Hyperothrix Attems, 1900

The monobasic genus

Hyperothrix Attems, 1900 View in CoL ,

with the single small species H. orophura Attems, 1900 , from a few of the larger granitic islands of the Seychelle Archipelago, has long attracted attention as another superficially ‘oniscoid’ polydesmidan still without clear family placement (Hoffman 1982 a; Golovatch & Korsós 1992; Golovatch 2001). This genus and species has repeatedly been assigned to or compared with such different families as Oniscodesmidae , Pyrgodesmidae , Cyrtodesmidae or Doratodesmidae , with the latest return to Pyrgodesmidae on the basis of a typically pyrgodesmid-like tergal lobulation pattern and, above all, the gonopod conformation ( Golovatch 2001). In H. orophura , in addition to the fairly detailed descriptions by Attems (1900 1940), the vertigial region of the head is granulorugose but not elevated; the collum is rather convex, somewhat enlarged, yet failing to cover the head from above ( Fig. 35 View Figs 32–36 ), and with a clearly elevated anterior rim showing an indistinct pattern of 6+6 lobulations. Tergum 2 is evidently, but not too dramatically, hypertrophied, with each of its paraterga deeply trilobate, andenlarged laterad ( Fig. 35 View Figs 32–36 ). The paraterga of body segments 3 and 4 are deeply bilobed, subsequent quadri- (pore-bearing segments) or trilobulate (poreless segments) laterally. The terga are generally very strongly convex but the paraterga are modestly broad, ending a little above the level of the sterna. The limbus is bacilliferous; the ozopores are normally located on low knobs and the pore formula is normal; the metatergal surface is rough, granular, very finely pilose, with the tuberculation rather poorly differentiated but the pattern typically pyrgodesmid, and this is especially evident toward the telson, which is fully concealed in dorsal view; the gonopods in situ are strongly sunken, flattened dorsoventrally, rather poorly exposed in lateral view, and the coxae are rather strongly hypertrophied ( Fig. 36 View Figs 32–36 ), completely hiding the relatively stout and complex telopodites inside a gonocoel; a solenomere branch is evident ( Fig. 36 View Figs 32–36 ).

Volvation can definitely be postulated as incomplete. The overlap is typical, starting from paraterga 4 onwards, i.e. as in Elassystremma except for the enlarged tergum 2 lacking any schism-like structures.