Brachystethus Laporte, 1832

Barcellos, Aline & Grazia, Jocélia, 2003, Revision Of Brachystethus (Heteroptera, Pentatomidae, Edessinae), Iheringia, Série Zoologia 93 (4), pp. 413-446 : 414-416

Brachystethus Laporte, 1832

Edessa (Brachystethus) LAPORTE, 1832:63; BURMEISTER, 1835:356.

Brachystethus ; SPINOLA, 1837:343; AMYOT & SERVILLE, 1843:160; HERRICH- SCHÄFFER, 1845:1; 1853:310; DALLAS, 1851:336; SIGNORET, 1851:344; STÅL, 1867:532 (key); 1872:48; WALKER, 1868:454; DISTANT, 1880:84; BERG, 1892:11; LETHIERRY & SEVERIN, 1893:187 (cat.); BERGROTH, 1908:178; KIRKALDY, 1909:152 (cat.); PIRÁN, 1955:337; ROLSTON et al., 1980:122 (key); FROESCHNER, 1981:69 (cat.); BRAILOVSKY, 1988:129 (diagnosis, distr.); RIDER, 1991:584 (key).

Daimonocoris KORMILEV, 1951:37; PIRÁN, 1955:337 (syn.).

Type species of Brachystethus , Cimex geniculatus Fabricius, 1787 , by monotypy; of Daimonocoris , D. bolivianus Kormilev, 1951 .

Diagnosis. Medium-sized, broad oval species (fig. 1), predominantly dull, but some species brightly colored ( figs. 2-13). Head small, short, jugae contiguous before tylus; first antennal segment surpassing apexof head. Rostrum short, notsurpassing mesocoxae. Metasternum elevated in an anteriorly partially bifurcated and posteriorly bifurcated carina, extended over part of mesosternum. Abdomen with medial tubercle apposed to the posterior margin of metasternal carina.

Description. Mediumsize (totallengthinmm,, 13-20.2,, 14.9-22.4). Broadoval shape. Head about one and a half wider than long, with transversal wrinkles on jugae and tylus, and small sinuated wrinkles between oceli. Punctures concentrated in 1+1 narrow, semi-circular and divergent stripesthat arise from base of oceli, directedforward until base of jugae, and in a medianarea between oceli, variable in length. Jugae rounded at apex and contiguous before tylus. Eyes large and prominent. Antennae with each segment progressively longer than the preceding. First antennal segment clearly surpassing apex of head. Bucculae elevated, anteriorly truncated, evanescent posteriorly. First rostral segment clearly surpassing them, by more than half of segment length. Rostrum not surpassing mesocoxae. Pronotum trapezoidal, strongly declivent onanterior half. Anterior margin slightly concave, openly U-shaped. Anterolateral angles prominent, forming a small tooth. Anterolateral margins slightly sinuous, subretilineous. Humeri rounded, little projected. Posterolateral and posterior margins straight. Punctures fine, more concentrated before cicatrices and regularly distributed over remaining disc of pronotum; among them, coarse punctures less frequent and irregularly distributed. Scutellum with broad and rounded apex, surpassing an imaginary line across middle of fifth connexival segment. Corium with punctures fine, dense and regularly distributed. Frenum slightly surpassing apical half of scutellum. Posterolateral angles rounded, attaining about the middle of sixth tergite. Membrane with more than five longitudinal and bifurcated veins. Tibiae dorsally sulcated. Ventral surface of thorax more densely punctured on propleura, mesoepisternum and metaepimerum. Evaporatory surface covering mesoepimerum and metaepisternum. Ostiolar rugae variable in length. Prosternum flat. Mesosternum slightly carinated. Metasternum carinated, producedover mesosternum. Anterior margin of metasternal carina with a deep median depression, partially bifurcated; posterior margin bifurcated, apposed to medial abdominal tubercle. Third urosternite with astout medial tubercle. Posterolateral anglesof connexivum slightly prominent. Spiracles elliptical. Trichobothria over or laterad to spiracularline.

Male genitalia. Pygophore ovoid to sub-quadrangular, shallowly open dorsally. Dorsal rim (dor) medially concave, forming or not 1+1 lateral lobes (ldor) variable in size and shape among the species. Tenthsegment (X) trapezoidal, wider basaly than apically. Parameres (pa) uniramous. Genital cup with dorsally visible, blade-like processes (gcp). Posterolateral angles of pygophore rounded and tumid. Phallus: basal plate (bp) wide; phallotheca (ph) tubular, elongated, curved dorsad and strongly esclerotized; vesica (v) short, about 1/5 of lengthof phallotheca, with 1+1 dorsal, hook-like processes, convergent at apex, and only one ventral membranous lobe; ductus seminis distalis (dsd) short, notsurpassing apex of vesica; conjunctiva absent.

Female genitalia. Laterotergites 8 and 9 (la8, la9) without apical spine. Spiracles on laterotergites 8 present. Laterotergites 9 not surpassing transverse band uniting laterotergites 8. Gonocoxites 9 (gc9) broad, trapezoidal, anterolateral angles extended in arms variable in length and thickness; anterior margin medially concave. Gonapophyses 9 (g9) with a medial thickening (mt). Thickening of vaginal intima (tvi) with a ventral, beak-like projection, visible in profile, bearing the orificium receptaculi (or). Chitinellipsen (ch) present. Ductus receptaculi (dr) thin anteriorly to vesicular area, and variable after that. Capsula seminalis (cs) with three digitiform processes, directed toward annular crests (aac, pac).

Distribution. Mexico, Centraland South America.

Comments. Brachystethus can be easily distinguished from other edessines by the broad, oval outline and the metasternal carina partially bifurcated. These characters, combined with the presence of blade-like processes on genital cup and of a medial thickening on gonapophyses 9, are diagnostic for the genus. The exam of the holotype of Ochlerus discolor , transferred to Brachystethus by KIRKALDY (1909), allowed to conclude that B. discolor should be removed from Brachystethus , since it presents morphological characters different from the remaining species of the genus, as the body outline, narrowly ovate, the first rostral segment concealed by bucculae and laterotergites 9 with acute apex, surpassing band joining laterotergites 8 dorsally. As the holotype presents one of the gonocoxites 8 deformed, and the metasternum can not be clearly observed because it is crossed by the pin, the species is here considered as incertae sedis.