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Ancotrema hybridum (Ancey, 1888)
Oregon Lancetooth
Family: Haplotrematidae
Species account author: Robert Forsyth.


© Kristiina Ovaska     (Photo ID #2496)


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Distribution of Ancotrema hybridum in British Columbia in British Columbia


This species is widespread and common species on the west side of the Coast Mountains. It is a forest-dwelling species (deciduous, coniferous or mixed forests) that is also found in marshes, and occurs under logs or rocks, and in humus and leaf litter. It is reported as a carnivorous species.

Species Information


Shell intermediate in size between the smaller A. sportella and the usually larger Haplotrema vancouverense. It bears the beaded colabral riblets of A. sportella except that these become obsolete on the last whorl and the surface is marked by minute, close, wavy spiral striae.


Medium-sized (maximum mature width, 18–27 mm); growth determinate; depressed-heliciform; moderately thick-walled; ± opaque. Whorls: ca 6; evenly increasing in width, more rapidly before mature lip; spire whorls slightly convex. Spire: low, domed; apex flattened. Suture: moderately indented. Last whorl: descending to the peristome; no crest behind palatal lip. Periphery: rounded, medial. Protoconch: smooth. Teleoconch sculpture: ± evenly spaced and sized colabral riblets, becoming obsolete on the last or penultimate whorl; microscopic spiral striae that cut tops of colabral riblets into beads. Periostracum: cuticular. Umbilicus: ca 1/4 of w; wide, open and not occluded by the columellar lip. Aperture: subovate (wider than high). Peristome: incomplete. Apertural dentition: none. Palatal and baso-columellar lip: narrowly expanded, thin-edged. Peristome, viewed from side: prosocline, strongly arched; forward-directed portion on between periphery and suture strongly down-turned. Parietal callus: glazed, transparent. Colour (periostracum): dark straw yellow, slightly shining; shell grey-white under periostracum; aperture and lip milky whitish.


Long, slender; cream-coloured, with dorsum, head and tentacles darker; mantle with fine, pale brown speckling.


This species occurs in forests, scrub area, and drier areas of marshes, and lives under rocks, vegetation, dead wood and logs, and in soft soil and leaf litter (Forsyth 2004). It is frequently found deep in the humus layer.


Global Distribution

Unalaska, Aleutian Islands, Alaska (Pilsbry 1946), to Del Norte and Humboldt counties, northern California (Roth 1991, Roth and Sadeghian 2003, 2006).

BC Distribution

Widespread and common on the west side of the Coast and Cascade ranges and on offshore islands (Forsyth 2004). There is a literature record of this species from Vernon, British Columbia (Baker 1931), but apparently no recent records.

Ecozones Pacific Maritime; Montane Cordillera (if the Vernon record is correct).


Long treated as a subspecies or form of Ancotrema sportella, this taxon was first used as a full species by Roth (1990, 1991) who noted that they occur together from Washington to northern California without intergradation. Where both species occur together in British Columbia (mostly in the south), they also appear not to intergrade. In the literature, this species is frequently combined with A. sportella under that name, and museum collections often misidentified as A. sportella or Haplotrema vancouverense.



Genus name derived from the Greek, "ankon", "a bend" or "valley", + "trema", "aperture" or "hole"; the gender is neuter. Species epithet is Latin for “mongrel” or “half-breed”.

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
NativeS5?YellowNot Listed

BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Notes

Recommended Reading

Forsyth, Robert G. 2004. Land Snails of British Columbia. Handbook, Royal BC Museum, Victoria.

Additional Range and Status Information Links

General References