Dineutus (Rhombodineutus) pectoralis monticola Ochs, 1955

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 : 54-55

Dineutus (Rhombodineutus) pectoralis monticola Ochs, 1955

Fig. 2

Dineutus (Rhombodineutus) pectoralis monticola Ochs, 1955: 144 .

Material examined. PAPUA NEW GUINEA, Milne Bay Prov.: 2 males, 6 females, New Guinea, Cloudy Mountains, headwater tributary to upper Watuti River, S. of Gelemalaia, 715 m. [2350 ft.], 10°29'50"S, 150°13'58"E, water temp. 22 °C., 10 April 2002, 16:00–17:30 hrs., CL 7175, D. A. Polhemus ( USNM); 7 males, 5 females, headwater reach of Goilayoli River above crossing on road from Watunou to Huhuna, 11.5 mi. ENE of Alotau, 275 m. [900 ft.], 10°18'43"S, 150°37'16"E, 6 April 2002, 10:00–13:00 hrs., CL 7161, D. A. Polhemus ( USNM); 3 males, 1 female, New Guinea, Muguwe Creek, W. of Naura, 16 mi. W. of Alotau, 70 m. [225 ft.], 10°17'20" S, 150°12'10" E, water temp. 25.5° C., 9 April 2002, 10:00–11:30 hrs., CL 7169, D. A. Polhemus ( USNM); 4 males, 6 females, D’Entrecasteaux Islands, Fergusson Island, east coast, upper Awaetowa River and rocky tribs., W. of Basima, 575– 650 m. [1885–2130 ft.], 9°30'34.3"S, 150°48'17.3"E, water temp. 22 °C., 27 January 2003, 10:00–14:00 hrs., CL 7225, D. A. Polhemus ( USNM); 2 males, 12 females, D’Entrecasteaux Islands, Normanby Island, east coast, upper Dibuwa River and rocky tribs., W. of Yeluyelua, 245 m. [800 ft.], 10°02'46.2" S, 151°14'53.0" E, water temp. 24° C., 30 January 2003, 09:30–12:30 hrs, CL 7231, D. A. Polhemus ( USNM). Central Prov.: 1 female, Owen Stanley Range, trib. to upper Mimani River, 0.8 km. W of Dorobisoro, 500 m. [1650 ft.], 9°27'39.1"S, 147°54'56.2"E, water temp. 23.5 °C., 9 October 2003, 08:30–12:30 hrs., CL 7264, D. A. Polhemus ( USNM).

Discussion. This subspecies occurs widely throughout the Owen Stanley Range and Papuan Peninsula, the portion of New Guinea corresponding to the East Papua Composite Terrane as defined by geologists. The new records below extend the range of this subspecies well eastward, into the D’Entrecasteaux Islands ( Fig. 2 ).

In the Alotau area of far eastern New Guinea this species was found on rocky upland streams in areas where the primary rain forest cover still remained largely intact. For instance, the upper Goilayoli River locality consisted of a clear, cool, upland stream set in a narrow channel, partly incised into bedrock, with pools 0.30–1.00 m. deep, alternating with riffles over cobble and gravel, or small cascades over bedrock sills, and experienced 60–70 percent shading from the overarching forest canopy. The captures on Fergusson and Normanby Islands, in the D’Entrecastaux group, came from streams with similar general characteristics.

Based on known collections, this subspecies occupies the Owen Stanley Mountains, Cloudy Mountains, and D’Entrecasteaux Islands areas of freshwater endemism (Areas 31, 34, and 35 respectively) as defined by Polhemus & Allen (2007). As noted by Brinck (1983) there is considerable variation among the overall size of the male specimens in a given series.

The records above were also provided in Kraus et al. (2006).

Figures

FIGURE 2. Distribution of certain Dineutus (Rhombodineutus) pectoralis 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.