Asphalidesmus Silvestri, 1910

Direct field observations ( Mesibov 2002) confirmed very poor volvatory capacities in still another enigmatic genus,

Asphalidesmus Silvestri, 1910 View in CoL ,

from Tasmania ( Figs 45, 46 View Figs 45 & 46 ). Both known species are small (5–6 mm long), showing a roughened vertex, an enlarged, cap-shaped, anteriorly non-lobulated collum which largely conceals the head from above ( Fig. 46 View Figs 45 & 46 ); metatergum 2 is rather strongly enlarged and is devoid of a schism but, as usual, it supports the anterolateral part of tergum 3; each metatergum subsequent to the second has numerous (5–6) transverse rows of uniform, low, setigerous tubercles; the ozopore formula is (nearly) normal, and each ozopore opens flush on the surface dorsal to a lobulated edge of the paratergum; the paraterga are strongly declined ventrad, yet they fail to reach the level of the sterna; antennomere 6 is the longest and largest ( Fig. 46 View Figs 45 & 46 ); the limbus is bacillary, upright, and prominent; the telson is ‘polydesmoid’, and the epiproct is conical, and readily visible from above ( Fig. 45 View Figs 45 & 46 ); the legs are rather stout, especially so in males, but otherwise unmodified ( Fig. 46 View Figs 45 & 46 ) ( Mesibov 2002).

The volvation is remarkable in being devoid of any switch to a typical pattern. Instead it remains the same from tergum 3 onwards, whence the anterior part of the paratergum rests on top of, not beneath, the caudolateral part of the previous paratergum. The overlap is thus simple, apparently plesiomorphic ( Fig. 45 View Figs 45 & 46 ), and totally different from the more specialised patterns observed in more readily or truly volvatory Polydesmida .

The genus Asphalidesmus has provisionally been referred to Haplodesmidae ( Mesibov 2002) . Indeed, superficially these animals look very much like true haploor pyrgodesmids, or Hyperothrix . However, the genitalic structure of Asphalidesmus is quite characteristic of that of Dalodesmidea , Dalodesmoidea, but maybe not of Dalodesmidae , because the sphaeriotrichomes typical of dalodesmids are missing. As in all other Dalodesmoidea so exemplary of the Southern Hemisphere, the gonopod aperture is ovoid, relatively small, and fully containing and concealing the small, medially fused, contiguous gonocoxae crowned with suberect, distally 2-branched, simple, medially contiguous but not fused telopodites, with hypertrophied prefemoral parts ( Fig. 46 View Figs 45 & 46 ). An allocation of Asphalidesmus to Vaalogonopodidae , a small Southern African dalodesmoid group comprising four genera (of which only three are described, cf. Hoffman 1982 b) likewise devoid of sphaerotrichomes, is not likely. Indeed, in contrast to Dalodesmidae , Vaalogonopodidae are rather pyrgodesmid-like in appearance, and all are mediumsized (10–20 mm long). Their hypertrophied, anteriorly lobed or scalloped collum conceals the head from above; the metatergal tuberculation is regular and somewhat differentiated; some ozopores are borne on porosteles placed at the lateral edge; the paraterga are relatively small and modestly declined ventrad and lobed laterally; the telson is strongly flattened dorsoventrally; and the gonopod coxae are somewhat better separated etc. ( Verhoeff 1940; Schubart 1956). Asphalidesmus is distinguished by the collum and tergum 2 being relatively modestly developed; the paraterga are very strong and prominently declined ventrad; the ozopores open inside flat craters located far off the paratergal lateral edge, and are never borne on porosteles; the telson is rather ‘polydesmoid’, the epiproct is subcylindrical, not flattened; the metatergal tuberculation is dense, uniform, setigerous; and the gonopod coxae as well as the telopodites are virtually contiguous medially, etc. ( Mesibov 2002).

In general, as the classification of Dalodesmidea is perhaps the most controversial within the entire order Polydesmida (cf. Hoffman 1980; Simonsen 1990), no family placement of Asphalidesmus is attempted here as this would apparently be premature.