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Superregnum: Eukaryota
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Spiralia
Cladus: Lophotrochozoa
Phylum: Mollusca
Classis: Gastropoda
Subclassis: Heterobranchia
Infraclassis: Euthyneura
Cohors: Tectipleura
Subcohors: Panpulmonata
Superordo: Eupulmonata
Ordo: Stylommatophora
Subordo: Helicina
Infraordo: Oleacinoidei
Superfamilia: Haplotrematoidea

Familia: Haplotrematidae
Subfamiliae (2): Austroselenitinae - Haplotrematinae

Haplotrematidae Baker, 1925

Baker, H. B. 1925. Agnathomorphous Aulacopoda. The Nautilus 38: 86–89 [1].

Haplotrematidae in the World Register of Marine Species

aplotrematidae is a taxonomic family of predatory air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Haplotrematoidea. [2]


These are North American land snails. They occur from Alaska, through British Columbia, and as far south as northern Mexico, but they are predominantly snails of the eastern and western United States.[3]
Three views of a shell of Haplotrema vancouverense from W. G. Binney[4]
Shell description

Their shells vary in size from small (7 mm in diameter, or about 0.3 inches) to medium (32 mm, about 1.3 inches), usually with a low, flattened spire, a very wide umbilicus, and usually with the upper lip margin (at the aperture) curving downwards or straightened.

They have a number of anatomical peculiarities.

The structure of the radula of these snails (their "teeth") is unusual. Essentially, haplotrematids have fewer cusps than most snails, but they are considerably elongated, suitable for the predatory life they follow. Members of this family have been given the common name "lancetooth" snails, presumably based on this last anatomical characteristic. Their sole food source consists, as far as is known, of other terrestrial mollusks.[5][3]

In this family, the number of haploid chromosomes lies between 26 and 30 (according to the values in this table).[6]

Genera within the family Haplotrematidae include:

Subfamily Austroselenitinae H. B. Baker, 1941

Austroselenites Kobelt, 1905
Zophos Gude, 1911[7]

Subfamily Haplotrematinae H. B. Baker, 1925

Ancomena H. B. Baker, 1931
Ancotrema H. B. Baker, 1931
Greggiella H. B. Baker, 1941
Haplotrema Ancey, 1881


Moerchia E. von Martens, 1860: synonym of Zophos Gude, 1911 (invalid: junior homonym of Moerchia A. Adams, 1860 [published earlier])
Selenites P. Fischer, 1878: synonym of Zophos Gude, 1911
Proselenites Thiele, 1927: synonym of Haplotrema (Geomene) Pilsbry, 1927 represented as Haplotrema Ancey, 1881


Baker, Horace B. (1931). Proc. Acad. Nat. Sci. Philadelphia 82: 405.
MolluscaBase eds. (2021). MolluscaBase. Haplotrematidae H. B. Baker, 1925. Accessed through: World Register of Marine Species at: on 2021-02-21
Pilsbry, Henry A. 1946. Land Mollusca of North America (North of Mexico). Acad. Nat. Sci. Philadelphia, Monograph 3, vol. 2(1): 201-230.
Binney, William G. 1878. The Terrestrial Air-Breathing Mollusks of the United States and Adjacent Territories of North America. Vol. 5 (plates). Bull. Mus. Comparative Zool., Harvard. Plate 20. Archived 2007-12-06 at the Wayback Machine Atkinson, Jim. Wings: Spring 2003. Living in a World of Tastes and Smells.
Barker G. M.: Gastropods on Land: Phylogeny, Diversity and Adaptive Morphology. in Barker G. M. (ed.): The biology of terrestrial molluscs. CABI Publishing, Oxon, UK, 2001, ISBN 0-85199-318-4. 1-146, cited pages: 139 and 142.

Gude (1911). Proc. malac. Soc. London 9: 269.

Bouchet P., Rocroi J.P., Hausdorf B., Kaim A., Kano Y., Nützel A., Parkhaev P., Schrödl M. & Strong E.E. (2017). Revised classification, nomenclator and typification of gastropod and monoplacophoran families. Malacologia. 61(1-2): 1-526

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