Asphalidesmus spp.

(Order Polydesmida, family uncertain)

Left:  Live A. leae.
Right:  Left lateral view of first segments of A. parvus.

These highly cryptic H+19 polydesmidans are only 5-7 mm long as adults and extremely slow-moving. They can be found in wet rotting wood and accumulations of leaf litter, and the two southern species also occur in caves. Adults (stadium VII) are yellow-brown and juveniles are pure white.

Ever since the first Asphalidesmus species was described in 1910, taxonomists have struggled to find a family in which to place the genus. The problem is still unsolved. As of 2009 Asphalidesmus is a 'free-floating' genus within the suborder Dalodesmidea.

Asphalidesmus leae Silvestri, 1910 and A. parvus (Chamberlin, 1920) were first collected early last century and are very similar in appearance. The ranges of these two species are highly disjunct (see map below), so a tentative identification can be made based on location. To be certain, examine the gonopod of a mature male (illustrated below) under high magnification. Both species are fairly common within their respective ranges and are ecologically resilient. A. leae is abundant in Pinus radiata plantations within its range (Bonham et al. 2002), A. parvus is abundant in eucalypt regrowth arising from clearfall-and-burn silviculture (Mesibov 1997b) and I have collected both species in badly degraded forest fragments on farms. Neither species has been found at high elevations (above 1000 m).

Gonopods of A. golovatchi (left), A. leae (middle) and A. parvus (right). Not to same scale.

Asphalidesmus golovatchi Mesibov, 2009 (below) is a rare southern species with a known range of about 600 km². Adults are easily recognised by the raised ridges on the animal's back, but these are missing in juveniles and some cave populations. A. golovatchi can also be separated from the co-occurring A. parvus by checking the shape of the paranota: long and narrow in golovatchi, short and rounded in parvus.

A fourth, undescribed Asphalidesmus is known from females collected on King Island. This species appears to be very rare as a result of habitat loss and degradation.

Localities for A. golovatchi (red), A. leae (green) and A. parvus (blue). Scale bar = 100 km.
For an interactive map with more up-to-date localities, go to the mapper page.

More information:
 
Taxonomy - Silvestri (1910), Chamberlin (1920), Mesibov (2002), Mesibov (2009a)
Distribution, conservation and general - Mesibov (1997b), Mesibov (1998b), Mesibov (1999), Bonham et al. (2002), Mesibov (2002)