Punctidae

Family Punctidae Morse, 1864

Key to Punctidae in Canada

1a Shell with distinctly larger, rather widely spaced riblets with smaller, usually >5, minor thread-like riblets in between — Paralaoma servilis

1b Shell with fine, closely spaced thread-like riblets, with usually <5 minor incremental threads between — Punctum  

Genus Paralaoma Iredale, 1913

  • Paralaoma Iredale 1913: 380; type species by subsequent designation (Iredale 1937): Paralaoma raoulensis Iredale, 1913.

Almost cosmopolitan, with reportedly one species, Paralaoma servilis, known from many places worldwide.

Etymology. Greek, para, beside or near to, + Laoma, a genus of punctid land snails; feminine.

Genus Punctum Morse, 1864

  • Punctum Morse 1864: 27; type species by monotypy: Helix minutissima Lea, 1841.
  • Patulastra L. Pfeiffer in L. Pfeiffer & Clessin 1878 (1878–1881): 87; type species by subsequent designation (Kobelt 1880 [1876–1881]): Helix pygmaeum Draparnaud 1801.

There are about ten species of Punctum distributed over the Holarctic realm, in the Hawaiian Islands, and southern Africa (Schileyko 2002, Horsák & Meng 2018). In North America, south to Mexico and in Bermuda (Pilsbry 1948).

Four species of Punctum occur in Canada, including P. lozeki Horsák & Meng, 2018 (B. Coles, pers. comm.), a recently described species which has a trans-Bering Strait distribution from Siberia to central Alaska and into Yukon.

It is possible that the Canadian species have reproductive biology as the European Punctum pygmaeum (Draparnaud, 1805). In this species, individual snails are capable of reproducing without a mate (Baur 1987). eggs averaged 0.41 by 0.50 mm and were laid singly at intervals of 2–8 days in the lab and incubation lasted from 1–34 days. Each snail laid on average 6 eggs during its lifetime (range 1–16 eggs) (Baur 1989).

Etymology. Latin: a point or small spot; neuter.

  • Punctum (Punctum) californicum Pilsbry, 1898
  • Punctum (Punctum) lozeki Horsák & Meng, 2018
  • Punctum (Punctum) minutissimum (I. Lea, 1841)
  • Punctum (Punctum) randolphii (Dall, 1895)