Aphelocheirus (Aphelocheirus) grik D. Polhemus & J. Polhemus, 1989

Polhemus, Dan A. & Polhemus, John T., 2013, Guide To The Aquatic Heteroptera Of Singapore And Peninsular Malaysia. Xi. Infraorder Nepomorpha- Families Naucoridae And Aphelocheiridae, Raffles Bulletin of Zoology 61 (2), pp. 665-686 : 682-683

Aphelocheirus (Aphelocheirus) grik D. Polhemus & J. Polhemus, 1989

( Figs. 47–52 )

Aphelocheirus grik D. Polhemus & J. Polhemus, 1989: 218

Material examined. — MALAYSIA, Perak: 50 brachypterous males, 50 brachypterous females, Kerunai River, 9 km N. of Grik , 135 m, 5°30'53"N, 101°07'50'E, 19 Aug.1985, CL 2078, D. A. & J. T . Polhemus coll. (paratypes, JTPC); 6 brachypterous males, 6 brachypterous females, stream 58 km S. of Grik , 19 Aug.1985, CL 2077, D. A. & J. T . Polhemus coll. (paratypes, JTPC); 1 female , Gerik [Grik], 17 Feb.1997, LHK324, coll. H. K. Lua coll. ( ZRC) .

Diagnosis. — Brachypterous forms with length 7.2–7.7 mm, maximum width (across abdomen) 4.8–5.0 mm ( Fig. 47 ); macropterous forms with length 7.9–8.3 mm, maximum width (across abdomen) 4.9–5.1 mm ( Fig. 48 ). Colouration of brachypterous forms uniformly blackish to brownish, with head dark yellow; colouration of macropterous forms entirely dark brown. This species may be immediately recognised by its relatively small size, the short, truncate female subgenital plate ( Fig. 50 ), the projecting tab on the posterior margin of abdominal sternite V in the male ( Fig. 49 ), and the male genitalic structures ( Fig. 51 ).

Distribution. — Described from peninsular Malaysia (Perak), with paratypes from additional Malaysian localities in that state, and from northern Thailand (Chiang Mai Province).

Discussion. — Aphelocheirus grik is the smallest of the species in the subgenus Aphelocheirus known to occur in Peninsular Malaysia, and may be quickly recognised by the distinctive ventral abdominal characters of both males and females as noted in the diagnosis. Brachypterous specimens of A. grik exhibit two distinct colour morphs, with some individuals brown, and others black, in each case with the head dark yellow. The macropterous forms also have a distinctive texture on the hemelytral corium consisting of small, raised, shiny dots on an otherwise dull background.

Figures

Figs. 47–52.Aphelocheirus (Aphelocheirus) grik D. Polhemus & J. Polhemus, structural details. 47. Brachypterous male, dorsal habitus, Malaysia, Perak, Grik. 48. Macropterous female, dorsal habitus, specimen from Thailand, Chiang Mai Prov.. Mae Ping River. 49. Male ventral abdomen, showing tab on abdominal ventrite IV. 50. Female subgenital plate. 51. Male parameres and phallotheca. 52. Proacetabula.