Porrorhynchus (Rhomborhynchus) depressus depressus Régimbart, 1892

Polhemus, Dan A., 2011, New distributional records for Gyrinidae (Insecta: Coleoptera) on New Guinea and nearby islands, with a checklist of the New Guinea species, Zootaxa 2900, pp. 51-68 : 52

Porrorhynchus (Rhomborhynchus) depressus depressus Régimbart, 1892

Fig. 1

Porrorhynchus depressus Régimbart, 1892: 996 .

Dineutus (Rhomborhynchus) depressus: Ochs, 1926: 64 .

Material examined. PAPUA NEW GUINEA, Gulf Prov.: 21 males, 20 females, Kikori River basin, Omo River at Omo, 40 m. [1310 ft.], 6°58'41"S, 144°18'15"E, water temp. 24° C., 28 February 1995, 09:30-14:00 hrs., CL 7001, D. A. Polhemus ( BPBM).

Discussion. The holotype male of the nominate subspecies of Porrorhynchus (Rhomborhynchus) depressus was collected by Loria in 1890 at Dilo, on the Kemp Welch River in what is now southern Papua New Guinea ( Ochs, 1955), and a second specimen was noted by Ochs (1955) from the Astrolabe Range, near Port Moresby. The species has apparently not been documented since. The new collection reported below comes from the lower Kikori River system, extending the range of this subspecies well to the west ( Fig. 1 ), and implies that this nominate subspecies of P. (R.) depressus may occur in the lower sections of the intervening Purari River basin as well.

The Omo River at the point where this species was collected was a moderately large, smoothly flowing lowland river. The bed consisted mostly of water-rounded cobbles, with alternating riffles and flowing pools, moderately well shaded by disturbed lowland rain forest interspersed with sago palms. Based on known collections, this subspecies occupies the Papuan Gulf Foreland area of freshwater endemism (Area 28) as defined by Polhemus & Allen (2007).

This is the species listed as “ Porrorhynchus sp.” in Polhemus (1995).

Figures

FIGURE 1. Distribution of certain Porrorhynchus (Rhomborhynchus) depressus subspecies on New Guinea and adjacent islands. Symbols with grey centers represent previous records; symbols with black centers represent new records presented in this paper.