A Field Guide to the Snails of Lord Howe Island

114 Family Punctidae (Pinhead or Dot Snails) The Punctidae are small to minute snails distributed in America, Europe, Africa, Australia, New Zealand, southeast Asia and islands of the Pacific Ocean. They have highly variable shell shapes (particularly the diverse New Zealand fauna) and it is likely that what is currently understood as Punctidae is not a monophyletic group. Shells range in shape from trochoidal to discoidal with a rounded to keeled periphery, generally with an open umbilicus (nearly closed in some taxa). The protoconch is sculptured with spiral cords, and the teleoconch usually has radial ribs with radial or spiral microsculpture. The radula (a ribbon of teeth) is thought to be a diagnostic feature which can be used to separate the family from the very similar Charopidae. Punctid radulae are not divided into lateral and marginal tooth fields, and the bicuspidate latero-marginals have minute accessory teeth. Some species are arboreal, others are litter-dwelling and still others live on rock faces. They are found in habitats ranging from rainforest to grass and dry scrub. On Lord Howe Island, the punctid fauna is very diverse and consists of 17 valid species, with the strong likelihood that more species remain undescribed. Most are very small to minute (shells 1.2-3.5 mm in diameter), with the exception of a single distinctive arboreal species ( Dignamoconcha dulcissima ) which has a shell diameter of 6 mm. The Lord Howe Island fauna are often separated by tiny differences and can be difficult to identify. Many species are only known from a single collection event. Dedicated leaf litter collecting is necessary to find these cryptic snails in any quantity. One species, Deliciola charis , is known only from a single damaged shell collected prior to 1944 and is likely to be extinct. It is not described or figured here. Semilaoma costata