CHEIROCHELINI, Montandon, 1897

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 : 257

CHEIROCHELINI La Rivers 1971

Diagnosis. – Large, robust naucorids, body shape elongate ovate to nearly round ( Figs. 1 , 2 , 18 ), strongly dorsoventrally flattened. Vertex strongly produced posteriorly behind the eyes. Antennae stout, segments I–III subequal in length with their widths roughtly equivalent to their lengths ( Fig. 4 ), segment VI slightly more elongate; antennae set into elongate, concave sockets on undersides of eyes. Labrum highly reduced, barely visible at base of rostrum. Rostrum and labrum recessed into a deep cavity on underside of head; maxillarly plates adjacent to this cavity lying in a horizontal orientation; anterior section of head strongly produced ahead of the eyes and rostral cavity, forming a marked anteclypeal projection formed by posteroventral folding of the preclypeal cephalic tergum. Legs with fore tarsi and claws fused to form a single segment; fore and hind tibiae bearing pads of short, dense setae ventrally at their apices. Abdominal sternites and paratergites fused to form single transverse plates on segments IV-VI, lateral sections of these plates adjacent to spiracles bearing groups of small, ovate, glabrous depressions amid the hydrofuge pile. Parameres symmetrical. Phallotheca symmetrical, with central portion sclerotized, apex lyre-shaped ( Fig. 29 ).

Discussion. – Members of the Cheirochilini display some of the most elegant adaptations to life in swiftly running waters seen anywhere in the insect world, including highly streamlined bodies enhanced by extreme dorsoventral flattening; posteroventral folding of the preclypeal head to form an acute prow; retraction of the labrum, rostrum and antennae into deep cavities on the underside of the head; and fusion of certain abdominal sternites and paratergites to create a smooth ventral surface. Additional apomorphic cheirocheline adaptations to life in fast water include development of large pads of bristle-like setae at the apices of the middle and hind tibiae to provide enhanced grip in strong currents, and the presence of apparent hydrostatic pressure receptors laterally on the paratergites ( Polhemus, 1986, Fig. 7 ). Although plastron respiration has not been conclusively demonstrated in the Cheirochelinae , it is very likely to occur, given the preponderance of brachypterous morphs, the presence of putative hydrostatic receptors, and preference for swift water habitats (for additional discussion see Polhemus, 1986).

Figures

Fig. 1. Coptocatus kinabalu Polhemus. Male, dorsal habitus. Drawn by Young Sohn.

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

Fig. 18. Gestroiella siamensis new species, female, dorsal habitus. Drawn by Young Sohn.

Figs. 3–6. Cheirochela assamensis Hope, holotype male, structural details: 3, Dorsal habitus; 4, Left antenna, dorsal view; 5, Terminal abdomen, ventral view; 6, Medial processes on abdominal ventrites IV and V, lateral view.

Figs. 26–30. Gestroiella species, male genitalia, structural details: 26, G. insignis, paramere; 27, G. limnocoroides, paramere; 28, G. siamensis, paramere; 29, G. limnocoroides, phallotheca; 30, G. siamensis, dorsomedial process of genital capsule.

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.