Nerthra macrothorax (Montrouzier)

Polhemus, Dan A. & Polhemus, John T., 2012, Guide To The Aquatic Heteroptera Of Singapore And Peninsular Malaysia. Ix. Infraorder Nepomorpha, Families Ochteridae And Gelastocoridae, Raffles Bulletin of Zoology 60 (2), pp. 343-359 : 357-358

Nerthra macrothorax (Montrouzier)

(Figs. 35, 38)

Galgulus macrothorax Montrouzier, 1855: 110

Scylaecus macrothorax Stål, 1861: 201

Peltopterus macrothorax Stål, 1863: 408

Nerthra macrothorax Todd, 1955: 348

Material examined. — SINGAPORE: 1 male, Pulau Hantu, in rotten wood, 8 Oct.1989, coll. K. Lim ( ZRC) ; 1 immature, Mandai mangrove, at base of intertidal tree, 26 Oct.1987, coll. D. H. Murphy ( ZRC) ; 1 immature, Sungai Buloh mangrove, lower area, 19 Sep.1988, coll. D. H. Murphy ( ZRC) .

Extralimital material examined. — JAPAN: 2 males, 2 females, Ogasawara Islands, Chichi Jima Is., Miyanohama, 24 Nov.1977, M. Tomokuni coll. ( JTPC); 1 male, 1 female, Ryukyu Islands , Iriomote Is., near mangroves, sea level, CL 2945, 25 Mar.1995, J. T . Polhemus ( JTPC) . INDONESIA, Papua Prov.: 1 female, Maffin Bay , Dutch N. Guinea, 1 Jul.1944, E. S. Ross ( JTPC) .

Diagnosis. — Length 7.9–10.6 mm, maximum width (across pronotum) 6.0– 8.2 mm. General colouration light brown, with slightly darker markings on central pronotum, hemelytral carinae, and basal portions of abdominal paratergites. Front of head bearing 3 large, rounded tubercles; pronotum with lateral margins gently curving, lacking sinuosities or lobes, posterior section lacking longitudinal carinae; body covered with short, broadly clavate bristles; abdomen moderately expanded laterally, but width less than that of pronotum. This species may be recognised by the relatively narrow abdomen, the width of which is less than the width of the pronotum, and by the shape of the male paramere, which is straight, slender and not widened distally ( Fig. 38 ).

Distribution. — Originally described from Woodlark Island, east of New Guinea ( Montrouzier, 1855). The extensive range of this species, which extends from eastern Africa to Australia, was listed in detail by Kment & Jindra (2008), and only new Singapore records are given here. In the region under study the species is documented from Taiwan, the Philippines, Borneo, Sulawesi, the Lesser Sunda Islands and New Guinea. Interestingly, there are currently no records from the coasts of continental Southeast Asia, with all captures having instead come from island coasts. The Singapore records provided above represent a new country record.

Discussion. — Nethra macrothorax occurs amid organic marine debris along tropical coastlines, and may apparently

be transported by rafting on floating wood and logs (Todd, 1959, 1960; Polhemus, 1976). As a result, it has an extremely wide distribution in the Indo-Pacific region. Specimens should be sought by turning over logs and vegetative debris at the strand line along beaches, or amid leaf litter in immediately adjacent coastal forests.

Figures

Figs. 36–38. Nerthra species, structural details (after Todd, 1955). 36, N. lobata, male right paramere. 37, N. lobata, female terminal abdomen, ventral view showing paired processes. 38, N. macrothorax, male right paramere, apical section.