Desmoxytoides, Mesibov, Robert, 2006

Mesibov, Robert, 2006, Dirt-encrusted and dragon millipedes (Diplopoda: Polydesmida: Paradoxosomatidae) from Queensland, Australia, Zootaxa 1354, pp. 31-44 : 32-33

Desmoxytoides n. gen.

Type species: Desmoxytoides hasenpuschorum n. sp., by present designation.

Diagnosis: Small paradoxosomatids (males ca. 10 mm long) with head+20 rings; paranota “antler-like” and raised slightly upwards; metatergites dorsally with 2 transverse rows of 4 large, setiferous tubercles on either side of transverse furrow; metazonite surface covered with minute tubercles. Distinguished from Desmoxytes by the solenomere arising posterior to the other telopodite process, rather than anterior, and by the other process being smaller than the solenomere and spine-like.

Etymology: Greek - eides (“like”), from the close resemblance to Desmoxytes ; masculine.

Remarks. Golovatch and Enghoff (1994) noted that the 19 species they assigned to the dragon millipede genus Desmoxytes exhibit a mosaic-like distribution of character states in gonopod form, paranotal development, and dorsal sculpturing and surface texture of the metazonites. For this reason, they cautioned that “the definition of Desmoxytes is somewhat fragile” ( Golovatch & Enghoff 1994, p. 62). Nevertheless, they regarded the group as monophyletic, and easily recognised by the spectacular “antler-like”, “spine-like” or “wing-like” paranota. At the time, all known species were restricted to southeast Asia apart from the pantropical tramp D. planata (Pocock, 1895) , whose native range is unknown. Nguyen Duc Anh, Golovatch and Anichkin (2005) added four new Vietnamese species to Desmoxytes without redefining the genus.

The finding of a dragon millipede in the Australian tropics raises again the question of how Desmoxytes should be circumscribed. The new form shares with at least some Desmoxytes species the following three apomorphic character states: “antler-like” paranota; two transverse rows of large, setiferous tubercles dorsally on the metazonites; and microtubercular texturing of the metazonite integument. Like most Desmoxytes species, the new form also has long, thin legs and a gonopod telopodite divided distally into a solenomere and a second, parallel, closely placed process. However, in all Desmoxytes previously described from males the solenomere is “protected”, i.e. it arises and stands anterior to the second process, which is often larger than the solenomere and sometimes complex in shape. In the new species, the solenomere arises and stands posterior to a small spine-like process ( Figs. 1 B, 2C). Intriguingly, the prostatic groove in the new species runs helically around the base of the solenomere, and it is possible to see this as evidence that the distal portion of the telopodite may have rotated in development so as to reverse the solenomere/second process arrangement seen in other dragon millipedes.

I am erecting Desmoxytoides for the Queensland species because of its divergent gonopod form. Future finds of new dragon millipedes, and of males of the species currently known only from females, may suggest that the Australian form is best placed within a single, highly variable genus Desmoxytes .

Figures

FIGURE 1. Desmoxytoides hasenpuschorum n. gen., n. sp. (A) lateral view of midbody ring; (B) posteroventral view of gonopods in situ; (C) ventral view of telson; (D) dorsal view of midbody ring; (E) enlargement of (A) showing spiracles and metazonite microtubercles (males, QM S 73968). Note: the ends of the gonopod telopodites shown in Fig. 1 B have rotated during drying; in alcohol-preserved material the curve of the telopodite lies in a nearly transverse plane, as shown in Fig. 2 C. Scale bar for (A) – (D) = 0.25 mm, for (E) = 0.1 mm.