Introduction

Most multipedes are millipedes. Tasmania has at least nine introduced millipede species and at least 160 natives. The introduced species are abundant on farms and in gardens, and are familiar to every householder. Few people, however, are aware of the remarkable diversity of our native millipedes, which are found in all terrestrial habitats from sedgeland to rainforest and from coastal dunes to rocky alpine areas. There are also cave-adapted millipedes in Tasmania and at least one semi-aquatic diving millipede.

You do not need to know a great deal about millipede anatomy for identification purposes. Be prepared, however, to count carefully the number of leg-bearing body segments on your specimen before going to the identification page. You will find that it is relatively easy to identify a Tasmanian millipede to order, but often very difficult to identify to species. The main reason is that most millipede species, taxonomically speaking, are defined by the structure of the male gonopods, which are modified legs used to transfer sperm during mating. In some millipede groups, adult males of different species are virtually identical in overall appearance, but have strikingly different gonopods. Unfortunately, there is currently no way to positively identify to species the females and juveniles of most millipedes. Help with locating gonopods is given in the appropriate places in this guide.

For an excellent general summary of millipede biology see Hopkin & Read (1992). In brief, millipedes feed mainly on decaying plants and fungi. They all have two pairs of legs on most posterior body segments, but there is a big range of body sizes and shapes in the group. Many species are night-wandering. In tropical areas and in most parts of the Northern Hemisphere, millipedes are highly seasonal and are hard to find during dry or cold periods. In contrast, most Tasmanian millipedes are active all year, although they may shelter deep in the soil during particularly dry summers.

A remarkable feature of the Tasmanian millipede fauna is that most species have small geographical ranges with very sharp boundaries (for example, see the map of Gasterogramma species). Where two species ranges meet along a common boundary, the transition zone where the two species mix may be less than 100 m wide. When collecting millipedes, it is very important to know where you are! Specimen labels should give the collecting locality as a 100 m grid square, or as latitude/longitude to the nearest second.