Gallobelicus tenuis (Reuter)

Usinger, Robert L., 1946, Hemiptera Heteroptera of Guam, Insects of Guam II, Honolulu, Hawaii: Bernice P. Bishop Museum, Bulletin 189, pp. 11-103 : 73-75

69. Gallobelicus tenuis (Reuter) ( fig. 18 , a, b).

Cyrtopeltis tenuis Reuter , Rev. d'Ent. 14: 139, 1895.

One specimen, Piti, May 1; 10 specimens, Piti, May 10, all on tomato, Usinger; one specimen, Agana Swamp, May 4, Usinger; two specimens, Talofofo, Nov. 18, Swezey; one specimen, Guam, Fullaway (1196); TODO 16 specimens, Machanao, June 30, on Nicotiana, Usinger ; one specimen, Fonte Valley , Aug. 7, on weeds, Swezey. Swezey and Zimmerman took specimens of tenuis in Samoa.

Few species of insects are in a more confused state both taxonomically and nomenclatorially than the dicyphine pests of tobacco and tomato. Their small size and superficial similarity have contributed to this but do not excuse the situation, for the male terminalia exhibit striking differences which are specifically distinct and point the way to a sound generic classification. The literature on the subject was summarized by China (Ann. Mag. Nat. Hist. XI, 1: 604- 607, 1938) although Kirkaldy's description of Cyrtopeltis (?) nicotianae (Linn. Soc. N. S. Wales, Proc. 33: 377, 1908), Froggatt's description of Dicyphus tabaci (Agric. Gaz. N. S. Wales 31: 715, 1920), and Knight's discussion of the genus Cyrtopeltis (Brooklyn Ent. Soc., Bull. 17:65-67, 1922) were omitted.

China concluded that nicotianae Koningsberger , crassicornis Distant , javanus Poppius, and nocivus Fulmek were all synonyms of tenuis Reuter , stating that Fulmek's figures of the left genital claspers of different species (Deli Proefstation, Bull. 25: 4, 1925) were not of the same organ but of different parts of the same insect. To quote China further, "Judging by the shape of the Haftzange in nicotianae it appears to be a broken portion of the inferior lateral margin of the pygophor (ninth abdominal segment) viewed from the left side of the pygophor but with the drawing actually reversed."

In the case of nocivus he figured the actual paramere, calling it again the "Zinke Haftzange." Careful comparison of Fulmek's figures with the two species which I found on tobacco on Guam reveals that Fulmek was correct, his drawings actually being of homologous structures of two distinct species. The left clasper of nicotianae is truly an amazing structure and corresponds, except for minor details in structure of the apex of the broad lobe, with my Guam specimens. The last abdominal segment also differs strikingly in the two species, nicotianae having a bifurcate posterior process suggestive of the American tobacco bug, Engytatus geniculatus Reuter ( fig. 19 , a, b), whereas tenuis (= nocivus Fulmek) has a simple main posterior process (see China's excellent figure of a cotype).

The generic classification of the Dicyphinae has long been confused so that Reuter, Poppius, and Horvath as well as other, lesser, authorities changed species from one genus to another with no apparent reason, only to change them back again. Knight has lumped many of these into the genus Cyrtopeltis , a practice which is at least consistent though making it almost impossible to use his keys to the genera. In this work I have concluded that the male terminalia provide us with the only sound basis for a generic classification of the Dicyphinae . Reluctance to base a higher classification upon characters of one sex is understandable but this practice has been found necessary in other groups (scale insects and Lepidoptera) and seems justifiable in the Dicyphinae considering the hopeless confusion that has resulted from attempts to classify these bugs on the basis of such superficialities as size of eyes or color of head and pronotum.

The following characters will suffice to distinguish the questionable Dicyphine genera in so far as my material is concerned. Modifications will undoubtedly be necessary when further material is examined. I have not seen the types of Dicyphus and Macrolophus .

Dicyphus Fieber (type pallidus Herrich Schaeffer ). Left genital clasper thickened at base, bent at middle, and tapering to acute apex. Last abdominal segment not produced into long spines, knobs, or processes. Pronotum more or less constricted at middle and eyes relatively large.

Macrolophus Fieber (type nubilus Fieber). Left genital clasper thickened at base, bent near middle, and flattened into a broad but apically tapering blade. Last abdominal segment not produced into long spines, knobs or processes. Eyes relatively small.

Cyrtopeltis Fieber (type geniculata Fieber). Left genital clasper as in Macrolophus . Last abdominal segment roundly produced as a short, broad, upturned lobe posteriorly and with a prominent rounded knob on the left side of the segment. Eyes relatively large. This is apparently monotypic.

Engytatus Reuter (type geniculatus Reuter ). Left genital clasper as in Macrolophus or with the thickened basal portion much enlarged and extending beyond the point of origin of the bladelike arm (as in nicotianae ). Last abdominal segment more or less strongly produced ventrally into an upturned process which branches into two arms apically. Eyes variable in size. Confusa Perkins and hawaiiensis Kirkaldy belong here. Geniculatus Reuter was a secondary homonym in Cyrtopeltis , where Reuter and Knight placed it. Hepce the name of the next oldest synonym, varians Distant, was used. According to the Banks and Caudell Code and the recommendations of the British Commission on Entomological Nomenclature, the name geniculatus may now be restored but the International Code is not so clear on this point.

Gallobelieus Distant (type crassicornis Distant = tenuis Reuter ). Left genital clasper abruptly elbowed and typically with the apical arm very long and tapering. Last abdominal segment produced ventrally into a more or less prominent, unbranched arm and with a second projection near base of clasper at least in the type species. I have collected another species of this genus on Luzon, and Knight's Marquesan species (B. P. Bishop Mus., Bull. 142: 173- 177, 1938) may belong here.

Figures

FIGURE 18.-Gallobelicus timuis: a, posterior ventral view of last abdominal segment of male showing long truncate projection and shorter tapering projection; b, posterior ventral view of left clasper of male showing short basal portion, abrupt elbow and long slender bladelike portion.

FIGURE 19.-Engytatiis geniculatiis: a, posterior ventral view of last abdominal segment of male showing two curved arms; b, posterior dorsal view of left clasper of male showing stout basal portion, abrupt elbow and bladelike apical portion.