A NEW CAVERNICOLOUS, SEMIAQUATIC SPECIES OF SERRADIUM (DIPLOPODA, POLYDESMIDAE) AND ITS TERRESTRIAL, SYMPATRIC CONGENER - WITH NOTES ON THEGENUS SERRADIUM

Serradium semiaquaticum sp. n. is described from several North Italian caves. The new species is very similar to, and probably the closest r elative of S. hirsutipes Verhoeff, 1941, which lives in the same caves as S. semiaquaticum but has a wider distribution. Serradium hirsutipe s is redescribed and newly recorded from several caves. Serradium semi aquaticum is remarkable by its semiaquatic habits and correspondingly modified spiracles and mouthparts, whereas S. hirsutipes is normal in these respects. The genus Serradium is reviewed, and a key to the know n species is given. Serradium as currently defined may not be a monoph yletic group. Serradium semiaquaticum and S. hirsutipes show strong go nopodal similarity (synapomorphy?) with species of Polydesmus, subgenu s Acanthotarsius.