Cheirochela thailandana, Dan & Polhemus & John & Polhemus & Sites, 2008

Dan, Polhemus, John, Polhemus & Sites, Robert, 2008, A Revision Of The Indochinese Genera Cheirochela And Gestroiella Heteroptera Naucoridae And A Review Of The Tribe Cheirochelini, Raffles Bulletin of Zoology 56 (2), pp. 255-279 : 265-267

Cheirochela thailandana new species

( Figs. 11 , 15, 17)

Description. – Brachypterous male: Of moderate size for genus, general body form rotund, widest across abdomen, basic colouration brown, hemelytra dark brown, wing membrane dark brown. Male length 24.70 mm; maximum width (across abdomen) 14.20 mm; female length 24.80 mm, maximum width 14.20 mm.

Head pale yellowish brown, with dark brown longitudinal markings medially and along inner eye margins; a pair (1+1) of long, irregular, longitudinal brown lines present to either side of midline on vertex between eyes; posterior margin broadly dark, width across eyes/length = 5.44/4.21; eyes black, shining, quadrate posteriorly, tapering anteriorly, width/length = 1.00/2.11, inner margins evenly curved and slightly divergent anteriorly, lateral margins less curved on anterior third, separated from vertex by shallow furrows, anterior/posterior interocular width = 4.00/3.16, lateral flange weakly developed; posterior margin of vertex rounded, stongly produced behind eyes; anteclypeus with anterior margin broadly rounded, strongly projecting ahead of eyes for 0.58× the length of an eye, projecting beyond rostrum about the length of exposed rostrum; rostral cavity deep, hiding segment one in lateral view; rostrum brown, second segment thickened, distal segments slender; antennae set in cavity, with all segments thickened, segments II, III and IV each about half the length of I, not extending to lateral margin of head.

Pronotum yellowish brown, mottled with darker brown at muscle attachments and irregularly dotted with numerous small brown punctations laterally; barely depressed medially behind vertex, width/length (midline) = 9.88/2.89, lateral margins narrowly explanate, medially granular, concave, anterolateral angles sharply angular, extending forward along eye 1/4 of eye length, posterolateral angles acute produced, posterior margin nearly straight, set off from remainder of pronotum by transverse sulcus. Scutellum dark yellow, medially orange-brown, surface sculptured, rugose, width/length (midline) = 5.34/3.66, lateral margins sinuate, sinuate transverse sulcus present along anterior margin. Hemelytra dark brown, trending to black in area of reduced membrane; surface coarsely rugose, bearing fine, pale, granular microstructure, each facet convex, shining, without setae; clavus and corium weakly defined, membrane highly reduced, obscure; tips of hemelytra rounded, extending past base of genital segment; embolium demarcated by deep narrow sinuate furrow along inner margin, with a thick fringe of long soft setae arising from outer margin.

Abdomen with lateral portions of segments II–VII exposed when viewed dorsally, all visible tergites orange-brown, darker laterally and posteriorly, posterolateral angles of tergite II symmetrical and truncate, of tergites III – VI produced into spines.

Ventral surface light yellowish-brown, with head, prosternum, mesosternum centrally and abdomen covered with thick recumbent gold hydrofuge pile; ventral keel of head with tooth at anterior terminus small, barely formed; typical static sense organ cupped into anterolateral angle of prothorax; propleura moderately reflexed posteriorly, barely covering basal portions of mesosternal plate; mesosternal plate not tumescent, medially with a shallow V-shaped sulcus, anterior margin slightly raised, posterior margin tapering and angulate. Abdominal sternites without sutures delineating parasternites; sternite III with a distinct angulate projection medially on posterior margin, sternite IV with a less pronounced projection.

Legs yellowish-brown; fore coxa anterior face with a patch of fine, raised gold setae; anterior trochanters each with a stout ventral tuft of stout setae appearing as a spine-like protuberance; anterior femur with numerous small, dark brown asperities on dorsal surface, bearing a thick pad of gold setae along anterior margin, and fringe of long gold setae along posterior margin; anterior tibia slender, gently curving, grooved along inner face; middle and hind coxae each bearing a single glabrous tubercle distally, plus a fringe of long gold setae; middle and hind trochanters unarmed, posteriorly set with thick recumbent pile; hind femora distally with a row of short dark spinules running legthwise along posterior margin, and a few short dark spinules scattered along anterior margins; middle tibiae beneath with a thick pad of golden setae on distal half, and a few scattered, stout reddish spines; hind tibiae beneath with a longitudinal pad of golden setae along anterior edge, widening distally to cover entire surface.

Male genitalia with paramere bearing a weakly developed basal lobe, distal arm with distinct subapical notch isolating a thumb-like apical process ( Fig. 11 ); male phallotheca with tip expanded, lyre-shaped; dorsomedial process of genital capsule narrowing distally, tip truncate (Fig. 15). Female subgenital triangular, lateral margins weakly sinuate, apex narrow.

Macropterous form: Unknown

Discussion. – This species is similar in size and general body form to both C. tonkina and C. birmaniensis . Within this assemblage, Cheirochela thailandana shares the well developed posteromedial tubercles on the abdominal venter with C. birmaniensis , although they are somewhat less pronounced. It and C. birmaniensis also have less prolonged preocular heads than in C. tonkina : in C. birmaniensis the length of the head ahead of the eyes is much shorter than the length of the eye, with the ratio of eye length/preocular head length being1.7/1.0 or greater, and in C. thailandana 1.64/1.0, while in C. tonkina the preocular head is more greatly prolonged, so that this ratio is more nearly equal, being only 1.25/1.0 or less. The most reliable characters separating these species are found in the male genitalia, especially the parameres (compare Figs. 9, 10, 11 ) and the median process of the genital capsule (compare Figs. 13, 14, 15).

Ecological notes. – Based on current records, C. thailandana is widely distributed in northern Thailand ( Fig. 17 ). The Nam Chai River at the type locality was a swift, clear stream 0.25–1.0 m deep running in a bed of mixed alluvial boulders, rocks, cobbles and gravel, and bordered by disturbed upland rain forest. Adults of C. thailandana were taken by dislodging large rocks in the swift midstream current and allowing the force of the water to carry them downstream into a net, while immatures were more common in slightly slower water along the channel margins. At this Nam Chai locality, C. thailandana occurred syntopically with a diverse array of other benthic-dwelling subaquatic Heteroptera, including Gestroiella limnocoroides Montandon , Aphelocheirus fang Polhemus & Polhemus , Aphelocheirus lahu Polhemus & Polhemus , Aphelocheirus thai Polhemus & Polhemus , Aphelocheirus brevirostris Polhemus & Polhemus , Heleocoris sp. and Ctenipocoris sp. Additional information on the benthic fauna of this river may be found in Polhemus & Polhemus (1989).

Types. – Holotype, brachypterous male, THAILAND, Chiang Mai Prov., Nam Chai River above hydro station intake at Fang Agricultural Research Station , 550 m, 15 Nov.1985, CL 2197, D. A. and J. T. Polhemus ( JTPC) . Paratypes: THAILAND: Chiang Mai Prov.: 2 brachypterous males, 7 brachypterous females, 23 immatures (not paratypes), same data as holotype ( JTPC); 1 brachypterous male, Doi Sutep N. P., Montathem Falls, 700–750 m, 6 Nov.1995, H. Zettel ( NHMW); 1 male, 1 female, Doi Inthanon National Park, Siriphum Waterfall , 18°32'N 98°31'E, 1,460 m, 9 May 2002, rock face, UMC & CMU teams, L-401 ( UMC); 1 female, Doi Inthanon National Park, Siriphum Waterfall at Ban Khun Klang , level 2, 1380 m, 18°32'N 98°31'E; 21 Mar.2002, R . W. Sites, L-314 ( UMC); 2 females, same locality, 26 Jun.2002, R . W. Sites, L-412 ( UMC); 1 female, same locality, 15 Nov.2001, R . W. Sites, rocks below waterfall, L-248 ( UMC); 1 male, same locality, gravel, UMC & CMU teams ( UMC); 1 female, Doi Inthanon National Park, Mae Pan Noi at Ban San Pathana , bedrock stream, 18°31'N 98°25'E, 750 m, 7 May 2002, gravel and rocks, UMC & CMU teams, L-393 ( UMC); 1 female, Doi Inthanon National Park, Mae Pan Waterfall , 18°31'N 98°27'E, 1100 m, 750 m, 3 Mar.2002, UMC & CMU teams, L-253 ( UMC); 1 male, Doi Inthanon National Park, Mae Klang River at Ecolodge , 18°32'N 98°32'E, 1000 m, 8 May 2002, leafpack, UMC & CMU teams, L-399 ( UMC); 1 male, same locality, 4 Apr.2002, rocks, UMC & CMU teams, L-324 ( UMC); 2 females, 1 male, Doi Suthep National Park, Huai Kaew at Nam Tok Sai Noi , 18°48'N 98°55'E, 1100 m, 22 Mar.2002, G. W. Courtney ( UMC); 1 male, Doi Suthep National Park , Huai Kaew above lower falls at Nam Tok Monthathan , 18°49'N 98°55'E, 750 m, 5 Mar.2002, Sites, Kirawanich, L-261 ( UMC) . Mae Hong Son Province: 1 male, 3 females, Namtok Maw Pang , 19°22'N 98°22'E, 850 m, 19 Mar.2002, UMC & CMU teams, L-305 (UMC). Phayao Prov.: 2 brachypterous males, 1 brachypterous female, Doi Nangka [= Doi Phu Lang Ka], N. Siam, 29 Apr.1931, H. M. Smith ( USNM) . LAOS, Xiang Khoang Prov. : 1 brachypterous male , Xieng Khouang, Ban Sai , 26 Nov.1917, R. V . de Salvaza ( BMNH) .

Additional material examined (not paratypes). – THAILAND, Chiang Mai Prov.: 2 immatures, Doi Inthanon National Park, Siriphum Waterfall , 18°32'N 98°31'E, 1,460 m, 9 May 2002, rock face, 21 Mar.2002, R. W. Sites, L-316 ( UMC) ; 1 immature, same locality, 2 Mar.2002, Penkhae, L-249 ( UMC) ; 2 immatures, Doi Inthanon National Park, Siriphum Waterfall at Ban Khun Klang , level 2, 1,380 m, 18°32’N 98°31'E; 2 Mar.2002, Vitheepradit, Kirawanich, L-251 ( UMC) ; 2 immatures, Doi Inthanon National Park, stream from Huai Sai Luang Waterfall , 18°31'N 98°27'E, 1,060 m, 3 Mar.2002, Vitheepradit & Kirawanich, L-254 ( UMC) ; 4 immatures, same locality, 20 Mar.2002, R. W. Sites, L-312 ( UMC) ; 1 immature, Doi Inthanon National Park, Nam Tok Vachiratharn , 18°31'N 98°27'E, 650 m, 3 Mar.2002, Vitheepradit & Kirawanich, L-256 ( UMC) ; 1 immature, Doi Suthep National Park., Sai Yoi Waterfall , 18°48'N 98°55'E, 1,100 m, 5 May 2002, gravel, CMU team, L-402 ( UMC) ; 1 immature, Doi Suthep National Park, Nam Tok Monthathan , 18°49'N 98°55'E, 700 m, 5 Mar.2002, Vitheepradit, Kirawanich, Sites, L-263 ( UMC) . Lampang Province: 1 immarture, Jae Sawn National Park, Nam Tok Jae Sawn ; 18°50'N 99°28'E, 650 m, 16 Mar.2002, CMU team, L-297 ( UMC) .

Figures

Figs. 7–11. Cheirochela species, male right paramere: 7, C. assamensis, holotype; 8, C. feana, paratype. 9. C. birmaniensis, holotype; 10, C. tonkina, paratype; 11, C. thailandana, paratype.

Fig.17. Distributions of Cheirochela species in Indochina:diamonds = C. tonkina; circles = C. thailandana; greyed symbols indicate localities where only immatures were collected.