Heleocoris montandoni Lundblad, 1933

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 : 675

Heleocoris montandoni Lundblad, 1933

( Figs. 25 , 31 )

Heleocoris bengalensis montandoni Lundblad, 1933: 70 Heleocoris montandoni: Chen et al., 2005: 418

Material examined. — SINGAPORE: 1 male, 1 female, Nee Soon Swamp Forest , 18 Jun.1994, coll. H. K. Lua et al., NS162A ( ZRC) ; 1 male, Bukit Timah Nature Reserve, Taban Valley , 26 Oct.2001, coll. M. S. Choy, CMS0104 ( ZRC) ; 1 male, Pulau Tekong , fresh water stream, 27 Nov.2001, YCM273 ( ZRC) ; 3 females, Nee Soon Swamp Forest , 3 May 1994, NS 1279 ( ZRC) ; 1 male, Selatar Reservoir Park , stream, 10 May 1991, coll. C. M. Yang et al., YKL0753 ( ZRC) . MALAYSIA, Penang: 1 male, Sungai Relau (upper reaches), Kampung Darat , 9 Jun.1993, coll. H. H. Tan & S. H. Tan, Y848 ( ZRC) . Johor: 1 male, Gunung Pulai , 20 May 1993, Y833 ( ZRC) . Perak: 2 females, stream 58 km S. of Grik , 19 Aug.1985, CL 2077, coll. D. A. & J. T. Polhemus ( JTPC) .

Extralimital material examined. — INDONESIA, Jambi Prov.: 2 males, Sumatra, Jambi, stream crossing road 40 km towards Bajubang from Jambi, 1°47’47”S, 103°25'23"E, 24 Jul.1997, THH9741, coll. H. H. Tan ( ZRC) . Riau Islands Prov.: 1 male, Pulau Bintan, TT3 ( ZRC) ; 1 female, Pulau Bintan, TT2 ( ZRC) . Kalimantan Barat Prov.: 1 male, Anambas Is. [Natuna Archipelago], S. Pulau Bajau, 19 Mar.2002, EA_DW14, coll. D. Wowor ( ZRC) . VIETNAM, Lam Dong Prov.: 1 female, small stream nr. Lan Hanh, 31 km E. of Di Linh, 825 m ., 11°36'15"N, 108°19'17"E, water temp. 24°C, 27 Mar.2001, coll. D.A. Polhemus, J. T. Polhemus & P. Nguyen ( JTPC) .

Diagnosis. — Length 7.6–9.5 mm, maximum width (across abdomen) 4.8–5.9 mm, general body form ovate. Head and pronotum dull yellowish brown, spotted and maculated with dark brown or black; scutellum uniformly dark brown; hemelytra finely rugulose, dark reddish brown, except anterolateral half of embolium translucent yellow, wing membrane black, poorly defined, venation obscure; abdominal laterotergites translucent yellow on anterior three-quarters of each, dark brown on posterior one-quarter of each, creating a striped appearance. This species may recognised by its small size for the genus (body length less than 10 mm), the predominantly dark hemelytra which lack yellow markings except on the outer section of the embolium, the distinctive male genitalic strucutures ( Fig. 25 ), and the shape of the female subgenital plate ( Fig. 31 ).

Distribution. — Originally described from Sumatra and Java ( Lundblad, 1933). Sites & Vitheepradit (2011) recorded this taxon (as H. bengalensis montandoni ) from Thailand, Laos, Vietnam, Malaysia (Johor, Penang, Kedah), Singapore, Java, Sumatra, and Anambas Island. As noted below, there are morphological variations in the male genitalia that suggest multiple species may exist across this geographic range.

Discussion. — This is a small Heleocoris species that is widespread in Singapore and Peninsular Malaysia, occurring amid leaf packs along small streams. It is occasionally syntopic with the superficially similar Ctenipocoris asiaticus , but may be easily separated by the characters given in the key to genera of Laccocorinae , and discussed further under C. asiaticus . In particular, the asymmetrical male phallotheca ( Fig. 25 ) of H. bengalensis is quite unlike the symmetrical male phallotheca of C. asiaticus ( Fig. 18 ). The eyes of both species are triangular when viewed from above, but in H. montandoni they do not fold under the head and reach their greatest point of convergence ventrally, as is the case in C. asiaticus ( Figs. 16 , 17 ).

Heleocoris bengalensis was described by Montandon (1910) from specimens taken in India from the Manbhum district of what is now West Bengal, immediately west of Calcutta. The populations conforming to the broad concept of Heleocoris bengalensis are widely distributed from India ( Distant, 1910; Montandon, 1910) eastward through Southeast Asia to the Greater Sunda Islands ( Lundblad, 1933; Sites & Vitheepradit, 2011). There are subtle localised variations in male genitalic morphology throughout this range, making precise delineation of species concepts challenging. Lundblad (1933) considered the populations occurring on Sumatra and Java to be sufficiently distinct from those in India and Ceylon to warrant separate designation as a variant under the name H. bengalensis montandoni . We concur with this assessment of regional differentiation, and treat this taxon as a full species herein, following the lead of Chen et al. (2005, pg. 418), although Zettel (in litt.) has questioned whether montandoni is an available name in the sense of Art. 45.6.4 ICZN. For the present we have assigned here all the specimens so far seen from the Greater Sunda Islands, Vietnam, Singapore, and Peninsular Malaysia. Even within this regional assemblage there is, however, a certain amount of variability in the male genitalic structure. Our examination of specimens from Singapore, Anambas Island, and Sumatra reveals small but potentially significant differences in the structure of the parameres and phallotheca, with the shape of the latter structure being most similar in the specimens from the two former areas, while that of the Sumatra specimen is less elongate. The proctigers of the three populations cannot be compared, because they are missing from the vials containing the dissected genitalia of the available Anambas and Sumatra specimens. The shape of this structure is in fact extremely useful in species separation ( Figs. 29, 30 ), and it should always be retained for subsequent examination. Overall, the status of species concepts in the H. bengalensis complex is a problem which requires further detailed study that is beyond the scope of the present work, and it should be anticipated that the taxonomy may be further revised in the future as additional character systems are analysed.

Figures

Figs. 24–28. Heleocoris species, male phallotheca. 24. Heleocoris malayensis, new species, specimen from Malaysia, Terengganu, Sungai Brang. 25. Heleocoris montandoni Lundblad, specimen from Singapore, Nee Soon swamp forest. 26. Heleocoris nebulosus Montandon, specimen from Indonesia, Bali, Melangit River. 27. Heleocoris ovatus Montandon, specimen from Vietnam, Lam Dong Prov., Pongour Falls, CL 3091. 28. Heleocoris strabus Montandon, specimen from Thailand, Chiang Mai Prov., Huay Hia Creek, CL 2198.

Figs. 31, 32. Heleocoris species, female terminal abdomen, ventral view, showing shape of subgenital plate. 31. Heleocoris montandoni Lundblad, specimen from Vietnam, Lam Dong Prov., CL 3094. 32. Heleocoris malayensis, new species, specimen from Malaysia, Perak, Kerunai River, CL 2078.

Figs. 17–20. Ctenipocoris asiaticus Montandon, structural details, specimen from Vietnam, Lam Dong Prov., nr. Lan Hanh, CL 3094. 17. Head, ventral view. 18. Male phallotheca. 19. Medial process of male phallotheca. 20. Male left paramere.

Fig. 16. Ctenipocoris asiaticus Montandon, female, dorsal habitus, specimen from Vietnam, Lam Dong Prov., nr. Lan Hanh, CL 3094 (Young Sohn illustration).

Figs. 29, 30. Heleocoris species, male proctigers. 29. Heleocoris montandoni Lundblad, specimen from Singapore, Nee Soon swamp forest. 30. Heleocoris malayensis new species, specimen from Malaysia, Terengganu, Sungai Brang.