Dasystigma spp.: Introduction

(Order Polydesmida, family Dalodesmidae)

The four described species of Dasystigma are robust, brown H+20 dalodesmids which reach 20-22 mm in length. On the Dasystigma identification page they are separated on features of the gonopods and the spiracles. The latter are most unusual. In the great majority of Polydesmida the spiracles are small, inconspicuous, ring-like structures just above the base of each leg. Spiracles are the entrances to the system of tubes (tracheae) which carry oxygen to the millipede's tissues. In Dasystigma, dense brushes of 'hair' emerge from each spiracle. To the naked eye these 'hairy' spiracles look white and slightly convex. In the top specimen in the image above, you can clearly see a pair of these peculiar spiracles above the base of each leg-pair.

Species in the genus Dasystigma form a tightly fitted distribution mosaic on the map of Tasmania, and it is possible to make an informed guess about the identity of a female or juvenile Dasystigma based on exactly where it was collected. However, only mature male Dasystigma can be positively identified to species.

All four Dasystigma spp. are forest-dwellers that shelter in leaf and woody litter. The eastern species D. bonhami and D. margaretae and the southern D. huonense are much more abundant than the western D. tyleri, and are present (sometimes in large numbers) in eucalypt regrowth forest arising from clearfall-and-burn silviculture.

More information:
 
Taxonomy - Jeekel (1984), Mesibov (2003c)
Distribution, conservation and general - Mesibov et al. (1995), Mesibov (2003c)