Boreohesperus Shear 1992

Genus Boreohesperus Shear, 1992

Fig. 1

Boreohesperus Shear, 1992: 778.

Boreohesperus capensis Shear, 1992, by original designation.

Boreohesperus may be distinguished from the four other genera of Australian paradoxosomatids whose gonopods divide into two main branches, Dicladosoma Brölemann, 1913, Dicladosomella Jeekel, 1982, Oncocladosoma Jeekel, 1985 and Somethus Chamberlin, 1920, by the two main branches of its gonopod arising from a distinct femorite that may vary from one-quarter to one-half of the acropodite length. In contrast, in Dicladosoma, the two thick gonopod branches arise from the prefemur, and the gonopods of each of the other three genera are split into two main branches much more deeply than in Boreohesperus, almost to the base of the acropodite.

The type species description remains unchanged from that set out in the first paper on Boreohesperus by Car & Harvey (2013).

The new species are considerably larger than those previously described, except B. capensis, ranging in length from approximately 16–20 mm. They, like B. capensis, also lack paranota. The gonopods of the three new species are also relatively larger (> 1 mm in length) and much more robust than the delicate structures of the other species, five of which have gonopods less than 1 mm in length. In all three new species, the gonopod femorite is relatively longer (approximately one-half the acropodite length), stockier and extremely broad when compared with those of the southern species, particularly that of the type species. It seems that the new Koolan Island species (B. vascellus sp. nov.) represents one extreme of femorite stoutness while B. capensis has the most slender femorite of all (Fig. 1). Finally, with the exception of B. capensis, each of the described southern species has a marked bifurcation of the solenomere tip: two of the new species carry a small process at the solenomere tip; in the third, a process is entirely lacking.