- H[elix] harpa Say 1824: 256, pl. 15 fig. 1.
Identification. Shell conic-ovate, fragile, poorly calcified. Spire raised, conical. Whorls c. 4, convex. Suture rather deeply indented. Periphery rounded. Aperture subovate, height > width, edentulous. Lip thin, simple; columellar lip expanded. Protoconch microscopically granular (or with exceptionally fine, uneven spiral striae; Schileyko 1998). Teleoconch with rather evenly, widely spaced, lamellar (periostracal) colabral ribs with irregular incremental striae between. Ribs sometimes in part obsolete or unequal in spacing and size. Umbilicus tiny. Shell very thin, slightly translucent, with a silky lustre; brown. Height to 3.4 mm (higher than wide).
Animal grey with darker ocular tentacles and pale foot; mantle dark grey, speckled with white. Foot prominently crenulated. Large labial lobes present. Sensory tentacles nearly obsolete (Pilsbry 1895 in 1893–1895, 1948).
Comparison. Zoogenetes harpa is unlike any other land-snail species in BC. The conic-ovate shell having widely spaced, thin lamellar ribs is distinctive.
Habitat. This species lives in dry to mesic forests and open habitats, often somewhat disturbed, such as roadsides. It often occurs in acidic habitats. Occasionally, it has been found in drier parts of marshes. Zoogenetes harpa frequently occurs in sporadic, discreet colonies, but where present, it is often abundant. Snails live in leaf litter and under rocks and coarse woody debris. During cool, wet weather, it has been reported climbing vegetation and tree trunks.
Geographic range. In BC, Z. harpa is common in the north-central interior of the province. It is apparently absent along the coast and possibly not so common in south-eastern BC (or at least there are fewer records).
Europe, mostly northern, through northern Asia. In North America, much of Canada and the northern USA south along the Rocky Mountains south to Colorado (Pilsbry 1948). Widespread across most of Canada, where it is known from every province and territory except Nunavut.
Biology. Animals are mostly aphallic (e.g. Schileyko 1998), and euphallic individuals, as figured by Pilsbry (1948: fig. 557) are less common. Zoogenetes harpa is ovoviviparous; that is, the young hatch from their egg within the parent and emerge as fully developed snails. At birth, the young snails are as large as the aperture of the adult shell (Pilsbry 1948).
Etymology. Zoogenetes: derived from Greek zoion, animal + genesis, origin or birth, in reference to the ovoviviparity (Pilsbry 1948). The gender is feminine. Harpa (Latin), a harp, likely the allusion of the riblets to strings on a harp.
References
- Pilsbry HA (1893–1895) (Helicidæ, vol. 7) Guide to the study of Helices. Manual of Conchology, Structural and Systematic with Illustrations of the Species Second Series: Pulmonata 9: i–xlviii, 1–366, 1–126, pls 1–71.
- Pilsbry HA (1948) Land Mollusca of North America (north of Mexico), vol. II, part 2. The Academy of Natural Sciences of Philadelphia, Monographs 3: i–xlvii + 521–1113.
- Say T (1824) Appendix. Part I. — Natural history. §1. In: Keating WH (Ed.) Narrative of an expedition to the Source of St Peter’s River, Lake Winnepeek, Lake of the Woods, &c &c performed in the year 1823, by order of the Hon JC Calhoun, Secretary of War, under the command of Stephen H Long, Major USTE Compiled from the notes of Major Long, Messrs Say, Keating, and Colhoun. H.C. Carey & I. Lea, Philadelphia, 253–378.
- Schileyko AA (1998) Treatise on Recent terrestrial pulmonate molluscs. Part 1: Achatinellidae, Amastridae, Orculidae, Strobilopsidae, Spelaeodiscidae, Valloniidae, Cochlicopidae, Pupillidae, Chondrinidae, Pyramidulidae. Ruthenica Supplement 2: 1–128.