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
Diagnosis
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.
Shell
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.
Animal
Long, slender; cream-coloured, with dorsum, head and tentacles darker; mantle with fine, pale brown speckling.
Habitat
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.
Distribution
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).
Taxonomy
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.
Notes
Etymology
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”.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2025-01-23 12:05:24 PM]
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