Cheirochela tonkina, 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 : 263-265

Cheirochela tonkina new species

( Figs. 2 , 10 , 14, 17)

Description. – Brachypterous male: Of moderate size for genus, general body form rotund, widest across abdomen

Brachypterous male: Similar in general structure and colouration to macropterous male, but with pronotum narrower and scutellum not so tumid. Body length 23.60, maximum width (across embolia) 13.00; pronotum length (midline) 9.60, width 2.80; scutellum length 6.00, width 4.00. Hemelytra brachypterous, venation obscure, corium shallowly and finely rugose, membrane rudiments strongly narrowed posteriorly, tips rounded, reaching beyond posterior margin of sixth visible abdominal tergite.

Discussion. – The two specimens collected by Fea in Burma and now in the Genoa Museum represent co-types of this species. The brachypterous specimen has the following labels (from top to bottom, commas indicate line breaks, slashes indicate separate labels; comments are in parentheses): “Catcin Cauri, Birmania, Fea. Ag November 1886 (black, printed)/TYPUS (red, printed)/ birmaniensis Mont. (script in Mondandon’s hand)/ Cheirochela , birmaniensis, Montand. , type brachypt. (script in Gestro’s hand).” The same data for the macropterous specimen reads “Catcin Cauri, Birmania, Fea. Ag November 1886 (black, printed)/TYPUS (red, printed)/ Cheirochela , birmaniensis Mont. , es. tip. (script in Mondandon’s hand)/ Cheirochela , birmaniensis, Montand. , type macropt. (script in Gestro’s hand).” Both specimens are in excellent condition, and the macropterous specimen is herein designated as the lectotype, based on the “es tip” ( Fig. 2 ), basic colouration brown, hemelytra dark brown, wing membrane dark brown. Male length 24.00 mm; maximum width (across abdomen) 12.50 mm; female length 25.00 mm, maximum width 14.00 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 bewteen eyes; posterior margin broadly dark, width across eyes/length = 5.44/4.41; eyes black, shining, quadrate posteriorly, tapering anteriorly, width/length = 1.18/2.06, inner margins evenly curved and slightly divergent anteriorly, lateral margins almost straight on anterior third, separated from vertex by shallow furrows, anterior/posterior interocular width = 3.82/3.38, lateral flange weakly developed; posterior margin of vertex rounded, stongly produced behind eyes; anteclypeus with anterior margin broadly rounded, stongly projecting ahead of eyes for 0.88X the length of an eye, projecting beyond rostrum about the length of exposed rostrum; rostral cavity deep, hiding half of segment two 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) = 10.44/3.31, lateral margins narrowly explanate, medially granular, concave, anterolateral angles sharply angular, extending forward along eye 1/5 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) = 6.32/3.82, 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, 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 much less pronounced projection, weakly developed.

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 well developed basal lobe, distal arm possessing only a weak subapical notch ( Fig. 10 ); male phallotheca with tip expanded, lyre-shaped; dorsomedial process of male genital capsule in the form of an elongate triangle, apex rounded, bearing a small, bilobed process (Fig. 14). Female subgenital plate triangular, slightly convex basally, lateral margins straight, apex narrow.

Macropterous form: Similar to brachypterous form in general structure and colouration, but lighter, dorsal colouration ranging from yellowish to brown; corium and clavus clearly delineated by a suture; wings fully developed, extending almost to tip of abdomen, membrane well defined in relation to corium, lacking venation; male length 23.00 mm, maximum width 12.70 mm; female length 23.50 mm, maximum width 12.40 mm.

Discussion. – This species is similar in size and general body form to C. birmaniensis , but may be separated by the absence of well developed posteromedial tubercles on the abdominal venter, and the much more prolonged preocular head. 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, while in C. tonkina the pre-ocular head is more greatly prolonged, so that this ratio is more nearly equal, being only 1.25/1.0 or less ( Fig. 2 ). The two species may also be easily separated by the form of the male paramere, which in C. tonkina bears a prominent basal lobe set off from the distal arm by a deep notch (compare Figs. 9, 10 ) and the differently shaped dorsomedial process of the male genital capsule (compare Figs. 13, 14).

Ecological notes. – Cheirochela tonkina appears to be endemic to the Annamite Mountain chain of Vietnam and associated outlying ranges ( Fig. 17 ). The type locality was a wide, swift, clear mountain river near Sapa, flowing in a bed of mixed alluvial boulders, rocks, gravel and sand. The bed profile was steep, with rapids and small cascades predominating. Immatures of Cheirochela tonkina were common here in the benthos, while adults were more localized, being found only in areas of high current velocity and saturated oxygen, particularly along the sides of large boulders swept by the main current.

Types. – Holotype, brachypterous male, VIETNAM, Lào Cai Prov., rocky river and small trib., 16 km NE of Sa Pa on Lào Cai road, 855 m, 22°24'52"N 103°53'51"E, water temp. 19°C., 7 Apr.2000, CL 4397, D. A. Polhemus, J. T. Polhemus and P. Nguyen ( USNM) . Paratypes: VIETNAM: Lào Cai Prov.: 7 brachypterous females, same data as holotype ( USNM) ; 1 macropterous male, 1 macropterous female, 1 brachypterous male, 1 brachypterous female, trib. of Muong Hoa Ho River , 15 km E. of Sapa, cobbles and boulders, 926 m, 7 May 1995, D. Currie, B. Hubley and J. Swann, ROM 956017 ( JTPC) ; 1 brachypterous male, Tonkin, Chapa [= Sapa], May 1916, R. V. de Salvaza ( CAS) ; 1 macropterous male, 1 macropterous female, reg. de Chapa [= Sapa ], 1,650 m, 1926, Poilane ( MHNP) . Vinh Phu Prov. : 1 brachypterous male, 1 immature (not paratype), Tam Dao, Sûoì Bac stream, 12 Oct.1984, T. Soldán ( JTPC) ; 1 brachypterous male, 3 immatures (not paratypes), Tam Dao , Sûoì Bac stream, 20–26 Oct.1984, M. Tonner ( JTPC) ; 1 brachypterous female, Tam Dao hill station, lower waterfall of stream flowing through town, 11 May 1996, B. Hubley and D. C. Darling, ROM 961029 ( JTPC) . Hòa Bình Prov.: 1 brachypterous female, Tonkin, reg. de Hoa Binh, 1927, A. de Cooman ( MHNP) . Hà Giang Prov.: 1 brachypterous female, Tonkin, region de Ha Giang, 1916, S. Olivier ( MHNP) . LAOS, Houaphan Prov.: 1 brachypterous male, 1 brachypterous female, 3 immatures (not paratypes), Ban Saleui , 1,350 m, Xamneua [Xam Nua], 21–24 Jun.2003, M. Sato ( JTPC) .

Additional material examined (not paratypes). – Immatures presumably belonging to this species were taken at the following localities: VIETNAM, Nghê An Prov.: 6 immatures, Choang River, nr. edge of Pu Mat Nature Reserve , 165 m, water temp. 78° F. (26°C), 2 Apr.2000, CL 4387, J. T . Polhemus and P. Nguyen ( USNM). Lai Châu Prov.: 2 immatures, cascading stream 12 km N. of Lai Châu , 290 m, 22°07’19”N 103°11’30”E, water temp. 22° C, 11 Apr.2000, 1345–1600 hrs., CL 4410, D. A. Polhemus, J. T . Polhemus & P. Nguyen ( USNM) .

Figures

Fig. 2. Cheirochela tonkina Polhemus & Polhemus. Male, dorsal habitus. Drawn by Young Sohn.

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.