Porrorhynchus (Subgenus Rhomborhynchus) Ochs, 1926

Discussion. Porrorrynchus species are relatively narrow, angulate, beautifully streamlined gyrinids that are very infrequently encountered along the streams of New Guinea, generally in gravel bottomed creeks and rivers at low to intermediate elevations. In such habitats, they are occasionally syntopic with Dineutus (Rhombodineutus) species. The last taxonomic treatment of Porrorhynchus for New Guinea by Ochs (1955) recognized a single species, Porrorhynchus (Rhomborhynchus) depressus, which was divided into 5 subspecies based on a very limited number of specimens. In aggregate, these subspecies occur throughout New Guinea, and on the closely proximal island of Misool to the west. Large series of two of these subspecies have recently been collected, and are reported below.