Tholerosoma, Mesibov, Robert, 2006

Mesibov, Robert, 2006, Dirt-encrusted and dragon millipedes (Diplopoda: Polydesmida: Paradoxosomatidae) from Queensland, Australia, Zootaxa 1354, pp. 31-44 : 37

Tholerosoma n. gen.

Type species: Tholerosoma monteithi n. sp., by present designation. Other assigned species: T. corrugatum n. sp.

Diagnosis: Medium-sized paradoxosomatids (males 18–22 mm long) with head+20 rings; most of body and appendages with a tenacious, variably thick coating of fine soil particles; paranota wide, inflated, with thick, rounded margins; waist with deep longitudinal corrugations; gonopod telopodite unbranched.

Etymology: Greek tholeros (“muddy”) + soma (“body”), neuter.

Remarks: On well-encrusted adults of Tholerosoma , the only parts of the body completely free of soil particles are the prozonites, spiracles and gonopods. A variably thick layer of soil covers the head, collum, metazonites (including sternites), telson, all podomeres and all antennomeres. The coating consists of organic and crystalline soil particles up to 0.2 mm across, as well as tiny fragments of plant debris. On some parts of the body the coating can be pulled off in sheet-like pieces. Ultrasonic cleaning for up to 20 minutes did not entirely remove the coating from two test specimens. The coating appears to have the same colour and composition as Tholerosoma gut contents. Stadium VII juveniles examined are all dirt-encrusted, although more lightly so than most adults; earlier juveniles are so far unknown.

How the coating originates, how and when it is applied and how it sticks so tenaciously are subjects for future research. The rough texture seen on all surfaces under the coating may assist the “grip” of an adhesive material holding the coating in place. The coating may act as camouflage to help the animals avoid detection by predators who sense their prey by sight, smell, taste, or texture. It may also make captured Tholerosoma less likely to be eaten.

There is some variation in gonopod and paranotal details (noted below) within each of the two named Tholerosoma taxa, and further study of these peculiar animals may show that splitting into additional species is justified.