularly curved spiral, while in the latter, the lamella is undulate. North American species have never been assigned to subgenera, which nevertheless seem artificial (Bank & Gittenberger 1985).
The animal has two conical-cylindrical tentacles; ocular tentacles are absent, and the eyes are located at the base of the tentacles. The narrow foot is not divided into two longitudinal sections as is typical for many marine ellobiids (Watson & Verdcourt 1953).
Animals are white and unpigmented, except for the small, black, oval dark eyes (Binney 1859, Adam 1960, Roth 1982), presumably in all species.
Etymology. Greek: karyx, a herald, signifying the ancient use of a shell (not Carychium!) as a trumpet (Kennard & Woodward 1926); neuter.
Carychium exiguum (Say, 1822)
Carychium exile H. C. Lea, 1842
Carychium minimum O. F. Müller, 1774 ◆ Introduced
Carychium nannodes G.H. Clapp, 1905
Carychium occidentale Pilsbry, 1891
Carychium tridentatum (Risso, 1826) ◆ Introduced
Key to Carychium species in Canada
- 1a Aperture height ≥40% of shell height – 2
- 1b Aperture height ≈30% of shell height. Whorls ca 5 with shell in apertural view – 3
- 2a Whorls ca 4 with shell in apertural view – C. minimum
- 2b Whorls ca 5 with shell in apertural view – C. tridentatum
- 3a Shell very minute (height to 1.4 mm); smooth without any trace of colabral striae/riblets. Palatal lip thin, recurved – C. nannodes
- 3b Shell larger (mature height >1.6 mm); with colabral striae/riblets of variable strength. Palatal lip thickened in most species (not C. occidentale which is larger, ≥2.0 mm when adult) – 4
- 4a Penultimate whorl bulging beyond plane of peristome when viewed from side. Shell relatively fat – 5
- 4b Penultimate whorl not bulging beyond plane of peristome when viewed from side. Shell relatively narrower – C. exile
- 5a Palatal lip thin edged in adults. British Columbia only – C. occidentale
- 5b Palatal lip somewhat thickened within. Alberta and east – C. exiguum
Subfamily Melampodinae Stimpson, 1851 (1850)
Genus Melampus Montfort, 1810
- Melampus Montfort 1810: 319, non Gray, 1865; type species by monotypy: Melampus coniformis (Bruguière, 1789) = Melampus coffeus (Linnaeus, 1758).
Etymology. Greek: melas, black + pous, foot. Masculine.
Subgenus Melampus Montfort, 1810
Melampus (Melampus) bidentatus Say, 1822
Subfamily Pythiinae Odhner, 1925 (1880)
Genus Myosotella Monterosato, 1906
- Myosotella Monterosato 1906: 126; type species by original designation: Myosotella payraudeaui “Shuttleworth” L. Pfeiffer, 1856 = Auricula myosotis Draparnaud, 1801.
Etymology. From the species epithet (myosotis; see species) + the Latin diminutive suffix ‑ella.
Myosotella myosotis (Draparnaud, 1801) ◆ Introduced