Geron Meigen

Hall, Jack C. & Evenhuis, Neal L., 2003, Review of the subgenus Geron (Geron) Meigen in the Nearctic Region (Diptera: Bombyliidae: Toxophorinae), Zootaxa 181, pp. 1-72 : 5-12

publication ID

https://doi.org/10.5281/zenodo.156842

DOI

https://doi.org/10.5281/zenodo.6273492

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scientific name

Geron Meigen
status

 

Genus Geron Meigen View in CoL View at ENA

Geron Meigen, 1820: 223 View in CoL . Rondani 1856: 165. Coquillett 1910: 546. Cresson 1919: 183. Bezzi 1924: 112. Painter 1932: 139. Hesse 1938: 873. Cole & Schlinger 1969: 234. Hull 1973: 203. Bowden 1974: 87. Evenhuis 1979: 13. Scarbrough & Davidson 1985: 1240. Evenhuis 1991: 42. Evenhuis 1994: 332. Evenhuis & Greathead 1999: 36. Type species: Geron gibbosus Meigen 1820 View in CoL [= Bombylius gibbosus Olivier, 1789 View in CoL ], by subsequent designation of Duponchel in d’Orbigny, 1845: 206.

The proper name to apply to the type species has led to nomenclatural confusion. Three different species have been listed as types of the genus, viz., Geron gibbosus Meigen ( Rondani 1856; Painter & Painter 1965; Evenhuis 1989; Zaitzev 1989; Evenhuis 1994; Evenhuis & Greathead 1999), Bombylius gibbosus Oliver, 1789 ( Painter 1932; Hull 1973; Bowden 1974; Evenhuis 1979), and Bombylius hybridus Meigen, 1804 ( Bezzi 1924; Cole & Schlinger 1969). Meigen (1820) described Geron with two included species ( G. gibbosus Meigen and G. halteralis Meigen ) without designating a type species. Duponchel in d’Orbigny (1845: 206) designated Geron gibbosus Meigen as the type species. It is the first valid subsequent designation and was followed by Evenhuis (1989, 1991, 1994) and Evenhuis & Greathead (1999), but most workers subsequent to d’Orbigny missed this designation. The confusion over the correct type species by subsequent workers arises in the following way: Geron gibbosus of Meigen (1820) was an unjustified replacement of name for Bombylius hybridus Meigen, 1804 . Earlier, Olivier (1789) described Bombylius gibbosus , which has been shown to belong to Geron ( Painter 1932) . Several authors therefore concluded that gibbosus Olivier is the oldest available name and should constitute the type species. With the inclusion of gibbosus Olivier in Geron , Geron gibbosus Meigen became a junior homonym. Meigen’s type of gibbosus [= hybridus Meigen ] is located in the Museum National d’Histoire Naturelle, Paris, and has been examined by the junior author. Olivier’s type of gibbosus is apparently lost. The original descriptions of all of the above species are short, vague, and will fit any number of species. Greathead (1999) clarified the species limits of the taxa within the Geron gibbosus and Geron halteralis species complexes through genitalic studies of types and topotypic material. Through this study, it was concluded that many authors had misidentified Geron olivierii Macquart as Geron gibbosus (Olivier) (e.g., Hesse 1938, Zaitzev 1966).

Description. Head. Male eyes holoptic; female eyes dichoptic; front in male small, triangular, with shining white or silver­white scales, hair normally wanting; antenna black, scape cylindrical, one and one­half to three times the length of pedicel; pedicel about as wide as long; first flagellomere narrow, elongate, tapering from broadened base to acuminate apex; style minute, apical; proboscis narrow, elongate, extending beyond oral margin one and one­half to two times the head height; palpus short, one­segmented.

Thorax. Mesonotum convex giving a hump­backed appearance to the habitus in profile; scutellum without bristles. Legs thin, tibiae and tarsi with small setae; fore tibial bristles usually minute; females with or without specialized palynophilic setae on fore tarsi ( Fig. 29 View FIGURE 29. a ) ( Neff et al. 2003); legs with white hair and scales; pulvilli present, about as long as claws.

Abdomen. Tubular, tapering from base to narrowed apex; slightly broader in females, narrower in males; both sexes with eight visible segments.

Wing ( Figs. 27–28 View FIGURES 27 – 28 ). Hyaline to slightly infumate, with two submarginal and three posterior cells; anal cell closed at or slightly before wing margin; crossvein r­m at or beyond middle of cell dm; second submarginal cell short, about as long as apical width; crossvein m­cu sinuous ( Fig. 28 View FIGURES 27 – 28 ), occasionally straight ( Fig. 27 View FIGURES 27 – 28 ); anal lobe moderately developed.

Male genitalia ( Figs. 30–57 View FIGURES 30 ­ 33 View FIGURES 34 – 37 View FIGURES 38 – 41 View FIGURES 42 – 45 View FIGURES 46 – 49 View FIGURES 50 – 53 View FIGURES 54 – 57 ). Complicated in digitate or closed condition with gonocoxa in lateral view elongate, boat­shaped with a membranous “window” near apical third; gonostylus usually narrow, two to three times longer than high, with small hairs apically; four rami present; dorsolateral ramus (part of upper margin of gonocoxa), variously shaped but usually elongate with rounded apex; lateral ramus attached basally to dorsolateral ramus, shiny, thin, usually slightly curved, normally acuminate apically and coextensive with gonostylus; aedeagus [= distiphallus of Yeates (1994)] narrow, long, apically acuminate; passing through scale­like epiphallus of varying shapes; gonocoxa in ventral view either flat, with or without small projection, or with two broadly depressed areas separated by central ridge; genitalia in rosette or open condition with gonocoxa folded upward and inward; gonostylus bent upward and outward; lateral ramus bent up and out at nearly a right angle; dorsolateral ramus bent up and out; aedeagus moved posteriorly, projecting; anal lobes moved upward; aedeagal sheath separated and flattened, wing­like on either side of aedeagus; nearly every condition between the two extremes (digitate and rosette) is expressed.

Female genitalia ( Figs. 1–26 View FIGURES 1 – 6 View FIGURES 7 – 12 View FIGURES 13 – 18 View FIGURES 19 – 24 View FIGURES 25 – 26 ) without acanthophorites or sand chamber; vaginal furca consisting of two parts, upper part slightly curved, V­ or narrow U­shaped, membranous medially with an opening for common basal spermathecal duct; lower part variously shaped, usually more densely sclerotized; three spermathecae present, capsule not sclerotized, composed of coiled filaments or tubes; spermathecal duct long, thin, upper portion, above sperm pump with minute glands; sperm pump short, sclerotized collars (end plates) not evident; common basal spermathecal duct short.

Remarks on diagnostic characters. Cresson (1919) was the first to report on the variable flexible nature of the male genitalia in North American species; and Painter (1932) elaborated further on this phenomenon. The female genitalic structures have been studied and illustrated by a few authors (e.g., Scarbrough & Davidson 1985; Greathead 1999, 2001) and have proven to be more diagnostic in separating species of Geron for many regions of the globe than the male genitalia. The most comprehensive study of genitalia of Geron was that by Theodor (1983) on a few Palearctic, Afrotropical, and one Nearctic species. The Nearctic species belonging to Geron are probably among the most difficult of all the Bombyliidae to identify. The species are remarkably similar in appearance and the character states formerly used for separation, especially color, have proven to be almost totally unreliable. The body covering of hair and tomentum is loosely attached and, as a consequence, specimens are easily denuded. The sexes cannot be reliably associated unless taken in copulation, or secondarily, if collected together on flowers of the same species or together in swarms. We have relied heavily on label data in associating the sexes. Specific identification depends entirely on the configuration of the female vaginal furca and to some extent the male genitalia. The two forms of the male genitalia, digitate (closed) and rosette (open or expanded) presented difficulty in identification and comparing specimens. Nearly every position between the two types of genitalic configuration has been observed. Comparison of parts between the two types is difficult and often impossible without dissection because of the great amount of movement involved and the resulting cryptic condition of some of the parts. In reviewing the female vaginal furca care must be exercised when making comparisons, because of the curvature of the furca. The furca in all of the following descriptions and illustrations were viewed from the dorsal aspect. The furca also shows a good deal of variation in sclerotization and in the development of the basal lobes, this is most apparent in the more widespread species such as G. holosericeus Walker , G. senilis (Fabricius) , and G. rufipes Macquart.

At present we are unable to specifically place most of the males in which the genitalia is in the rosette condition, unless reliably associated with identified females. There remain in the collections studied many probable new species. We have refrained from naming and describing them because of either the poor condition of the male genitalia or the paucity of specimens.

Bezzi, M. (1924) The Bombyliidae of the Ethiopian Region. British Museum (Natural History), London, 390 pp.

Bowden, J. (1974) Studies in African Bombyliidae. VIII. On the Geroninae. Journal of the Entomological Society of Southern Africa, 37, 87 - 108.

Cole, F. R. & Schlinger, E. I. (1969) The flies of western North America. University of California Press, Berkeley, 693 pp.

Coquillett, D. W. (1910) The type species of the North American genera of Diptera. Proceedings of the United States National Museum, 37, 499 - 647.

Cresson, E. T. (1919) Dipterological notes and descriptions. Proceedings of the Academy of Natural Sciences, Philadelphia, 71, 171 - 194.

d'Orbigny, C. V. D. (1845) Dictionnaire universel d'histoire naturelle resumant et completant tous les faits presentes par les encyclopedies les anciens dictionnaires scientifiques les oeuvres completes de Buffon, et les meilleurs traites speciaux sur les diverses branches des sciences naturelles; donnant la description des etres et des divers phenomenes de la nature l'etymologie et la definition des noms scientifiques, les principales applications des corps organiques et inorganiques, a l'agriculture, a la medecine, aux arts industriels, etc.; dirige par M. Charles d'Orbigny, et enrichi d'un magnifique atlas de 288 planches gravees sur acier. Tome sixieme. [Livraison 65.] C. Renard, Paris.

Evenhuis, N. L. (1979) Studies in Pacific Bombyliidae (Diptera). II. Revision of the genus Geron of Australia and the Pacific. Pacific Insects, 21, 1 - 35.

Evenhuis, N. L. (1989) Family Bombyliidae. In: Evenhuis, N. L. (ed.), Catalog of the Diptera of the Australasian and Oceanian Regions. E. J. Brill, Leiden & Bishop Museum Press, Honolulu, pp. 359 - 374.

Evenhuis, N. L. (1991) World catalog of genus-group names of bee flies (Diptera: Bombyliidae). Bishop Museum Bulletin in Entomology, 5, 1 - 105.

Evenhuis, N. L. & Greathead, D. J. (1999) Catalog of the bee flies of the world (Diptera: Bombyliidae). Backhuys Publishers, Leiden, xlviii + 756 pp.

Hesse, A. J. (1938) A revision of the Bombyliidae (Diptera) of southern Africa. [I.] Annals of the South African Museum, 34, 1 - 1053.

Hull, F. M. (1973) Bee flies of the world. The genera of the family Bombyliidae. Bulletin of the United States National Museum, 286, 1 - 687.

Meigen, J. W. (1820) Systematische Beschreibung der bekannten europaischen zweiflugeligen Insekten. Zweiter Theil. F. W. Forstmann, Aachen, xxxvi + 363 pp.

Neff, J. L., Simpson, B. B., Evenhuis, N. L. & Dieringer, G. (2003) Character analysis of adaptations for tarsal pollen collection in the Bombyliidae (Insecta: Diptera): the benefits of putting your foot in your mouth. Zootaxa, 157, 1 - 14.

Olivier, G. A. (1789) Insectes [part], In: Encyclopedie methodique ou par ordre de matieres; par une societe de gens de lettres, de savans et d'artistes; precedee d'un Vocabulaire universel, servant de table pour tout l'ouvrage, ornee des portraits de MM. Diderot & d'Alembert, premiers editeurs de l'Encyclopedie. Histoire naturelle. Tome quatrieme. Panckoucke, Paris & Plomteux, Liege, pp. 45 - 331.

Painter, R. H. (1932) A monographic study of the genus Geron as it occurs in the United states (Diptera: Bombyliidae). Transactions of the American Entomological Society, 58, 139 - 167.

Painter, R. H. & Painter, E. M. (1965) Family Bombyliidae. In: Stone, A., Sabrosky, C. W, Wirth, W. W., Foote, R. H. & Coulson, J. R .. (eds.), A catalog of the Diptera of America north of Mexico. United States Department of Agriculture, Agriculture Handbook, 276, pp. 406 - 46.

Rondani, C. (1856) Dipterologiae Italicae prodromus. Vol: I. Genera Italica ordinis Dipterorum ordinatim disposita et distincta et in familias et stirpes aggregata. A. Stoschi, Parmae [= Parma], 226 + [2] pp.

Scarbrough, A. G. & D. A. Davidson (1985) Review of the Caribbean Geron Meigen (Diptera: Bombyliidae). Journal of the New York Entomological Society, 93 (4), 1240 - 1260.

Theodor, O. (1983) The genitalia of Bombyliidae (Diptera). Israel Academy of Sciences and Humanities, Jerusalem, vi + 275 pp.

Yeates, D. K. (1994) The cladistics and classification of the Bombyliidae (Diptera: Asiloidea). Bulletin of the American Museum of Natural History, 219, 1 - 191.

Zaitzev, V. F. (1966) [Parasitic flies of the family Bombyliidae (Diptera) in the fauna of Transcaucasia]. Nauka, Moscow & Leningrad, 375 pp. [In Russian.]

Zaitzev, V. F. (1989) Family Bombyliidae, pp. 43 - 169. In: A. Soos & L. Papp, eds., Catalogue of Palaearctic Diptera. Vol. 6. Therevidae-Empididae. Akademiai Kiado, Budapest, 435 pp.

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FIGURE 29. a, fore tarsi of bombyliid showing modified erect palynophilic setae used to collect pollen while feeding; b, detail of erect palynophilic setae.

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FIGURES 27 – 28. Geron wings. 27, G. nigripes Painter. 28, G. rufipes Macquart.

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FIGURES 30 ­ 33. Geron male genitalia. 30, G. albipennis Painter; a, lateral view; b, tip of gonocoxa, ventral view. 31, G. albipilosus Hall & Evenhuis, sp. nov.; a, lateral view; b, ventral view. 32, G. arenicola Painter; a, lateral view; b, tip of gonocoxa, ventral view. 33, G. argutus Painter; a, lateral view; b, ventral view.

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FIGURES 34 – 37. Geron male genitalia. 34, G. borealis Hall & Evenhuis, sp. nov.; a, lateral view; b, tip of gonocoxa, ventral view. 35, G. confusus Hall & Evenhuis, sp. nov.; a, lateral view; b, tip of gonocoxa, ventral view. 36, G. cressoni Hall & Evenhuis, sp. nov.; a, lateral view; b, tip of gonocoxa, ventral view. 37, G. elachys Hall & Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, ventral view.

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FIGURES 38 – 41. Geron male genitalia. 38, G. eriogonae Hall & Evenhuis, sp. nov.; a, lateral view; b, tip of gonocoxa, ventral view. 39, G. halli Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, ventral view. 40, G. holosericeus Walker; a, lateral view; b, tip of gonocoxa, ventral view. 41, G. infrequens Hall & Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, dorsal view, epiphallus and phallic complex removed.

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FIGURES 42 – 45. Geron male genitalia. 42, G. johnsoni Painter; a, lateral view; b, tip of gonocoxa, ventral view. 43, G. monticola Hall & Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, dorsal view. 44, G. nevadensis Hall & Evenhuis, sp. nov.; a, lateral view; b, tip of gonocoxa, dorsal view. 45, G. nigripes Painter; a, lateral view; b, gonocoxa, ventral view.

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FIGURES 46 – 49. Geron male genitalia. 46, G. niveus Painter; a, lateral view; b, tip of gonocoxa, dorsal view, epiphallus removed. 47, G. notios Hall & Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, dorsal view. 48, G. painteri Hall & Evenhuis, sp. nov.; a, lateral view; b, tip of gonocoxa, ventral view. 49, G. parvidus Painter; a, lateral view; b, gonocoxa, dorsal view, epiphallus and phallic complex removed.

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FIGURES 50 – 53. Geron male genitalia. 50, G. peucon Hall & Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, ventral view. 51, G. prosopidis Hall & Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, ventral view. 52, G. rufipes Macquart; a, lateral view; b, tip of gonocoxa, dorsal view. 53, G. senilis (Fabricius); a, lateral view; b, gonocoxa, dorsal view, phallic complex removed.

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FIGURES 54 – 57. Geron male genitalia. 53, G. stenos Hall & Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, ventral view. 55, G. subauratus Loew; a, lateral view; b, gonocoxa, ventral view. 56, G. vitripennis Loew; a, lateral view; b, tip of gonocoxa, ventral view. 57, G. weemsi Hall & Evenhuis, sp. nov.; a, lateral view; b, gonocoxa, ventral view.

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FIGURES 1 – 6. Geron vaginal furcae. 1, G. albidipennis Loew. 2, G. albipilosus Hall & Evenhuis, sp. nov. 3, G. arenicola Painter. 4, G. argutus Painter. 5, G. borealis Hall & Evenhuis, sp. nov. 6, G. confusus Hall & Evenhuis, sp. nov.

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FIGURES 7 – 12. Geron vaginal furcae. 7, G. cressoni Hall & Evenhuis, sp. nov. 8, G. elachys Hall & Evenhuis, sp. nov. 9, G. eriogonae Hall & Evenhuis, sp. nov. 10, G. halli Evenhuis, sp. nov. 11, G. holosericeus Walker. 12, G. infrequens Hall & Evenhuis, sp. nov.

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FIGURES 13 – 18. Geron vaginal furcae. 13, G. monticola Hall & Evenhuis, sp. nov. 14, G. nevadensis Hall & Evenhuis, sp. nov. 15, G. nigripes Painter. 16, G. notios Hall & Evenhuis, sp. nov. 17, G. painteri Hall Evenhuis, sp. nov. 18, G. parvidus Painter.

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FIGURES 19 – 24. Geron vaginal furcae. 19, G. peucon Hall & Evenhuis, sp. nov. 20, G. prosopidis Hall & Evenhuis, sp. nov. 21, G. rufipes Macquart. 22, G. senilis (Fabricius. 23, G. stenos Hall & Evenhuis, sp. nov. 24, G. subauratus Loew.

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FIGURES 25 – 26. Geron vaginal furcae. 25, G. vitripennis Loew. 26, G. weemsi Hall & Evenhuis, sp. nov.

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Diptera

Family

Bombyliidae

SubFamily

Toxophorinae